sounds out of my league... all I can suggest is see if the ground rails are intact on all of the cards... I had ground traces demolished one time when smoke and fuses were involved...
-----Original Message-----
From: mrmuchomusic <
musicalfix@...>
To:
yamahacs80@yahoogroups.comDate: 03/21/13 10:18
Subject: [POSSIBLE SPAM] [yamahacs80] CS80 no square or saw oscillator sound.
HI all, this is my first post on here and my first CS80 repair. I wonder if anyone can shed any light on this repair I am hoping to carry out. This unit was mostly working fine, before the upper frame fell down and shorted out on to the keyboard with a bang and some smoke :-/.
I have identified and replaced a few blown 4000 series ICs, mostly on the KBC boards.
When switched to panel mode the only audio output I get is when the sine wave (which has a another tone, falling in pitch behind it) or VCF level faders are raised.
There are no saw or square wave audio ouputs, although I checked MII and could see them present on the VCO ICs that I have checked, the frequency does vary in sympathy with the keys, they seem to disappear around CP3 on the voice card.
Both upper and lower voices are the same.
I'm not seeing much in the way of channel outputs on the DAC on the KBC. I have tested all the logic on the input side of the DAC and I have swapped the YM26700 for the one on the KAS board and there it produces between 0 and 4.2volts, as does the original.
I would appreciate any further suggestions on places to check. Many thanks. Andy
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