71B Stuck CMT Modules

[Raymond Del Tondo]

(02-03-2018 09:46 PM)Dave Frederickson Wrote:  I've noticed that the CMT RAM and EPROM modules for the 71B are difficult to insert and extract compared to the HP modules. I've compared the dimensions between modules and the IDS with no significant differences and checked PCB insertion/removal forces. I can't figure out what the problem is, or more precisely, what I can do to fix it.

Actually the CMT module cases are slightly larger than the HP ones. It may just be some micrometers, but it's sufficient to make the slot somewhat too narrow.
The increased friction can be noticed before the module has contact to the PCB.

However even some HP-IL modules sit very tight in the slot. I have seen various HP-71 units where the previous owner tried to remove the HP-IL module without success. Can easily be seen when there are scratches or case deformations in the area where one puts his thumb to remove the module.

One possible solution is to use a plastic stick from the other side, and push the module out. This also works for some of the front slots with CMT modules;-)