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]> 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 > > 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 > > > >
