Date   

Re: Tektronix 7514 issues

g_kupka <ghm1@...>
 

Hi Albert

I measured with a DMM(10MOhm input resistance) between grid and cathode and found -80Volt, while the trace was very bright and the intensity pot was couterclockwise. I could not change trace brightness with the intensity pot(-40volt with pot clockwise). After 10mins the trace brightness became normal and I could change it from very dim to very bright.

Gerhard

--- In TekScopes@yahoogroups.com, "Albert" <aodiversen@...> wrote:

Hi Gerhard,

I suppose you measured the input to the Grid Bias, not the control grid itself? If you measure the grid to ground the load will be far to much (unless you have a very very high resistance meter). If you can reach 2 suitable points for the test leads, you can monitor the voltage difference between grid and cathode.

Albert

there is now drift on the ZAxis output and no drift at the control grid. My 7514 issue remembers me a similar thread (37826) in this forum, but there was no answer on the problem.

Gerhard


"L" with strange front panel color...

tubesnthings@...
 

This is coming my way - anyone know about this color scheme?
Bernd
 


Re: Tektronix 7514 issues

Albert <aodiversen@...>
 

Hi Gerhard,

I suppose you measured the input to the Grid Bias, not the control grid itself? If you measure the grid to ground the load will be far to much (unless you have a very very high resistance meter). If you can reach 2 suitable points for the test leads, you can monitor the voltage difference between grid and cathode.

Albert

there is now drift on the ZAxis output and no drift at the control grid. My 7514 issue remembers me a similar thread (37826) in this forum, but there was no answer on the problem.

Gerhard


Re: TM5006 fan airflow for rack and desktop?

ditter2
 

Dave,

They do have two different fans, the higher CFM one in the rackmount version. I don't know the CFM rating, but if my memory is correct, the rackmount uses a 15 W fan, while the desktop uses a 9 W one. They are the standard "muffin" fans. They did not need to switch voltage, as they were wired across one of the primary windings of the line frequency transformer. Any tap or 115/230 V strapping option feeds the fan the same voltage.

Steve

--- In TekScopes@yahoogroups.com, David Gravereaux <davygrvy@...> wrote:

Hi,

I was wondering if anyone knows the CFM specs? I'm considering using a
Maxim MAX6643 pwm DC fan controller and running it off the 8V buss for
temperature feedback to keep the flow, thus acoustical noise in the lab,
to a minimum.

My six mainframes are making a hell of a noise when they're all on. The
two rack units must be flowing twice the air rate compared to the desktops.

Once I know max flow rate, I can work backwards from there.
--
David Gravereaux <davygrvy@...>


Re: Tektronix 7514 issues

g_kupka <ghm1@...>
 

Albert

there is now drift on the ZAxis output and no drift at the control grid. My 7514 issue remembers me a similar thread (37826) in this forum, but there was no answer on the problem.

Gerhard

--- In TekScopes@yahoogroups.com, "Albert" <aodiversen@...> wrote:

Hi Gerhard,
I don't have the manual but suppose it's similar to for instance 7603. I would first of all check the output of the Z amplifier where it feeds the Grid Bias circuit. It is sufficient to use a DMM at DC and check for drift during warming up, time base free running. If no severe drift there (several volts) the Grid Bias circuit is the next candidate.
Albert

--- In TekScopes@yahoogroups.com, "g_kupka" <ghm1@> wrote:

I got a Tektronix 7514. It had some issues with the vertical amplifier, the readout system and the horizontal interface. I could fix them except an issue with the intensity. When the cold mainframe is powered up, the trace is very bright and can't be adjusted with the intensity pot. After a while(between 10mins and 60mins) the trace brightness becomes normal and can be adjusted with the intensity pot. During such a "normal" stage I could adjust the ZAxis board. But after powering up the cold mainframe the trace is very bright again. Who can help?


Re: TM5006 fan airflow for rack and desktop?

Albert <aodiversen@...>
 

105 and 75 CFM, see electrical parts list manual. Also search for TM5006/TM5006A fan replacement in the old messages.
Albert

I was wondering if anyone knows the CFM specs?
---
David Gravereaux <davygrvy@...>


Re: Tektronix 466 Oscilloscope

Bob Albert
 

I have a 465B parts unit that may have what you need.  Will it work?

Contact me off list.  bob91343@...

Bob


--- On Wed, 10/3/12, joseph.cawood wrote:

From: joseph.cawood
Subject: [TekScopes] Tektronix 466 Oscilloscope
To: TekScopes@...
Date: Wednesday, October 3, 2012, 10:30 AM

 

Over the last few weeks I have been troubleshooting my Tektronix 466. The scope has had a high voltage issue in the CRT, and was found to have a bad HV transformer. So I wanted to know if anyone had a Tektronix 466 or 464 that was being used for parts. I am looking for the high voltage transformer for the CRT (tek part # 120-0909-01). I have found suppliers that are willing to sell me one, but the price is to high. If anyone can help me please let me know, thank you for your help on the matter.

Joseph, KF7LPU
Blessings, 73s


Re: 500 series type R and S plugin

Tim Phillips <tim@...>
 

from Tim P (UK)
I am pretty sure that the Mercury relay doesn't like being upside-down -
something to do with the capilliary effect between the contacts.
I have an 'S' and an 'R'. Also a 109 and 110. All except the 'R' have
broken Mercury relays, which are just about impossible to find NOS.
(I think Dean had some.)
Tim
 


Tektronix 466 Oscilloscope

joseph.cawood <joseph.cawood@...>
 

Over the last few weeks I have been troubleshooting my Tektronix 466. The scope has had a high voltage issue in the CRT, and was found to have a bad HV transformer. So I wanted to know if anyone had a Tektronix 466 or 464 that was being used for parts. I am looking for the high voltage transformer for the CRT (tek part # 120-0909-01). I have found suppliers that are willing to sell me one, but the price is to high. If anyone can help me please let me know, thank you for your help on the matter.

Joseph, KF7LPU
Blessings, 73s


Re: 500 series type R and S plugin

PA4TIM
 

Thanks Dennis for this nice info. I do hve the O plugin. The opamp. I had to match tubes for one and it is allmost at factory specs. It is a very nice plugin ( i hate breadboards) to make quick test setups. The reason I wanted a 132 was my 1S2 but for most the O plugin.
I used it to measure less as 10 pF. That was great fun ( see my site under measuring femto farads, i can not link from this device) . Egge Siert gave me a manusl from a later type plugin with even more applictions usable for the O. After the R is finnished I am going to use the O in an experiment to measure BH curves ( and for the dirty minded this is about inductors ;-) )

Today I went on with the calibration and upto now all goes perfect. The offset is gone now so the trace is mid screen, the gain is OK , psu voltages too.

Only strange thing, standing in the normal position the pulser is softly ratteling doing his job, stnding upside down it makes twice the noise but on its side it stops.

I have no experience with mercury wetted reedrelais but should I be worried about this ?

Fred

--- In TekScopes@yahoogroups.com, "Dennis Tillman" <dennis@...> wrote:

Fred,

The R and the S are scarce plugins Tek developed from the days when
transistor risetimes and diode stored charge needed to be measured to
characterize these devices for the very first time. They probably arose out
of Tek's own internal engineering need to better understand how to select
the best semiconductors for their designs. They are valuable since I don't
think many are left. I'm glad you are interested in preserving them. I
always thought they were one of the more interesting plugins Tek ever made.
At a later date Tek made faster stand-alone boxes with GR connectors on them
(I believe they were called the 291 and 292) so sampling scopes could be
used to test even faster devices.

Two more interesting 500 series plugins that are becoming rare are the
Strain Gate plugins, and the OpAmp plugins. All four of these plugins never
had equivalents for the 7000 series of scopes that superseded the 500
series. By the time the 7000 came out there was no need for the R, the S,
and the OpAmp plugins.

But it always surprised me that the Strain Gauge plugin did not show up for
the 5000 series of scopes. It seems like there would still be a need for
this when the 5000 series was announced.

Good for you for preserving the R plugin.

Dennis

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of fred
Sent: Wednesday, October 03, 2012 3:35 AM

Thanks.
http://www.pa4tim.nl/?p=3729. Pictures and screenshots ( before calibration)
of minre.

Frec

--- In TekScopes@yahoogroups.com, d.seiter@ wrote:

I'll make some scans/photos and send them to you.
-Dave

----- Original Message -----
From: "fred" <fredschneider@>
To: TekScopes@yahoogroups.com

Hi Dave,
I have a plugin extender for calibration or repair so thats no problem.
But it would be great to have a picture from an adapterplate front and
back.
I now used short crocodil wires connected to a 576 adapter and that worked
but I want to make a better connction. I had hoped the connectors on he
frondpanel fitted the small size bananabusses I had here but the pins turn
out to be thinker. No problem, I make some some in the right size from
copper or so and solder thise to the pcb. It looks like the two holes above
the pins are there for ground and holding the pcb.

I havetried it and it works but it needs a scopr sith a delayline and
I have not Looked yet in the 547 manual if this has one. The scopes I have
seen with a delayline have bunch of coax inside but I have seen lines made
out of coils and C's too.

Fred

--- In TekScopes@yahoogroups.com , d.seiter@ wrote:

Hi Fred-

Although I do have one of the short adaptors for the 500 series scopes,
what I use most often is a cable adaptor I made from a dead plugin, the
female plugin connector from a dead scope, and some cable. The cable is
about 3 feet long, so the plug-in under test has great access. The plugin
carcass serves only to make inserting the adaptor a no-brainer.


I also only have the R (with one adaptor plate) and no S. The S/N is 745
(no leading zeros), and it was an ex-navy unit based on etched markings on
the back of the unit.

-Dave

----- Original Message -----
From: "fredschneider2001" <fredschneider@>
To: TekScopes@yahoogroups.com

Can someone give some more background on who used these plugins. Were
they made for educational use or used by manufactureres of transistors to
make datasheets, or designers of equipment. I only have the R, the S looks
intresting ( diode recovery time)

Are they rare ? If I look st the serial numbers in the manual they must
made thausants of then. Mine is SN: 002223, Someone hase a working one ?

I'm restoring my type R transistor respons test plugin It is been stored
in a plugin hostile environment ( lots of oxide) I'm cleaning it and testing
components before firing up.

Problems yet :
- have no adapter boards but It must not be difficult to make something.
( could use some detailed pictures)

- few rotten leaking electrolytic caps, easy to replace.

- leaking 250 uF 6VDC NP cap ( measures 1000 uF leaks 250 uA ERS 0.3
ohm)
NP is as far as I know non polarity so a huge bipolar cap. Not find a
replacement yet.

- defect 1Ohm WW resistor, repaced it.

- cleaned everything and stucked knobs and buttons are moving smooth
again.

Expected poblems:
A nice collection of prehistoric germanium transisors inside, all severe
oxidised housings. I 'm afraid for the usual like whiskers, leakage and
being very capacitive ( had to replace all of them in a GR because most
tranformed in to single-part oscillators)
Lot of work to get them out for testing on the CT. But they are just for
psu use so silicium replacements probably will do fine.

Fred pa4tim


Re: 500 series type R and S plugin

 

Fred,

The R and the S are scarce plugins Tek developed from the days when
transistor risetimes and diode stored charge needed to be measured to
characterize these devices for the very first time. They probably arose out
of Tek's own internal engineering need to better understand how to select
the best semiconductors for their designs. They are valuable since I don't
think many are left. I'm glad you are interested in preserving them. I
always thought they were one of the more interesting plugins Tek ever made.
At a later date Tek made faster stand-alone boxes with GR connectors on them
(I believe they were called the 291 and 292) so sampling scopes could be
used to test even faster devices.

Two more interesting 500 series plugins that are becoming rare are the
Strain Gate plugins, and the OpAmp plugins. All four of these plugins never
had equivalents for the 7000 series of scopes that superseded the 500
series. By the time the 7000 came out there was no need for the R, the S,
and the OpAmp plugins.

But it always surprised me that the Strain Gauge plugin did not show up for
the 5000 series of scopes. It seems like there would still be a need for
this when the 5000 series was announced.

Good for you for preserving the R plugin.

Dennis

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of fred
Sent: Wednesday, October 03, 2012 3:35 AM

Thanks.
http://www.pa4tim.nl/?p=3729. Pictures and screenshots ( before calibration)
of minre.

Frec

--- In TekScopes@yahoogroups.com, d.seiter@... wrote:

I'll make some scans/photos and send them to you.
-Dave

----- Original Message -----
From: "fred" <fredschneider@...>
To: TekScopes@yahoogroups.com

Hi Dave,
I have a plugin extender for calibration or repair so thats no problem.
But it would be great to have a picture from an adapterplate front and
back.
I now used short crocodil wires connected to a 576 adapter and that worked
but I want to make a better connction. I had hoped the connectors on he
frondpanel fitted the small size bananabusses I had here but the pins turn
out to be thinker. No problem, I make some some in the right size from
copper or so and solder thise to the pcb. It looks like the two holes above
the pins are there for ground and holding the pcb.

I havetried it and it works but it needs a scopr sith a delayline and
I have not Looked yet in the 547 manual if this has one. The scopes I have
seen with a delayline have bunch of coax inside but I have seen lines made
out of coils and C's too.

Fred

--- In TekScopes@yahoogroups.com , d.seiter@ wrote:

Hi Fred-

Although I do have one of the short adaptors for the 500 series scopes,
what I use most often is a cable adaptor I made from a dead plugin, the
female plugin connector from a dead scope, and some cable. The cable is
about 3 feet long, so the plug-in under test has great access. The plugin
carcass serves only to make inserting the adaptor a no-brainer.


I also only have the R (with one adaptor plate) and no S. The S/N is 745
(no leading zeros), and it was an ex-navy unit based on etched markings on
the back of the unit.

-Dave

----- Original Message -----
From: "fredschneider2001" <fredschneider@>
To: TekScopes@yahoogroups.com

Can someone give some more background on who used these plugins. Were
they made for educational use or used by manufactureres of transistors to
make datasheets, or designers of equipment. I only have the R, the S looks
intresting ( diode recovery time)

Are they rare ? If I look st the serial numbers in the manual they must
made thausants of then. Mine is SN: 002223, Someone hase a working one ?

I'm restoring my type R transistor respons test plugin It is been stored
in a plugin hostile environment ( lots of oxide) I'm cleaning it and testing
components before firing up.

Problems yet :
- have no adapter boards but It must not be difficult to make something.
( could use some detailed pictures)

- few rotten leaking electrolytic caps, easy to replace.

- leaking 250 uF 6VDC NP cap ( measures 1000 uF leaks 250 uA ERS 0.3
ohm)
NP is as far as I know non polarity so a huge bipolar cap. Not find a
replacement yet.

- defect 1Ohm WW resistor, repaced it.

- cleaned everything and stucked knobs and buttons are moving smooth
again.

Expected poblems:
A nice collection of prehistoric germanium transisors inside, all severe
oxidised housings. I 'm afraid for the usual like whiskers, leakage and
being very capacitive ( had to replace all of them in a GR because most
tranformed in to single-part oscillators)
Lot of work to get them out for testing on the CT. But they are just for
psu use so silicium replacements probably will do fine.

Fred pa4tim


TM5006 fan airflow for rack and desktop?

David Gravereaux
 

Hi,

I was wondering if anyone knows the CFM specs? I'm considering using a
Maxim MAX6643 pwm DC fan controller and running it off the 8V buss for
temperature feedback to keep the flow, thus acoustical noise in the lab,
to a minimum.

My six mainframes are making a hell of a noise when they're all on. The
two rack units must be flowing twice the air rate compared to the desktops.

Once I know max flow rate, I can work backwards from there.
--
David Gravereaux <davygrvy@pobox.com>


Win an HP 1200B diff-in 100uV scope

Michael Dunn
 


Re: Help with a Tek 575 Curve tracer - New to group

 

The one fixture I have for my 7CT1N has ferrite beads for suppressing
oscillation on the transistor connections.

I tested some two transistor cascodes which oscillated despite the
ferrite bead suppression in the test fixture but adding low value
snubber resistors or ferrite suppression beads externally fixed that
problem.

On Wed, 3 Oct 2012 08:31:45 -0700, "Dennis Tillman"
<dennis@ridesoft.com> wrote:

Max Mazza's comments about the 2N2222 causing the oscillation are right on!
That is easy to test as he explains by simply switching to a slower
transistor (one with a lower frequency response. Power transistors like a
2N3055 are ideal and usually easy to come by in dozens of cheap plastic case
variants if you don't have an actual 2N3055. Alternatively a small ceramic
cap from B to C will work swamp out the possibility of oscillation.


WTB or trade: DM502A chassis parts

Mike
 

I have a working unit (option 2 = no thermometer) which needs a serviceable front subpanel and display lens.

Would consider trading this instead for something interesting...

While I'm begging, I could also use a hook tip for a P6201, p/n 013-0135-00, if anyone's parting out a kit.

Contact off-list please.

mike


Re: DSO suffers aliasing problem

Michael Dunn
 

For those who need to brush up on sampling concepts, I've got an ongoing series - Intuitive Sampling - running on Scope Junction. It starts here:

http://www.scopejunction.com/author.asp?section_id=1835&doc_id=247908

At 4:30 PM -0700 10/2/12, Bernice Loui wrote:
How do AA filters affect the information digitized, then displayed and stored?


Filters (analog or ___) in the signal path going in and going (DSP) out will have their effects on the signal.

There is far more than just "flat frequency response" to all this data conversion stuff.


Not saying DSOs are worst or better than analog, just one really needs to understand their limitations and how their inherent system nature can affect the measurement, waveforms displayed and data acquired.


Re: Help with a Tek 575 Curve tracer - New to group

 

The ripple on the last two supplies is what concerns me. The DC level can be adjusted via a pot but that AC ripple is way out of line indicating the power supply electrolytics are dying. They are not dead yet or you wouldn’t have such a promising display on your CRT. For a quick test of what replacing the electrolytics will do for you try jumping a good electrolytic across the 100V supply (and the 300V as well) then take another picture.

 

Max Mazza’s comments about the 2N2222 causing the oscillation are right on! That is easy to test as he explains by simply switching to a slower transistor (one with a lower frequency response. Power transistors like a 2N3055 are ideal and usually easy to come by in dozens of cheap plastic case variants if you don’t have an actual 2N3055. Alternatively a small ceramic cap from B to C will work swamp out the possibility of oscillation.

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Scott Harris
Sent: Tuesday, October 02, 2012 8:46 PM
To: TekScopes@...
Subject: Re: [TekScopes] Help with a Tek 575 Curve tracer - New to group

 



I checked the supply voltages and they are way out of whack:

 

Test point                    DC                  AC RMS w/voltmeter             Nominal ripple V pk-pk from manual 

 

-150V                          -159     4 mV                                                   10mV

 

100V                           94.3V  6.13V                                                  10mV

 

300V                           368V   2.92V                                                  25mV

 

 

So I definitely need to start replacing caps.

 

Thanks,

-Scott

 

On Oct 2, 2012, at 8:35 PM, "Dennis Tillman" <dennis@...> wrote:



 

 

Scott,

 

A picture is worth a thousand words! Generally speaking there are no SERIOUS problems showing on this 575 screen. Among the things I do see all are relatively minor and easily fixed or adjusted for.

 

·         First thing I notice is too many steps. I thought the 575 was limited to 10 steps per family. You have 14! So either I am remembering wrong or your step generator subsystem needs adjustment. Anything beyond 10 steps and the trace is moving too slowly to keep up with the phosphor decay rate so steps start to show different brightness levels because the trace can’t get back to the beginning fast enough to refresh the screen. Try turning the base step generator knob down to no more than 10 steps per family for now and retake the picture.

 

·         Next, the vertical line in the lower left quadrant looks like beam retrace, and is not really important but you could adjust it as well. It will be in the Z axis or CRT Blanking subsection of adjustments. The way the brightness changes on the first few curves is another indication that the Z Axis / Blanking circuit is not working right or it needs adjustment.

 

·         Third thing I notice is the curves are not suffering from stray capacitance so the loops are not due to too tiny base steps. Instead the pattern of each step looks like it might be due to weak or dried out power supply electrolytics. The curves are generated at 120Hz or 240hz so AC ripple will show up on the traces and distort them. Check the ripple and regulation on all the supplies. Try switching the Step/Sec toggle to all 3 positions to see what effect that has. Usually one position will be much better than the other two.

 

·         Fourth thing I see is random noise on several of the curves. I’m not sure what is doing that but I suppose it could be the power supply electrolytics again or a noisy pot.

 

·         Lastly, the bottom most step (0 current) is horizontal so that tells me you do not need to adjust the Beam rotation. However

 

On the 2nd photo (short between emitter and collector) you also have a loop. That could again be due to power supply electrolytics. The loop is tilted but because of my last comment above I do not think this is due to a trace rotation issue. Instead it is probably due to the power supply electrolytics again.

 

Since the power supply electrolytics affect everything else, and since they are almost guaranteed to have exceeded their lifetime by now, I would replace them first and observe how it improves everything else before making any adjustments. Bottom line is you appear to have a good 575 on the verge of working perfectly with a little work and tender loving care.

 

Dennis

 

From: TekScopes@... [mailto:TekScopes@yahoogroups.com] On Behalf Of Scott Harris
Sent: Tuesday, October 02, 2012 2:24 PM


 

Here's what I get when I trace a 2N2222

 

<image001.jpg>

 

 

And here is the trace wit the base stepper off. 2V 1k series resistor, collector current vs base current

 

 

On Oct 2, 2012, at 2:03 PM, Bob Koller <testtech@...> wrote:




 

 

A picture of the CRT trace would be very helpful. As the other post indicated, check the power supplies first for both regulation and ripple. Also, it is quite common to have poor and unmatched tubes in these. I have repaired several, and often found weak tubes. Does this one have tubes or the FET retrofit in the front ends? A pass through the cal procedure will often lead to the problem area. One other thing, be suspicious of resistors that have gone out of tolerance, often by a lot, as well as leaky caps.

 

 


From: bldrbldr5 <scottrharris@...>
To: TekScopes@...
Sent: Tuesday, October 2, 2012 9:36 AM
Subject: [TekScopes] Help with a Tek 575 Curve tracer - New to group

 

 

Hi, I just got a Tek 575 and it seems to generally work. E.g. I can get a I-V trace for a diode and neon bulb that makes sense. When I trace a 2N2222 transistor plotting collector I-V and stepping base current, I get the general shape that I expect. However, the horizontal traces going out and back on collector voltage sweep are not on top of each other; they are displaced vertically, and one of the traces has a odd hitch in it.

Brief troubleshooting (I've only had the unit since Sunday):

1. I can not get the AB phase plots to look like those in the manual. The vertical traces that should be lines look like very narrow, tall triangles.

2. If I short C to E and with a load resistor of 1K, sweep collector voltage and plot collector current vs base voltage with the step generator turned off, I don't get a vertical line as expected. I get a tall, skinny oval.

Any ideas about where to start would be very helpful.

I'm also hoping to find somebody in the Denver/Boulder area with a tube tester so I can test all the tubes.

I can post pictures of the traces if that will help.

Thanks for any suggestions.

-Scott, N8YY

 

 

 

 

 





Re: Hi All Looking for Tektronix 500 series extender cables for plug

 

Some guy on ebay has the standard rigid 500 series extender listed all the
time.
I remember seeing it for at least a year. So he must have a store.
I don't think it was much money either. $10 comes to mind as the asking
price.
It was a rigid one.

Dennis

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of Morris Odell
Sent: Wednesday, October 03, 2012 1:18 AM

Hi all,

The best way to get around this for the standard plugin extender is to find
a junked 500 series scope and plugin, remove the connectors and make a cable
yourself. Regrettably these are not hard to find at hamfests etc. You do
need to be mindful of the shock hazard as the extenders carry the power
supplies and there's a lot of potentially fatal juice there!!! A plastic
cover over the connections is a good idea and be very careful working on the
outboard plugin.

The 555 also requires a special extender for the timebases and it's needed
for calibration. Finding the connectors for that one is not so easy and you
will need to be patient. I was lucky enough to find one on e**y years ago
for my 555 and it's one of my most treasured possessions.

Good luck!

Morris


Wow. You aren't kidding on the crazy expensive. $82 for a connector?
Oy.

Mark







------------------------------------

Yahoo! Groups Links


Re: P6139A probe question

ditter2
 

Jim,

Tek never published the schematics for the comp boxes in the P613x series. These probes have mid time constant correction networks that are tuned to the specific scope series they were designed to work with – they are not interchangeable without some degradation in high speed pulse response.

The schematics were not published because they do not consider the SMT parts to be serviceable, and they did not want to make it easy for the low end probe manufacturers to design knock offs.

That said, I am surprised that components on the comp board would be damaged from exceeding the power/frequency derating curve. Before you spend a lot of time troubleshooting the board, I would try swapping the tip attenuator capsule with another known good P6139A. You may find the damage is in the capsule.

- Steve

--- In TekScopes@yahoogroups.com, "Jim Garland" <4cx250b@...> wrote:

I burned out a P6139A probe yesterday, measuring a motorboating on a 300V
power supply (which I incorrectly assumed the probe would handle). I took
the probe apart and the fault appears to lie in the little PCB in the probe
housing, but I don't have a schematic, and some of the SMT components are
unmarked. Anybody have any suggestions for diagnosing the problem, or have a
circuit diagram? No diagram is included in the manual, and the parts listing
doesn't show any of the circuit board components. Thanks.

Jim W8ZR


Re: Help with a Tek 575 Curve tracer - New to group

Bob Koller <testtech@...>
 

No, I have never seen any docs, and speaking with knowledgeable ex-Tek guys, as I recall, they thought it was a factory mod, but didn't have any documentation. I have only worked on one or two that had it.



From: Tom Miller
To: TekScopes@...
Sent: Tuesday, October 2, 2012 1:27 PM
Subject: Re: [TekScopes] Help with a Tek 575 Curve tracer - New to group

 

Interesting. Is there any documentation on a fet conversion for the 575?
 
I fully agree that the tube matching makes a difference. You might try swapping a few around looking for an improvement. If you pulled all the tubes to clean the scope, that will mess things up for sure. Please don't ask me how I know this fact :(.
 
Thanks Bob.
 
 
Tom
 
----- Original Message -----
From: Bob Koller
Sent: Tuesday, October 02, 2012 4:03 PM
Subject: Re: [TekScopes] Help with a Tek 575 Curve tracer - New to group

 
A picture of the CRT trace would be very helpful. As the other post indicated, check the power supplies first for both regulation and ripple. Also, it is quite common to have poor and unmatched tubes in these. I have repaired several, and often found weak tubes. Does this one have tubes or the FET retrofit in the front ends? A pass through the cal procedure will often lead to the problem area. One other thing, be suspicious of resistors that have gone out of tolerance, often by a lot, as well as leaky caps.



From: bldrbldr5
To: TekScopes@...
Sent: Tuesday, October 2, 2012 9:36 AM
Subject: [TekScopes] Help with a Tek 575 Curve tracer - New to group

 
Hi, I just got a Tek 575 and it seems to generally work. E.g. I can get a I-V trace for a diode and neon bulb that makes sense. When I trace a 2N2222 transistor plotting collector I-V and stepping base current, I get the general shape that I expect. However, the horizontal traces going out and back on collector voltage sweep are not on top of each other; they are displaced vertically, and one of the traces has a odd hitch in it.

Brief troubleshooting (I've only had the unit since Sunday):

1. I can not get the AB phase plots to look like those in the manual. The vertical traces that should be lines look like very narrow, tall triangles.

2. If I short C to E and with a load resistor of 1K, sweep collector voltage and plot collector current vs base voltage with the step generator turned off, I don't get a vertical line as expected. I get a tall, skinny oval.

Any ideas about where to start would be very helpful.

I'm also hoping to find somebody in the Denver/Boulder area with a tube tester so I can test all the tubes.

I can post pictures of the traces if that will help.

Thanks for any suggestions.

-Scott, N8YY





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