Missing segments on HP-65

[Moggul]

I just acquired an HP-65 which was advertised as non working. It came in a beautiful case with the Standard and Math 1 pacs so I thought to give it a try.

Turns out the previous owner tried to power it up directly from the charger with no suggess, but when I installed a good power pack it instantly came to life.

The problem is some of the LED segments do not light up. As you can see in the pictures digits 3, 5 and 8 do not light up properly (the display should read -8888888888.-88).

Is there a known cure for this? Should I open it up and clean the contacts? Or is it a lost cause?

Thanks!!!

[grsbanks]

A Classic should run on the charger alone. If yours doesn't then there's probably a fault in the power supply within the calculator or even with the charger.

Re the LED, I think it's the LED display itself that's faulty. A fault in the anode driver would result in the same segment(s) missing from every digit and a fault in the cathode driver would mean entire digits not working. At least I think this is the case. Someone who knows more about the electronics will no doubt be able to put me right if I'm wrong (Tony? Bernhard?)

[teenix]

It looks like those LED segments have failed either fully or partially. I have seen segments fail like this before and it looks like the only way to fix it is to try to find replacements for the 5 digit LED modules (any classic types will do) or another key/display board.

cheers

Tony

(12-10-2019 09:29 PM)Moggul Wrote:  I just acquired an HP-65 which was advertised as non working. It came in a beautiful case with the Standard and Math 1 pacs so I thought to give it a try.

Turns out the previous owner tried to power it up directly from the charger with no suggess, but when I installed a good power pack it instantly came to life.

The problem is some of the LED segments do not light up. As you can see in the pictures digits 3, 5 and 8 do not light up properly (the display should read -8888888888.-88).

Is there a known cure for this? Should I open it up and clean the contacts? Or is it a lost cause?

Thanks!!!

[PANAMATIK]

(12-11-2019 12:22 AM)teenix Wrote:  --- the only way to fix it is to try to find replacements for the 5 digit LED modules (any classic types will do) ....

Search for QDSP6061 bubble display. Relatively easy to find.

Edit: But I'm not sure if this is the type with the decimal dot inside the number.

Bernhard

[Moggul]

(12-11-2019 07:26 AM)PANAMATIK Wrote:  

(12-11-2019 12:22 AM)teenix Wrote:  --- the only way to fix it is to try to find replacements for the 5 digit LED modules (any classic types will do) ....

Search for QDSP6061 bubble display. Relatively easy to find.

Edit: But I'm not sure if this is the type with the decimal dot inside the number.

Bernhard

Thanks Bernhard.

I found these on ebay:

https://www.ebay.es/itm/Vintage-bubble-H...%7Ciid%3A1

However I believe they are the wrong type: "Vintage 7 segment LED display, 5 DIGITS, decimal dot outside the digit." I am looking for "decimal dot inside the digit", right?

(12-10-2019 09:49 PM)grsbanks Wrote:  A Classic should run on the charger alone. If yours doesn't then there's probably a fault in the power supply within the calculator or even with the charger.

I checked and the calculator runs when connected to the charger alone, so at least that part is good

[teenix]

(12-11-2019 04:46 PM)Moggul Wrote:  However I believe they are the wrong type: "Vintage 7 segment LED display, 5 DIGITS, decimal dot outside the digit." I am looking for "decimal dot inside the digit", right?

Yes, in the middle of the CDEG segments.

cheers

Tony

[Moggul]

(12-11-2019 06:05 PM)teenix Wrote:  

(12-11-2019 04:46 PM)Moggul Wrote:  However I believe they are the wrong type: "Vintage 7 segment LED display, 5 DIGITS, decimal dot outside the digit." I am looking for "decimal dot inside the digit", right?

Yes, in the middle of the CDEG segments.

cheers

Tony

These, right?

https://www.ebay.es/itm/VINTAGE-ORIGINAL...1372399431