While I wait for the Cloud9 512k upgrade I ordered, I figured I'd operate on another CoCo3 and do a CPU transplant. What was the point of getting 10 63C09EP's if I didn't intend to install them? The very first one I did on my repack (seems like ages ago) I carefully removed in an effort to save the CPU. For what, I have no idea. That could have turned to disaster as the heat was enough to slightly warp the motherboard, so I doubt the CPU survived anyway.
These latest ones I found myself just clipping the damn things out, cleaning everything up and soldering in the sockets. Repack CPU swap time, somewhere around 4 hours. Clip & solder swap time, about 30 minutes. Yeah, don't think I'll be wasting time like that again.
Above is a pic of the bottom of the motherboard, showing the 'cleaned-out' holes. Of course I got the bright idea to take some pics AFTER I had already started to solder the socket in... oh well....
Above are the two recent sacrifices. Didn't dawn on me until I was writing this that the damn things were upside-down in the picture... sigh....
Well, I don't consider myself a vintage computer repairman by any stretch, but, that didn't stop me from getting out my malfunctioning MPI on Saturday and going thru it again. When I last had it out, Gene and I had been diagnosing a strange problem (yes, those seem to follow me...). With a floppy plugged into it, it might load, or might not load a program. Sockmaster's Donkey Kong is a no-go with an error in line 15. I Can get DIR commands to complete, but, they take longer than they should and the drive sounds like it's going to throw an I/O error. The O-90 cart seems to work by itself, can't get any disk access, tho. The REALLY weird part is, with the FDC in slot for, and the speech and sound cart plugged in - does not matter which slot it's in, and the selector on '4', the CoCo boots to a Ext Color Basic 1.1 screen. Essentially a CoCo 1/2 screen. I have replaced the 74LS245 chip and all of the 74LS367 chips. When this problem started way back in '07, I think Robert Gault suggested to check the power supply. I'll be doing that this coming weekend...
Later,
Brian
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