Just thought I'd report this in case people don't know about it. I got a couple of 7A16P plug-ins years ago, and found that they really were intended to go with the 7912 and such transient digitizers, not with regular 7K frames. I tried them out in regular, and they messed up the readouts because the "P" is for programmable, using the programmable frames and digitizers with a GPIB bus in the main interface, which is normally for the 7K readout system. On studying these things I had figured out that the older-looking unit had some jumpers that somehow could be set to work it in a regular frame, but not reliably. It had other problems too, so I junked it into the custom plug-in carcass/parts department, but I kept the better one intact for all these years.
I've been sorting out all my plug-ins recently, figuring out what to keep, what to fix, and what to junk out. I revisited the whole 7A16P affair, and studied the manuals some more, and found what I think is the way to make it actually work right. Simply clipping a lead of R1612 (1k) on sheet 6 schematic, removes the drive from Q1512, so that U1500 never goes into GPIB bus mode. It only does its logic things needed to synchronize the internal microprocessor-generated readout info with the standard mainframe system. I'm not a hundred percent sure of this fix, since I haven't been able to find info on U1500, which is a Tek hybrid 155-0164. I thought that when I first went through this way back, I did find some info somewhere, but now I can't. If anyone does have info, please let me know. Somewhere in other manuals, maybe it's all figured out and explained.
Anyway, it seems to work just fine, with no apparent bad effects on the readout. This plug-in is now nicely usable in 7K, and I don't need it for any "P" frame anyway. If I ever do, I can just re-hook R1612.
Ed
