[Coco] Unreliable Coco3

[David Ladd]

Besides trying to clean the cart slot.  It is possible that you could
have a cold solder joint somewhere too.

I just got done repairing a 128K CoCo3 that had multiple cold solder
joints.  A couple were on the GIME socket and 4 on the CPU socket that
had been installed into this CoCo3.

Plus the CPU socket that had been installed also had really bad flux
which had to be cleaned off.

This is just another possible problem.  There could be cold solder
joint(s) on the cart slot connector as well.



On Mon, Oct 22, 2012 at 9:20 AM, Retro Canada <retrocanada76 at gmail.com> wrote:
> oh yeah, cleaning the expansion board pins too hehe. TLW is a good
> troubleshooting reference :)
>
> You should check the coco3 service manual too, there is a
> troubleshooting about random characters on screen.
>
> Check the cassette port too. It might get you the state of other chips
> IC7 (Cassete/DAC) and the RS-232 (IC8).
>
> There are 2 test points on a coco3 PCB. The voltage is written right
> on it. One is 5 volts. When the symptoms appear you could measure the
> voltage on it if it still is doing 5V. A bad PSU could be the cause of
> all your trouble too. It's hard to "remote troubleshooting as Mark
> Marlette told me once ;) "
>