Hello,
I don't have an official schematic but I do have a M-100 that was
purchased in Australia. That M-100 was missing its modem part because
Australia uses CCITT tone pair where USA uses Bell, so the modem was not
authorized for use in Australia.
The IC numbers you quoted for the M-102 (I have one of those as well)
are very close to the modem and UART chips, so I would not be surprised
if your unit has been hobbled in the same way as mine.
I hope that helps!
Regards, Bert
On 3/18/25 18:21, Stephen Adolph wrote:
I think there is a very good chance the part is the same and it is wired
up the same. Hopefully you can confirm pin 2 of M33 connects to R139
for example. Also that pin 11 on M24 connects to pin 3 on the rs232
port via a 6.2k resistor.
You get the idea here I'm sure!
Good luck
Steve
On Tuesday, March 18, 2025, James Reed <[email protected]
<mailto:[email protected]>> wrote:
Hi all
I've just bought a Tandy 102 and am having a few issues. I'm in the
UK, and it looks like the one I bought was used in Germany. As a
result it has the European PCB number PPPCG2007A*01 referenced here:
https://bitchin100.com/wiki/index.php?title=Model_and_ROM_information
<https://bitchin100.com/wiki/index.php?title=Model_and_ROM_information>
Whilst there is no obvious battery leakage, it does have signs of
corrosion here and there. I have had to replace most of the F key
switches with new ones as the old ones had very rusty legs, and also
a few of the keys needed cleaning.
The big problem I now have is that the RS232 port transmits data
fine, but does not receive anything. I noticed that there was some
quite significant corrosion on pin 20 of the UART (which is where
the received data is fed), and I've cleaned it up and reflowed the
solder joint but it still doesn't work. I'm wondering if the trace
leading from pin 20 was damaged although it's hard to see where it goes.
The Tandy 102 service manuals all seem to reference the US edition,
and the PCB layout does not match mine. The schematic is also for
the US edition, and shows pin 20 of the UART connecting to pin 4 of
another chip, M33. There is no continuity between pin 20 and pin 4
of M33 on mine, but I'm a bit nervous as to whether the schematic is
actually correct for the Euro edition I have.
So - does anyone know if there is a schematic / PCB layout available
for the edition I have?
If not, does anyone have a Euro edition and would be willing to
check if pin 20 of the UART does indeed go to pin 4 of M33... or
somewhere else?
It's really frustrating, this unit is in great condition and it's
almost working... but without this I can't use any TPDD emulators
etc and it's essentially an ornament.
Any help would be most welcome
James
