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Re: 2440 CCD Problem - HELP!

Rich Miller
 

Hi Peter:

To answer your question, over by the gain cell board's; two SD5000's
Switching IC's, one of which is common to channel one. I investigated this
IC, and could find nothing wrong. I then brushed my hand against the CCD
hybrid heat sink, and was surprised how hot it was. I did have a small
muffin fan blowing over the circuit board, but I don't think it was enough.

As a result, I now have large blower in place, and things seemed to have
stabilized. I am going to attempt CCD calibration one more time, and
hopefully this is the answer to the problem.

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of Peter Gottlieb
Sent: Saturday, September 25, 2010 4:35 PM
To: TekScopes@...
Cc: Rich Miller
Subject: Re: [TekScopes] 2440 CCD Problem - HELP!

Do you think the fault is temperature related or time running related?

I don't have my 2440 manual here but what is common to all 4 "sides"?
Could an input start getting a DC drift?

Peter


On 9/25/2010 1:35 PM, Rich Miller wrote:

Hello All:

I had hoped fixing the +5V power supply issue would have solved my CCD
issue. Unfortunately, this was not the case. Last night I attempted to
complete the CCD Adjustment Procedure, as outlined in section 5. When
I completed Section 8E - Do a SEL CAL and verify initial CCD gain, I
am getting a FAIL status on 7230 for Sides 1, 2, 3, and 4 of Channel
1. At that point I decided to swap hybrid's U450, and U350 to see if
the fault followed the hybrid to Channel 2, but to my surprise the
faults remained on Channel 1.

Another symptom which makes this fault incredibly difficult to
diagnose, is the fact that is only shows up after the unit has been
running for a period of time (i.e. 15 - 20 minutes). If I restart the
scope, all test pass without issue, and it's not until after some time
has passed before FAULT 7230 shows up. For this reason it makes it
very difficult to test while the fault condition exists.

I am going to proceed with the calibration procedure (Beyond Step 8E),
in the hope that a parameter is so far out of whack, it is triggering
the fault. Has anyone else seen this before, and if so what where your
findings?

Rich


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

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Re: 7704A Saga continued.

John Griessen
 

On 09/25/2010 04:07 PM, Jerry Massengale wrote:
I have an attitude problem at the moment. I like the idea of connecting the clamps to ground rather than
the + and - 15V.
Sounds like a reasonable mod to do. Or you could clamp with two diode drops each side.
If you're talking about the signal going into an op amp one
diode drop would be a fine protection circuit and not bother the signal.

John

Re: 7704A Saga continued.

Jerry Massengale <jmassen418@...>
 

Goran,
 
I checked all the components around U10 and did not find anything wrong. I replaced the .01 cap and the 2 .001 caps with higher voltage rating caps. I replaced the diode clamps with 600V 1n4937s and tried it again. The anode popped again. I removed the CRT lead and connected my HV probe to the HVPS output. I the range switch on 20KV as I thought the anode voltage was 12KV. I powered up and the DVM went blank and the HV probe sizzled. I shut it off quickly but U10 sent up smoke signals again. I pulled the display unit off the aquisition unit and found one of the jumper connectors on the connector assembly that connects the top to the bottom was unplugged. I traced the blue wire back to the z-axis board. It is the Z axis Inhibit line. What happens with that line open is not clear to me now. I checked the DVM and HV probe on a good unit and the dvm/hv probes reads 20KV with a very light sizzle from the probe which is a beckman HV-211. I am thinking now that I may have an overvoltage condition on the HV. If someone can tell me what will happen with the connector jumper unplugged I would be very grateful. I am replacing the 741 again and will decide what comes next. I have an attitude problem at the moment. I like the idea of connecting the clamps to ground rather than the + and - 15V.
 
jerry


--- On Sat, 9/25/10, Göran Krusell wrote:

From: Göran Krusell <goran.krusell@...>
Subject: [TekScopes] 7704A Saga continued.
To: "TekScopes@..."
Date: Saturday, September 25, 2010, 3:41 PM

 
Jerry,
I had a very similar problem with my 7904. The IC was broken in some way, the input offset was 1V, and my guess was that the circuit was destroyed by an input pulse being too high. I exchanged the IC and moved the two protecting diodes to clip around ground instead of +/-15V. There after no problem.

Göran
Re: 7603

Tom Miller <tmiller@...>
 

Have you verified all the power supply voltages are good?
 
Tom
 
 

----- Original Message -----
From: milesdj8
Sent: Saturday, September 25, 2010 4:10 PM
Subject: [TekScopes] 7603

 

Hello .
I have a 7603 with a 7A26 vert amp, now with no signal trace. If I connect a sig gen with 2Khz sine wave signal, all I see on the screen is the screen information numbers jumping up and down for a while before they settle down, but no signal trace. I have noticed for some months, that it was difficult to get the trace in the centre of the screen on some ranges, but I didn't think anything of it.

Has anyone any idea what could be wrong?

David Miles.
Re: 7603

jvanderwall1941
 

Just to narrow it down, can you use a different vertical plug-in? Have you tried both channels of the 7A26?

What do you see when you either free-run the sweep or trigger it from the line and activate the beam finder?

Regards.

Jonathan

--- In TekScopes@..., "milesdj8" <bwex@...> wrote:

Hello .
I have a 7603 with a 7A26 vert amp, now with no signal trace. If I connect a sig gen with 2Khz sine wave signal, all I see on the screen is the screen information numbers jumping up and down for a while before they settle down, but no signal trace. I have noticed for some months, that it was difficult to get the trace in the centre of the screen on some ranges, but I didn't think anything of it.

Has anyone any idea what could be wrong?

David Miles.
7704A Saga continued.

Göran Krusell <goran.krusell@...>
 

Jerry,
I had a very similar problem with my 7904. The IC was broken in some way, the input offset was 1V, and my guess was that the circuit was destroyed by an input pulse being too high. I exchanged the IC and moved the two protecting diodes to clip around ground instead of +/-15V. There after no problem.

Göran

Re: 2440 CCD Problem - HELP!

Peter Gottlieb <hpnpilot@...>
 

Do you think the fault is temperature related or time running related?

I don't have my 2440 manual here but what is common to all 4 "sides"? Could an input start getting a DC drift?

Peter

On 9/25/2010 1:35 PM, Rich Miller wrote:

Hello All:

I had hoped fixing the +5V power supply issue would have solved my CCD issue. Unfortunately, this was not the case. Last night I attempted to complete the CCD Adjustment Procedure, as outlined in section 5. When I completed Section 8E - Do a SEL CAL and verify initial CCD gain, I am getting a FAIL status on 7230 for Sides 1, 2, 3, and 4 of Channel 1. At that point I decided to swap hybrid's U450, and U350 to see if the fault followed the hybrid to Channel 2, but to my surprise the faults remained on Channel 1.

Another symptom which makes this fault incredibly difficult to diagnose, is the fact that is only shows up after the unit has been running for a period of time (i.e. 15 - 20 minutes). If I restart the scope, all test pass without issue, and it's not until after some time has passed before FAULT 7230 shows up. For this reason it makes it very difficult to test while the fault condition exists.

I am going to proceed with the calibration procedure (Beyond Step 8E), in the hope that a parameter is so far out of whack, it is triggering the fault. Has anyone else seen this before, and if so what where your findings?

Rich
7603

Göran Krusell <goran.krusell@...>
 

David,
what do you get in the other vertical slot? Or with no vertical plug-in at all, only the time base in auto mode?

Göran

7603

milesdj8 <bwex@...>
 

Hello .
I have a 7603 with a 7A26 vert amp, now with no signal trace. If I connect a sig gen with 2Khz sine wave signal, all I see on the screen is the screen information numbers jumping up and down for a while before they settle down, but no signal trace. I have noticed for some months, that it was difficult to get the trace in the centre of the screen on some ranges, but I didn't think anything of it.

Has anyone any idea what could be wrong?

David Miles.

F/S: Redout encoding BNC connectors

Dave Casey <dcasey@...>
 

Howdy all -
 
I have a limited quantity of crimp style male BNC connectors available. These have the plastic outer housing with the spring loaded pin and resistor for 10x readout encoding. These look exactly like the connectors used on the probe compensation boxes except they are to be crimped on to a cable.
These appear to be sized for RG-58. I DO NOT have the center pins or crimping ferrules (this design already has the teflon insulator built in), so you'll have to source those elsewhere.
These are brand new and the plastic is pliable, so you could remove the readout bits and put them on another connector, however the connector has to be notched in order for things to fit properly.
You could also probably use the parts to repair a broken probe compensation box if the readout pin was damaged or missing.
Photos (including an exploded view of one I took apart) are available upon request.
 
$3 each, plus $5 S/H within the US, regardless of quantity. International shipping will be extra.
 
First come, first serve until all are spoken for. If you'd like more than 5, please consider your fellow TekScopers and defer yourself to the back of the line for any additional pieces.
Please reply off list.
 
Dave Casey
Sent from my PC
Re: HV supply tektronix 535A

majefepe
 

Hi, sorry for my

--- In TekScopes@..., guy allo <tek508@...> wrote:
hi, actually the high voltage is +8650 v. The comparator is a 12AU7A valve and 6au6 for 100v. I downloaded the cathode voltage up to-1200v and then went up to -1400V. but in the grid I have always comparator-161v. I checked the circuit, but always I have this voltage. so that any variation in load does not affect this tension, is always fixed. Any idea? Thank you.
Hi,
I have one one my bench.
Which high voltage supply ? CRT high voltage +8650Volts?
What is the comparator valve number?  V664 for the +100V supply?
Tek508



________________________________
From: majefepe <majefepe@...>
To: TekScopes@...
Sent: Sat, September 25, 2010 5:57:29 PM
Subject: [TekScopes] HV supply tektronix 535A

I need help, I have a tektronix 535A and I have a problem at the source of high
voltage, the comparator output is always 160 volts, the output is independent of
the cathode voltage, which does not stabilize this tension, which can be the
problem? changed and high voltage capacitors and comparator valve to no avail.
The resistance of the comparator are good, what can be the problem? Thank you
all for your help.



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

Yahoo! Groups Links
Re: HV supply tektronix 535A

guy allo
 

Hi,
I have one one my bench.
Which high voltage supply ? CRT high voltage +8650Volts?
What is the comparator valve number?  V664 for the +100V supply?
Tek508

From: majefepe <majefepe@...>
To: TekScopes@...
Sent: Sat, September 25, 2010 5:57:29 PM
Subject: [TekScopes] HV supply tektronix 535A

I need help, I have a tektronix 535A and I have a problem at the source of high voltage, the comparator output is always 160 volts, the output is independent of the cathode voltage, which does not stabilize this tension, which can be the problem? changed and high voltage capacitors and comparator valve to no avail. The resistance of the comparator are good, what can be the problem? Thank you all for your help.



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

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2440 CCD Problem - HELP!

Rich Miller
 

Hello All:

 

I had hoped fixing the +5V power supply issue would have solved my CCD issue. Unfortunately, this was not the case. Last night I attempted to complete the CCD Adjustment Procedure, as outlined in section 5. When I completed Section 8E - Do a SEL CAL and verify initial CCD gain, I am getting a FAIL status on 7230 for Sides 1, 2, 3, and 4 of Channel 1.  At that point I decided to swap hybrid's U450, and U350 to see if the fault followed the hybrid to Channel 2, but to my surprise the faults remained on Channel 1.

 

Another symptom which makes this fault incredibly difficult to diagnose, is the fact that is only shows up after the unit has been running for a period of time (i.e. 15 - 20 minutes). If I restart the scope, all test pass without issue, and it's not until after some time has passed before FAULT 7230 shows up. For this reason it makes it very difficult to test while the fault condition exists.  

 

I am going to proceed with the calibration procedure (Beyond Step 8E), in the hope that a parameter is so far out of whack, it is triggering the fault. Has anyone else seen this before, and if so what where your findings?

 

 

Rich

 

 

 

 
7704A Saga continued.

Jerry Massengale <jmassen418@...>
 

Hi,
 
After re-repairing the anode lead on a 7704A crt I ran the 7704A the rest of the day yesterday(maybe 8 hours) and fired it up this morning. After an hour I stepped out of the room to refill my coffee and heard the unit snapping again. I assumed it was HV leaking and came back to shut it down. Much to my surprise it snapped again and U4110, a 741 on the z-axis board let the smoke out.
 
This leads me to wonder if it was the z-axis board that was snapping Wednesday. Looking at the schematic, U4110 is protected somewhat by clamping diodes to plus and minus 15V. I have removed the z-axis unit and am checking the components around U4110 and am not seeing problems. I have checked C4106, my first suspect, and it test good and holds up being run at the highest voltage my curve tracer will output.
 
I am tempted to replace the 741 and try again. Any advice will be welcome. The old 741 cracked in 3 pieces. 
 
jerry
Re: Tek 7904 vertical drift.

Jerry Massengale <jmassen418@...>
 

Hi,
 
I have never seen this problem on a 7904 but I once had a 7603 that required the mounted hardware on the vertical amp to be tightned down. You might retighten the mounting hardware and the ground strap hardware and uninstall and reinstall the ICs a couple of times.
 
jerry


--- On Sat, 9/25/10, Peter Ricardo wrote:

From: Peter Ricardo
Subject: [TekScopes] Tek 7904 vertical drift.
To: TekScopes@...
Date: Saturday, September 25, 2010, 8:46 AM

 
Hi forum.
My 7904 is basically working fine, but... sometimes after switching the unit on, the horizontal trace and the readout are not where they should be, meaning both are about 2/10 of an inch (5mm) below there proper position. After a while both slowly move to there correct position. The same problem occurs sometimes while the scope was running for hours.
I found out that (scope still on power) by pushing one or both of the Y units the trace(s) and readout are moving  to the correct position. So what was is more obious as looking for a bad contact? I removed both Y plug in units and switched on. The X trace as well as the readout are shifted by about the same amount as described above.
The vertical Amp is located between the two Y channel sockets. The ser# of the scope is 260000 up. So when I pushed slightly on the printed circuit, especially one of the two big IC's, the trace on the CRT jumps to the correct position and does not move again. I removed the Y amp from the frame but could not find anything to be suspected. If only one vertical plug in is inserted, the problem occurs also, then by sliding my hand in to the empty Y location and pushing at the Y PCB the trace and readout jump to there correct position.
Is there anything known about bad contacts I could not see or find? Alle the little coax connectors are ok. The little stud connectors look ok.
It's not really a big thing, but no problem at all would be better.
Thanks a lot for any help.
Peter
HV supply tektronix 535A

majefepe
 

I need help, I have a tektronix 535A and I have a problem at the source of high voltage, the comparator output is always 160 volts, the output is independent of the cathode voltage, which does not stabilize this tension, which can be the problem? changed and high voltage capacitors and comparator valve to no avail. The resistance of the comparator are good, what can be the problem? Thank you all for your help.

Tek 7904 vertical drift.

peter19a
 

Hi forum.
My 7904 is basically working fine, but... sometimes after switching the unit on, the horizontal trace and the readout are not where they should be, meaning both are about 2/10 of an inch (5mm) below there proper position. After a while both slowly move to there correct position. The same problem occurs sometimes while the scope was running for hours.
I found out that (scope still on power) by pushing one or both of the Y units the trace(s) and readout are moving  to the correct position. So what was is more obious as looking for a bad contact? I removed both Y plug in units and switched on. The X trace as well as the readout are shifted by about the same amount as described above.
The vertical Amp is located between the two Y channel sockets. The ser# of the scope is 260000 up. So when I pushed slightly on the printed circuit, especially one of the two big IC's, the trace on the CRT jumps to the correct position and does not move again. I removed the Y amp from the frame but could not find anything to be suspected. If only one vertical plug in is inserted, the problem occurs also, then by sliding my hand in to the empty Y location and pushing at the Y PCB the trace and readout jump to there correct position.
Is there anything known about bad contacts I could not see or find? Alle the little coax connectors are ok. The little stud connectors look ok.
It's not really a big thing, but no problem at all would be better.
Thanks a lot for any help.
Peter
Re: 7704a crt repair

Jerry Massengale <jmassen418@...>
 

Greg,
 
No, the pix are from the 23rd, the day I repaired the lead. A picture is worth a thousand words. You can go to the yahoo groups icon on your toolbar, select TekScopes from your list of groups, select photos, add photos. Your can also create albums. It is user friendly and will not hurt to play with it. You can add or delete photos as you please. I enjoyed talking to you. It occured to me later that I should have asked you about the scope you will be taking the CRT from. Can you describe what you have available for sale and your asking price excluding shipping cost. I am retired and spend my days repairing and rebuilding scopes. Even hardware and knobs and such are important to me.
 
jerry
 
ps; My cellphone works very poorly in my remote location. I rarely try to make long distance calls.


--- On Sat, 9/25/10, Greg_A wrote:

From: Greg_A
Subject: Re: [TekScopes] 7704a crt repair
To: TekScopes@...
Date: Saturday, September 25, 2010, 8:19 AM

 
Jerry hi,

was good to talk to you on phone already....

7704acrt 004 - those only from Sept 24th?
Show the anode area RTV high voltage...good pictures.

Question - how to upload like saved photo's to the Yahoo site - like you did yours? Is some other password needed and maybe some software?

be in touch,

Greg


At 08:07 AM 9/24/2010, you wrote:
 

hi,
 
see album 7704a crt lead.
 
jerry
Re: 7704a crt repair

Greg_A <greg.a@...>
 

Jerry hi,

was good to talk to you on phone already....

7704acrt 004 - those only from Sept 24th?
Show the anode area RTV high voltage...good pictures.

Question - how to upload like saved photo's to the Yahoo site - like you did yours? Is some other password needed and maybe some software?

be in touch,

Greg


At 08:07 AM 9/24/2010, you wrote:

 

hi,
 
see album 7704a crt lead.
 
jerry
THS 700 series portable scope

coolhand_21_21 <coolhand21_21@...>
 

Hi does anyone have experience with these portable scope, how do they compare with the fluke 190 series?

They seen to have limited memory, would aliasing be a issue?

thank cool

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