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

[Ryan Pritchard]

According to data sheets the 4116 chips require the 5/12 dual voltage.

I did not test the voltages at the sockets before putting the 4164 chips
in.  But all the jumpers on the CoCo are clearly labelled for which memory
setting I am chosing.  So unless this board was magically mis-screened, my
voltages should be fine.  I can only conclude that I fried too much memory.

On the other hand I also cannot get the CoCo to boot up with the 4116 chips
and the jumpers all back to original, so I have to wonder if maybe I scraped
a trace when cliping the capacitors.  I'll take a closer look this weekend,
then decide how to proceed with the acquiring of more 4164 chips or not.

On Fri, Sep 26, 2008 at 1:21 PM, Mike Pepe <lamune at doki-doki.net> wrote:

> Phill Harvey-Smith wrote:
>
>> 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 :( ).
>>
>>
> Phill,
>
> I'm reasonably certain that the 4116's are +5V only. I know for sure the 4K
> RAMs also needed -5 & +12V
>
>
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-- 
Regards,

Ryan Pritchard
Fun Extends All Basic Life Expectancies