Hp 41 CX not turning on
#1

Just wondering anyone can help

I just recently got an HP 41cx. Unfortunately with a new set of batteries, it doesn't seem to turn on at all. I tried all the usual reset turn on methods mentioned in one of the articles on here. Even twisting and applying some pressure didn't do anything. All keys have good nice feeling.

It seems that the calculator might have undergone prior repair or opening. The rubber feet look like they were tampered with.

Any suggestion on any chance of a simple self repair? I have a feeling that as it looks like this was opened, a repair was already attempted unsuccessfully.

Should i send it to repair? would cost at least $80.

Or should I just forget it?

Thanks

Edited: 4 Jan 2008, 10:59 p.m. after one or more responses were posted

#2

No one has any other suggestions so far?

#3

Seems likely that the posts are broken, as this is the most common problem. Search the archives and/or articles for discussions on 41 damage/repair. Basically, you'll have to repair the four posts that the screws screw into. Small cracks are no big deal, but sometimes the posts are really bad off and have to be rebuilt with new plastic.

#4

hmm, i opened the thing. All 3 cpu to keyboard interconnectors are gone ;(. no wonder it doesn't turn on. i am really suspecting that my calc was used for parts before i acquired it.

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv014.cgi?read=64837

I am considering direct wiring the cpu to keyboard as above. but before i do that, anyone know what i need to look for to make sure the board i have is actually a 41 cx board and not a 41 c or cv board. This is a fullnut ver. i guess i could be doing a lot for nothing if the cpu is bad also

Much appreciated. thanks

#5

This is all explained in the thread that you posted a link to but here goes again:

The CX has a 20 pin x 0.3" dip (1LF6-0001) along the right side of the board, it is the real-time clock. A 22meg resistor and a small round crystal are mounted below. The board is also used for the C and CV so if it is one of those, the board will be empty in those locations. If the board does not have those holes, with or without the components, it cannot be a CX.

Quote:
I am considering direct wiring the cpu to keyboard as above

Once you start soldering wires between the logic board and keyboard, it becomes a throw-away unit. It is the worst possible solution you could ever implement. *Don't do it* as you'll never be able to test anything by exchanging parts.

Stated another way, if you don't know that all the parts are good before you solder the thing together, and then it doesn't work, you'll just end up pitching the thing in the bin.

Chances are that if the zebras were missing, you probably should consider the unit non-working. Using zebras from a good machine, swap a known good logic board into this one to test the keyboard and display. Once you know that is good, bring the old logic board back in and test.

Quote:
All 3 cpu to keyboard interconnectors are gone

Only the two long strips of connections are used. The short group of four in the middle are not needed.

Edited: 5 Jan 2008, 9:05 a.m.

#6

very good points. unfortunately, i don't have another fullnut to get the interconnetors to test out. i have another halfnuet 41 cv, which i dont think have any interconnectors which i can use to test this out ;(

#7

Also checked the CPU board. I do have a CX board.



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