Repairing/Restoring 48SX

[EugeneNine]

My trusty 48sx quit turning on last year and I've been meaning to work on it ever since. My first attempt to disassemble messed up the metal keyboard overlay pretty good so I picked up another non-working on the auction site for cheap, then recently saw a working with minor screen damage and an equation library card so I grabbed it too. I've used the other two for learning how to disassemble without damage so I figured I'd share my notes so far.

First we have the box of parts. I have now: 3) 48SX, 1) Equation Library Card, 1) Printer.


I found the best way to dissolve the adhesive on the overlay is plain old IPA dabbed on with cotton balls and left to soak a while

You can't see the lcd damage real good here, there is some blue leakage at the top and a mark just above the A and B keys.

So then a drill bit on the 10 pins at the top and my old case cracker tool (black plastic wedge) to open the side and bottom clips.

And now we have it open


next a pair of flat (no teeth) pliers to twist the 6 tabs


And the board is separate from the lcd


This one has been repaired before, there is a rubber band in the connector to press it to the board.


Now to clean it up, swap LCD's and find some foam tape to replace whats there.

[Zaphod]

You can buy adhesive remover , it makes for less work than IPA

[rprosperi]

(10-24-2018 08:51 PM)EugeneNine Wrote:  Now to clean it up, swap LCD's and find some foam tape to replace whats there.

Buy a 39g/40g/49g on the bay (they are all cheap to real-cheap), cull the black LCD and install that in your 48SX. It not only makes it MUCH easier to read, it also becomes one of the best-looking calculators ever.

Edited list to remove ARM-based models (39g+, 39gs, 40gs) as they are NOT compatible with the Saturn-based 48 machines.

[DavidM]

(10-24-2018 10:06 PM)rprosperi Wrote:  Buy a 39g/40g/39g+/39gs/40gs on the bay (they are all cheap to real-cheap), cull the black LCD and install that in your 48SX. It not only makes it MUCH easier to read, it also becomes one of the best-looking calculators ever.

Thumbs up, +1, second, amen, etc.

I prefer the feel of my 48sx keyboard (despite its age and wear) to any of my other 48's (or 50g, and especially the awful 49g and 49g+). The black LCD display on that unit definitely gives it a nice presentation.

[burkhard]

(10-24-2018 10:06 PM)rprosperi Wrote:  

(10-24-2018 08:51 PM)EugeneNine Wrote:  Now to clean it up, swap LCD's and find some foam tape to replace whats there.

Buy a 39g/40g/39g+/39gs/40gs on the bay (they are all cheap to real-cheap), cull the black LCD and install that in your 48SX. It not only makes it MUCH easier to read, it also becomes one of the best-looking calculators ever.

Does the 49G (plain G) work for that as well? Maybe it's not as cheap, but I thought that also would serve as a black screen donor. Please correct me if I err.

Of the whole list of eligible donors, which *tends* to be the cheapest?

Any caveats of serial number ranges or anything else to be avoided?

[rprosperi]

(10-25-2018 05:12 PM)burkhard Wrote:  Does the 49G (plain G) work for that as well? Maybe it's not as cheap, but I thought that also would serve as a black screen donor. Please correct me if I err.

Of the whole list of eligible donors, which *tends* to be the cheapest?

Any caveats of serial number ranges or anything else to be avoided?

I am confidant the 49G LCD will also work, but I didn't list it because it (generally) is not available cheaply.

I have purchased more than 1 HP-39gs for under $10, shipping included, always from China. After that, the 39G is probably the most common/has least demand, so likely 2nd best choice.

Edit: Note the above is true, however the 39gs is NOT a compatible LCD donor for a 48, only the machines listed in my updated post above.

If there are 'good' and 'bad' serial number ranges, I'm not aware of them.

[burkhard]

(10-25-2018 05:38 PM)rprosperi Wrote:  

(10-25-2018 05:12 PM)burkhard Wrote:  Does the 49G (plain G) work for that as well? Maybe it's not as cheap, but I thought that also would serve as a black screen donor. Please correct me if I err.

Of the whole list of eligible donors, which *tends* to be the cheapest?

Any caveats of serial number ranges or anything else to be avoided?

I am confidant the 49G LCD will also work, but I didn't list it because it (generally) is not available cheaply.

I have purchased more than 1 HP-39gs for under $10, shipping included, always from China. After that, the 39G is probably the most common/has least demand, so likely 2nd best choice.

If there are 'good' and 'bad' serial number ranges, I'm not aware of them.

Perfect, Bob, I'll look for one of those cheapies! I'm a little reluctant to crack a very nice 48 open, but that is another topic... :-P

[EugeneNine]

If you crack it open carefully enough you can put it back together

I found this one for a screen
https://www.ebay.com/itm/New-Original-HP...1438.l2649

[burkhard]

(10-25-2018 10:33 PM)EugeneNine Wrote:  If you crack it open carefully enough you can put it back together

I found this one for a screen
https://www.ebay.com/itm/New-Original-HP...1438.l2649

Well, that was easy. You convinced me :-)
But now I need to get a cheap 48 to learn case-cracking on.
And once it's apart I might as well put the 39gs screen in...
And then I'll need another 39gs to be the donor for my primo 48GX...

Oh when does it ever end?

[Joe Horn]

(10-26-2018 01:26 PM)burkhard Wrote:  Oh when does it ever end?

It doesn't, thank goodness.

[RMollov]

IMO the most idiotic idea of HP calculator division was to make their calculators not repairable.
As of today I'd like to have HP48 in the body of DM42 with HP48 quality keyboard.
That would be the only new calculator I'd buy in the rest my life.

[franz.b]

who knows if they will do a DM48 ...?

[John Keith]

(10-27-2018 08:22 AM)RMollov Wrote:  ...
As of today I'd like to have HP48 in the body of DM42 with HP48 quality keyboard.
That would be the only new calculator I'd buy in the rest my life.

My ideal version would have the key colors and layout of the 48SX, the processor, memory, and display of the Prime G2, and hot-switching between NewRPL and the 50g 2.15 ROM.

We can all dream, can't we?

[Craig Bladow]

(10-24-2018 08:51 PM)EugeneNine Wrote:  So then a drill bit on the 10 pins at the top and my old case cracker tool (black plastic wedge) to open the side and bottom clips.

How do you keep it together after the 10 pins have been drilled out?

I have a 39gs on hand but only one 48gx, and the blue lcd looks great, have been looking for a 48gx with a bad display, but auction sellers seem to be asking quite a bit for those these days.

[TomC]

How did you get the metal overlay off so cleanly/'non-creased'?

TomC

(10-24-2018 08:51 PM)EugeneNine Wrote:  My trusty 48sx quit turning on last year and I've been meaning to work on it ever since. My first attempt to disassemble messed up the metal keyboard overlay pretty good so I picked up another non-working on the auction site for cheap, then recently saw a working with minor screen damage and an equation library card so I grabbed it too. I've used the other two for learning how to disassemble without damage so I figured I'd share my notes so far.

First we have the box of parts. I have now: 3) 48SX, 1) Equation Library Card, 1) Printer.


I found the best way to dissolve the adhesive on the overlay is plain old IPA dabbed on with cotton balls and left to soak a while

You can't see the lcd damage real good here, there is some blue leakage at the top and a mark just above the A and B keys.

So then a drill bit on the 10 pins at the top and my old case cracker tool (black plastic wedge) to open the side and bottom clips.

And now we have it open


next a pair of flat (no teeth) pliers to twist the 6 tabs


And the board is separate from the lcd


This one has been repaired before, there is a rubber band in the connector to press it to the board.


Now to clean it up, swap LCD's and find some foam tape to replace whats there.

[EugeneNine]

(10-26-2018 01:26 PM)burkhard Wrote:  

(10-25-2018 10:33 PM)EugeneNine Wrote:  If you crack it open carefully enough you can put it back together

I found this one for a screen
https://www.ebay.com/itm/New-Original-HP...1438.l2649

Well, that was easy. You convinced me :-)
But now I need to get a cheap 48 to learn case-cracking on.
And once it's apart I might as well put the 39gs screen in...
And then I'll need another 39gs to be the donor for my primo 48GX...

Oh when does it ever end?

I watch for the non-working-parts only.
Now don't you go out bidding me

[EugeneNine]

(10-27-2018 07:01 PM)Craig Bladow Wrote:  

(10-24-2018 08:51 PM)EugeneNine Wrote:  top and a mark just
So then a drill bit on the 10 pins at the top and my old case cracker tool (black plastic wedge) to open the side and bottom clips.

How do you keep it together after the 10 pins have been drilled out?

I have a 39gs on hand but only one 48gx, and the blue lcd looks great, have been looking for a 48gx with a bad display, but auction sellers seem to be asking quite a bit for those these days.

some small push pins or screws. They make pins that have knurling to prevent them from backing out, but ideally I want to find small screws so they can be taken apart again.

[EugeneNine]

(10-27-2018 07:11 PM)TomC Wrote:  How did you get the metal overlay off so cleanly/'non-creased'?

TomC

Dabbed IPA on with cottenballs and let it soak in overnight.

[EugeneNine]

(10-27-2018 04:11 PM)John Keith Wrote:  

(10-27-2018 08:22 AM)RMollov Wrote:  ...
As of today I'd like to have HP48 in the body of DM42 with HP48 quality keyboard.
That would be the only new calculator I'd buy in the rest my life.

My ideal version would have the key colors and layout of the 48SX, the processor, memory, and display of the Prime G2, and hot-switching between NewRPL and the 50g 2.15 ROM.

We can all dream, can't we?

My long term goal is to get x48 sources working on a microcontroller (PIC, AVR, etc) and then 3d print new enclosures to duplicate the 48 series.

[brickviking]

(10-27-2018 04:11 PM)John Keith Wrote:  My ideal version would have the key colors and layout of the 48SX, the processor, memory, and display of the Prime G2, and hot-switching between NewRPL and the 50g 2.15 ROM.

We can all dream, can't we?

I'd specifically want a separate 50G for NewRPL. Incidentally, what's in the 2.16 ROM? I can't extract it, nor install it on my 50G (because I can't extract it). Additionally, because I've only really known the 50G, how much brainbending would I have to get used to the 48SX/GX key layouts?

(10-27-2018 08:26 PM)EugeneNine Wrote:  My long term goal is to get x48 sources working on a microcontroller (PIC, AVR, etc) and then 3d print new enclosures to duplicate the 48 series.

I suspect you'll never quite have the same keyboard feel ever again. And, does x48 work as well as you can get it to work? Or could it be improved?

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