Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default PLEASE!! Still need help with an SAE Two A-14

rockinnomo wrote:
I posted this a while back and am still needing help so here it is
again. PLEASE E mail me directly


Hell, no. This is a discussion newsgroup, not your personal slave crew.

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Default PLEASE!! Still need help with an SAE Two A-14


"rockinnomo" wrote in message
...
I posted this a while back and am still needing help so here it is
again. PLEASE E mail me directly

My electronics tech is having trouble fixing an SAE Two amplifier
model A-14. It has no audio output. If he shorts across a relay the
audio works fine. He has a good service manual but can't track down
what the problem is. Does anyone know what the problem may be
specifically? It was repaired for the same problem by another tech
and
the repair didn't last long. I do know that 4 ohm speakers are a no-
no. He's testing with headphones. Sure would appreciate some help
here. Please eMail me at .
Harvey


If there is no obvious problem, such as DC offset, that is causing the
protect relay driver circuit to fail to drop in, and the amp is otherwise
producing good audio, then this must actually be a very simple problem, that
should not be any problem for an experienced engineer, armed with a full
service manual, to track down. If your service tech is unable to do this,
then I would have to suggest that he is not the right person to be looking
at it.

Assuming that it uses a TA7317 as the protect IC, then common problems are
the timing cap for the switch-on delay, and the high(ish) value resistor
that charges said cap. There is also usually a quite high value resistor
between the relay coil, and the drive pin of the IC, and don't forget the
relay coil itself. Rarely, the IC might be faulty. If your tech does not
understand the inner workings of the 7317, he should download a spec sheet
for it, where all will be revealed ...

Arfa


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