Does anyone know how to open a 38G?


Dear All,

Following the message posted by HrastProgrammer some days ago, I decided to try to repair my 38g. Does anyone know how I can open it without damaging it? Many thanks for your help.



It's very easy. Peel off the plastic keyboard surround. You'll see six heat stakes that hold the front a back halves together. With an appropriately sized twist drill, by hand, shave down the tops of the posts. Pop the + battery contact off the case tab and seperate the front from the back. It's now open.


Since its a 38G, they are cheap on ebay. Just buy another. They usually sell for around $20 plus S&H. Not worth much time unless you want the experience of repair (an experienced repairman would need 20-30 minutes if he had everything ready, many hobbyests would need 1-2 hours, and a complete novice who KNEW what he was doing could spend 2-4 hours and still wind up with a piece of junk). Just a word of warning.

The other fellows advice sounds like it is for the 48G, but there are instructions on how to open a 38G on Colin Crofts website (I don't know the address offhand, but should show up on a websearch)

Actually, you might consider upgrading to an Hp39G+. It has a few more features most importantly, a decent amount of RAM, better stat functions and lots faster (though the 38G wasn't considered slow, like the 48G series). These are often available for $50-60 on ebay also.

For any old timers that don't keep tabs on all the Hp's, the above are algebraic only graphics calculators.


"The other fellows advice" was what the poster asked for, a 38G. The 48G has an aluminum overlay and ten heat stakes :^)


No, I confess, I have never opened a 38G as they have always been Cheap (and well made).


Hi there,

Thank you very much for your help and advice. I have followed Randy's instructions and found the six heat stakes. I'll now work on them!

Have a nice weekend.


PS: The reason I want to open this one is to learn how to do it. If it goes wrong, it is not too bad as I have another one and I got this one for free!


Dear All,

You may like to know that my 38G is now safe and back to work! The problem was similar to the one described by HrastProgrammer and I am very proud of the result.

Many thanks, especially to Randy and HrastProgrammer!



OK - I give up! How did you close the 38G?


--- Les



The case halves have snaps at the top and sides, it stays together fairly well without any further help.

You could use small flat-head screws on two the bottom posts as some 48 methods do for additional strength if desired. A piece of tape along the bottom edge works too if you want quick access and don't want to peel the surround off again to get to screws.

The 38G is the most easily opened saturn hack platform there is. That 30 pin standard memory pad screams for a custom rom.


Thanks, Randy - it was the mention of heat-stakes that made me curious. My wife's HP-18C has a dead column of keys on the alpha keyboard, so I was thinking of trying to fix it - only I've heard horror stories of the machines held together with heat-stakes. . .


--- Les



A clamshell with problems is pretty much a lost cause. Here's an old thread about 28's but 18/19C's are the same construction:


That's what I thought, Randy. Oh, well, it was just a notion. . .


--- Les



I'd like to buy 18C, 19B, and 19BII units with failed keyboards,
if anyone is willing to sell them cheap. I just want working
electronics for the extraction of the ROM code.

I can't afford to spend the money to buy working ones, nor do I
want to destroy them if they're perfectly good. But if the
keyboard has already failed, they're not much good for anything

Also intereseted in the Pioneers for the same reason, though
dumping the ROMs from models other than the 17B, 27S, and 42S
will be quite difficult.



Eric, I've just spoken to She Who Must Be Obeyed, and she's happy to donate her dying 18C to the cause. Email me a postal address, and next time I'm going past the post office - probably Tuesday or Thursday of next week - I'll pop it in the mail.


--- Les



You don't mean that!. The 19C is a Sting series, and is relatively easy to take apart non-destructively -- screws on the bottom, there are 3 PCBs inside, keyboard at the top, then processor/logic, finally PSU/printer in the lower case. After removing the screws, you can seperate the case parts, the PSU/printer PCB is connected to the logic PCB by those spring contacts that HP used in all machines at that time.

The machine that's built like a 28 (Clamshell case) is the 19B (and 19BII).


But putting back together a 19C can be a little bit of a problem... getting the stake pins together undamaged is always fun.


But a lot easier than reassembling a 19B (at least if you want the latter to stay together and work).


Hi Joao,

Good work ... I am happy to see that my post motivated a few people to try to fix their calculators :-)

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