[Coco] Audio out on the coco3

Robert Gault robert.gault at att.net
Sun Apr 15 09:10:39 EDT 2018

Before you start changing parts, you should check to see that the voltage on that section (Q4) is 
correct. Specs call for 8v at the connection of R33 and R34. If that voltage is low, the sound 
output should be lower than normal.
The voltage to that section is generated starting at the four diode AC package where the connection 
of D4 to D1 should be about 9v AC. That goes to the voltage regulator IC36 which should be 
generating 8v DC.


Zippster wrote:
> Assuming you’re referring to the RCA audio out jack, you might check (replace) the AC coupling caps
> on the transistor amp there.  C55 and C56.  These would be small electrolytic caps that might be failing
> and not passing the audio at full level.
> - Ed
>> On Apr 14, 2018, at 8:35 PM, rietveld rietveld <rietveldh at hotmail.com> wrote:
>> I blew up the 6309 on my coco so I swapped it out for another coco3 while I wait for a replacement cpu. I hooked the other coco3 up and noticed the audio out was a lot lower. I just checked a third coco3 and it has a normal audio level. What should I be looking at as the cause for a quieter than normal audio out on the back of the coco3
>> Sent from my BlackBerry Passport Red Edition.
>> --
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>> Coco at maltedmedia.com
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