[Coco] CoCo 2 problem

[Arthur Flexser]

You might want to also (first?) try socketing and replacing the 6809.
Seems like every time I had a hardware problem, the culprit turned out
to be the CPU.

Art

On Sat, Aug 6, 2011 at 11:28 PM, Chad H <chadbh74 at hotmail.com> wrote:
> Ok it seems it would be too costly to have someone else repair the board so
> I'm going to take my time and take a crack at replacing the RAM chips myself
> to start with..unsoldering the existing ones and installing socketed RAM.  I
> purchased a "CoCo 64K upgrade kit" off ebay that consists of the 8 x 4164
> chips I've heard about.  I'm "assuming" that these will work in place of the
> 8 identical RAM chips already soldered in.  However, I cannot find any
> information on the factory installed chips anywhere.  They are 8 x 16-pin
> DIP, labeled "8042665 / FQD8433" with "TC" and Motorola Logos.  Anyone?
>
> -----Original Message-----
> From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On
> Behalf Of Chad H
> Sent: Thursday, August 04, 2011 10:58 PM
> To: 'CoCoList for Color Computer Enthusiasts'
> Subject: Re: [Coco] CoCo 2 problem
>
> I was kinda leaning towards "failed ram" as the most likely culprit.
> Unfortunatley, with this particular board, almost all chips are soldered in
> place.  While I can solder 'OK' sometimes, I wouldn't want to risk damaging
> the board or making a mess by taking a crack at it myself.  I'm wondering
> how expensive it would be have someone replace the RAM chips with socks,
> maybe even the soldered 6809 as well.  Would like to get it back to full
> operation if is not overly expensive.
>
> A photo of the board is here... http://www.mediafire.com/?12hf7zus7ebl49x
>
> Would anyone be interested in such a soldering task?
>
> - Chad
>
> -----Original Message-----
> From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On
> Behalf Of Michael Graham
> Sent: Thursday, August 04, 2011 7:38 PM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] CoCo 2 problem
>
> I had a similar problem with my CoCo 3 once, and re-seating the RAM
> chips fixed it.  I can't remember whether the RAM is socketed in any of
> the CoCo 2 models - If it is, try re-seating it, if it isn't, it could
> be one or more of your RAM chips has microfractures in it, which are
> causing the chip to fail as the casing expands from the heat produced by
> operation.
>
> Don't take me as an expert on this though, I'm only speaking from two
> experiences I've had with this kind of thing - Once with my CoCo 3, and
> once with my TI-99/4a (the latter actually had all of its RAM chips
> fail). The microfracture thing is a theory I read from someone else.
>
> On 8/4/2011 7:30 PM, Chad H wrote:
>> Ok, I just acquired a new CoCo 2 unit (26-3127B) of unknown condition.
> The
>> unit looks immaculate inside and out, I had good hopes.  It did operate
>> great for about 5 minutes then started acting funny with disk access.  I
>> turned off the computer and rebooted and would either get garbage (columns
>> of funny text characters) or a good boot screen (Microware copyright
>> statement with "OK") but there is no flashing cursor.  Anyone ever see
> this
>> behavior before or know what it probably is?
>>
>>
>> --
>> Coco mailing list
>> Coco at maltedmedia.com
>> http://five.pairlist.net/mailman/listinfo/coco
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>