Another One! - Let's Service This Pioneer SX-780! (Easy!!) 

I’ve missed Tinkering with T!!

These non-sanyo darlington power packs have a poor reputation in the diyaudio forums. Fine for low volume, but don't expect them to last at high output. There are some pictures comparing the internals. And there are reverse-engineered mini-board kits available, but pricey. Fwiw i had an sx580 which could not hold a candle to the nad 7125 which replaced it, particularly for bass reproduction. I would love to hear an all-original 780 compared to one with the replacement power packs, or even see the sine waves at high power. I know there is a lot of love for some of these late 70s pioneers, but i ended up donating my 580 to my staff for their lunchroom system.

You're all good, T! Hope all is well!

Thanks for the detailed instructions. I’ll be making those adjustments to my 780 receiver. I bought new in 79. Starting to be a little “off” sounding lately. Would like to have seen a little more detail on switch cleaning but, I’ll getter done. Looked like WD40 is what you used ?.

I don’t understand the input connections from the phone into the receiver with 1000 kh signal. Please clarify. Thanks.

Please is possible change el transformador de Pioneer sx-780 al Pioneer sx-820 que tiene los mismos 45watts . Please help me. Thank very much.