Quote:
Originally Posted by M.Joshi
Hello,
I am trying to diagnose a fault with an Aiwa P30 DC Stereo Power Amp. It is part of a mini separates system consisting of a separate tuner and pre-amp.
The power amplifier does not output any audio to the speakers from either channels. I have checked that the startup relay engages and both the positive and negative power rails seem to be OK?
Any other pointers would be useful.
Thank you.
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I have investigated further - the gain sections appear to be working fine. If I inject a 1KHz signal at the input on the RCA jacks, an amplified version is present on one side of the protection relay. The other side feeds the speaker output terminals. The relay is just not switching for some reason? I have tested the relay out of circuit and it does work.
The protection circuitry is built around a TA7137P IC.
I also found a zener diode which is measuring short circuit. The part number is D162 - I cannot seem to find any data on this?
Thanks.