I have a SA-929 stereo receiver from 1989 that works almost perfectly except sometimes there's no audio but dropping it a tiny bit fixes it. I was worried there were bad solder joints or broken leads or PCB traces and... it turns out it's just one stubborn clicky boi.
Also I literally have no idea how to replace it without removing the entirety of the guts of this thing. It's one giant circuit board blocked in by a massive heatsink and front panel daughter boards.
So the relay, as far as I can tell, simply disconnects the outputs of the PA from the headphone jack/speakers output. That's it. Why does it need to disconnect it from the output? If it's overloaded, apparently. Now, I can't guarantee I have the right datasheet as the chip is labeled "SVI3001" but the datasheet is the "STK4191V" that someone else suggested it was a rebranding of, but if that's right the amp has a mute pin.
Turns out the bottom panel comes right off after just removing nearly a dozen screws.
I got the relay out, aaaaand accidentally cracked the traces on the PCB that connected the wires to the transformer. Gonna make a replacement PCB and considering putting a connector of some sort on it so I can more easily remove the damn transformer from it.
NONE of the cables in the damn system are connectorized, they're all soldered directly into the PCBs. I think this right around when Technics started cutting costs, so it's not entirely surprising.
Easy peasy. Just waiting for the new PCB to show up so I can fix the transformer connection.
The old relay is a Matsushita JR2a-DC24V-Y3 and the new one is Omron Electronics G2R-2A-DC24, for those wondering.
