Post Reply 
Missing segments on HP-65
12-10-2019, 09:29 PM
Post: #1
Missing segments on HP-65
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!!!


Attached File(s) Thumbnail(s)
       


11C 12C 15C 17BII 18C 19BII 21 25 27S 28S 32E 32S 32SII 33C 33S 34S 35S 38C 39gs 39GII 40gs 41C 41CV 41CX 42S 45 48G+ 48GII 49G 49G+ 50 67 71B 97
Find all posts by this user
Quote this message in a reply
12-10-2019, 09:49 PM
Post: #2
RE: Missing segments on HP-65
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?)

There are only 10 types of people in this world. Those who understand binary and those who don't.
Find all posts by this user
Quote this message in a reply
12-11-2019, 12:22 AM
Post: #3
RE: Missing segments on HP-65
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!!!
Find all posts by this user
Quote this message in a reply
12-11-2019, 07:26 AM (This post was last modified: 12-11-2019 07:32 AM by PANAMATIK.)
Post: #4
RE: Missing segments on HP-65
(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

That's one small step for a man - one giant leap for mankind.
Find all posts by this user
Quote this message in a reply
12-11-2019, 04:46 PM
Post: #5
RE: Missing segments on HP-65
(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 Smile


11C 12C 15C 17BII 18C 19BII 21 25 27S 28S 32E 32S 32SII 33C 33S 34S 35S 38C 39gs 39GII 40gs 41C 41CV 41CX 42S 45 48G+ 48GII 49G 49G+ 50 67 71B 97
Find all posts by this user
Quote this message in a reply
12-11-2019, 06:05 PM
Post: #6
RE: Missing segments on HP-65
(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
Find all posts by this user
Quote this message in a reply
12-11-2019, 06:14 PM
Post: #7
RE: Missing segments on HP-65
(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


11C 12C 15C 17BII 18C 19BII 21 25 27S 28S 32E 32S 32SII 33C 33S 34S 35S 38C 39gs 39GII 40gs 41C 41CV 41CX 42S 45 48G+ 48GII 49G 49G+ 50 67 71B 97
Find all posts by this user
Quote this message in a reply
Post Reply 




User(s) browsing this thread: 1 Guest(s)