Yes, I measured the voltage on pin 24 of the RAM chips (IC19, IC20, IC2) and I'm getting 3 volts with the board removed and just powered with the CR2032. I'm in the process or shotgun recapping the entire main board. I'm about 90% percent done, I just need to replace the 1uF/50V caps and the single 2.2uF/50V one. Some of the 1uF caps are bi-polar including the single 2.2uF one. All the other capacitors though are polarized and I've verified that I've installed them correctly. The board has markings that indicate the negative side of the capacitor. I've sourced all my replacement capacitors from DigiKey and they are exact replacements with no change in the voltage or capacitance.Hi there - and welcome to the forum![(Y)]( "thumbs-up")
Just some questions: did you measure the voltage at Pin24 of the ICs 19, 20 and 21 (RAM) against ground when the synth is switched OFF? Must be a little less than the battery voltage...
Please check if the voltage at Pin8 of C5 (white wire) on the PSU is around +5V.
Can you show us a picture of bottom of the mainboard - especially the area of the (ex)battery?
BTW: a new battery mostly is about 3.2V - so this is no issue.
Someone told me I should check TR1 and TR3 (transistors) on the board too. I have a full schematic in high quality and these transistors are connected to the battery voltage. TR1 is a 2SA1015, but in my board it's a 2SA933, but they are basically the same transistor according to my research. TR3 is a 2SC1815.
I am sure I am getting my +5V from the PSU as I recapped it and I did check with my multimeter after I recapped it. But I will check again, and I will send some pictures of the bottom of the mainboard tomorrow.
I'm going to submerge the mainboard in 91% isopropyl after I'm done recapping and replacing those transistors because it is somewhat dirty and a good submersion should help.
Statistics: Posted by KylesDigitalLab — Tue May 21, 2024 3:29 am