Vintage Synth Repair

I picked up an old Yamaha CS15 from a friend, and upon powering the beast up, I found that the notes drone on endlessly regardless of what settings I use in the EG sections. There is no switch for a drone or a hold, and it can't be a keyboard issue because the note that sustains is the note you just pressed. I've tried everything, setting all EG parameters to zero, and still nothing. Also, I can hear the attack and the decay change, but not the release.

What could be causing this issue? Also, there is a switch that was added to the front panel, looks like a mod. The wires of the switch go underneath what seems to be a missing trimpot in the EG section of the PCB. The switch does not affect the sound in any way.

That's a classic by now .... 

There's a pot called Initial Level..

You might have tried it but I have had a few in for repair..I turn it on , turn down initial level and it's fine. I charge for that service now :)

 

----- Upprunalegt skeyti -----
Frá: "Mark" <casiotone1331@...>
Til: vintagesynthrepair@yahoogroups.com
Sent: Fimmtudagur, 30. september, 2010 17:00:46 GMT -08:00 Tijuana / Baja California
Efni: [vintagesynthrepair] Help! Yamaha CS15 notes sustain indefinitely-- no release!






I picked up an old Yamaha CS15 from a friend, and upon powering the beast up, I found that the notes drone on endlessly regardless of what settings I use in the EG sections. There is no switch for a drone or a hold, and it can't be a keyboard issue because the note that sustains is the note you just pressed. I've tried everything, setting all EG parameters to zero, and still nothing. Also, I can hear the attack and the decay change, but not the release. 

What could be causing this issue? Also, there is a switch that was added to the front panel, looks like a mod. The wires of the switch go underneath what seems to be a missing trimpot in the EG section of the PCB. The switch does not affect the sound in any way.

>>>>>>. There is no switch for a drone or a hold, and it can't be a keyboard issue because the note that sustains is the note you just pressed. <<<<<<

Hi, there should be a HOLD switch, maybe two of them (i don´t remember,....does the cs 15 has 1 or 2 VCAs?)

Or is it a CS15m????

Cheers martin

Sorry, there is NO switch, it´s a pot! Every VCA has a Pot namend "Initial Level". Fully clockwise you will have a drone, counterclockwise the sound disappeares and the EG begins to get activ. You should turn the EG Depth Pot 1/2 - 2/3 clockwise.

Best regards Martin