James, is the type of part M33 on your board the same as M33 in the manual?
If so, you could buzz out the circuits on other pins of M23 to confirm the use of thebpsrt is the same. 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 > > > >
