I have recently acquired Getto Boombox from Sanyo from Ebay , Model is M7700LG, it unit came on its own so I had to scramble and get a power supply connected. The seller confirmed that the radio and cassette works but the cassette playback sounds wobbly. I pluck some courage and opened the unit partially , I was able to see the belts and it seem aged and loosen. I have a incomplete copy of service manual and its daunting the get it fully disassembled, does anyone here knows how disassemble to change those belts. Also the tuning and the stereo LEDs have no light even though if I managed to tune some stations. Any ideas? BTW the unit is quite heavy given its size and looks and sounds beautiful.
If it helps you can get the full 27 page service manual for free from https://elektrotanya.com/sanyo_m7770k_sm.pdf/download.html#dl Make sure you click on the right link. There was a Recapcha test on it and Elektrotanya always adds an additional delay. After that the file downloaded.
We all do this the same way, most service manuals are for some disassembly and electronic values and aren't great for belt replacement, most don't even list belt sizes. Take photos, use JIS Screwdrivers (I bought mine on Amazon), they don't strip the screws as easily. It looks like the green board only has two screws but I think that has to be lifted to get more access, I don't think you'll be able to get it fully out. The loose belt looks like the tape counter belt and it looks really loose, which is better than gooey but it's hard to get an accurate size since it's stretched. When it's lifted see if you can follow the LED light wire, they might have a common wire which might be lose at one of the connections. Even tiny cracks in the solder can be an issue but those little lights rarely fail but the wires will.
I have M7750 and M7770, both need to have belts replaced. I've read a blog entry of a guy who did that, and he had to de-solder wires from the circuit board and remove the board to get access, because wires are from all the sides, he could not simply flip it over. Sadly, he did not make pictures of each step. I don't know whether he had a service manual, I think he did not. So, five or so years passed, I even bought belts for it, but cannot get myself to open it up. If you are going to proceed further, please, make pictures EDIT: Here is that blog post. In Russian. No repair pictures. Seems that he removed both the circuit board and the chassis. He de-soldered some wires from the board and removed "top plate from the mechanism", I think it is the same plate that the guy in the link below has removed, the one that holds the motor. Here is a different blog post about M7800, looks very similar to yours. In Russian. Not very detailed. What I gathered is that he did not de-solder wires. Also, he writes that he pulled out / removed the whole mechanism. It looks that he also pulled both the circuit board and the mecha to the back of the corder, then removed the motor to replace capstan belt. He did not replace ff/rew belt.
