old amp starts to fail, but not sure wat.

[milanhofman]

hi there,

i have a few old amps (stage accompany two 900C's and one 500C)
these amps are baslicy tow mono amps in one case, separate power supply and everything
the system is actively filtert, (an amp on eatch driver directly)

now for the fun part,
THE PROBLEM:
sometimes i turn the system on, and then after 10 or 20 seconds one side of one amp goes TICK!  (i believe full power)
the signal led does come on, (no protect or overload leds)
usually ones, sometimes twice. other times no TICK at all..

even less often the same side of the amp's signal led comes on and stays on until i give it a "technical tap"
(whack it on the face of the amp  )
usually its gone then, but sometimes when the signal led goes on by means of signal being pressend it stays on even if i mute the audio, "technical tap" it again and it goes away,
last time i measured there was no DC on output, (or AC)


somehow this sounds like an op-amp to me

all the other amps/sides are just fine,


i don't have mutch equipment, only a basic multimeter and a fixed 13.8 volt powersuply

any suggestions about what it may be?


thanks for your time and help 
Milan Hofman

[DrGeoff]

Check all the solder joints first. Resolder any that look suspect.
Often in older equpment (particularly if it has been roaded) the solder joints can go cold or brittle, and lead to symptoms similar to what you describe.

[milanhofman]

it has not rely bin on the road, but still not a bad start

what else could fail in a amplifier like this?

[retrolefty]

somehow this sounds like an op-amp to me

 That sounds like a logical leap of faith with no foundation. A technical tap is not a very valuable troubleshooting method other then saying you have something intermittent or thermo going on. What it is will have to take more precise troubleshooting steps.

[DrGeoff]

it has not rely bin on the road, but still not a bad start

what else could fail in a amplifier like this?

Connector corroded or wire termination intermittent. That includes any sockets used for IC's.
Assuming that you have already checked the obvious things like PSU rail presence and stability.