Date   

Re: Source for premade BNC patch cables or DIY

Mark Wendt <mark.wendt@...>
 

On 09/10/2013 02:36 PM, Stefan Trethan wrote:


For what it's worth, I use mostly cheap ($30) crimpers.
Yes there is a quality difference, but I can't justify $400 pliers.
I always inspect and test the crimps, to make sure quality is satisfactory.
There are many booklets and wallcharts that will tell you the basics of crimp connection inspection so you will know what to look for.

Apart from durability (harder material) the main difference between the cheap and expensive crimpers is die geometry and crimping force consistency. You need to make sure the die geometry is right, and sometimes adjust crimping force. You can most likely forget durability for personal use.

I have found some used high quality crimping pliers for the most used connectors on Ebay, but the others are cheap ones.

For BNC connectors you mostly need the hexagonal crimp of the shield. The pin is sometimes crimped, but I prefer to solder them. The hexagonal crimp is not all that challenging, it will be just fine with the correct size die.

So yes, the pro tools would be nice, but I really can't justify them for all connectors.

ST
Ebay is your friend for the dies. I've picked up a few here and there. Hamfests are another good source for quality used parts like this. I picked up a nice Phoenix crimper at a hamfest for $20 and outfitted it with dies from Ebay and other hamfests. Total cost so far is less than $100.

Mark


TDS460 acq fail

tmoranwms <tmoranwms@...>
 

Turned on my TDS460 the other day and got an "acq fail" on the POST.

Following the service manual procedure, the "Select All" test finds the same fault. Unfortunately, the service manual does not make any use whatsoever of the actual self-test results, which I find rather bizarre...

Anyway, the error log contains: "ERROR: diagnostic test failure / trigComparatorTest, TRIGA status after trigger: exp = 1, act". Ideas?

General advice, of course: reseat boards and connectors, inspect for bad caps, etc... Before I take open it up I thought I'd fish for ideas.

Thanks,

Tim


Re: 2465A +5vd Power Supply Problem

 

Hi Machine Guy


Here is the voltage test as requested


Load on +5d and all other regulated outputs

P232-5  -12.7v

P233-5  89.2v

P233-3  45.7v

P234-5  17.65v

P234-4  6.5v

P234-2  -6.8v

P234-1  -17.7v


Load on +5d only NO load on regulated outputs

P232-5  -13.1v

P233-5  95v

P233-3  47.75v

P234-5  18.85v

P234-4  7.13v

P234-2  -7.01v

P234-1  -19.1v


I can upload the traces of the regulated outputs. Should I do the test with loads or no loads?


HOWEVER ...I Think you may be on to something with the 27k test to Pin 4


With +5v loaded voltage is 5.58v. With resistor 27K to junction of R1044/R1045 and quickly touched to Pin 4 the voltage jumps to +5.85v !!  





--- In TekScopes@..., <tekscopes@...> wrote:

Well, we are learning things.  These tests bolster the theory that the optocoupler is failing.  Here is my interpretation.
 
1.  The 4.7 K in parallel with R1270 made no difference.  That implies either the call for voltage is not passing to the inverter or the inverter is already running at maximum capacity.
2.  The 27 K in parallel with R1044 made no difference.  That implies either U1040 is not conducting or the inverter is not able to produce more voltage.
3.  The voltage at T1060 Pin 7 is less than 120 volts so there should be more capacity in the inverter.
4.  The resistance measurements at C1110 indicate that CR1110 is not shorted and the filter capacitors do not have a solder ball shorting them.
5.  The scope trace at C1110 shows a balanced rectification by CR1110 and a reasonable amount of ripple (note, this ripple and noise should be smoothed away by L1110 and C1111 before it becomes +5Vd).
 
Most likely, the optocoupler has failed or is failing.  Some other things to measure:
1.  The voltage between pins 5 and 4 of U1040.  Zero volts here will tell us U1040 is calling for more voltage and something else is keeping the inverter from achieving it.
2.  Scope traces and DC values referenced to chassis (for convenience P232 pin 3 or 4) of all other unregulated voltages (ie. P232 pin 5, P233 pin 5, P233 pin 3, P234 pin 5, P234 pin 4,  P234 pin 2, and P234 pin 1).  This will let us see if all unregulated voltages are low by the same rough percentage.  If one is drastically lower than we have found a short or open that could be complicating our search. 
 
If this further confirms the optocoupler failure I suggest we try faking it.  (I would like anyone else to weigh in here if they see something wrong with this idea.)  This test will take a bit of care but should be simple to do.  I want to try "touching" a 27 k resistor in parallel with R1045 this time.  By this I mean to use a clip lead to connect one end of a 27 K resistor to the junction of R1044 and R1045, start the supply and monitor the +5 Vd with a voltmenter.  Then use the resistor as if it were a probe to touch pin 4 of U1040.  The +5 Vd should rise when the resistor is touched to U1040.  I don't want to put the resistor in place permanently because it may be demanding too much increase.  We just want to see if the inverter has more capacity when we use the resistor to call for it.  Take care, we already know this part of the circuit is running at 113 volts and above.  But if the voltage rises we know the inverter has more capacity but the optocoupler is unable to call for the proper voltage.  If the voltage does not rise, we know the inverter is unable to produce more voltage even if the optocoupler does call for it.   

From: "bpl521@..." <bpl521@...>
To: TekScopes@...
Sent: Tuesday, September 10, 2013 9:03 PM
Subject: RE: Re: [TekScopes] RE: RE: 2465A +5vd Power Supply Problem
 
All

4.7Kohm resistor in parallel with  R1270 no difference in +5d output Still low at 4.55v either way

27kohm resistor in parallel with R1044 no difference either in +5d voltage

Voltage at Pin 7 of T1060 and Ref 2 is 113 volts


Resistance from chassis ground to junction of L1110 and C1110 is 145 ohms (no load on +5d). Reversing the multimeter and it starts at over 140 Mohm and slowly draws down.

Link below is a photo of the ripple output at the junction of L1110 and C1110 with a load on +5d. Looks like the inverter puts out a a fair bit of noise

 







 
--- In TekScopes@..., <tekscopes@...> wrote:
David,
Shouldn't it be possible to test this by bridging R1044 with a 27 K resistor?  If the +5 Vd supply voltage increases we know its the optocoupler.

From: David <davidwhess@...>
To: TekScopes@...
Sent: Tuesday, September 10, 2013 4:28 AM
Subject: Re: [TekScopes] RE: RE: 2465A +5vd Power Supply Problem
 
1.07 volts indicates that either the optocoupler is bad do to low or no output, R1044 is open, or that there is an open circuit in series with R1044 and the optocoupler output. I was wrong earlier about the possibility of C1048 being shorted. All of my service manuals so SOC123A which I suspect is a Tektronix house number. My Tektronix parts catalog shows Motorola MOC1005 which is a very close match to the Toshiba TLP631. Current transfer ratio is the ratio of output to input current which is sort of like gain. 50% means that for every 1mA of input, the output will be 0.5mA. The optocouplers are graded by CTR which is why there is an F and GBF version. The CTR should not be critical in this circuit so either of the ones you mention should work fine. If you want another test to confirm where the problem is, then the voltage between pin 7 of T1060 and REF1 with an inverter load should be about 120 volts DC which indicates that the optocoupler output is missing and the pre-regulator is set for the minimum output voltage as determined by R1045 and R1046. Another thing you could try is halving the value of R1270 on the low voltage regulator board near U1371C by temporarily placing a 3.9 or 4.7 kOhm resistor in parallel with it. That will double the current into the optocoupler so if its CTR has degraded with age, the higher current will allow it to work for now.
On 10 Sep 2013 00:10:39 -0700, you wrote:

>David:
>
>The voltage at Pin 1 to chassis ground was 1.07v (+5d is 4.5v)
>
>The service manual references U1040 as a TLP631 this is a Toshiba product and is still available from DigiKey There is two variants of this chip the
>
>TLP631-FND and the TLP631-GBF-ND. The F-ND has a current transfer ratio of 50%@5ma and the GBF-ND has a current transfer ratio of 100%@5ma. Whatever that all means?
>
>Machine Guy:
>
>I could not get any accurate measurements with all 3 comb connectors removed I had to leave P232 connected For what it is worth here is the measurements
>
>233B
>
>1 2v
>
>2 32v
>
>3 70v
>
>4 14v ?? this should be GND
>
>5 122v
>
>234B
>
>1 -8v
>
>2 0
>
>3 16v
>
>4 0v
>
>5 37v
>
>--- In TekScopes@..., <tekscopes@...> wrote:
>
>With the low voltage regulator board and your dummy load still attached measure:
>
>1. The voltage from pin 1 of U1040 to chassis ground or pin 2. The schematic says it should be about 0.96 volts but I bet it is higher because pin 8 of U1371C is very high which is to be expected when +5VD is low.
>
>If the voltage is low, below 0.96 volts, then the connection between pin 2 of U1040 and pin 8 of U1371C is open.
>If the voltage is high, above 0.96 volts, then R1044 could be open, or C1048 could be shorted, or most likely U1040 is dead.
>
>U1040 is an M0C1005 type optocoupler which I believe is a UL/VDE version of a 4N25 or 2N26. A CNY75A is the closest modern match I found but any of these 3 should work fine.
>
>I do not think the problem is with U1030 or anything to the left of the junction of R1045 and R1046 because with no feedback, the pre-regulator appears to be working correctly.
>
>I think machine guy was right when he said, "They use an optical feedback system to tweak the inverter and adjust +5 Vd.Ã LED's age and are sensitive to noise.Ã So that could be a source of inverter sag."
>
>On 09 Sep 2013 16:36:06 -0700, you wrote:
>
>>Hmm, I wonder if Pin 8 is so high because of a short in R1284 or R1285 or something with U1300B


Re: 2465A +5vd Power Supply Problem

 

Well, we are learning things.  These tests bolster the theory that the optocoupler is failing.  Here is my interpretation.
 
1.  The 4.7 K in parallel with R1270 made no difference.  That implies either the call for voltage is not passing to the inverter or the inverter is already running at maximum capacity.
2.  The 27 K in parallel with R1044 made no difference.  That implies either U1040 is not conducting or the inverter is not able to produce more voltage.
3.  The voltage at T1060 Pin 7 is less than 120 volts so there should be more capacity in the inverter.
4.  The resistance measurements at C1110 indicate that CR1110 is not shorted and the filter capacitors do not have a solder ball shorting them.
5.  The scope trace at C1110 shows a balanced rectification by CR1110 and a reasonable amount of ripple (note, this ripple and noise should be smoothed away by L1110 and C1111 before it becomes +5Vd).
 
Most likely, the optocoupler has failed or is failing.  Some other things to measure:
1.  The voltage between pins 5 and 4 of U1040.  Zero volts here will tell us U1040 is calling for more voltage and something else is keeping the inverter from achieving it.
2.  Scope traces and DC values referenced to chassis (for convenience P232 pin 3 or 4) of all other unregulated voltages (ie. P232 pin 5, P233 pin 5, P233 pin 3, P234 pin 5, P234 pin 4,  P234 pin 2, and P234 pin 1).  This will let us see if all unregulated voltages are low by the same rough percentage.  If one is drastically lower than we have found a short or open that could be complicating our search. 
 
If this further confirms the optocoupler failure I suggest we try faking it.  (I would like anyone else to weigh in here if they see something wrong with this idea.)  This test will take a bit of care but should be simple to do.  I want to try "touching" a 27 k resistor in parallel with R1045 this time.  By this I mean to use a clip lead to connect one end of a 27 K resistor to the junction of R1044 and R1045, start the supply and monitor the +5 Vd with a voltmenter.  Then use the resistor as if it were a probe to touch pin 4 of U1040.  The +5 Vd should rise when the resistor is touched to U1040.  I don't want to put the resistor in place permanently because it may be demanding too much increase.  We just want to see if the inverter has more capacity when we use the resistor to call for it.  Take care, we already know this part of the circuit is running at 113 volts and above.  But if the voltage rises we know the inverter has more capacity but the optocoupler is unable to call for the proper voltage.  If the voltage does not rise, we know the inverter is unable to produce more voltage even if the optocoupler does call for it.   

From: "bpl521@..."
To: TekScopes@...
Sent: Tuesday, September 10, 2013 9:03 PM
Subject: RE: Re: [TekScopes] RE: RE: 2465A +5vd Power Supply Problem
 
All

4.7Kohm resistor in parallel with  R1270 no difference in +5d output Still low at 4.55v either way

27kohm resistor in parallel with R1044 no difference either in +5d voltage

Voltage at Pin 7 of T1060 and Ref 2 is 113 volts


Resistance from chassis ground to junction of L1110 and C1110 is 145 ohms (no load on +5d). Reversing the multimeter and it starts at over 140 Mohm and slowly draws down.

Link below is a photo of the ripple output at the junction of L1110 and C1110 with a load on +5d. Looks like the inverter puts out a a fair bit of noise

 







 
--- In TekScopes@..., wrote:
David,
Shouldn't it be possible to test this by bridging R1044 with a 27 K resistor?  If the +5 Vd supply voltage increases we know its the optocoupler.

From: David
To: TekScopes@...
Sent: Tuesday, September 10, 2013 4:28 AM
Subject: Re: [TekScopes] RE: RE: 2465A +5vd Power Supply Problem
 
1.07 volts indicates that either the optocoupler is bad do to low or no output, R1044 is open, or that there is an open circuit in series with R1044 and the optocoupler output. I was wrong earlier about the possibility of C1048 being shorted. All of my service manuals so SOC123A which I suspect is a Tektronix house number. My Tektronix parts catalog shows Motorola MOC1005 which is a very close match to the Toshiba TLP631. Current transfer ratio is the ratio of output to input current which is sort of like gain. 50% means that for every 1mA of input, the output will be 0.5mA. The optocouplers are graded by CTR which is why there is an F and GBF version. The CTR should not be critical in this circuit so either of the ones you mention should work fine. If you want another test to confirm where the problem is, then the voltage between pin 7 of T1060 and REF1 with an inverter load should be about 120 volts DC which indicates that the optocoupler output is missing and the pre-regulator is set for the minimum output voltage as determined by R1045 and R1046. Another thing you could try is halving the value of R1270 on the low voltage regulator board near U1371C by temporarily placing a 3.9 or 4.7 kOhm resistor in parallel with it. That will double the current into the optocoupler so if its CTR has degraded with age, the higher current will allow it to work for now.
On 10 Sep 2013 00:10:39 -0700, you wrote:

>David:
>
>The voltage at Pin 1 to chassis ground was 1.07v (+5d is 4.5v)
>
>The service manual references U1040 as a TLP631 this is a Toshiba product and is still available from DigiKey There is two variants of this chip the
>
>TLP631-FND and the TLP631-GBF-ND. The F-ND has a current transfer ratio of 50%@5ma and the GBF-ND has a current transfer ratio of 100%@5ma. Whatever that all means?
>
>Machine Guy:
>
>I could not get any accurate measurements with all 3 comb connectors removed I had to leave P232 connected For what it is worth here is the measurements
>
>233B
>
>1 2v
>
>2 32v
>
>3 70v
>
>4 14v ?? this should be GND
>
>5 122v
>
>234B
>
>1 -8v
>
>2 0
>
>3 16v
>
>4 0v
>
>5 37v
>
>--- In TekScopes@..., <tekscopes@...> wrote:
>
>With the low voltage regulator board and your dummy load still attached measure:
>
>1. The voltage from pin 1 of U1040 to chassis ground or pin 2. The schematic says it should be about 0.96 volts but I bet it is higher because pin 8 of U1371C is very high which is to be expected when +5VD is low.
>
>If the voltage is low, below 0.96 volts, then the connection between pin 2 of U1040 and pin 8 of U1371C is open.
>If the voltage is high, above 0.96 volts, then R1044 could be open, or C1048 could be shorted, or most likely U1040 is dead.
>
>U1040 is an M0C1005 type optocoupler which I believe is a UL/VDE version of a 4N25 or 2N26. A CNY75A is the closest modern match I found but any of these 3 should work fine.
>
>I do not think the problem is with U1030 or anything to the left of the junction of R1045 and R1046 because with no feedback, the pre-regulator appears to be working correctly.
>
>I think machine guy was right when he said, "They use an optical feedback system to tweak the inverter and adjust +5 Vd.Ã LED's age and are sensitive to noise.Ã So that could be a source of inverter sag."
>
>On 09 Sep 2013 16:36:06 -0700, you wrote:
>
>>Hmm, I wonder if Pin 8 is so high because of a short in R1284 or R1285 or something with U1300B


Re: Source for premade BNC patch cables or DIY

 

I just ordered a set of 8 50 Ohm BNC patch cables from JPM supply, total, with shipping is under $30.  I cant make them for much less than that.  No affiliation with JPM.  I will post results when they arrive.

From: Mark Wendt
To: TekScopes@...
Sent: Tuesday, September 10, 2013 5:43 AM
Subject: Re: [TekScopes] Source for premade BNC patch cables or DIY

To each his own.  It's cheaper and easier for me to make up my own
cables that to pay someone else to make them.  As others have said, you
can pick up decent used silver conductor BNC connectors and good cabling
at hamfests.  The tooling to cut, prepare and crimp cables can be
purchased there too.

Much, much cheaper than buying pre-made ones.

Mark


On 09/10/2013 06:22 AM, Stefan Trethan wrote:
>
>
> I've found the cost rather prohibitive.
> Angled connectors were like $10, each.
> (Straight crimp connectors are much cheaper.)
>
> It's always good to have to capability to install any type of
> connector (sometimes the other end of the cable isn't free), but to
> build up a base stock of cables I wouldn't make them myself, personally.
>
> ST
>
>
> On Tue, Sep 10, 2013 at 12:04 PM, Mark Wendt <mark.wendt@...
> mark.wendt@...>> wrote:
>
>    With the right tooling, and a little practice, BNC cabling really
>    is not
>    that difficult to do your own.  I've made hundreds of BNC cables over
>    the years and it's really handy to have one the exact length you need.
>    Sometimes it's hard to find the correct length with bought cables.
>
>    Mark
>



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Re: 7104 in Oklahoma

Michael A. Terrell
 

Larry Snyder wrote:
Like St. Julien's Creek blue-stripers. Sad end to a magnificent piece of gear.
I always wanted one of the R390 receivers, the best I've ever had is a National NC183R and a couple frequency selective voltmeters (HP and Sierra) and a Boonton tuned amp. I used the FSV and amp to do AM BCB DX back in the '70s.


Re: Help, 475 trigger problem

honolulusnowwhite
 

Hi Mike,


The noise that your probe is picking up has a high-frequency component which apparently does not impact the 60 MHz bandwidth Hitachi.  Probes intended for use with lower bandwidth scopes have relatively long ground leads which contribute to picking up high-frequency electrical noise.  


If you want the P6136 probe to actually perform at 350 MHz you will have to use the short (around 2" length) grounding lead in place of the longer ground lead with alligator clip. 


Patrick Wong AK6C


--- In TekScopes@..., <tekscopes@...> wrote:

Hi Patrick,

I connected a BNC cable as you suggested although it's bedtime and I didn't search out the 50 ohm termination.

The result was the trace locked on all time bases I checked and down to very low amplitude.

So I'm with you on the probes, with one caveat, I've been using these probes on a 60Mhz Hitachi scope without noticing any problems. So it''s a little confusing.

 Any idea what I might do to fix these probes?


 I have a P6136 350Mhz probe coming soon, I'll try that on the 475. (bought for another scope)


                Thanks, Mikek

 


Re: 2465A +5vd Power Supply Problem

mosaicmerc
 

Can you measure the power or current consumption of the scope?
As I recall my 2465a clocks in at 70Watts.

Perhaps you have a solder bridge/ball creating a phantom load.
I am going to do an LVPS recap this week. Perhaps an A1 as well.

If you like I can setup a similar loading and we can skype so that I can do measurements on the LVPS before I recap so that you have known good working Volt. references.


Re: Help, 475 trigger problem

lamontcranston17
 

Hi Patrick,

I connected a BNC cable as you suggested although it's bedtime and I didn't search out the 50 ohm termination.

The result was the trace locked on all time bases I checked and down to very low amplitude.

So I'm with you on the probes, with one caveat, I've been using these probes on a 60Mhz Hitachi scope without noticing any problems. So it''s a little confusing.

 Any idea what I might do to fix these probes?


 I have a P6136 350Mhz probe coming soon, I'll try that on the 475. (bought for another scope)


                Thanks, Mikek

 



--- In TekScopes@..., <tekscopes@...> wrote:

Hi Mike,


It appears that the problem may be with your probes and their grounding.  Try using a short length of RG-58 with BNC connectors on both ends to connect your HP signal generator to your scope.  If your scope's vertical channels do not have a 50 ohm input, use a BNC T-connector at the vertical channel input and a BNC 50 ohm load on one side of the T; or else a 50 ohm passthrough attenuator.


The 475 DC triggering spec is for 0.3 major vertical division triggering up to 40 MHz and 1.5 major vertical division triggering at 200 MHz.  If your scope will trigger properly according to that spec then you can say your scope is good and the probes are the issue.


If the probes you are using on the 475 have compensation that can be adjusted to work with your other scope, you might try swapping probes to see what happens.


Good luck,


Patrick Wong AK6C


--- In TekScopes@..., <tekscopes@...> wrote:

 1.  What is the p-p amplitude of the signal that you are looking at?


I experimented and found when I'm on a timebase that locks I can go as low as 3/4 of a division and get a reliable lock, When it it doesn't lock it can be 1 or 6 divisions and it still won't lock.

 I think that covers 2. and 3.


4. have you tried using the noise-rejection, low frequency, and high frequency triggering input modes?


 I just did, it locks good with HF REJ switched on! 


The signal I'm using is an HP signal generator with a clean sinewave. It also locks with the internal calibration squarewave. BUT, the trace is very wide on the internal calibrator squarewave.

Photo here.

http://s395.photobucket.com/user/Qmavam/media/P1010017_zps53b1b972.jpg.html


5.  I notice the trace is not sharp.  What does the horizontal trace look like when the sweep is set to AUTO and no signal is input?  Can you focus the trace better? 


I have tried focus and astig, it's as good as it gets. With no signal the trace isn't terrible, but maybe just a little wide.


 Now some odd stuff, the photo I posted shows the display of the internal calibrator squarewave with a thick trace. I connected my other scope to the 475 calibrator and it looks great on the other scope..

 I then changed probes just as a check, still a wide trace, but then I laid the extra probe cable across the top of the scope case and the trace got thin and looks normal.

Photo of cable laid on top here.

http://s395.photobucket.com/user/Qmavam/media/P1010018_zps1eb5f91b.jpg.html

Here's the trace with cable on top,( yes, I tweaked the freq.response cap)

http://s395.photobucket.com/user/Qmavam/media/P1010026_zpsa8f6c9c4.jpg.html


                                Thanks for your help.


Re: Help, 475 trigger problem

honolulusnowwhite
 

Hi Mike,


It appears that the problem may be with your probes and their grounding.  Try using a short length of RG-58 with BNC connectors on both ends to connect your HP signal generator to your scope.  If your scope's vertical channels do not have a 50 ohm input, use a BNC T-connector at the vertical channel input and a BNC 50 ohm load on one side of the T; or else a 50 ohm passthrough attenuator.


The 475 DC triggering spec is for 0.3 major vertical division triggering up to 40 MHz and 1.5 major vertical division triggering at 200 MHz.  If your scope will trigger properly according to that spec then you can say your scope is good and the probes are the issue.


If the probes you are using on the 475 have compensation that can be adjusted to work with your other scope, you might try swapping probes to see what happens.


Good luck,


Patrick Wong AK6C


--- In TekScopes@..., <tekscopes@...> wrote:

 1.  What is the p-p amplitude of the signal that you are looking at?


I experimented and found when I'm on a timebase that locks I can go as low as 3/4 of a division and get a reliable lock, When it it doesn't lock it can be 1 or 6 divisions and it still won't lock.

 I think that covers 2. and 3.


4. have you tried using the noise-rejection, low frequency, and high frequency triggering input modes?


 I just did, it locks good with HF REJ switched on! 


The signal I'm using is an HP signal generator with a clean sinewave. It also locks with the internal calibration squarewave. BUT, the trace is very wide on the internal calibrator squarewave.

Photo here.

http://s395.photobucket.com/user/Qmavam/media/P1010017_zps53b1b972.jpg.html


5.  I notice the trace is not sharp.  What does the horizontal trace look like when the sweep is set to AUTO and no signal is input?  Can you focus the trace better? 


I have tried focus and astig, it's as good as it gets. With no signal the trace isn't terrible, but maybe just a little wide.


 Now some odd stuff, the photo I posted shows the display of the internal calibrator squarewave with a thick trace. I connected my other scope to the 475 calibrator and it looks great on the other scope..

 I then changed probes just as a check, still a wide trace, but then I laid the extra probe cable across the top of the scope case and the trace got thin and looks normal.

Photo of cable laid on top here.

http://s395.photobucket.com/user/Qmavam/media/P1010018_zps1eb5f91b.jpg.html

Here's the trace with cable on top,( yes, I tweaked the freq.response cap)

http://s395.photobucket.com/user/Qmavam/media/P1010026_zpsa8f6c9c4.jpg.html


                                Thanks for your help.


Re: 7104 in Oklahoma

Larry Snyder <teamlarry@...>
 

Like St. Julien's Creek blue-stripers.  Sad end to a magnificent piece of gear.


On Mon, Sep 9, 2013 at 10:15 PM, Michael A. Terrell <mike.terrell@...> wrote:
 

Peter Gottlieb wrote:
>
> Do you have specific evidence of mistreatment of surplus by government
> employees
> or just dislike them in general? We were talking about direct
> experience with
> mistreatment by Govliquidation employees.
>
> Note that when equipment is determined to be "scrap" it is likely to
> be treated
> as such by both government and private personnel alike. Just because you
> consider a 7104 to be valuable and deserving of good treatment does
> not mean it
> will get such treatment once it is written off as scrap materiel.
> That's just
> the reality of the situation. The 485 I had destroyed was a CC "A"
> item meaning
> it should have been ready for use and in good condition. This isn't
> hearsay, I
> saw it happen right in front of me by one of their employees.
>

That surplus yard in Orlando had a bunch of R390 receivers on
pallets. One plaltet had the forks of a fork lift run through it. I was
there to help a freind pick up what he's won. There pallets of
electronics were missing.


Re: 2465A +5vd Power Supply Problem

 

All


4.7Kohm resistor in parallel with  R1270 no difference in +5d output Still low at 4.55v either way


27kohm resistor in parallel with R1044 no difference either in +5d voltage


Voltage at Pin 7 of T1060 and Ref 2 is 113 volts



Resistance from chassis ground to junction of L1110 and C1110 is 145 ohms (no load on +5d). Reversing the multimeter and it starts at over 140 Mohm and slowly draws down.


Link below is a photo of the ripple output at the junction of L1110 and C1110 with a load on +5d. Looks like the inverter puts out a a fair bit of noise


http://groups.yahoo.com/neo/groups/TekScopes/photos/albums/888008784/lightbox/222918246

 








 



--- In TekScopes@..., <tekscopes@...> wrote:

David,
Shouldn't it be possible to test this by bridging R1044 with a 27 K resistor?  If the +5 Vd supply voltage increases we know its the optocoupler.

From: David <davidwhess@...>
To: TekScopes@...
Sent: Tuesday, September 10, 2013 4:28 AM
Subject: Re: [TekScopes] RE: RE: 2465A +5vd Power Supply Problem
 
1.07 volts indicates that either the optocoupler is bad do to low or no output, R1044 is open, or that there is an open circuit in series with R1044 and the optocoupler output. I was wrong earlier about the possibility of C1048 being shorted.

All of my service manuals so SOC123A which I suspect is a Tektronix house number. My Tektronix parts catalog shows Motorola MOC1005 which is a very close match to the Toshiba TLP631.

Current transfer ratio is the ratio of output to input current which is sort of like gain. 50% means that for every 1mA of input, the output will be 0.5mA. The optocouplers are graded by CTR which is why there is an F and GBF version.

The CTR should not be critical in this circuit so either of the ones you mention should work fine.

If you want another test to confirm where the problem is, then the voltage between pin 7 of T1060 and REF1 with an inverter load should be about 120 volts DC which indicates that the optocoupler output is missing and the pre-regulator is set for the minimum output voltage as determined by R1045 and R1046.

Another thing you could try is halving the value of R1270 on the low voltage regulator board near U1371C by temporarily placing a 3.9 or 4.7 kOhm resistor in parallel with it. That will double the current into the optocoupler so if its CTR has degraded with age, the higher current will allow it to work for now.

On 10 Sep 2013 00:10:39 -0700, you wrote:

>David:
>
>The voltage at Pin 1 to chassis ground was 1.07v (+5d is 4.5v)
>
>The service manual references U1040 as a TLP631 this is a Toshiba product and is still available from DigiKey There is two variants of this chip the
>
>TLP631-FND and the TLP631-GBF-ND. The F-ND has a current transfer ratio of 50%@5ma and the GBF-ND has a current transfer ratio of 100%@5ma. Whatever that all means?
>
>Machine Guy:
>
>I could not get any accurate measurements with all 3 comb connectors removed I had to leave P232 connected For what it is worth here is the measurements
>
>233B
>
>1 2v
>
>2 32v
>
>3 70v
>
>4 14v ?? this should be GND
>
>5 122v
>
>234B
>
>1 -8v
>
>2 0
>
>3 16v
>
>4 0v
>
>5 37v
>
>--- In TekScopes@..., <tekscopes@...> wrote:
>
>With the low voltage regulator board and your dummy load still attached measure:
>
>1. The voltage from pin 1 of U1040 to chassis ground or pin 2. The schematic says it should be about 0.96 volts but I bet it is higher because pin 8 of U1371C is very high which is to be expected when +5VD is low.
>
>If the voltage is low, below 0.96 volts, then the connection between pin 2 of U1040 and pin 8 of U1371C is open.
>If the voltage is high, above 0.96 volts, then R1044 could be open, or C1048 could be shorted, or most likely U1040 is dead.
>
>U1040 is an M0C1005 type optocoupler which I believe is a UL/VDE version of a 4N25 or 2N26. A CNY75A is the closest modern match I found but any of these 3 should work fine.
>
>I do not think the problem is with U1030 or anything to the left of the junction of R1045 and R1046 because with no feedback, the pre-regulator appears to be working correctly.
>
>I think machine guy was right when he said, "They use an optical feedback system to tweak the inverter and adjust +5 Vd. LED's age and are sensitive to noise. So that could be a source of inverter sag."
>
>On 09 Sep 2013 16:36:06 -0700, you wrote:
>
>>Hmm, I wonder if Pin 8 is so high because of a short in R1284 or R1285 or something with U1300B


Re: S-52 drift in TD trigger

Don Black <donald_black@...>
 

Is all this discussion on drift a fault or just the requirement to allow a reasonable warm up time before making measurements (I guess that's what the discussion is all about). And hence the way the equipment was designed and always operated. Most test equipment instructions  seems to say allow (20 minutes?) warm up before calibrating. Can anyone with past experience and long memories give some insight.

Don Black.

On 11-Sep-13 4:53 AM, aodiversen@... wrote:
 

I am not conviced that my nice camel is not ok. My other S-52 shows about the same camel, be it with nearly no dip between the humps. What I measure is the TD output, not the snap-off diode (CR66) voltage. It looks like there is a slow oscillation superimposed which causes the humps. I think LR64 might be responsible for this. In the 7S12 the DC bias current for CR66 is supplied via L64 of LR64. When the 7S12 interrupts that current L64 might cause (heavily damped) oscillations.

Meanwhile I followed David's S-53 suggestion. S-53 free running, S-53 Trigger output via delay line and attenuator fed into the S-6. The trigger pulse now drifted to the left, about 500 ps. Similarly I put the S-6 in a 7S11 in the left slot along with the 7S12. Again drift to the left but only 300 ps (here I am not sure the units were completely cooled down initially). I ignore that the 7S11 might introduce drift also; I set the delay dial at minimum.

Inside the 7S12 it means that the delay from S-53 trigger to S-6 strobe pulse increases with temperature. The  path to the internal sampling head contains an extra delay which is set by R380. This extra delay has its own drift of 200 ps it seems.

If the 7S12 determined delay from S-52 (pre)trigger to S-52 TD triggering were constant, then the above findings would imply a drift to the left of the TD pulse. A 600 ps drift to the right can only be explained by an even larger positive drift of 1.1 ns in delay from S-52 (pre)trigger to S-52 TD triggering. I can imagine that this delay, mainly set by R594, is temperature dependent.

Or am I thinking the wrong way around with events coming later and earlier?


Albert





--- In TekScopes@..., wrote:

Maybe not only a psych experiment. Now I have a migraine from reading that. But anyway your trigger does look kind of sick. That double hump cannot be the right kind of camel.


Re: Help, 475 trigger problem

lamontcranston17
 

 1.  What is the p-p amplitude of the signal that you are looking at?


I experimented and found when I'm on a timebase that locks I can go as low as 3/4 of a division and get a reliable lock, When it it doesn't lock it can be 1 or 6 divisions and it still won't lock.

 I think that covers 2. and 3.


4. have you tried using the noise-rejection, low frequency, and high frequency triggering input modes?


 I just did, it locks good with HF REJ switched on! 


The signal I'm using is an HP signal generator with a clean sinewave. It also locks with the internal calibration squarewave. BUT, the trace is very wide on the internal calibrator squarewave.

Photo here.

http://s395.photobucket.com/user/Qmavam/media/P1010017_zps53b1b972.jpg.html


5.  I notice the trace is not sharp.  What does the horizontal trace look like when the sweep is set to AUTO and no signal is input?  Can you focus the trace better? 


I have tried focus and astig, it's as good as it gets. With no signal the trace isn't terrible, but maybe just a little wide.


 Now some odd stuff, the photo I posted shows the display of the internal calibrator squarewave with a thick trace. I connected my other scope to the 475 calibrator and it looks great on the other scope..

 I then changed probes just as a check, still a wide trace, but then I laid the extra probe cable across the top of the scope case and the trace got thin and looks normal.

Photo of cable laid on top here.

http://s395.photobucket.com/user/Qmavam/media/P1010018_zps1eb5f91b.jpg.html

Here's the trace with cable on top,( yes, I tweaked the freq.response cap)

http://s395.photobucket.com/user/Qmavam/media/P1010026_zpsa8f6c9c4.jpg.html


                                Thanks for your help.






--- In TekScopes@..., <tekscopes@...> wrote:

Hi Mike,


A few questions that might help:


1.  What is the p-p amplitude of the signal that you are looking at?

2.  If the amplitude is weak, try a stronger signal.

3.  What happens if you increase the vertical amp volts/div sensitivity so that the trace occupies 6 vertical divisions or so?

4.  I'm not familiar with your scope, but have you tried using the noise-rejection, low frequency, and high frequency triggering input modes (if your scope has those options)?

5.  I notice the trace is not sharp.  What does the horizontal trace look like when the sweep is set to AUTO and no signal is input?  Can you focus the trace better?  


Patrick Wong AK6C



--- In tekscopes@..., <nojunk@...> wrote:

Hi Guys,
I need a starting point for a strange trigger problem.

It triggers ok on .5ms but looks like it double trigger on .2ms (two waveforms).


Here is a picture of wide trace at 0.5ms

http://s395.photobucket.com/user/Qmavam/media/P1010014_zpsccad5399.jpg.html


Here is trace at 0.2ms with trigger adjusted, it changes but doe not trigger properly

http://s395.photobucket.com/user/Qmavam/media/P1010015_zpsde0fde0c.jpg.html


Other time bases have similar issues.


                        Thanks, Mikek



Re: Help, 475 trigger problem

honolulusnowwhite
 

Hi Mike,


A few questions that might help:


1.  What is the p-p amplitude of the signal that you are looking at?

2.  If the amplitude is weak, try a stronger signal.

3.  What happens if you increase the vertical amp volts/div sensitivity so that the trace occupies 6 vertical divisions or so?

4.  I'm not familiar with your scope, but have you tried using the noise-rejection, low frequency, and high frequency triggering input modes (if your scope has those options)?

5.  I notice the trace is not sharp.  What does the horizontal trace look like when the sweep is set to AUTO and no signal is input?  Can you focus the trace better?  


Patrick Wong AK6C



--- In tekscopes@..., <nojunk@...> wrote:

Hi Guys,
I need a starting point for a strange trigger problem.

It triggers ok on .5ms but looks like it double trigger on .2ms (two waveforms).


Here is a picture of wide trace at 0.5ms

http://s395.photobucket.com/user/Qmavam/media/P1010014_zpsccad5399.jpg.html


Here is trace at 0.2ms with trigger adjusted, it changes but doe not trigger properly

http://s395.photobucket.com/user/Qmavam/media/P1010015_zpsde0fde0c.jpg.html


Other time bases have similar issues.


                        Thanks, Mikek



Help, 475 trigger problem

lamontcranston17
 

Hi Guys,
I need a starting point for a strange trigger problem.

It triggers ok on .5ms but looks like it double trigger on .2ms (two waveforms).


Here is a picture of wide trace at 0.5ms

http://s395.photobucket.com/user/Qmavam/media/P1010014_zpsccad5399.jpg.html


Here is trace at 0.2ms with trigger adjusted, it changes but doe not trigger properly

http://s395.photobucket.com/user/Qmavam/media/P1010015_zpsde0fde0c.jpg.html


Other time bases have similar issues.


                        Thanks, Mikek



Re: Anyone have 21A & 22A schematics?

sipespresso <sipespresso@...>
 


Re: 2465A +5vd Power Supply Problem

 

David:


I will try both tests tonight and led the group know of the results. The service manual that I downloaded has a section of all the components and their mfg and part number. It definitely states U1040 as a TLP631, although the schematic states different. 


Machine Guy:


I need to rerun the resistance test you referred to. But late last night I tried and put my DMM at the junction of C1110 and L1110  to cahssis gnd and there was resistance of about 1.5K. With the leads reversed it was well into 15Mohms or more. (Did not realize there would be a difference with a  DMM in the resistance settings).


Want to double check, because can't remember if I had a load attached. Will upload the scope results as well.


Will try the parallel resistance on R1270 as well


Thanks again everyone.



 



--- In tekscopes@..., <machineguy59@...> wrote:

David,
Shouldn't it be possible to test this by bridging R1044 with a 27 K resistor?  If the +5 Vd supply voltage increases we know its the optocoupler.

From: David <davidwhess@...>
To: TekScopes@...
Sent: Tuesday, September 10, 2013 4:28 AM
Subject: Re: [TekScopes] RE: RE: 2465A +5vd Power Supply Problem
 
1.07 volts indicates that either the optocoupler is bad do to low or no output, R1044 is open, or that there is an open circuit in series with R1044 and the optocoupler output. I was wrong earlier about the possibility of C1048 being shorted.

All of my service manuals so SOC123A which I suspect is a Tektronix house number. My Tektronix parts catalog shows Motorola MOC1005 which is a very close match to the Toshiba TLP631.

Current transfer ratio is the ratio of output to input current which is sort of like gain. 50% means that for every 1mA of input, the output will be 0.5mA. The optocouplers are graded by CTR which is why there is an F and GBF version.

The CTR should not be critical in this circuit so either of the ones you mention should work fine.

If you want another test to confirm where the problem is, then the voltage between pin 7 of T1060 and REF1 with an inverter load should be about 120 volts DC which indicates that the optocoupler output is missing and the pre-regulator is set for the minimum output voltage as determined by R1045 and R1046.

Another thing you could try is halving the value of R1270 on the low voltage regulator board near U1371C by temporarily placing a 3.9 or 4.7 kOhm resistor in parallel with it. That will double the current into the optocoupler so if its CTR has degraded with age, the higher current will allow it to work for now.

On 10 Sep 2013 00:10:39 -0700, you wrote:

>David:
>
>The voltage at Pin 1 to chassis ground was 1.07v (+5d is 4.5v)
>
>The service manual references U1040 as a TLP631 this is a Toshiba product and is still available from DigiKey There is two variants of this chip the
>
>TLP631-FND and the TLP631-GBF-ND. The F-ND has a current transfer ratio of 50%@5ma and the GBF-ND has a current transfer ratio of 100%@5ma. Whatever that all means?
>
>Machine Guy:
>
>I could not get any accurate measurements with all 3 comb connectors removed I had to leave P232 connected For what it is worth here is the measurements
>
>233B
>
>1 2v
>
>2 32v
>
>3 70v
>
>4 14v ?? this should be GND
>
>5 122v
>
>234B
>
>1 -8v
>
>2 0
>
>3 16v
>
>4 0v
>
>5 37v
>
>--- In TekScopes@..., <tekscopes@...> wrote:
>
>With the low voltage regulator board and your dummy load still attached measure:
>
>1. The voltage from pin 1 of U1040 to chassis ground or pin 2. The schematic says it should be about 0.96 volts but I bet it is higher because pin 8 of U1371C is very high which is to be expected when +5VD is low.
>
>If the voltage is low, below 0.96 volts, then the connection between pin 2 of U1040 and pin 8 of U1371C is open.
>If the voltage is high, above 0.96 volts, then R1044 could be open, or C1048 could be shorted, or most likely U1040 is dead.
>
>U1040 is an M0C1005 type optocoupler which I believe is a UL/VDE version of a 4N25 or 2N26. A CNY75A is the closest modern match I found but any of these 3 should work fine.
>
>I do not think the problem is with U1030 or anything to the left of the junction of R1045 and R1046 because with no feedback, the pre-regulator appears to be working correctly.
>
>I think machine guy was right when he said, "They use an optical feedback system to tweak the inverter and adjust +5 Vd. LED's age and are sensitive to noise. So that could be a source of inverter sag."
>
>On 09 Sep 2013 16:36:06 -0700, you wrote:
>
>>Hmm, I wonder if Pin 8 is so high because of a short in R1284 or R1285 or something with U1300B


Anyone have 21A & 22A schematics?

ditter2
 

I have a 22A with the older TD trigger circuit  (the ceramic strip version, not the circuit board).  Stan Griffiths’ book says the calibration of the older version tends not to be stable, requiring constant adjustment.  This was corrected with the newer version that is mounted on a small circuit board.  My documentation only covers the original 555 with 21 and 22 (non A model time bases).

 

Does anyone have a scanned 555 manual with the newer 21A and 22A in it?  If you have a hard copy only, could you scan the schematics of the trigger circuits? I would be interested in both the older (ceramic strip) version and the newer circuit board version.  I don’t know where the serial number break is.

 

- Steve

 


Re: S-52 drift in TD trigger

Albert Otten
 

I am not conviced that my nice camel is not ok. My other S-52 shows about the same camel, be it with nearly no dip between the humps. What I measure is the TD output, not the snap-off diode (CR66) voltage. It looks like there is a slow oscillation superimposed which causes the humps. I think LR64 might be responsible for this. In the 7S12 the DC bias current for CR66 is supplied via L64 of LR64. When the 7S12 interrupts that current L64 might cause (heavily damped) oscillations.

Meanwhile I followed David's S-53 suggestion. S-53 free running, S-53 Trigger output via delay line and attenuator fed into the S-6. The trigger pulse now drifted to the left, about 500 ps. Similarly I put the S-6 in a 7S11 in the left slot along with the 7S12. Again drift to the left but only 300 ps (here I am not sure the units were completely cooled down initially). I ignore that the 7S11 might introduce drift also; I set the delay dial at minimum.

Inside the 7S12 it means that the delay from S-53 trigger to S-6 strobe pulse increases with temperature. The  path to the internal sampling head contains an extra delay which is set by R380. This extra delay has its own drift of 200 ps it seems.

If the 7S12 determined delay from S-52 (pre)trigger to S-52 TD triggering were constant, then the above findings would imply a drift to the left of the TD pulse. A 600 ps drift to the right can only be explained by an even larger positive drift of 1.1 ns in delay from S-52 (pre)trigger to S-52 TD triggering. I can imagine that this delay, mainly set by R594, is temperature dependent.

Or am I thinking the wrong way around with events coming later and earlier?


Albert





--- In TekScopes@..., <tekscopes@...> wrote:

Maybe not only a psych experiment. Now I have a migraine from reading that. But anyway your trigger does look kind of sick. That double hump cannot be the right kind of camel.

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