Date   

Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail

Göran Krusell <goran.krusell@...>
 

Hello guys,

I think Jerry is right. A 100mV ripple on +100V DC is not the problem in this case. In some cases the ripple enters as a common mode signal and this is never a problem. Of course, if you want to do the experiment and insert an LCL-filter you can do that. Such a filter calls for some calculations but first you need to measure the DC current. It is quite possible to build such a filter using some standard components. But my guess is that you will not see any difference at all.

If you have a substantial rippel on a supply voltage (like 10%) then it would show up as a problem but this is not the case here. The problem is somewhere in the amplifier chain I believe...

On the other hand, what tells you that this ripple has the same frequency as the ripple/noise that you see on the CRT...?

Göran


Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail

Tom Miller <tmiller@...>
 

Hi Tom,
 
I think you may be on to something. There is a wire jumper (W-955) that could be lifted and a series impedance with a cap to ground would clean up the +100Va buss. Maybe a small choke and a 10 uF 168 volt cap? Or just add a larger low ESR cap across the 33 uF cap for a test. The +100Vb1 has a 10 ohm resistor and a 0.1 uF cap for decoupling.
 
Vauga is in a good position to work this out. If he had an isolation transformer, that would make things much easier. May he lives near someone on the list that has one?
 
 
Regards,
Tom M
 
 
 

----- Original Message -----
From: tom jobe
Sent: Monday, May 23, 2011 4:53 PM
Subject: Re: [TekScopes] Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail

 

Hi Vauga,
I was studying the service manual for the 2235 military version, which is
what it looks like you have. The military 2235 seems to be a slightly higher
quality 22xx scope in my experience, even though all of what I think of as
the "Beaverton design" 22xx's are quite nice and quite similar.
The +100 volt supply is used on several circuits that go to the CRT such as
the Horizontal Deflection Plates, the Grid Bias, the Z axis ,and the
Geometry circuits. The +100 volt supply is used very directly to these
circuits with a very small capacitor right at the point of each use.
Look at the far right side of schematic <6> and notice how many places the
+100 volt supply is used just before those horizontal leads that go up to
the CRT. It is no surprise that this seemingly small ripple might be causing
so much grief.
Since this problem seems so common in the 22xx scopes, I'm thinking that you
are not looking for a defective component, I think we are looking for a
modification of some kind.
I wonder what kind of a modification it would take to eliminate the 100 mV
ripple from a +100 volt supply? Maybe we will luck out and the brighter and
more experienced folks on Tekscopes will offer some suggestions on this
matter.
"Thank You!" in advance to anyone who might have any thoughts on this
problem or on my speculations.
tom jobe...

----- Original Message -----
From: "vaugha69" <vaugha_brewchuk@...>
To: <TekScopes@...>
Sent: Monday, May 23, 2011 10:37 AM
Subject: [TekScopes] Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU
rail

Hello Tom,

Thank you for your quick response! Yes, I replaced C940, but the closest I
could source was a 1200uF Nichicon PW, which in the worst case scenario
could fall outside of the maximum specified tolerance of 1000uF + 30%. Mind
you, I had to do pretty much the same for most of the other capacitors,
except all the other replacements fall within the original tolerance bands:
C954 47uF vs. 33uF; C956 390uF vs. 270uF; C960 etc. 1200uF vs. 840uF; C942 &
C943 15uF vs. 10uF.

I also have at the ready a United Chemi-Con 100uF, 400V (could not source
450V) KXG series capacitor, so I can easily replace C906. I got a bit of a
cold feet syndrome since the KXG is 1/4 the size of the Sprague cap, and I
also read elsewhere that the Sprague telephone grade caps last "forever". I
found that last bit hard to believe mind you, since it is an electrolytic
after all. I could not find the ripple current rating of the Sprague
capacitor, but I'm guessing that the KXG will work just fine. Maybe I
should jus go ahead and replace C906?

I was wondering whether replacing the original 0.01uF 3000V caps with
polypropylene could have disrupted the power supply somehow? Or perhaps it
could be the overall collection of slightly higher than nominal capacitance
on all the output filter caps?

I realize that I am shotgunning the whole issue, but I really did not mind
replacing all the electrolytics. I have been doing this for most of my
other equipment at around 15 to 20 years of use as preventative maintenance.
Unfortunately I do not have access to an isolation transformer.

Thank you again,
Vaugha.

--- In TekScopes@..., "Tom Miller" wrote:
>
> Hello Vaugha,
>
> I would replace C-906 as it is the main filter for the supply.
>
> You can't really check the ripple on that cap without an isolation
transformer.
>
> Did you replace C-940? Without an isolation transformer you are just
shotgunning for the main problem.
>
>
>
> Tom
>
>
>
> ----- Original Message -----
> From: Vaugha Brewchuk
> To: TekScopes@...
> Sent: Monday, May 23, 2011 11:05 AM
> Subject: [TekScopes] 2235 with 360 kHz 100mV P-P ringing on +100V PSU
rail [1 Attachment]
>
>
>
> [Attachment(s) from Vaugha Brewchuk included below]
>
> Good day,
>
> This is my first post about my first scope that I purchased recently. I
am also not an electronics technician, so please be gentle with me :-).
>
> The scope is in excellent condition and has been recently calibrated.
However, when using the scope I noticed occasional small ripples in the
traces. I opened the scope and tested the power supplies and determined that
the ripple on all the rails was 2 to 3 times larger than the limit quoted in
the service manual. Consequently I replaced all electrolytic capacitors in
the power supply, except the C906 input filter capacitor, with Nichicon PW
series capacitors. I used the exact same capacity components where the
originals were +/-20% and the next larger capacity where the originals
were -10% to +30, +50 or +100%. I also replaced the four 0.01uF 3000V
capacitors with CDE 940C30S1K-F polypropylene capacitors.
>
> Unfortunately the occasional ripples have not completely disappeared
after the overhaul even though the traces seem to be a bit sharper. The
ripples on all the power supply rails have significantly reduced, with the
exception of the +100V rail. Here the actual low frequency ripple seems to
be in check at approximately 30mV P-P, but every second ripple peak exhibits
damped high frequency ringing at approximately 350 - 360kHz with 100mV P-P
amplitude. I attached an image showing the ripple and the ringing on the
+100V rail.
>


Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail

tom jobe <tomjobe@...>
 

Hi Vauga,
I was studying the service manual for the 2235 military version, which is
what it looks like you have. The military 2235 seems to be a slightly higher
quality 22xx scope in my experience, even though all of what I think of as
the "Beaverton design" 22xx's are quite nice and quite similar.
The +100 volt supply is used on several circuits that go to the CRT such as
the Horizontal Deflection Plates, the Grid Bias, the Z axis ,and the
Geometry circuits. The +100 volt supply is used very directly to these
circuits with a very small capacitor right at the point of each use.
Look at the far right side of schematic <6> and notice how many places the
+100 volt supply is used just before those horizontal leads that go up to
the CRT. It is no surprise that this seemingly small ripple might be causing
so much grief.
Since this problem seems so common in the 22xx scopes, I'm thinking that you
are not looking for a defective component, I think we are looking for a
modification of some kind.
I wonder what kind of a modification it would take to eliminate the 100 mV
ripple from a +100 volt supply? Maybe we will luck out and the brighter and
more experienced folks on Tekscopes will offer some suggestions on this
matter.
"Thank You!" in advance to anyone who might have any thoughts on this
problem or on my speculations.
tom jobe...

----- Original Message -----
From: "vaugha69" <vaugha_brewchuk@...>
To: <TekScopes@...>
Sent: Monday, May 23, 2011 10:37 AM
Subject: [TekScopes] Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU
rail


Hello Tom,

Thank you for your quick response! Yes, I replaced C940, but the closest I
could source was a 1200uF Nichicon PW, which in the worst case scenario
could fall outside of the maximum specified tolerance of 1000uF + 30%. Mind
you, I had to do pretty much the same for most of the other capacitors,
except all the other replacements fall within the original tolerance bands:
C954 47uF vs. 33uF; C956 390uF vs. 270uF; C960 etc. 1200uF vs. 840uF; C942 &
C943 15uF vs. 10uF.

I also have at the ready a United Chemi-Con 100uF, 400V (could not source
450V) KXG series capacitor, so I can easily replace C906. I got a bit of a
cold feet syndrome since the KXG is 1/4 the size of the Sprague cap, and I
also read elsewhere that the Sprague telephone grade caps last "forever". I
found that last bit hard to believe mind you, since it is an electrolytic
after all. I could not find the ripple current rating of the Sprague
capacitor, but I'm guessing that the KXG will work just fine. Maybe I
should jus go ahead and replace C906?

I was wondering whether replacing the original 0.01uF 3000V caps with
polypropylene could have disrupted the power supply somehow? Or perhaps it
could be the overall collection of slightly higher than nominal capacitance
on all the output filter caps?

I realize that I am shotgunning the whole issue, but I really did not mind
replacing all the electrolytics. I have been doing this for most of my
other equipment at around 15 to 20 years of use as preventative maintenance.
Unfortunately I do not have access to an isolation transformer.

Thank you again,
Vaugha.

--- In TekScopes@..., "Tom Miller" <tmiller@...> wrote:

Hello Vaugha,

I would replace C-906 as it is the main filter for the supply.

You can't really check the ripple on that cap without an isolation
transformer.

Did you replace C-940? Without an isolation transformer you are just
shotgunning for the main problem.



Tom



----- Original Message -----
From: Vaugha Brewchuk
To: TekScopes@...
Sent: Monday, May 23, 2011 11:05 AM
Subject: [TekScopes] 2235 with 360 kHz 100mV P-P ringing on +100V PSU
rail [1 Attachment]



[Attachment(s) from Vaugha Brewchuk included below]

Good day,

This is my first post about my first scope that I purchased recently. I
am also not an electronics technician, so please be gentle with me :-).

The scope is in excellent condition and has been recently calibrated.
However, when using the scope I noticed occasional small ripples in the
traces. I opened the scope and tested the power supplies and determined that
the ripple on all the rails was 2 to 3 times larger than the limit quoted in
the service manual. Consequently I replaced all electrolytic capacitors in
the power supply, except the C906 input filter capacitor, with Nichicon PW
series capacitors. I used the exact same capacity components where the
originals were +/-20% and the next larger capacity where the originals
were -10% to +30, +50 or +100%. I also replaced the four 0.01uF 3000V
capacitors with CDE 940C30S1K-F polypropylene capacitors.

Unfortunately the occasional ripples have not completely disappeared
after the overhaul even though the traces seem to be a bit sharper. The
ripples on all the power supply rails have significantly reduced, with the
exception of the +100V rail. Here the actual low frequency ripple seems to
be in check at approximately 30mV P-P, but every second ripple peak exhibits
damped high frequency ringing at approximately 350 - 360kHz with 100mV P-P
amplitude. I attached an image showing the ripple and the ringing on the
+100V rail.


Re: Test Procedure manual for 7854 Diagnostic Troubleshooting on eBay

 

I never saw the Microlab 1 as I am in the UK, and it was probably a US only action - if I'd seen it I would probably have bought it.

D.

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Egge Siert
Sent: 23 May 2011 19:02
To: TekScopes@...
Subject: [TekScopes] Re: Test Procedure manual for 7854 Diagnostic Troubleshooting on eBay

Hi David,

Scans of this Manual can be found as addition on aa4df's 7854 Service Manual.

Regarding the Tektronix Microlab 1 Mainframe (aka 067-0892-00). A few months ago this item (in like new condition) was for sale on eBay.com several times. Eventually the price dropped to USD 39.95 and the auction ended still without any bid. I saved several pictures of it and will upload them asap to the Calibration Fixtures Photo Album.

Egge Siert



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

Yahoo! Groups Links


Value of a collection

silver_pelt <silver_pelt@...>
 

I'm considering selling or parting out my collection of scopes.

I have 2 Type 547, one 7633, and one Navy surplus (not Tek) whose model # I have to dig out.

All scopes are on carts.

547 Plugins:
3 each type A
Type E
Type Z
Type 1A4
Type O
Type 82
Type 1L10
Type 1A7A
Type 2A63
Type 53C

7633 plugins:
7A26
7A22
2 each 7B53A
7L13

Also a C27 camera.

Any expressions of interest or opinions on value welcome. Equipment is located in eastern MA.


Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail [1 Attachment]

jmassen418a@...
 

Vaughn,
 
I do not think 100mv and a 100V line is a problem worth replacing components for. Your placement of the probe ground could be affecting what you see. I do not believe your problem needs fixing.
 
jerry



-----Original Message-----
From: Vaugha Brewchuk
To: TekScopes
Sent: Mon, May 23, 2011 10:15 am
Subject: [TekScopes] 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail [1 Attachment]

 
[Attachment(s) from Vaugha Brewchuk included below]
Good day,

This is my first post about my first scope that I purchased recently. I am also not an electronics technician, so please be gentle with me :-).

The scope is in excellent condition and has been recently calibrated. However, when using the scope I noticed occasional small ripples in the traces. I opened the scope and tested the power supplies and determined that the ripple on all the rails was 2 to 3 times larger than the limit quoted in the service manual. Consequently I replaced all electrolytic capacitors in the power supply, except the C906 input filter capacitor, with Nichicon PW series capacitors. I used the exact same capacity components where the originals were +/-20% and the next larger capacity where the originals were -10% to +30, +50 or +100%. I also replaced the four 0.01uF 3000V capacitors with CDE 940C30S1K-F polypropylene capacitors.

Unfortunately the occasional ripples have not completely disappeared after the overhaul even though the traces seem to be a bit sharper. The ripples on all the power supply rails have significantly reduced, with the exception of the +100V rail. Here the actual low frequency ripple seems to be in check at approximately 30mV P-P, but every second ripple peak exhibits damped high frequency ringing at approximately 350 - 360kHz with 100mV P-P amplitude. I attached an image showing the ripple and the ringing on the +100V rail.



In addition, I also noticed that all of the supply rails exhibit intermittent
noise peaks overlayed on top of the ripple waveform.  These are perhaps 2mV P-P
on the low voltage rails and closer to 20mV P-P on the high voltage rails.  I am
guessing that this and the 100V ringing is not normal and that this is likely
the root cause of my trace ripples.

I would very much appreciate any words of wisdom from the experts regarding this
issue.  I spent some time studying the service manual schematic, but the power
supply design it is really beyond my level.

Thank you very much in advance!
Vaugha.


Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail

tom jobe <tomjobe@...>
 

Hi Vauga,
Your initial question is one of my ongoing 22xx mysteries too.
The 22xx's all seem to have the fine ripple in the trace, that comes and
goes as you use the scope. Some 22xx's have it worse than others but they
all seem to have it to some degree.
I checked a 2215A I have been working on and the trace at the plus lead of
C954 was the same as the picture you posted, with the exception that the
overall peak to peak voltage was 70 mV instead of the 95 mV you show (C954
is a new capacitor). The ringing was almost exactly the same, and the period
from ring to ring was about the same. This 2215A has many new capacitors in
it, but C904 and C906 are the original caps that check out fine with the ESR
meter. Now that you mention it, I don't think I have ever seen C906 be bad
on the ESR test, so I don't think I have ever replaced a C906 capacitor, or
a C904 for that matter, but then I have only worked on maybe 30 of these
22xx's.
It is great to see that Tom Miller has taken an interest in your question,
he really knows his stuff!
I'm like you, I barely know what I'm doing around these electronic marvels.
tom jobe...

----- Original Message -----
From: "vaugha69" <vaugha_brewchuk@...>
To: <TekScopes@...>
Sent: Monday, May 23, 2011 10:37 AM
Subject: [TekScopes] Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU
rail


Hello Tom,

Thank you for your quick response! Yes, I replaced C940, but the closest I
could source was a 1200uF Nichicon PW, which in the worst case scenario
could fall outside of the maximum specified tolerance of 1000uF + 30%. Mind
you, I had to do pretty much the same for most of the other capacitors,
except all the other replacements fall within the original tolerance bands:
C954 47uF vs. 33uF; C956 390uF vs. 270uF; C960 etc. 1200uF vs. 840uF; C942 &
C943 15uF vs. 10uF.

I also have at the ready a United Chemi-Con 100uF, 400V (could not source
450V) KXG series capacitor, so I can easily replace C906. I got a bit of a
cold feet syndrome since the KXG is 1/4 the size of the Sprague cap, and I
also read elsewhere that the Sprague telephone grade caps last "forever". I
found that last bit hard to believe mind you, since it is an electrolytic
after all. I could not find the ripple current rating of the Sprague
capacitor, but I'm guessing that the KXG will work just fine. Maybe I
should jus go ahead and replace C906?

I was wondering whether replacing the original 0.01uF 3000V caps with
polypropylene could have disrupted the power supply somehow? Or perhaps it
could be the overall collection of slightly higher than nominal capacitance
on all the output filter caps?

I realize that I am shotgunning the whole issue, but I really did not mind
replacing all the electrolytics. I have been doing this for most of my
other equipment at around 15 to 20 years of use as preventative maintenance.
Unfortunately I do not have access to an isolation transformer.

Thank you again,
Vaugha.

--- In TekScopes@..., "Tom Miller" <tmiller@...> wrote:

Hello Vaugha,

I would replace C-906 as it is the main filter for the supply.

You can't really check the ripple on that cap without an isolation
transformer.

Did you replace C-940? Without an isolation transformer you are just
shotgunning for the main problem.



Tom



----- Original Message -----
From: Vaugha Brewchuk
To: TekScopes@...
Sent: Monday, May 23, 2011 11:05 AM
Subject: [TekScopes] 2235 with 360 kHz 100mV P-P ringing on +100V PSU
rail [1 Attachment]



[Attachment(s) from Vaugha Brewchuk included below]

Good day,

This is my first post about my first scope that I purchased recently. I
am also not an electronics technician, so please be gentle with me :-).

The scope is in excellent condition and has been recently calibrated.
However, when using the scope I noticed occasional small ripples in the
traces. I opened the scope and tested the power supplies and determined that
the ripple on all the rails was 2 to 3 times larger than the limit quoted in
the service manual. Consequently I replaced all electrolytic capacitors in
the power supply, except the C906 input filter capacitor, with Nichicon PW
series capacitors. I used the exact same capacity components where the
originals were +/-20% and the next larger capacity where the originals
were -10% to +30, +50 or +100%. I also replaced the four 0.01uF 3000V
capacitors with CDE 940C30S1K-F polypropylene capacitors.

Unfortunately the occasional ripples have not completely disappeared
after the overhaul even though the traces seem to be a bit sharper. The
ripples on all the power supply rails have significantly reduced, with the
exception of the +100V rail. Here the actual low frequency ripple seems to
be in check at approximately 30mV P-P, but every second ripple peak exhibits
damped high frequency ringing at approximately 350 - 360kHz with 100mV P-P
amplitude. I attached an image showing the ripple and the ringing on the
+100V rail.


Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail

Tom Miller <tmiller@...>
 

I don't think it would hurt to try the 400 volt cap but it will leave very little headroom as on a 120 volt line, the cap voltage will run over 360 volts. Why not just tack it in and see what happens? Remember, it will hold a pretty good amount of energy and can be dangerous if you are not very careful. You can always go with a higher voltage capacitor.
 
The modern capacitors are much smaller than the old ones. They also have a lower ESR.
 
Since the problem is stable, why not do the same with the other caps while you monitor the waveform? Take a look at the 1 uF C-907 also.
 
Get a 1K 5 watt resistor and connect a pair of test leads to use to discharge the caps. Check them all with a DVM before touching them.
 
One more thing, are you sure the ground that you are connecting the scope probe to is not dirty? take a look at the negative end of C-954 to be sure.
 
An isolation transformer is essential now days since everything is switch mode off the line.
 
 
 
Regards,
Tom
 
 
 

----- Original Message -----
From: vaugha69
Sent: Monday, May 23, 2011 1:37 PM
Subject: [TekScopes] Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail

 

Hello Tom,

Thank you for your quick response! Yes, I replaced C940, but the closest I could source was a 1200uF Nichicon PW, which in the worst case scenario could fall outside of the maximum specified tolerance of 1000uF + 30%. Mind you, I had to do pretty much the same for most of the other capacitors, except all the other replacements fall within the original tolerance bands: C954 47uF vs. 33uF; C956 390uF vs. 270uF; C960 etc. 1200uF vs. 840uF; C942 & C943 15uF vs. 10uF.

I also have at the ready a United Chemi-Con 100uF, 400V (could not source 450V) KXG series capacitor, so I can easily replace C906. I got a bit of a cold feet syndrome since the KXG is 1/4 the size of the Sprague cap, and I also read elsewhere that the Sprague telephone grade caps last "forever". I found that last bit hard to believe mind you, since it is an electrolytic after all. I could not find the ripple current rating of the Sprague capacitor, but I'm guessing that the KXG will work just fine. Maybe I should jus go ahead and replace C906?

I was wondering whether replacing the original 0.01uF 3000V caps with polypropylene could have disrupted the power supply somehow? Or perhaps it could be the overall collection of slightly higher than nominal capacitance on all the output filter caps?

I realize that I am shotgunning the whole issue, but I really did not mind replacing all the electrolytics. I have been doing this for most of my other equipment at around 15 to 20 years of use as preventative maintenance. Unfortunately I do not have access to an isolation transformer.

Thank you again,
Vaugha.

--- In TekScopes@..., "Tom Miller" wrote:
>
> Hello Vaugha,
>
> I would replace C-906 as it is the main filter for the supply.
>
> You can't really check the ripple on that cap without an isolation transformer.
>
> Did you replace C-940? Without an isolation transformer you are just shotgunning for the main problem.
>
>
>
> Tom
>
>
>
> ----- Original Message -----
> From: Vaugha Brewchuk
> To: TekScopes@...
> Sent: Monday, May 23, 2011 11:05 AM
> Subject: [TekScopes] 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail [1 Attachment]
>
>
>
> [Attachment(s) from Vaugha Brewchuk included below]
>
> Good day,
>
> This is my first post about my first scope that I purchased recently. I am also not an electronics technician, so please be gentle with me :-).
>
> The scope is in excellent condition and has been recently calibrated. However, when using the scope I noticed occasional small ripples in the traces. I opened the scope and tested the power supplies and determined that the ripple on all the rails was 2 to 3 times larger than the limit quoted in the service manual. Consequently I replaced all electrolytic capacitors in the power supply, except the C906 input filter capacitor, with Nichicon PW series capacitors. I used the exact same capacity components where the originals were +/-20% and the next larger capacity where the originals were -10% to +30, +50 or +100%. I also replaced the four 0.01uF 3000V capacitors with CDE 940C30S1K-F polypropylene capacitors.
>
> Unfortunately the occasional ripples have not completely disappeared after the overhaul even though the traces seem to be a bit sharper. The ripples on all the power supply rails have significantly reduced, with the exception of the +100V rail. Here the actual low frequency ripple seems to be in check at approximately 30mV P-P, but every second ripple peak exhibits damped high frequency ringing at approximately 350 - 360kHz with 100mV P-P amplitude. I attached an image showing the ripple and the ringing on the +100V rail.
>


R3361B Spectrum Analyzer from TEK

 

Dear members:

I have a R3361B Spectrum Analyzer without any option when I purchase it long time ago.I want to add the options :OPT 04 ------ Occupied bandwidth measurement / adjacent channel leakage power measurement and OPT15 -------Controller feature ( including parallel I/O and serial I/O )
As I know it is phase out and no support from advantest since 2006.

I need some suggestion ,if I taken the OPT04 or OPT15 from other R3261B ( NOT R3361B )? if I can find other unit of R3261B with options on the open market. Any document can let me know ? or some option is software only !
Anyone can help ?
I did try to ask Advantest Japan,but the results are negative, same as other Japanese brand , poor service after sales !even documention for technical support always nothings !

Regard
Tony Cheung
VR2XGD
MAY 24 2011


Re: Test Procedure manual for 7854 Diagnostic Troubleshooting on eBay

Egge Siert <eggeja@...>
 

Hi David,

Scans of this Manual can be found as addition on aa4df's 7854 Service Manual.

Regarding the Tektronix Microlab 1 Mainframe (aka 067-0892-00). A few months ago this item (in like new condition) was for sale on eBay.com several times. Eventually the price dropped to USD 39.95 and the auction ended still without any bid. I saved several pictures of it and will upload them asap to the Calibration Fixtures Photo Album.

Egge Siert


TDS420 and 460

centrion1956
 

Does anyone have a copy of the last (or newer) firmware upgrades for the TDS420 and 460? Also looking for a manual on the TDS460, 070-8037-00 Module Level Service Manual. I'm trying to repair the old 460 and get rid of the FP fail and the ACQ fail messages. The built-in square wave generator is not functioning on the front panel, so I'm hoping that is causing the error there. The ACQ seems to be functioning somewhat, as I can use the probes on all of the inputs and they look ok so far. Comparing the 420 against the 460, the 420 has a FW version of 2.5.5e (if I remember right) and the 460 has something like 1.2. The 420 FW Version is a much better interface to operate. I'm going to test the caps and see if I see anything major that jumps out at me.

Thanks a Million !!!
Joe


Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail [1 Attachment]

Vaugha Brewchuk
 

Hello Tom,

Thank you for your quick response! Yes, I replaced C940, but the closest I could source was a 1200uF Nichicon PW, which in the worst case scenario could fall outside of the maximum specified tolerance of 1000uF + 30%. Mind you, I had to do pretty much the same for most of the other capacitors, except all the other replacements fall within the original tolerance bands: C954 47uF vs. 33uF; C956 390uF vs. 270uF; C960 etc. 1200uF vs. 840uF; C942 & C943 15uF vs. 10uF.

I also have at the ready a United Chemi-Con 100uF, 400V (could not source 450V) KXG series capacitor, so I can easily replace C906. I got a bit of a cold feet syndrome since the KXG is 1/4 the size of the Sprague cap, and I also read elsewhere that the Sprague telephone grade caps last "forever". I found that last bit hard to believe mind you, since it is an electrolytic after all. I could not find the ripple current rating of the Sprague capacitor, but I'm guessing that the KXG will work just fine. Maybe I should jus go ahead and replace C906?

I was wondering whether replacing the original 0.01uF 3000V caps with polypropylene could have disrupted the power supply somehow? Or perhaps it could be the overall collection of slightly higher than nominal capacitance on all the output filter caps?

I realize that I am shotgunning the whole issue, but I really did not mind replacing all the electrolytics. I have been doing this for most of my other equipment at around 15 to 20 years of use as preventative maintenance. Unfortunately I do not have access to an isolation transformer.

Thank you again,
Vaugha.

--- In TekScopes@..., "Tom Miller" <tmiller@...> wrote:

Hello Vaugha,

I would replace C-906 as it is the main filter for the supply.

You can't really check the ripple on that cap without an isolation transformer.

Did you replace C-940? Without an isolation transformer you are just shotgunning for the main problem.



Tom



----- Original Message -----
From: Vaugha Brewchuk
To: TekScopes@...
Sent: Monday, May 23, 2011 11:05 AM
Subject: [TekScopes] 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail [1 Attachment]



[Attachment(s) from Vaugha Brewchuk included below]

Good day,

This is my first post about my first scope that I purchased recently. I am also not an electronics technician, so please be gentle with me :-).

The scope is in excellent condition and has been recently calibrated. However, when using the scope I noticed occasional small ripples in the traces. I opened the scope and tested the power supplies and determined that the ripple on all the rails was 2 to 3 times larger than the limit quoted in the service manual. Consequently I replaced all electrolytic capacitors in the power supply, except the C906 input filter capacitor, with Nichicon PW series capacitors. I used the exact same capacity components where the originals were +/-20% and the next larger capacity where the originals were -10% to +30, +50 or +100%. I also replaced the four 0.01uF 3000V capacitors with CDE 940C30S1K-F polypropylene capacitors.

Unfortunately the occasional ripples have not completely disappeared after the overhaul even though the traces seem to be a bit sharper. The ripples on all the power supply rails have significantly reduced, with the exception of the +100V rail. Here the actual low frequency ripple seems to be in check at approximately 30mV P-P, but every second ripple peak exhibits damped high frequency ringing at approximately 350 - 360kHz with 100mV P-P amplitude. I attached an image showing the ripple and the ringing on the +100V rail.


Re: 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail [1 Attachment]

Tom Miller <tmiller@...>
 

Hello Vaugha,
 
I would replace C-906 as it is the main filter for the supply.
 
You can't really check the ripple on that cap without an isolation transformer.
 
Did you replace C-940? Without an isolation transformer you are just shotgunning for the main problem.
 
 
 
Tom
 
 
 

----- Original Message -----
Sent: Monday, May 23, 2011 11:05 AM
Subject: [TekScopes] 2235 with 360 kHz 100mV P-P ringing on +100V PSU rail [1 Attachment]

 

Good day,

This is my first post about my first scope that I purchased recently. I am also not an electronics technician, so please be gentle with me :-).

The scope is in excellent condition and has been recently calibrated. However, when using the scope I noticed occasional small ripples in the traces. I opened the scope and tested the power supplies and determined that the ripple on all the rails was 2 to 3 times larger than the limit quoted in the service manual. Consequently I replaced all electrolytic capacitors in the power supply, except the C906 input filter capacitor, with Nichicon PW series capacitors. I used the exact same capacity components where the originals were +/-20% and the next larger capacity where the originals were -10% to +30, +50 or +100%. I also replaced the four 0.01uF 3000V capacitors with CDE 940C30S1K-F polypropylene capacitors.

Unfortunately the occasional ripples have not completely disappeared after the overhaul even though the traces seem to be a bit sharper. The ripples on all the power supply rails have significantly reduced, with the exception of the +100V rail. Here the actual low frequency ripple seems to be in check at approximately 30mV P-P, but every second ripple peak exhibits damped high frequency ringing at approximately 350 - 360kHz with 100mV P-P amplitude. I attached an image showing the ripple and the ringing on the +100V rail.


2235 with 360 kHz 100mV P-P ringing on +100V PSU rail

Vaugha Brewchuk
 

Good day,

This is my first post about my first scope that I purchased recently. I am also not an electronics technician, so please be gentle with me :-).

The scope is in excellent condition and has been recently calibrated. However, when using the scope I noticed occasional small ripples in the traces. I opened the scope and tested the power supplies and determined that the ripple on all the rails was 2 to 3 times larger than the limit quoted in the service manual. Consequently I replaced all electrolytic capacitors in the power supply, except the C906 input filter capacitor, with Nichicon PW series capacitors. I used the exact same capacity components where the originals were +/-20% and the next larger capacity where the originals were -10% to +30, +50 or +100%. I also replaced the four 0.01uF 3000V capacitors with CDE 940C30S1K-F polypropylene capacitors.

Unfortunately the occasional ripples have not completely disappeared after the overhaul even though the traces seem to be a bit sharper. The ripples on all the power supply rails have significantly reduced, with the exception of the +100V rail. Here the actual low frequency ripple seems to be in check at approximately 30mV P-P, but every second ripple peak exhibits damped high frequency ringing at approximately 350 - 360kHz with 100mV P-P amplitude. I attached an image showing the ripple and the ringing on the +100V rail.



In addition, I also noticed that all of the supply rails exhibit intermittent noise peaks overlayed on top of the ripple waveform. These are perhaps 2mV P-P on the low voltage rails and closer to 20mV P-P on the high voltage rails. I am guessing that this and the 100V ringing is not normal and that this is likely the root cause of my trace ripples.

I would very much appreciate any words of wisdom from the experts regarding this issue. I spent some time studying the service manual schematic, but the power supply design it is really beyond my level.

Thank you very much in advance!
Vaugha.


Re: FYI; very clean 1L20 FS on ebay - now RG-62/93 ohm cables...

Jim Reese
 

Hi Bernd,
 
They are yours! $17 total.
 
Do you want any more if I find some?
 
Let me know your address again.
 
Paypal is fine to: jreese7010@...
 
Please use the gift payment option if you can.
 
Jim
 
Jim Reese
7010 Palmer Rd.
New Carlisle, Oh, 45344
937-845-3057


--- On Sun, 5/22/11, tubesnthings@... wrote:

From: tubesnthings@...
Subject: Re: [TekScopes] Re: FYI; very clean 1L20 FS on ebay - now RG-62/93 ohm cables...
To: nfeinc@..., TekScopes@...
Date: Sunday, May 22, 2011, 7:49 PM



In a message dated 5/22/2011 4:11:28 PM Pacific Daylight Time, nfeinc@... writes:
FYI,

I found 4 each 1 meter RG-62 (Belden 9269) cables with crimped BNC (M) connectors on them.

Let me know if anyone needs some. Figure $3 each plus shipping.

Regards,

Jim

 
I'll take 'em, Jim.
Bernd



Re: 2465(B) power supply recapping recommendations

 

You're welcome to disagree if you like. Most techs do, until they find themselves in the same boat ;-)

Investigation after the fact lead me to conclude the following:
The combination of high capacitance, low ESR and high lead inductance is a recipe for creating high-Q LC tank circuits and unwanted resonances at frequencies as low as a few kHz to 10s of kHz.
Those resonances will destroy associated semiconductors.

Any of you fellow techs out there who are more knowledgeable than me in LC design are welcome to expand on the issue.

You can hear the whistling, the (explosive) pop, then the tell-tale smell...

Been there, done that, learnt from experience.

Menahem Yachad
http://www.condoraudio.com


Test Procedure manual for 7854 Diagnostic Troubleshooting on eBay

 

<http://cgi.ebay.com/120726657765>

I spotted this the other day, I hope a group member will buy this and scan it ... I'm sure there's useful information in there beyond just using the unobtainable Microlab 1 and diagnostic ROM board.

Regards,
David Partridge


Re: Tek 'Handshake' newsletter (very long answer)

d.seiter@...
 

So the W prefix was original, and was later changed to P?  What do the prefixes designate?  I've always wondered about the P prefix, which was normally applied to probes.

Dave

----- Original Message -----
From: "Steve"
To: TekScopes@...
Sent: Thursday, May 19, 2011 8:36:22 PM
Subject: [TekScopes] Re: Tek 'Handshake' newsletter (very long answer)

 

--- In TekScopes@..., "Tim Phillips" wrote:
>
> from Tim P (UK)
> just had a filing-cabinet 'purge' and turned up a copy of something called
> 'Handshake - Newsletter of the Signal Processing Systems Users Group'
> It's dated Fall / Winter 1979, presumably a quarterly.
> It has examples in TEK SPS BASIC with code-segments for (in my copy)
> driving a 7912AD with a 4050 controller.
> Anyone familiar with this publication ? Are there any more issues archived anywhere?
>
> Tim
>

Hi Tim,

When I started at Tek as a design engineer in TM5000, we were in a division that included a sister product line – the transient digitizers. This included the engineers who wrote SPS Basic and the transient digitizer (hardware) group that the software supported.

SPS stood for "Signal Processing Software". This group pioneered the algorithms that went from mathematics text books to the practical application with digitized waveforms. Essentially, they did the ground work of what became ALL of the classical measurements in all DSOs today – including the first practical application of the Fast Fourier Transform (FFT) that generated frequency domain representation of time domain data.

The original code ran on a PDP 11 series minicomputer. We had several PDP11-34s for test beds in the department. It ran very fast and was very efficient – better than many of the early implementations in DSOs.

The hardware that acquired the signal that fed the code were a series of transient digitizers. I worked on the hardware of one of these – the 7612D. These used scan conversion technology to acquire a very short record (512 – 1024 samples) at a very high sampling rate for the day. The short capture time and relative long rearm time essentially limited them to fast single shot capture – which greatly limited the applications.

To overcome this limitation, a new product was proposed. The hardware group worked with the 7000 series design team to develop what was really the first DSO. The 7000 series team was starting a project to upgrade the 7704 into an "A" model, and with some political pull, the digitizer team was able to get the 7K team to add a feature to the new design – make the display section in a unit that could be separated from the "acquisition unit", similar to the topology used in 5000 series scopes. It was really a simple process, which is probably why it was approved. Essentially, the Acquisition unit was the lower half of the scope and contained the plug in slots, channel switching and trigger selection, and power supply. The Display section was the upper half and contains the CRT, Z axis circuit, and readout logic board. A single connector that separated the low frequency and differential X, Y, and Z signals from one side to the other was included – probably the most expensive part of this addition. Finally, the two units could be mechanically separated by removing a connection bar that latched them together. All 7704A units have this feature, and if you own one, you can separate them easily.

With this modification in hand, the digitizer group designed the "W7001". It was a module that would mounted between the 7704A Acquisition and Display sections. It contained a digitizer, and a waveform processor, based on the TI99000 16 bit microprocessor. (I believe it was the only application of that processor at Tek). The front panel included a key pad that had many pre-stored math waveforms, along with some user keys that allowed the user to program custom waveform analysis subroutines.

The waveform analysis was all based on SPS basic routines, and the same software team coded it. While the user interface was crude by today's standards (Still infinitely better than 11000 series which followed nearly a decade later), it had the basic concepts of waveform storage and recall worked out. I don't know the sampling rate, but it was not the full bandwidth of the 7704A. Unlike the transient digitizers, that had rather long rearm times, this acted more like a modern DSO, and allowed reasonable up date rate.

The product only really sold in the research and academia segments, and not to general scope users. But that was the way it was marketed. The marketing was done by the SPS group, not 7000 series. But the product paved the way for the 7854, which was grew on many of the W7001 basic concepts. You can almost equate it to how the Apple Lisa did the marketing groundwork for the Mac. Few people know of the Lisa or had ever seen one (I used one quite a bit at Tek), and by itself, it was a financial loser for Apple. But that was not the point. Rather it was a test platform to work out the concepts that ended up in the Mac. Same with the 7854.

Getting back to the original question – "Handshake" was a quarterly publication of the marketing group from SPS. It featured applications learned from customer interaction of the SPS software, as well as discussed the new product offerings. As the marketing group was in the same division as TM5000, when it came out, Handshake took on an additional role covering applications and technical notes from this product line. The publication morphed into a definition of applications news on any programmable instrumentation. At that time, it was pretty much limited to the digitizers and TM5000. Wilsonville was putting GPIB in their computing products (starting with the 4051 graphics controller), and because they chose an incredible intelligent IO addressing scheme in their architecture, these quickly became the controller of choice for automating data collection in engineering characterization applications.

(IMO – to this day, no one who has integrated GPIB into a PC platform (such as National Instruments) has come up with such an elegantly simple and easy to use method to pass data to and from the instruments to the program than the 4050 series does.)

- Steve


Re: FYI; very clean 1L20 FS on ebay - now RG-62/93 ohm cables...

widgethunter
 

In a message dated 5/22/2011 4:11:28 PM Pacific Daylight Time, nfeinc@... writes:
FYI,

I found 4 each 1 meter RG-62 (Belden 9269) cables with crimped BNC (M) connectors on them.

Let me know if anyone needs some. Figure $3 each plus shipping.

Regards,

Jim

 
I'll take 'em, Jim.
Bernd


Re: ESR meters?

ehsjr
 

John Sehring and Fred PA4TIM wrote:

_Nice_ posts on ESR & caps - thanks!

Ed