Gamma servo controller one channel kaput

marknoir

Active Member
Like RisanaDanna used to say - “If it’s not one thing, it’s another” )) Right channel on my Gamma SCU died today. Any ideas on repair?
Thx
 
I sure wish I was close enough to bring a few chilly buddies & my spectacles ;). I’ve got an oscilloscope, multi meter and cap reader thingy. I’m sure we could do some damage....LOL.
 
I've seen it mentioned that since you have one channel still working you can use it as a reference for voltages, continuity, and such.
Hope someone will give you some ideas where to start.
 
@ Marcnoir, can you describe or specify the defect in more detail? "The channel died today" is a little less than a statement. How does the error express itself exactly?

Klaus
 
I sure wish I was close enough to bring a few chilly buddies & my spectacles ;). I’ve got an oscilloscope, multi meter and cap reader thingy. I’m sure we could do some damage....LOL.

:)

Thx Gearhead
That’s what I did today: put a 100 hz thru and put my scope on the other. At first right channel was MIA, and I couldn’t find any problems at the chips, but as I was switching all the controls and especially gain in the back, it just as mysteriously reappeared... Problem can also be with the two little relays... I don’t know. I have to do some more preventive poking. I’m just happy I don’t need to change the chips!
 
I've seen it mentioned that since you have one channel still working you can use it as a reference for voltages, continuity, and such.
Hope someone will give you some ideas where to start.

Hi
That’s what I did. As I mentioned in another reply, sound in the right channel has reappeared just as mysteriously as it has disappeared before :)). But now I know which chip is which chanbel, and have some idea of what each one does :)))
 
@ Marcnoir, can you describe or specify the defect in more detail? "The channel died today" is a little less than a statement. How does the error express itself exactly?

Klaus

All of a sudden, there was no output from right channel. Zero. After hooking the SCU to a freq. generator and a scope, checking signal path and moving all the controls, it reappeared. I think that the culprit may be the gain switch in back, oxidised from long non-use, or one of the relays, for the same reason. The usual suspect - RCA solder joints - seem to be fine. Let’s see if this happens again...
 
Those intermittent problems can sometimes be difficult to diagnose but sounds like you know what you are doing and have already made progress.:thumbsup:
 
I had the same thing happen to one of my servo control units. I reflowed all the solder joints and it solved the issue.
 
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