HELP!!!! TRS-80 Mod III M/B NEEDED!!!! - test-drb@ccmp.vtda.org

28 Dec 1998

...
 I would bet on the FDC still being OK, though. I've
found the 1793 chip
(the big 40 pin one) is very easy to zap. And you'll not test that without
a working CPU board (the motor on/drive select logic is totally separate,
BTW)
 Probably.  No paper clips had fallen into it, and no signs of external
damage.  I really won't know if it's good or not 'till I get a new board.
Even if it is blown, I have a good, spare one.

...
 If you connect the CPU board to the PSU does the PSU
still come on? Don't
connect any other cables at this point. Do you have a scope or logic
probe? If so, is there any activity on the Z80 pins?
 It still turns on, but makes the CPU board seem more like a fog machine than
a computer, and it stinks up the house pretty bad.
I have a scope that someone was going to trash that appears to work, but I
don't have any cables but a couple of old multitester cables.
I doubt there would be any _useful_ activity on the Z80 pins.  The chip is
basically melted.  Most of the chips are like that.  There's paper clips
permanantly fused to other parts of the board.

...

The model 4 keyboard is the same as the model 3 keyboard but with 5 etra
swtiches. They're both 8*8 matrices of swtiches with some positions
unused. And the keys are in the same electrical position on the 2 keyboards.
...

So a model 3 keyboard should work with a model 4 CPU board - you just
won't have the control/caps/F1/F2/F3 keys. Model 3 software running on
the 'Model 4' shouldn't mind that. Some model 4 software will be hard to
use without those extra keys, though.

Anyone have a spare Model 4 board laying around anywhere??
Model III?

ThAnX,
--
                 -Jason Willgruber
               (roblwill(a)usaor.net)
                  ICQ#: 1730318
<http://members.tripod.com/general_1>