I think my power supply board has gone bad.
Where can I get one or maybe parts for this old one. (Even a new one will be an old one!)
I think that the power supply boards for the 21 voice and the 32 voice are different.
Thankfully, the power supply can likely be repaired, and it’s easy to check the voltages coming out of it to see if it is indeed faulty. The service manual will show what voltages you should be getting. So make sure the fuses on the power supply board are good, unplug the connectors that feed power to the rest of the synth, and then power it on. See if you are getting the correct voltages. If not, you might have a bad regulator, electrolytic capacitor, or diode on the power supply - all of which are easily obtainable parts.
Thank you for responding.
I tried replacing the fuses and then powered up only to have two fuses instantly blow.
Should I replace them again and power up with the connector to the main board removed?
Yes, and remove the connector that powers the display board as well. If no fuses blow, try plugging in just one of those boards at a time, and that will let you determine which board is faulty.
Thank you.
I will try that procedure.
Hi did you ever resolve your issue? I have the same issue with the 2 fuses on power supply board blowing. When power supply disconnected from main board they do not blow. Everything seems to work on the keyboard except for no audio output.
I think I narrowed it down to the jack board. The analog jack plug from main board causes fuses F4 and F5 to blow on power supply board. How can I test the jack board?
I guess my question is how do I know if it’s the jack board or the power supply board?