SAE Two amplifier model A-14...no audio output. Help?

I had one of those years ago that did the exact same thing. The first time, it was the relay itself. The contacts were corroded. I replaced the relay which fixed the problem for a few months. Then whatever drives the relay went out. I ended up just bypassing the relay with intentional solder bridges and using it like that for another few years. The only thing the relay does is avoid a minor "thump" on power-up so it isn't really needed if the amp is operating normally otherwise. ...Pat

I'm sorry, but that is absolutely *not* the most important reason for the relay. Whilst there is a delay in activating it to avoid the switch on thump that would otherwise ensue as a result of the output stage supply rails stabilzing, its much more important function is to disconnect the speakers from the output stages in the event of a fault developing which causes there to be a DC offset at the midpoint. If this is allowed to find its way to the output terminals, the result will likely be a destroyed speaker cabinet.

So, whilst bridging the (non active) relay will cure a lack of output, assuming that it is not failing to close because its control circuit *is* actually detecting a fault, you will have lost any future insurance against speaker damage, if an output fault should occur ...

Arfa

You are correct. In my case, I made sure there were no problems before using it that way, but you are correct that I was risking a future problem damaging my speakers.

Hello Harvey,

While I don't know this amp in specific, see if it uses the TA7317 protection IC. It's a great IC and was used by many manufacturers. I've seen the electrolytic capacitors around the IC cause problems, as well has high value (150K or 220K as I recall) resistors go off value. The IC itself rarely fails.

I would not suggest bypassing the relay.

Regards, Tim Schwartz Bristol Electronics