Bringing a Voyager (10c -- 16c) LCD back from the dead

[BarryT]

Hi All,
This is my first post here... so my apologies in advance if this has been well documented somewhere, I can't seem to find anything on the topic though, so here goes... :-)

What I'm mainly really really wanting to know is... how the heck the LCD Displays work on these things? Does anyone have any information on how these things work? I'd love to know! :-)

Ok... now here's the "why".
I recently acquired a 15c, ( serial 2537A..., so 1985 ), that wasn't working... it's in pristine shape both inside and out, just nothing what so ever happens at power on. I carefully took it all apart, hoping it would be something as simple as a corroded\broken battery contact. Well... I found that corroded was correct. Not terribly, but far too much.

So, I grabbed my jewelers glass and started cleaning the board and the traces to get all the ugly green corrosion off. I even checked the board for power... it has good voltage, and when jumping across the individual buttons with the voltmeter, depressing the buttons shows flow. The traces on the board all 'appear' to be good, no broken circuits anywhere.

Afterwards, I tried again... and got a brief random batch of segments showing up, but then nothing. OK, now I know it has some life left... so onto removing the little heat stakes, ( wow, I sure would like to kick the person at HP who thought this was a good design... has the person never heard of screws? :-o ). These came off easily enough so I flipped the board over and found a good deal more corrosion, including under the LCD.

So, now I have a nice little LCD, nothing 'appears' to be wrong with it, so I set it aside. Next I take to cleaning the traces and board on this side. I even checked the resistor and, to the best I could with it on the board, I checked the capacitor, which I believe is also in working order.
After cleaning everything, and being totally befuddled by what traces on the PCB light up the various segments on the LCD, I decide to put the thing back together... and VOILA... there are more signs of life. I get some segments showing up, can input numbers, SIN and COS give me correct answers, etc. However, the thing is ghosting like crazy. The numbers are not whole, they are partial, and, despite the fact that the Multiply and Divide functions actually work, correctly, the self tests do absolutely nothing. :-( If Multiply and Divide work... I have no idea what would cause the two self-tests to not work.

Ok... so now I try one last time, in case there were parts that still didn't get cleaned, and now I get almost a completely alive display... still some segments out, on the very bottom, the "f" and a few others... AND, the self tests actually run now!!! Then after futzing with it, it goes dead again. :-o

OK, so that's where I'm at. I have this thing apart... it "appears" to want to live again, but the LCD wasn't displaying 100%. Might anyone have any advice on how to get this thing fully resuscitated?

Oh... also, does anyone know what the two teeny tiny springs are for? All they appear to do is connect the metal on the bezel to that on the back panel, and, that on the keyboard to the back panel. Grounding of some sort? To avoid static discharge perhaps?

Thanks in advance everyone.

Barry

[BarryT]

Update... ok, so I've now got it back to where I had it earlier... almost the entire display is alive. Unfortunately though, not the entire thing :-( Any suggestions on how to get the missing segments to light up? For reference, I've attached a picture of what I'm seeing.

[BarryT]

Ooooooooooooo Kkkkkkkkkkkkkkkkkkkkkk ... Houston, we have lift-off!!!

So, persistence and patience have payed off. It turns out the little rubber contact strips on the edges of the LCD are EXTREMELY temperamental. I probably took the LCD off a good dozen times, looking it and the PCB contacts over for corrosion, putting it back together and getting no progress.

Then, I got curious... I put LCD in the little bezel that locks it against the PCB, but this time when I looked at the rubber strips with the jewerler's glass I specifically looked for inconsistencies in how it was laying against both the PCB and the LCD itself.

What I discovered was they weren't laying "flat", the bottoms were angled out ever so slightly. So, I very carefully popped up one edge of the locking bezel so the strip on that side was free to move, then, with the metal tip of a mechanical pencil, I proceeded to very gently push the strip in a bit so it would lay more flatly, and popped the bezel back into place. I then repeated with the other edge.

Once that was done, back together once again it went, and I powered it on. To my surprise and relief... VOILA!!! Success! Upon running both self-tests, ALL segments of the LCD now light up, and the keyboard test passes as well.

Thanks to everyone for listening to my working rant as I walked through the process ... hopefully this may help others with LCD issues and\or dead displays.

Barry

[Duane Hess]

The screws are for static discharge to protect the unit as you handle it.

Can't help with anything else, sorry. Have a calc with the same problem myself.