[Coco] CoCo 2 problem

[Chad H]

Arthur, you were correct in this case!  Thanks!  I replaced one of the RAM chips first....bit of a sloppy effort though.  I had no proper desoldering tools so I took a dremel cutter and cut the pins at the top of the chip..leaving the chip useless and mamed with pins sticking out of board.  Then I took needle nose pliers and tugged each one out individually while applying soldering iron till I had the socket cleared.. got socket mounted and soldered, but was really too big of solder and kept applying a bit too much.  Im not really much experienced with "fine" electronics soldering.
Well, I did good enough job with that and it turned back on but started exhibiting same behavior.  Then I got to thinking about the 6809 HALT line...that causes the CPU to literally freeze at certain times right?  So maybe the HALT was screwy since it always booted to copyright notice and didn't freeze till cursor appeared.

Well today I went to the ole radio shack and got a decent de-soldering iron with bulb built onto it and the thinnest solder they had, .022.  I replaced the 6809 with socket and put the same cpu back in...it showed same behavior but I must say im impressed with the work I did this time...just beautiful..and easy to boot.  Well, replacing that 6809 with one of my spare Hitachi HD68B09EP's did the trick...finally!  Its been on for a couple of hours now without a glitch :)  before, it would freeze after a few minutes at most.  

I guess I will go ahead and "socket" the existing RAM, just because I feel like having it socketed and now I have a better understanding of how to go about it.  Thanks everyone! :)

"J.P. Samson" <coco+list at jeanpaulsamson.com> wrote:

>I sure am glad that Tandy with their grand finale CoCo 1--the large  
>white-cased model with the "melted" keyboard--socketed just about  
>every chip on the board.  It makes life a whole bunch easier than  
>trying to desolder/clip out all those RAM chips!  (This is the only  
>CoCo 1/2 I own.)
>
>You are aware that you also have to solder in a jumper to activate the  
>additional RAM? Hopefully your kit came with instructions on this.   
>(Probably need to connect pads J1 and 64K, found near IC7.)
>
>-- JP
>
>
>On Aug. 6, 2011, at 9:58 PM, Arthur Flexser wrote:
>
>> 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.
>>
>>
>> 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?
>
>
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