|HP-41C partially repaired, help with "ROM", alpha glitches|
Message #1 Posted by MattMalone on 25 Sept 2012, 10:33 a.m.
About 4 years ago, I discovered my HP-41C had a battery leak. Honestly, the leak could have happened any time in the 4 years before that, I had not used it. I cleaned out the leak, by now all dry and crystalline, tested the 41 perhaps not thoroughly, and it seemed to work.
I went back to it a couple of times a year in the last few years. Some times it lit up no problem, sometimes I had to do a hard reset, take out batteries, short battery terminals, whatever, it eventually came up. This last time, nothing. So I found the screws, opened it up and found more battery leakage inside. I carefully cleaned it up. I have reassembled the calculator and it comes up. I was trying more extensive tests, and to use it, but there are glitches. When I hit [program] the first time, I get "00 REG 46" like I expect, but from there it has problems.
When I press XEQ [alpha] (in program, user or normal mode) preparing to enter a command name, it comes up with "IQ -" or something similar on the screen, and I cannot type keys to enter a command name. The message was the same in dozens of experiments. (After a second cleaning, the message changed slightly, still starting with "IQ" and from that point on was again consistent.)
Soon after, regardless of what keys I press, I get the "ROM" message. Some sequences lead to the calculator shutting itself off.
Once there has been any glitch, Goto.. does not get it back to "00 REG 46" or ".end." or whatever is normal. It typically comes up with "ROM" again after a few keystrokes.
Same thing happens when I try to enter an alpha after any command, including LBL.
When I enter program mode, after a few keystrokes, it says "ROM".
Once it has thrown this error once, only a "memory lost" reset gets it back to "00 REG 46" when I hit [program] the first time.
Any ideas on where I should clean next to get this to work ?
(I have used no solvents, only a clean cloth with DI water-fully dried after, and gentle mechanical methods were used to clean)