View Full Version : Help needed for two ISA 8bit Multi I/O cards (QUADRAM and Mitsuba), please.

September 1st, 2013, 06:08 AM

This is a Multi I/O card from MITSUBA. As far as i guessed, it offers : video, clock, game part, 1 serial, 1 parallel and memory expansion (perhaps 128KB or 256KB)
the model seems to be "RMV 100" (top left)
P5 is the game port connector.
P6 is a serial part connector.
I believe that C2C2 C1C1 jumpers are for the serial port (1 or 2) and L1,L2 and L3 jumpers are for Printer port. (see top right)
I bet that SW1 and J4 J5 are for memory expansion (configuration unknown).
Unknown : J1 (near video port), J2 (right of j5 & j4), J3 (near UM2300 IC).

Help needed, please, for :
SW1, J1, J2, J3, J4 and J5 settings.


This is QUADRAM Multi I/O card, but i didn't managed to find informations about it. It's pretty close from the Quadram Quadboard (1982).
But it hasn't got a parallel port, only two serial ports : i believe that J1 is a second serial port.
The battery leaked a lot and destroyed completly four ceramic capacitors. i couldn't read anymore their capacitance. I unsoldered their remains (C66, C67, C68,C69). They were located between the battery and the first row of RAM (see the second picture).

Help needed, please, for :
1- the capacitance of C66, C67, C68, C69 : if someone could own the same board...
2- the switch settings of SW1/SW2 : it should be different from the first Quadboard, but its settings might be useful. I'll try different settings if nobody has informations about it.

What i still have to do :
- Unsolder and replace the first four RAM sockets from the row near the battery. I already unsoldered the baterry and cleaned the PCB : i put it again onto the board only for taking the pictures.
- Unsolder and replace SW1 : nearly all the switches from SW1 don't work anymore (SW2 is ok). I found the same model, same manufacturer on eBay US ! :D
- replace one ceramic capacitor and one tantalum capacitor (values known), near the first row of memory chips.
- Fix several damaged tracks : it shouldn't be too hard, it's a double side PCB, not a four layers+ one ...

Thanks all.

September 1st, 2013, 07:42 AM
Please remove the battery as soon as you can on the Quadram. It is leaking on the board and destroying the circuit board runs. Do it now. Use some electronic type cutters. Or desolder it.

September 2nd, 2013, 01:37 AM
This is QUADRAM Multi I/O card, but i didn't managed to find informations about it. It's pretty close from the Quadram Quadboard (1982).
I see that your board has the part number of 8920-4
According to an earlier post, user generic486 has a Quadram card of part number 8920-3 (not much difference). He may be able to help you.

September 2nd, 2013, 06:24 PM
I have a Quadboard, part number 8920-3, and the capacitors on it are marked 470. I believe that translates to 47pf. I had patched this board up from battery damage, but it failed on me again shortly, before I puzzled out if it had two serial ports, or an odd male printer port connector. I believe the switches followed Quad's usual scheme, with SW1 controlling memory, and SW2 controlling features. This text file lists the settings I believe I used on my card before it died.


September 8th, 2013, 02:38 AM

Thanks all for your help, i'll post here the results if i manage to fix this board.