s2000 502 board sound wiring

[startek2]

hey guys i thought i would try to put in a ground loop filter to see if i cfan get rid of that 502 mpu buzz.  there is a connector that has the sound input to the amp, but maybe i am assuming too much.  can anyone tell me the locations on this plug (in the top box)
for the plus and minus for left and right?  this looks like maybe it is mono....i assumed white/blue and green/blue were a channel and white/yellow,green/yellow was the other channel but looks like not the case....any ideas?

[DB26]

I cannot answer your main question about the wiring. But I can offer a solution to the buzz. I have added this mod (See attachments) to all my 502s and it makes the buzz almost nonexistent. Basically you’re just reinforcing the 502 boards ground, which is what the 504 board later ended up doing in its redesign.

[startek2]

ok thanks!  i will have a soldering session then!

[Retro tech repair]

I cannot answer your main question about the wiring. But I can offer a solution to the buzz. I have added this mod (See attachments) to all my 502s and it makes the buzz almost nonexistent. Basically you’re just reinforcing the 502 boards ground, which is what the 504 board later ended up doing in its redesign.

So glad to see more people using this. I do it to all early 50x boards i repair

[DB26]

I cannot answer your main question about the wiring. But I can offer a solution to the buzz. I have added this mod (See attachments) to all my 502s and it makes the buzz almost nonexistent. Basically you’re just reinforcing the 502 boards ground, which is what the 504 board later ended up doing in its redesign.

So glad to see more people using this. I do it to all early 50x boards i repair

I’m with you! I am going to advertise that repair every chance since I get. I feel like the speaker with resistor mod is just as much work as this solder job and far less superior.