I own a HP-42S for about 12 years. The display was probably wrong since the beginning but it began to be bad in last 2 years. The left side of the display is getting black, probably caused by air coming right between the LCD cover and a polarisation filter. The black spot now covers almost x and y characters, so I can still use it, but it is still slowly going on and on. Is there any chance how to change the display? eg. take one from other damaged device with a good LCD? Or does HP still offer some kind of service?
Thanks for any opinion,
Pavel Rans
There are at least two articles available here thate are relevant to your problem:
MoHPC – Repairs & Batteries – Pioneer Repairs
MoHPC – Articles Forum -- #199: Increasing HP-42s Memory to 32K
Read all, go SLOW, and be careful.
I'd offer to help, but I'm WAYYYYYY overdue supposedly helping someone else, and I don't want to cause any more grief in the community!
HP offered an exchange service for five years after the 42S was discontinued in 1995. That service ended in 2000. I believe Paul Brogger has suggested transplanting a display from a 17BII, which appears to be identical to the 42S display. That doesn't look easy, but may be possible. If you really want a 42S (and who wouldn't?), and have a spare $200 to $250, there's always eBay...
An LCD turning black nearly always means that the liquid crystal itself is leaking out, probably because of damage to the seal between the 2 parts of the display. The polarising filters can often be removed and replaced without problems, and slight air gaps between the filters and the display don't matter.
Anyway, you need a new display. It's best to find a broken 42S with a good display and keyboard and just swap the logic board (see the article others have mentioned for how to open the case, then just twist the tabs holding the PCB to the metal frame and lift it off. Do NOT press on the CPU chip -- you can tear it (and ruin the machine)).
It is not easy to remove the display from the metal frame (it's glued in place) without breaking it, and it's not easy to align a new display so that it makes contact with the right traces on the PCB. It probably is possible (the contacts aren't at that fine a pitch), and IIRC a display from a 17B would work as well.
Don't even think about dismanting the keyboard sandwich (i.e. removing the metal frame from the top case). I have done this on a wrecked 42S, and I wouldn't want to try to get it to all stay together again.
Thanks for everybody's advices.
I still can use the machine, the black spot is partly outside the "matrix" area. Do you think I could prevent LCD from further leaking by putting some glue where the seal is broken???
Anyway, buying HP-42S from ebay for $200 seems relly crazy to me. Is it really such "hot stuff"??
Pavel Rans
I don't have a 42 of any kind, but from what I have heard others say about it, let me ask you - would you trade yours for another model?
Hmmm... I wasn't thinking about it yet. This machine is really cool. The only thing I miss is IR input.
"Anyway, buying HP-42S from ebay for $200 seems relly crazy to me. Is it really such "hot stuff"??"
The short answer: yes. ;-)
The long answer: Just try to go buy a comparable new replacement calculator! By that, I mean one that is as compact, powerful, and easy to program as the 42S. The _only_ RPNs that HP sells today are the 12C, 17BII, and 19BII business calculators, and the _big_ 48g+/gx graphing "compu-calc.s" (the big 49 graphing "compu-calc" _can_ be RPN, but it has no real [Enter] key; you have to use the tiny [=] key in the bottom corner...yuk! ;-) ).
Bruce.
Actually, I fail to see why the 42S is so desirable. OK, it runs the same user code programs as the HP41, but all the good bits (synthetic programming, HPIL, plug-in modules, time module, extended fnctions, ...) are missing. I'd rather have my 41CX stuffed with modules.
My 42S tends to get used as just a calculator -- I don't generally bother to program it as there is no way to save the programs on another device.
And yo answer your question, of course there are models that anyone would trade a 42S for. The HP95C is one of them. So (I suspect) is an HP01.
So, the result is that 42S is one of the best calculators (with few issues) and I can hardly imagine buying one of the newest models. Trading for similar model of same age is better option. But I still hope to get a spare LCD display.....
Pavel Rans
At last, someome who agrees with me about the 42S! It's a nice calculator and I wouldn't mind having one, but not at the prices I see on eBay. My 41CX is my idea of the perfect calculator -- it does everything I need, and with the card reader and/or HPIL it has unlimited storage.
I will agree with both of you.
I got my 41 in '80(still have it) and one day when I went into the store were I got it I saw the brand new 42.
I was told it was compatible with the 41.
I then asked were are the expansion ports for all the other great hardware I had for my 41?
There aren't any I was told. So I reply how is that compatible? And what do I do with my 41 hardware?
I looked at it in the case and said to myself boy that thing looks cheaply made and I have to type in my programs(some big) by hand.
With that and the price I said pass and walked away. To this day I don't regret it.
I picked up a 32SII that I use as a banger for check book etc. and I have a feeling if I had bought the 42 it would have this duty right now and would have been a waste of my money at the time. which wasn't cheap at the time.
I wrote a program for the 41 that accesses a big DB on the DCD. How could I do this with the 42? No it will not fit in 32K.
So I guess I will 3'rd this one.
Christopher
I am a supporter of the 42S, but I do admit it has minuses against a 41. There are pluses too.
Pluses are BASE, MATRIX, STATS, PROB, SOLVE and INTEGRATION preprogrammed functionality and rather good menus, apart from a lower price, better size and no corrossion prone parts. I bought my 42 mainly because it was very expensive then to repair my corroded 41C backplane (which also left it I/O-less!)
The 42S certainly should have had some kind of BIDIRECTIONAL I/O, a serial port might have been acceptable. And also, the ALPHA keyboard is clumsy. It also should have been repairable instead of a sealed unit.
If the 32SII had been not so inconsistent, it could fill the role of a reasonable scientific calc, with lots of preprogrammed functions, but it should had a BEEPer, some more memory (less than 400 bytes for programs and data... no comment), and more consistency about equations, complex numbers, etc. The way the 32SII "does" an AVIEW involves toggling a syntax-error-override flag, and then use a purpose-invalid equation (!!)
Well, and HP41 Advantage Pac will add some of those functions to the HP41. In fact I generally consider the HP42 to have the advantage pac (and little more) built-in. The problem with the advantage pac on the 41 is that it has the same XROM IDs as the DevIL ROM, and you can guess which one I find more useful :-).
Now you say that there are no internal bits in the 42 that corrode and need cleaning. Well, agreed the 41s do suffer from bad contacts. But it's not too hard to open up a 41 and clean the contacts. Opening a 42 is much harder and I have seen 42s with keyboard problems due to damaged/dirty contacts. It's possible to dismeantle the keyboard, but it's next-to-impossible to get it to stay together again. And the 42 keyboard is _cheap_ (like the 48 keyboard, etc). The 'PCB' is a thin plastic sheet with carbon traces printed onto and through it. I am not suprised it fails. In fact I am suprised that it ever works at all!
Against the 42S are the lack of any external input other than the keyboard (I do not like having to retype programs, OK), and the horrible alpha keyboard/menus which (IIRC) you can't get into a known state by just pressing keys (even 'Exit' doesn't always behave consisently) -- you have to look at the display as well to see where you are. Some menus go away after you've selected something from them, others don't. And the alpha mode is plain unpleasant. I must admit I don't much like programming the 42 (unlike the 41, which is nice to use IMHO).
Has anyone ever actually dismantled a pioneer keyboard
and successfully re-assembled it?
Well, I can tell you how one comes apart and why it's so hard to put back together. Start by Peeling off the metal overlay and removing the bottom case (we've been through this many times).
Stwist the 6 metal tabs behind the display so that they will fit through the slots on the pCB (look to see which way they were originally twisted and 'undo' it). Some of the tabs have little grounding spikes on them -- flatten these with pliers after untwisting them so that that they will fit through the slot and so they will make good contact when reassembled.
Now lift off the PCB (take care to avoid electrostic damage) and remove the 2 zebra strips for the display connections. So far it's not hard to put back toegther.
Look at the back of the keyboard. It's covered in a metal plate with a _lot_ of heat-stakes holding it down. Cut them off, not forgetting the 2 'above' the display. Do not attempt to separate the display from the metal frame.
Now lift off the metal plate and separate the keyboard layers. There's a plastic insulator, then the 'PCB' (very thin, almost paper-like), then another insulator, then the sheet with the dome contacts on it.
No for the problem in putting it back together. It has to be fairly solid so as to stand up to having the keys pressed. But there's not enough plastic to re-heat-stake the pegs. You can't use metal screws because there's not enough clearance between the keyboard and the PCB and you'll get short-circuits on the main PCB tracks. You can't get tiny plastic screws for the obvious reason. I've not found a way of doing it yet...