Post Reply 
Found these inside a non-working 71B
03-09-2018, 10:22 PM (This post was last modified: 03-09-2018 10:28 PM by MikeSD.)
Post: #3
RE: Found these inside a non-working 71B - What are they?
(03-09-2018 08:31 PM)Dave Frederickson Wrote:  The bottom pic shows what looks like a couple of CMT memory modules, just like the pic of the P01 internals on your website. The top one could be a ROM as you speculated.

EduCALC offered an internal module installation service back in the day.


The fact that it's on the port 4 end seems significant as well.

I've got some better photos and the internal wiring. Hardly a schematic but might be a clue. I tediously replace the wirewrap bypass on the flex circuit that was removed. Some of those wires broke off. I used shorter wire that I have had success with before. Powered it up and right half of display lit up and a couple of cursors but no activity.

Then, I buzzed everything out and it was ok. Buzzed pin to adjacent pin. And end to end on the wires. All looked good there.

Then, I peaked under these devices to see if it was going to be able to check for broken wires. Sure enough there was another broken wire. However, I'm not sure where it goes. I have my suspicion. Need to drag out the tech manuals and see if I can figure out where it might go. There is a wire end still on the device, that looks like where it broke off, but I hesitate to hook it up without knowing.

I had done a triage on these once upon a time, and had this one marked "No Hope". I didn't even notice the internal wired components at that time. Glad I took a 2nd look.

Will post more photos later. And by more I mean better. Wink

This is what was in the programmer. I think this is two 32K RAMS. Maybe that is a 32K RAM. That would be nice, even if I never get the 71B working. But I think I can, unless one of the HP chips are bad.

[Image: CMT-71-P01l.jpg]
Find all posts by this user
Quote this message in a reply
Post Reply 

Messages In This Thread
RE: Found these inside a non-working 71B - What are they? - MikeSD - 03-09-2018 10:22 PM
What's U10? - Dave Frederickson - 03-15-2018, 03:43 PM

User(s) browsing this thread: 1 Guest(s)