The Museum of HP Calculators

HP Forum Archive 14

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Problem with 48GII
Message #1 Posted by Iqbal on 18 July 2004, 8:57 a.m.

Every probably 3-4 weeks or so, I encounter a strange problem on my 48GII. The 1,2,3 and F buttons work. There is no way to do the self test. All other buttons work fine. But if I take out the batteries and leave it off for maybe a day or so, it starts back to work like normal. It doesn't seem to be a problem with the actual buttons involved. Any ideas what could be causing that?

Re: Problem with 48GII
Message #2 Posted by Vieira, Luiz C. (Brazil) on 18 July 2004, 11:46 a.m.,
in response to message #1 by Iqbal

Hi, Iqbal! Are you well?

I'm curious: how many times did it happen? Or how often does this KBD weirdness happen?

I'm asking about this because I was requested by a student to try to repair an HP20S (Pioneer) where the [INPUT], [+/-], [(], [)] and [<-] row no longer works. I "gently" tried squeezing and twisting the case closer to the "zebra" contact that connects the keyboard flex contacts to the main PCB, and I succeed making the [<-] work once. But I didn't think of resetting the calculator or leave it without batteries. I once had an HP42 with sort of a "bad behavior" with the keyboard: without the back half case it worked fine, but no key worked after putting the back case in place. I had to add some thin foam fastener below the zebra contacts to ensure it would "touch" the mainboard contacts.

What I wonder is about the possibility of the batteries compartment being right below the keyboard/main PCB contacts. In the HP48/49, the batteries compartment was in the bottom of the calculator case, now the HP49G+ (I'm not sure about the HP48GII) has it in the top, opposed to the earlier models. Would removing/replacing batteries somehow "shake" these contacts and cause them to work /not work? My HP49G+ works perfectly fine since I got it, but your concerns and your HP48GII behavior must be considered as well.

I'd wait for a while and observe. If the calculator is new and you still can do that, ask for a new unit. If everyone does it, HP will surely (probably???) do something to avoid replacing defective units by enhancing quality... should we expect so?

Cheers and best regards.

Luiz (Brazil)

Edited: 18 July 2004, 11:48 a.m.

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