Here we have a Yamaha TG-77 Vintage Synthesizer in for repair. Customer was asking to replace display and batteries. First thing I did was to replace the battery in the extension card. Then I replaced the battery in the TG-77 with a battery holder, so that customer can replace it himself next time.
The new holder needed an extra hole on the pcb, but it fits quite nicely. After that I did a reset and all errors were gone, the TG worked well. Now I disassembled the front to get access to the display. I used a modern black and white 5V 240 x 64 graphic display, so the inverter wasn´t needed anymore. I desoldered the ribbon wires from the old display and soldered them to the new one. I found two leaky electrolytic capacitors on the back of the old display.
Last but not least I changed R476 with a 10k potentiometer to get the right contrast.
I’m documenting repairs for my reference and yours.
I do synth restorations and repair with a specialty in vintage synthesizers, drum machines and other vintage gear, based in Düsseldorf, GER.
Get in touch about your synth situation!