[Coco] Audio Noise Coco 1 87009285 board

[Neil Cherry]

On 1/22/19 10:00 PM, Kevin Becker wrote:
> My MC-10 has a similar issue so I’m curious if you find the solution.

>> On Jan 22, 2019, at 9:36 PM, Carlos Camacho <idevgames at gmail.com> wrote:
>>
>> Working on a Coco 1... the one that Paul did the cost measure to. Always
>> forget the name of the board. It's number is 87009285. Ala the L shape
>> board.
>>
>> Ok, so this machine has terrible noise. The noise tends to build up.
>>
>> On the bottom of the board, it looks like pin 3, the sound track lifted up.
>> So last owner has a jumper from pin 3 to under the tape and serial din.
>> Following now on the top of the board, it seems to go to the relay. If
>> that's correct, it's far different from the tech book.
>>
>> Resting brings the noise back down but it sound comes back. I have a new RF
>> modulator in the machine.

My guess is that a capacitor is charging up or that a line that was pulled
up or down is now floating (probably need a cap). Could also be tied into
an op-amp.

-- 
Linux Home Automation         Neil Cherry       ncherry at linuxha.com
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Author of:    	Linux Smart Homes For Dummies