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I have a Yamaha YC45D , I have fixed multiple problems , but now have hit a wall. The lower black bass keys (shared with the pedal) are almost all emitting a grumbling sound when played. the note is musically accurate , but there is a popping and change in amplitude when played on just these black inverse notes and the bass section. Boards BM,BF and BE seem likely candidates as they have some 2sc458 transistors on them ( i heard they are weak ). I regret this is a problem i caused when i cleaned the contacts on the bass section (and the unit was live!). So i do know that the were working fine beforehand (and the bass pedals too).
Also i have probed the Power Supply rails , they should be -12V , -26V and +2V . The -12V and -26V are fine now adjusted after recapping , but the +2V is reading +5.75Volts on my meter ?
Everything else is working fine on all stops etc , its just the lower Black keys , and the strangely high power supply reading.
Would anyone have any ideas on either of these ? i have spent almost 3 months on this restoration , but this has me stumped.
It was working fully so i know it is fixable . ..
Many thanks
Tim
Also i have probed the Power Supply rails , they should be -12V , -26V and +2V . The -12V and -26V are fine now adjusted after recapping , but the +2V is reading +5.75Volts on my meter ?
Everything else is working fine on all stops etc , its just the lower Black keys , and the strangely high power supply reading.
Would anyone have any ideas on either of these ? i have spent almost 3 months on this restoration , but this has me stumped.
It was working fully so i know it is fixable . ..
Many thanks
Tim