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AWG2005 Issues and Repair Question.


Michael W. Lynch
 

I recently obtained a SONY/TEKTRONIX AWG2005. It had a couple of issues. First the power supply would quit working after it warmed up for about 30 minutes and would not restart until it cooled overnight. After I replaced the power supply, I was able to start the unit and leave it running overnight, so the supply was now "good".

Currently, the unit powers up normally, goes through the startup routine and passes all the Self-Tests with flying colors. Never shows an error code upon start up. The display is bright an clear, every function and control appears normal. Unfortunately, it only works properly for a few minutes then keyboard response to each button press seems to first slow down and finally freezes up for lack of a better word. It does not shut down, it simply stops responding to all front panel commands. I must unplug the power cord and then restart, it will repeat the entire process again.

I have pulled all the boards and looked for obvious signs of corrosion or other damage. There appear to be no leaky caps and the thing only uses a very few electrolytic caps (excluding the powers supply). I do not see any chips that are in sockets, everything seems to be soldered directly to the PC boards, as you would expect. No signs of any previous repairs. All the boards appeared to never have been disturbed before I removed them for inspection. I have also re seated all the ribbon cable and other inter-board connectors, again, there does not appear to be any visible problem with these.

Anyone have an idea of where I should start looking? I have very little experience with these digital devices, I can find my way around an older analog scope and a schematic, but this is a different animal.

Thanks!
--
Michael Lynch
Dardanelle, AR


Martin Hodge
 

I worked on a awg2021 and I'll bet your problem is overheating. The 2000 series uses ECL logic and those chips get extremely hot! With the cover off be sure to always place a good powerful fan pointing at the card cage on the right side of the unit. When I worked on mine I sat it on its left side and rested a 12v PC fan on top of it pointing down. Make sure that the fan in yours is working 100% and really moving air. It's loud but absolutely necessary. It should draw air in through the holes in the back-right of the cowling, through the length of the card cage to the front, across to the CRT unit and power supply on the left and out the left-rear.


Michael W. Lynch
 

On Tue, Aug 4, 2020 at 09:20 AM, Martin Hodge wrote:


Make sure that the fan in yours is working 100% and really moving air. It's
loud but absolutely necessary.
Martin,

One thing that I am certain of, that fan is working. It sounds like a jet engine next to my 465B. That being said, overheating or issues with the ECL chips could still be a problem. The problem is, how to find the offending component? This sounds like the proverbial "needle in the haystack" exercise. I have been careful to maintain airflow with the case off. Perhaps looking for a "hot" or "cold" chip on the boards might be a clue, one or more chips that are much hotter or cooler than their neighbors?

--
Michael Lynch
Dardanelle, AR


Stephen
 

Stephen 3:40am #170085

I’ve read somewhere, maybe TekWiki, that when working on these digital/analog “hybrid” scopes, you could fry a chip within a few minutes if it’s open and not properly cooled. I don’t know if this applies here though.


Michael W. Lynch
 

On Tue, Aug 4, 2020 at 09:41 AM, Stephen wrote:


Stephen 3:40am #170085

I’ve read somewhere, maybe TekWiki, that when working on these
digital/analog “hybrid” scopes, you could fry a chip within a few minutes
if it’s open and not properly cooled. I don’t know if this applies here
though.
Stephen,

Yes, I have a 2440 and that is one of the scopes that must be constantly cooled to prevent overheating of the A/D Converters and the CCD Hybrids. I think that Martin makes a good point, even if the problem might be less catastrophic on the AWG series. That noisy fan is there for a reason.

--
Michael Lynch
Dardanelle, AR


Stephen
 

On Tue, Aug 4, 2020 at 03:55 AM, Michael W. Lynch wrote:

Yes, I have a 2440 and that is one of the scopes that must be constantly
cooled to prevent overheating of the A/D Converters and the CCD Hybrids. I
think that Martin makes a good point.
Yep. Very good piece of advice indeed.
I don’t personally know that series, but I trust you guys on that.