[Coco] Weird CoCo3 problem...

[Brian Blake]

I'll take part of that back - that is R22 that has been shorted and R23 looks like one of it's legs had been cut, then re-soldered. R22 & R23 go to /RAS & /CAS on the GIME - at this point I don't know if that would have anything to do with the problem I'm having with this one or not... still digging.


Brian



________________________________
From: Brian Blake <random_rodder at yahoo.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Fri, January 1, 2010 2:05:13 PM
Subject: [Coco] Weird CoCo3 problem...



All of these new developments on the CoCo front finally lit the fire under my arse to set up real hardware again. Besides my repack project, I have 3 other CoCo3's, two with 512k upgrades (one C9 and one PBJ) and one 128k. The one with the C9 upgrade works fine - can load and play Sockmaster's Donkey Kong. 

The one with the PBJ upgrade, not so... At boot, it comes up as it should with the proper display. However, any floppy commands are met with no response from the floppy drive (with an FD-502 controller) at all. Almost like the drive is off. The drive responds as it should in the other two machines. Upon removing the top case and k/b, I saw two wires, each had been soldered to opposite sides of R23. Now, under the keyboard, is another wire with alligator clips on each end, and the clips are holding on to the bare end of the wires soldered to R23, effectively bypassing the resistor. I'm looking for the PBJ instructions, pretty sure I have them, to find out if this is called for. I can also see where C65 & C66 have been cut and re-soldered. I have reseated the GIME and the PBJ memory chips, and cleaned the 40 pin connector. 

Any other suggestions? My 100MHz o'scope bit the dust so I don't have that tool any more (anybody have a CRT for a Leader 3 channel 100MHz scope??)


Thanks,

Brian


      

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