CMD CQD-220TM problems

Here's a quandary that I've posted a few places, with varying success. I have a CMD CQD-220TM SCSI board (QBUS MSCP SCSI, drive and tape) which was working fine when I got it. It's now only partially functional with a few odd symptoms on my 11/23+. The basic problem is that the CPU (it's actually an embedded 8086 system) seems unstable, but in a somewhat deterministic way. I can have it copy the PDP-11 online utility into RAM and execute that, and I can perform a few operations on that before it bugs out (basically the CSR stops responding to requests and the utility hangs waiting for a confirmation code). The most interesting is when I try to run the "other utilities"; it starts up, but then crashes when trying to display the serial number. I should also mention that the UART doesn't seem to work, and I've tried both wirings (NULL modem and non) with no success. It's wired up like a standard DEC serial port (the header on the board has the same Rx/Tx and GND pins, which are all that are connected in my adaptors), so I just attached one of my adaptors to it. Here's the really interesting bit. After running over both the PDP and the 8086 side for a while with IDA Pro (which has been a lifesaver on many projects), it looks like the "other utilities" section actually talks directly to the 8086; the software on the board redirects the character output to one of the CSRs and the PDP and the 8086 converse that way. You get the same output as the UART. This is only true for the "other utilities" section, though; the rest of it executes natively on the PDP. Has anyone experienced this sort of problem with this (or a similar) card? I'm not really keen on building up a trace module to figure out what the 8086 is doing (though I have a few FPGA eval boards which would work just fine if I use SignalTap; I just don't want to go through the trouble of building it if the answer is simple). I'm honestly puzzled by this; it was working fine when I got it, and then I plugged it in after a move and no dice. I'm still banging on it with IDA pro. I hope it's not a busted PAL/GAL/PLA (of which there are about 20 on the board), because for the most part there's no way of redoing any of those without spending weeks on the assembly trying to figure out what they're supposed to do. The SCSI chip (a 53C90A) is a socketed PLCC, and they're not impossible to find second-hand, so if it turns out to be a problem there, I should be able to fix that by just throwing some money at it. - Dave