One working 33C out of two? - Printable Version +- HP Forums (https://archived.hpcalc.org/museumforum) +-- Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum-1.html) +--- Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum-2.html) +--- Thread: One working 33C out of two? (/thread-9504.html) |
One working 33C out of two? - Daniel CLEMENT - 05-24-2001 Hello, I have come across a 33c which is apparently willing to function - except that the keys do not respond (minor detail...) On the other hand, I have a 31e with fuctional keyboard but battery contact and display problems. I'm thinking of some surgery. Is there any chance to sucessfully adapt the 31 keyboard contacts onto the 33? I've not opened anything yet - waiting for expert advice.
TIA - best regards, Daniel CLEMENT
Re: One working 33C out of two? - Viktor Toth - 05-24-2001 If none of the keys work, chances are that the problem is not with the keyboard contacts, but with the calculator electronics, so swapping the keyboard will not work. Also, keep in mind that there were at least two versions of HP-3x series calculators out there, in one of which the chips are actually soldered onto the keyboard "sandwich" assembly. There may also be other differences between the 31E and the 33C keyboard circuit layout. By the way, many 3x-series problems are simply due to the pressure contacts used in these machines, so it is possible that you may be able to restore both to good working order with a simple disassembly and thorough cleaning of these contacts.
Re: One working 33C out of two? - Raymond Del Tondo - 05-26-2001 Hello,
another mayor problem with the 30 series is corrosion on the battery contacts and/or the charger plug slider contacts.
If someone knows a method to open these calcs w/o scratching the plastics, Raymond
BTW: the 34C I have for sale doesn't have any corrosion;-)
Re: One working 33C out of two? - Viktor Toth - 05-29-2001 Well, corrosion is of a problem in any calculator with NiCd cells. But you're right, for some reason these 30-series machines seem to be more prone to it than others. I once received a 33E that was stored in its case for years with a set of partially dead batteries inside. When I opened it, there was white crystalline stuff (potassium carbonate, probably), tons of it, even on the outside! The flexible cable connecting the battery contacts to the power supply PCB easily rots, too. The only other machines I've seen that are as prone to corrosion are TI's third generation scientifics, like the TI-55 and the like, with the BP-7 electronic battery packs. In those, battery packs, the circuitry tends to rot away completely. As for opening a 30-series machine, until today I'd have been one of those suggesting that you really need to pull the case apart with force. (Worked for me so far without breakage.) However, I just read a post here that suggests that it is possible to slide the case apart after all, without applying excessive force. I'll give it a try.
Re: One working 33C out of two? - Tony Duell - 05-30-2001 Opening the HP3x series without excessive force is probably my post. Yes, it certainly works, or at least |