[Coco] Weird CoCo3 problem - AAAARRRGGGGGHHHHH!!!!

[Bob Devries]

Thanks, Chris,

That was a better explanation than mine.

Between all of us here, I'm sure we will get the problem solved. :)

Regards, Bob Devries
Goulburn, NSW, Australia

--
Besides a mathematical inclination, an exceptionally good mastery of one's 
native tongue is the most vital asset of a competent programmer.

Edsger W.Dijkstra, 18 June 1975

----- Original Message ----- 
From: "Christopher Hawks" <chawks at dls.net>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Monday, January 04, 2010 9:34 AM
Subject: Re: [Coco] Weird CoCo3 problem - AAAARRRGGGGGHHHHH!!!!


> Brian Blake said the following on 01/03/2010 03:35 PM:
>> The latest;
>>
>> Upon further testing, R22 was not doing anything. The solder pad on the 
>> bottom of the mobo was broke, an the leg on the end that's supposed to 
>> connect to C65 had been lifted. I took R22 completely out and replaced it 
>> with a new 120-ohm resistor. Then I took a short piece (3/16 - 1/4") of 
>> speaker wire and soldered it to the leg of R22 that is supposed to go to 
>> pin 4 of the GIME, scraped away some green stuff and soldered the other 
>> end directly to the trace. Continuity restored. Continuity from R23 was 
>> fine. Cleaned up the solder pads from where I clipped out the 6809, 
>> soldered in the socket, installed the 6309 and put everything back 
>> together. Turn her on and was greeted with the 'Extended Color 
>> Basic....yada, yada' greeting, okay that worked. Tried Tetris, S/S Pak 
>> and O-90, all worked as expected. Still have the same problem with the 
>> FD-502; POKE &HFF40,1 does not turn on the drive light, and any disk 
>> commands end up with an I/O? error with no activity
>>  being present on the drives when the commands are issued... 
>> AAAARRRGGGGGHHHHH!!!!
>>
>> I went to R/S today only to find out they no longer carry a logic probe, 
>> so I'm stuck with using my DMM for now. When issuing a POKE &HFF40,1 in a 
>> loop, IC9 pin 6 is 'HI' on the DMM in logic mode, but, in frequency mode 
>> it shows up as a 192.5-kHz signal. Pin 36 of the 40 pin connector shows 
>> the same results. Other than evidently ruining a perfectly good 6809, so 
>> far the only thing I've accomplished is completing a 6309 swap on a CoCo3 
>> with 'floppy phobia'... So, I'm still open for suggestions. Tomorrow I'll 
>> be bringing home my 50-MHz scope so I'll at least be able to look at 
>> waveforms. At this point,based on my limited knowledge and materials I'm 
>> looking at, I'm leaning towards replacing IC9 to see if that helps, but, 
>> I'd rather not start chip swapping just for the heck of it, so PLEASE, if 
>> you guys who are far more knowledgeable than I have any suggestions, I'm 
>> listening!!!
>
> Brian:
>
> The Speech/Sound Pak (and I think the Orchestra Pak) are self-decoding. 
> They don't use Pin 36 <SCS>.
>
> Pin 6 of IC 9 connects to Pin 40 of the cartridge slot <SLENB> (and is 
> pulled Hi). Pin 9 of IC 9 connects to Pin 36 <SCS> of the cartridge slot. 
> If Pin 36 doesn't change, Pin 9 of IC probably isn't either. IC 9 must be 
> at least partly working since the internal ROM, Disk ROM, and PIAs are 
> selected correctly (pins 15, 14, and 13). If you check these Pins, be 
> aware that the ROM selects will only be active at startup when the ROMs 
> are copied to RAM. You could also check IC 9 Pins 1, 2, and 3. These are 
> the Pins that the GIME drives to select the outputs of IC 9. According to 
> IC 9's datasheet Pin 9 will be low when Pin 1 is low and Pins 2 and 3 are 
> high. You should see Pin 3 pulsing during the Poke.
>
> -- 
> Christopher R. Hawks
> HAWKSoft
> ---------------------------------------------------------
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>
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