Date   

Re: TDS 754D

David Wilson
 

Just an update, working at desoldering the CH2 hybrid of the TDS380 is slow and difficult. I decided to desolder the IO shield which makes things easier and I am making progress. Using the desoldering gun on one side and a soldering gun on the other side this appears to be working on those stubborn through holes. My next post in the future might contain interesting results so stay tuned.


Re: 2440 CCD Gain channel 2-1 fail

bc
 

I have a very strong suspicion on the root cause now based on the data I collected but it's only a theory and would be hard to verify without probing the internals of the CCD, but may be easy to demonstrate if it truly fixes it. Based on how things looked, this somewhat makes sense:

Intermittent R455

I'm going to wait till it fails again till I look at it further but since I probably applied some stress to the components there while trying to probe it, it might stay good for a while, maybe it won't. So far it's still passing after some hours of use.

With test 7255 passing, the waveform looks virtually normal now:


I posted four pics, CH1 is on BOTTOM and CH2 on TOP

Yahoo! Groups https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/23194713?orderBy=mtime&;sortOrder=desc&photoFilter=ALL

https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/23194713?orderBy=mtime&;sortOrder=desc&photoFilter=ALL

Yahoo! Groups https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/23194713?orderBy=mtime&;sortOrder=desc&photoFilter=ALL Oops! Sorry, an error occurred while loading the content.



View on groups.yahoo.com https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/23194713?orderBy=mtime&;sortOrder=desc&photoFilter=ALL
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fail-cal_up.JPG - Calibration on CH2, GND on CH1 @ 2ns/div (linear interpolation) - Samples: 1 bad 2,(3),4 good, 5 bad, 6,7,8 good, 9 bad, 10, 11, 12 good. Notice that Ch1 also has some issues that I need to address...

Yahoo! Groups https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/351455134?orderBy=mtime&;sortOrder=desc&photoFilter=ALL

https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/351455134?orderBy=mtime&;sortOrder=desc&photoFilter=ALL

Yahoo! Groups https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/351455134?orderBy=mtime&;sortOrder=desc&photoFilter=ALL Oops! Sorry, an error occurred while loading the content.



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pass-cal.JPG - Calibration on both CH1 and CH2 after a bit of ext cal. Yep, Ch1 now has my next challenge :( Alas it's very subtle and it's still very usable like it is.

Yahoo! Groups https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/881145877?orderBy=mtime&;sortOrder=desc&photoFilter=ALL

https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/881145877?orderBy=mtime&;sortOrder=desc&photoFilter=ALL

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pass-gnd.JPG - GND coupling on both CH1 and CH2. Ditto with Ch1, but CH2 looks ok.

Yahoo! Groups https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/915721517?orderBy=mtime&;sortOrder=desc&photoFilter=ALL

https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/915721517?orderBy=mtime&;sortOrder=desc&photoFilter=ALL

Yahoo! Groups https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/915721517?orderBy=mtime&;sortOrder=desc&photoFilter=ALL Oops! Sorry, an error occurred while loading the content.



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pass-gnd_UP.JPG - also GND coupling but moved traces up a bit... notice it looks a little cleaner now, both about expected..



Note that I had a question about 100ns/div that I posed earlier... I found the answer: It's the first setting when the scope goes full bore at 500MSa/sec.


-Ben


Re: 576 curve tracer with poor CRT brightness

wsj@...
 

Thanks, my CR70 has not arrived yet.


Re: 2440 CCD Gain channel 2-1 fail

 

Have you checked component solders around Q460 (maybe replace Q460) and
tracks from there to both U350/U450 C1 inputs?
If U350/U450 have been swapped without change could the problem lie in the
socket?

Paul

2016-06-19 18:34 GMT+02:00 laser92awd@yahoo.com [TekScopes] <
TekScopes@yahoogroups.com>:

AAAHH got it into the "pass" condition again somehow!

While I was probing clocks... for a short while I noticed something very
bad on the C1 clock, though I can't reproduce it. When I was losing 1 out
of 4 samples, the C1 clock had REALLY bad ringing on it on the rise edge
but not fall edge. But somehow the ringing disappeared... and the sample
problem along with it!

No! This is ridiculous! Intermittent issues are annoying!

I measured C1/C2 to be (yay 2465!) 19ns rise and 65ns fall. 500KHz
clock. C1 = ~C2. I didn't get to measure the duration, frequency, or
amplitude of the ringing before it went away.

-Ben





------------------------------------
Posted by: laser92awd@yahoo.com
------------------------------------


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

Yahoo Groups Links




Re: 576 curve tracer with poor CRT brightness

Paul Amaranth
 

Did you get the settings book with your CR70? In the back of mine there's a page for
scope tubes. The Neg Bias is set for most tubes at -68V and the gun select on Scope.

Using the universal adapter, set F1 to 1, F2 to 2, K to 3, G1 to 4 and G2 to 5.

This in my list of things to do on my 576.

On Sun, Jun 19, 2016 at 01:12:15PM -0700, wsj@garlic.com [TekScopes] wrote:




I have a Tektronix 576 curve tracer with poor CRT brightness. My Sencore CR70 Beam Builder Universal CRT Analyzer Restorer manual makes a few references to scope CRTs, but does not include settings or a procedure. I have an old Heathkit scope I can use to develop a procedure that does not destroy the CRT. Any help would be greatly appreciated.




Free CR70 manual at http://elektrotanya.com/?q=keres http://elektrotanya.com/?q=keres

Here is a link to information on scope CRT restoration. CRT Restoration for the (Brave) Experimenter http://www.ke5fx.com/crt.html


http://www.ke5fx.com/crt.html

CRT Restoration for the (Brave) Experimenter http://www.ke5fx.com/crt.html This page recounts a 45-day experiment in restoring or "rejuvenating" the cathode-ray tube in an HP 85662A spectrum analyzer display unit.



View on www.ke5fx.com http://www.ke5fx.com/crt.html
Preview by Yahoo









!DSPAM:5766fb2c241481186915274!
--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@AuroraGrp.Com | Unix & Windows


Re: 2440 CCD Gain channel 2-1 fail

Siggi
 

On Sun, 19 Jun 2016 at 12:35 laser92awd@yahoo.com [TekScopes] <
TekScopes@yahoogroups.com> wrote:

AAAHH got it into the "pass" condition again somehow!
Awesome - stay there!

This is ridiculous! Intermittent issues are annoying!
Yups, intermittent is the worst!
What does the captured waveform look like in the PASS condition? What does
a DC signal look like?
Can you provoke/revoke trouble with heat/cooling? Do you have freeze spray
and/or a hot air gun at hand?


Re: 453 with no trace, meets willing novice troubleshooter with DMM !

Rg P
 

OK Guys,First off, thanks for all the input.I got the troubleshooting guide pdf. I will read that first, and start over.I checked the LV power supply, and got reasonable supply(12, 75, 150) readings so, I have to move on from there. Several thoughts from you guys, on where to go from there. I would like to get a starting point on the suspected board to start the voltage check from, and what the differing readings (more volts/less volts) would mean. An idea of which components are usual culprits in this "no beam" situation would be helpful. This is where a knowledge of signal flow/circuit operation theory would also help.I also see from the service manual, that particular front panel settings are used to do the checks. How important are those to the expected voltage readings?Also, someone mentioned heater voltage, which could be checked to verify CRT is working. Any more on that? I notice that generally it is supposed that the CRT is functional. How do I verify that via DMM?RIc.

On Friday, June 17, 2016 6:38 AM, "hewpatek@gmail.com [TekScopes]" <TekScopes@yahoogroups.com> wrote:


  It could be that the Post Deflection Acceleration (PDA) voltage (~15 KV) broke down, often caused by a malfunctioning High Voltage Multiplier (HVM).
Since you have no way to measure it (safely), you may try and see if there is a very faint trace or dot on the screen by observing in a dark(ened) room, adjusting the intensity knob back and forth.
It may be difficult at this stage to distinguish this situation from a bad Z-axis control, although with the latter, you may see the retrace in normal YT mode in a dark room. The retrace is where the beam moves from the far right of the screen back to the left after each timebase "stroke". Normally, this is blanked (made invisible) but with a malfunctioning Z-axis control, it may be as "bright" as the beam itself.
Did you try just turning the Z-axis adjustment a bit, like say + and - 45 degrees?
Use an insulated or preferably, plastic screwdriver.
*** Do be careful with unknown voltages! ***

Raymond



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[Non-text portions of this message have been removed]


576 curve tracer with poor CRT brightness

wsj@...
 

I have a Tektronix 576 curve tracer with poor CRT brightness. My Sencore CR70 Beam Builder Universal CRT Analyzer Restorer manual makes a few references to scope CRTs, but does not include settings or a procedure. I have an old Heathkit scope I can use to develop a procedure that does not destroy the CRT. Any help would be greatly appreciated.




Free CR70 manual at http://elektrotanya.com/?q=keres http://elektrotanya.com/?q=keres

Here is a link to information on scope CRT restoration. CRT Restoration for the (Brave) Experimenter http://www.ke5fx.com/crt.html


http://www.ke5fx.com/crt.html

CRT Restoration for the (Brave) Experimenter http://www.ke5fx.com/crt.html This page recounts a 45-day experiment in restoring or "rejuvenating" the cathode-ray tube in an HP 85662A spectrum analyzer display unit.



View on www.ke5fx.com http://www.ke5fx.com/crt.html
Preview by Yahoo


Re: 7K Flexible Extende 7L13 HELP

 

Hi Roberto,
The usual place to find them is Ebay. There is one on Ebay right now
(Number: 291681738338) for $379 or best offer. They usually go for $150 to
$225 each on Ebay.

It turns out I have three Tek flexible extenders which I can send you for a
total of $425 plus shipping.

Roberto, Contact me off list (dennis@ridesoft.com) if you are interested.

Note to others who might need a flexible extender: I'm not interested in
selling them one at a time.

Dennis Tillman W7PF

-----Original Message-----
Sent: Saturday, June 18, 2016 3:39 PM
To: TekScopes@yahoogroups.com

Hi all I'm looking for three cable extension to repair my spectrum analyzer
tek 7L13 someone can tell me where I can find them thank Roberto

------------------------------------
Posted by: rfmicrowave1@libero.it
------------------------------------


Re: 2440 CCD Gain channel 2-1 fail

bc
 

AAAHH got it into the "pass" condition again somehow!

While I was probing clocks... for a short while I noticed something very bad on the C1 clock, though I can't reproduce it. When I was losing 1 out of 4 samples, the C1 clock had REALLY bad ringing on it on the rise edge but not fall edge. But somehow the ringing disappeared... and the sample problem along with it!

No! This is ridiculous! Intermittent issues are annoying!

I measured C1/C2 to be (yay 2465!) 19ns rise and 65ns fall. 500KHz clock. C1 = ~C2. I didn't get to measure the duration, frequency, or amplitude of the ringing before it went away.

-Ben


Re: 7K Flexible Extende 7L13 HELP

David DiGiacomo
 

On Sat, Jun 18, 2016 at 5:08 PM, JON <jonbatters32@gmail.com> wrote:

You didn’t spec what you needed, but I make up cable extension w/parts from:

WWW.JAMECO.COM .
Of course he did, he wants Tek 7000 extenders. You *can't* buy the
necessary edge connectors from Jameco or any other distributor, and
anyway that doesn't help with the card edge end.


Re: 2440 CCD Gain channel 2-1 fail

bc
 

I've tried "Cold start" both when the scope is cold from being off, and when warmed up, and then go through the self cal several times. The time when it actually worked was when I ran the cold start routine from a previous power up, and then a self cal on the next power up - after the scope was off for a while... and it started working. But moments later it failed again without touching the scope.

This morning from a cold scope, I ran a cold start and two self cals - a self test - and another self cal - and still fail 7255. At this point I do not believe any self cals will fix this problem, there truly is some hardware problem that's not any of the hybrids (oddly enough).

I have a hard time believing U780 is at fault because it's in the signal path after the first point of failure that I can see: pins on U350 and pins of the A32 GCB, and on the pass condition U350 outputs look different than the fail condition. The output of the peak detector looks good in both fail and pass conditions.

Currently thinking clocks but don't know how to test this theory... One thing I wasn't sure of: there are no 250MHz clocks on the PCB, all of that 250MHz is inside the hybrid?


Re: 2440 CCD Gain channel 2-1 fail

Siggi
 

So what was the sequence of events?

Here's what I understand:
You go through COLD START and SELF CAL to get sane constants and good
waveforms? Was this from cold, or had the scope been running a while
already?
You then leave it running for a while and then you get "symptoms"? What
were these symptoms on the waveform before you ran SELF CAL again?
This is the crucial question, as I don't believe you would have seen the
1-in-4 dropout due to low gain at that point. This would have been
different symptoms, and they would point to the real cause(TM) of the
calibration going off-reserve.

Now, if the scope is reducing the gain on the gain cells during SELF CAL,
then that would suggest to me that the gain or offset were too high, or
maybe there was noise injection to those two lanes.
While we don't know how the scope does self-cal, we do know what hardware
it has at its disposal, and I believe the only injection the scope can do
is to inject DC by manipulating the offset controls (... time passes ...) -
well, there's the calibration amplifier, which routes a differential, but
essentially a DC signal to the peak detectors.
In any case, since you can repro this with DC, it's easiest to test with DC.
It'll still be a PITA to look at the CCD outputs without a storage scope,
as the repetition rate is so low (26 WFM/s?).

Note that once the gain constants are wonked out, those would be causing or
masking the symptoms you observe. In your shoes, I'd try and go through
COLD START and SELF CAL again to sane constants. Once you reproduce the
failure, don't SELF CAL again, as that'll just mask the real problem.

Since you haven't been able to provoke the trouble with the CCDs swapped,
and because those are hard-to-find and expensive, I'd try and eliminate
trouble in the supporting circuitry.
As I noted before, apart from the S&H switch that's common to all 4
sides, *U780*
is the only component I see that's common only to sides 1&3.
This would be a prime suspect, IMHO.
Maybe those are candidates for hot/cold torture?


On Sun, 19 Jun 2016 at 01:21 laser92awd@yahoo.com [TekScopes] <
TekScopes@yahoogroups.com> wrote:



Unfortunately I did try self cal again to no avail. However the numbers
are now:

Good -> Bad

GN21: was ~790 -> now 4095 once again
GN22: was ~700 -> now ~620
GN23: was ~905 -> now ~2850
GN24: was ~410 -> now ~1240

Actually the 1000s-2000s numbers isn't bad, it's when it's within 10% of
the ends (i.e. less than 400 or greater than 3700 or so) as with dynamic
gain could possibly run over the end (it fluctuates +/- 200 or so). Dynamic
gain should compensate as long as it can do so within that +/- 1.346 volts.

I don't like GN22 either, if all of them moved relative to each other it
would be nice...







[Non-text portions of this message have been removed]


Re: TEK465 fan set screw size ?

iamrogerholden@...
 

Many thanks for all the info :) tool ordered :)


Re: O.T.

KeepIt SimpleStupid
 

There is one thing that you can try:  Short the power connections (without power applied). Usually a minute works.  I just fixed a USB wireless mouse, the wireless side, by shorting the battery terminals overnight.  A minute made it "better", but not quite right. You might have to sort out dim.
An automobile clock, I did while it was on the vehicle.  I died after the car was jumped.
A few other devices were fixed that way.  It's worth a shot.

[Non-text portions of this message have been removed]


Re: 2440 CCD Gain channel 2-1 fail

bc
 

Unfortunately I did try self cal again to no avail. However the numbers are now:

Good -> Bad

GN21: was ~790 -> now 4095 once again
GN22: was ~700 -> now ~620
GN23: was ~905 -> now ~2850
GN24: was ~410 -> now ~1240

Actually the 1000s-2000s numbers isn't bad, it's when it's within 10% of the ends (i.e. less than 400 or greater than 3700 or so) as with dynamic gain could possibly run over the end (it fluctuates +/- 200 or so). Dynamic gain should compensate as long as it can do so within that +/- 1.346 volts.

I don't like GN22 either, if all of them moved relative to each other it would be nice...


Re: 2440 CCD Gain channel 2-1 fail

Siggi
 

On Sat, 18 Jun 2016 at 20:21 laser92awd@yahoo.com [TekScopes] <
TekScopes@yahoogroups.com> wrote:

The scope was just sitting there turned on, idling with a fan blowing at
it, displaying the probe calibrator signal while I was typing out the
seemingly victory mail. It then turned into failure once again without any
intervention.
Intermittent is the WORST. However, if it's repeatable, maybe you can
narrow it down enough to see what's up.
Also, if you haven't done a SELF CAL since the problem recurred, you should
now be able to see where it's really at, before the scope attempts to
compensate with calibration.

Are you seeing the same symptoms? One in four samples on CH2 is wonked?

List the calibration constants again (maybe you have flaky NVRAM), and if
they're still at ~hundreds rather than ~thousands then trace the signal
path again with DC inputs. If the calibration constants have changed from
what you documented before, then maybe you need to look at the digital
section. List the constants here - if only for moral support :).


Re: 2440 CCD Gain channel 2-1 fail

bc
 

The scope was just sitting there turned on, idling with a fan blowing at it, displaying the probe calibrator signal while I was typing out the seemingly victory mail. It then turned into failure once again without any intervention.


Well, the problem is that theoretically these gains seem to have nothing to do with the actual problem. As far as I can tell, these are a symptom, not a cause because when I measured the CCD output which is in the signal path before these gain cell boards, the waveforms looked very similar to each other during a "properly working" condition where the signal is completely attenuated when it failed. Unless the gain boards present a significant load when the voltage to the sink transistor in increased?


There is a manual DAC adjustment, I tried that a few days ago and other than the fact that I couldn't get them to save (probably that "dynamic gain adjustment" thing is constantly writing in new gain numbers) reducing the voltage *decreased* (or seemingly decreased) the waveform I saw at the gain board output. I can't correlate this right now - I might have to dump this through spice or build the circuit on a protoboard to play with - but data seems to point to ruling out the GCB and the DAC outputs.


-Ben


Re: Tek 466 factory kludge? and repair

Vladimir _
 

Hi Leon,

Thank you for pointing this out. All four solder joints on that rectifier are cracked. I've been meaning to touch them up with a soldering iron, but keep putting it off because it still works and I don't have a tip that would allow me to reflow these joints quickly enough.

Before s/n B200000 this bridge was a 152-0488 that was soldered flush with the board. In later 466s Tek used a larger 152-0556, so they had to bend the leads to make it fit:

Tek realized that that particular bridge rectifier in serial numbers before B250000
[in 475s] were underrated. The original design used the common 152-0488-00 rated at
an amp. We always replaced this part, which notoriously ran hot, with a larger one
that had to be installed parallel to the PCB in order to clear the case, leads bent
to fit the closer-spaced board holes.
_________________
Dean, Electronics Curmudgeon
Contributing editor emeritus in Poptronics magazine, R.I.P.


Re: 2440 CCD Gain channel 2-1 fail

Siggi
 

On Sat, 18 Jun 2016 at 18:46 laser92awd@yahoo.com [TekScopes] <
TekScopes@yahoogroups.com> wrote:



And moments after I post that... the problem came back!

Specifically what did you do, how did it recur?
Was the scope just sitting there, when all of a sudden the gains went
wonky, or was there an action you did that preceded/coincided/caused the
problem?

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