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HP-45 Repair Service
12-29-2018, 01:07 AM
Post: #1
HP-45 Repair Service
I am sure the members get this question all the time, but please bear with me on this one. I have an HP-45 that I have owned since it was new in about 1975. It is still in pretty good shape but was was retired years ago in favor of an HP-32SII and later an HP-35S. The display flashes and is erratic when turned on. It may be something as simple as the on/off switch, or it may be more serious. In years past, I sent it back to HP in Washington State for repairs on a couple of occasions. I am interested in finding somebody that currently repairs these things - if anyone still does. Thanks in advance for your reply.

JB
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12-29-2018, 10:35 AM
Post: #2
RE: HP-45 Repair Service
(12-29-2018 01:07 AM)JBerry001 Wrote:  I am sure the members get this question all the time, but please bear with me on this one. I have an HP-45 that I have owned since it was new in about 1975. It is still in pretty good shape but was was retired years ago in favor of an HP-32SII and later an HP-35S. The display flashes and is erratic when turned on. It may be something as simple as the on/off switch, or it may be more serious. In years past, I sent it back to HP in Washington State for repairs on a couple of occasions. I am interested in finding somebody that currently repairs these things - if anyone still does. Thanks in advance for your reply.

JB

Hi,

Maybe as for a lot of the models that had the batteries left in and corroded a few things. As you mention, switch could be faulty, but jiggling it would probably give an indication of good or bad.

Remove the batteries and look for corrosion. If you can, open it up by removing the 6 screws underneath, behind lower rubber feet and back label and inside battery cover.

The circuit board can be removed by alternately levering up the lower left and right corners so it disconnects from the keyboard pins.

Check on top and underneath for corrosion.

Handle the board from edges only as circuits can be damaged by the static electricity built up on your body.

If it cannot be repaired, try to contact Harald on this forum and get a MultiCalc upgrade board. As well as the HP-45, you will also have 26 other models to use all running genuine code.

cheers

Tony
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12-29-2018, 01:17 PM
Post: #3
RE: HP-45 Repair Service
Thanks Tony. The calculator was stored without the battery in place, so there is no corrosion in the battery hold. I will explore removing the back - there are good examples for removing the screws on several sites, and explore the insides. There is a TV repair shop (one of the few still in business around here - Michigan - and I may check with them regarding the repair work especially if I can get instructions on how exactly to replace to boards. Thanks again for your input on this.

Regards,

JB
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12-29-2018, 02:29 PM
Post: #4
RE: HP-45 Repair Service
(12-29-2018 01:17 PM)JBerry001 Wrote:  Thanks Tony. The calculator was stored without the battery in place, so there is no corrosion in the battery hold.

You might be lucky if there is just a bit of corrosion between the CPU circuit board and the connectors that run along the bottom to the keyboard and display circuitry. They are just spring tensioned to snug fit in the circuit board holes.

Maybe just wiggling the board or removing and replacing it might clear it up.

Batteries ok?

cheers

Tony
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12-29-2018, 02:41 PM
Post: #5
RE: HP-45 Repair Service
Right - the battery is OK. I just replaced it and checked the charge on the new battery.

JB
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12-30-2018, 07:56 PM (This post was last modified: 12-30-2018 07:57 PM by Harald.)
Post: #6
RE: HP-45 Repair Service
I doubt a TV repair shop will be able to do much. Unless you get a donor to supply spare parts.
And that is what I would suggest you do. Just find a working HP45 on eBay and swap parts. Most likely the problem will be either the main pcb which is easily swapped or it will be the display drivers on the display and keyboard pcb. That is also easily swapped, but your donor might have a bad keyboard. If that is the case, the TV repair shop might come in handy swapping the display driver ICs.

Good luck with the repair!
Harald
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12-31-2018, 02:26 PM
Post: #7
RE: HP-45 Repair Service
Thanks Harald - appreciate the advice. I just checked and there are a few working calcs on ebay right now.

JB
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