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R/E/P => R/E/P Archives => Bruno Putzeys (Designer) - Dave Hecht (Master Tech) => Topic started by: zywot66 on March 07, 2009, 12:16:48 PM

Title: soundcraft 800B
Post by: zywot66 on March 07, 2009, 12:16:48 PM
hello, thanks for any help. i am using a recapped 800B. the aux master #1 level is always pegged through the roof. it just started and its like its oscillating. i tried resetting the op amps in there seats but no good. what other methods could i try to fix this.

sorry for being short on the explanation of the symptoms

mg
Title: Re: soundcraft 800B
Post by: ssltech on March 07, 2009, 04:11:05 PM
Scope, and trace it backwards. -Where it stops... You've found the problem.

That really is the only way that I know of.

You say "re-capped". It sounds ominous the way you include that particular piece of info, like you mean "this happened when it was re-capped"... In which case it's probably whatever mistake was made when the re-capping was done... which nobody may be able to predict.

If it's not coincident time-wise, there's probably no connection.

Keith
Title: Re: soundcraft 800B
Post by: zywot66 on March 07, 2009, 07:06:01 PM
thanks for the advice keith. today i switched op amps out on that master from another aux master card i have and problem went away. guess op amps go bad
Title: Re: soundcraft 800B
Post by: compasspnt on March 08, 2009, 03:00:32 AM
Opamps can go bad.

Guess you'll just need to keep moving the good one to where you need it.
Title: Re: soundcraft 800B
Post by: ssltech on March 08, 2009, 08:35:50 AM
Coming soon to Fox video special...

When op-amps go bad!!!

Yes. -It happens. Also, dodgy soldering anywhere around the inverting input/negative feedback path can cause that sort of thing.

Sounds like you've sorted it though.

Keith