[Coco] CoCo 1 64K upgrade failed :(.

[Phill Harvey-Smith]

Ryan Pritchard wrote:
> Hi all,
> 
> The CoCo does not boot.  I have cut all eight of the correct capacitors 
> C31, C35, C45, C48, C61, C64, C67, C70, moved all the jumpers to the 32K 
> setting, and tried both the LOW and the HIGH back jumper positions.

Did you check the voltage pins with a meter before plugging in the 64K 
rams, IIRC 4116s (which would be in for the 16K), use +5V, +12V, and -5V
applying the +12/-5 to the 4164s will almost cirtainly fry them (managed 
to do this by mistake once, and the magic smoke definatly exscaped :( ).

> I think I may have burnt out the 64K x 1 DRAMs.  I don't know what else 
> it could be and since I removed all eight caps breaking a couple in the 
> process I can't return to the 16K system :(.

You could try setting it back to the 16K position and replacing the 
4116s, it may well work, ok out of spec :)

> I guess my options are find a good set of 64K x 1 DRAM, or cut my losses 
> and pick up a CoCo 3 from Cloud 9.

Like Mike said Jameco sell 4164s, if you have some old PC or other 
vintage machine ram cards with socketed 4164s those may be worth 
pinching too, though I guess if you had some socketed ones, you wouldn't 
have been desoldering them.....

Cheers.

Phill.

-- 
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !

"You can twist perceptions, but reality won't budge" -- Rush.