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Roland GR-30 Guitar Synth cap replacement

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  • #31
    IC25 is correct - this is the memory chip that needs the battery voltage to retain the contents. Given that the memory is retained then we can rule out that part of the circuit as the chip has to have more than 2v otherwise it will lose the settings when power cycled.

    Again, there are two parts to this circuit - the battery voltage to the memory (established as being OK by inference) and the voltage being provided to the CPU for it to report on the battery condition when the unit is powered. I think you have either a missing voltage on pin 7 of IC20, or R87 is maybe open. Check the voltage at both sides of R87. If you get no voltage either side then IC20 isn't working correctly for some reason, (or D27 is shorted on pins 2 & 3). If you get voltage one side and not the other then R87 is open.

    The cap is unrelated and there's no cap fault with the battery circuit.

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