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NoEqualsButton · 07-24-2019, 07:31 AM

I just scored a HP 65 in immaculate condition. Cosmetically near perfect and works perfectly with the exception of the card reader. I have replaced the batteries and fully charged them. When a card is inserted the motor does not start. No noise. The display just blinks 0.00.

Any ideas? I know the gummy wheel needs replacing anyway, but I'd expect it to at least try and read the cards.

Namir · 07-24-2019, 09:02 AM

(07-24-2019 07:31 AM)NoEqualsButton Wrote: I just scored a HP 65 in immaculate condition. Cosmetically near perfect and works perfectly with the exception of the card reader. I have replaced the batteries and fully charged them. When a card is inserted the motor does not start. No noise. The display just blinks 0.00.

Any ideas? I know the gummy wheel needs replacing anyway, but I'd expect it to at least try and read the cards.

Your HP-65 needs a gummy wheel repair job. This happens due to age and regardless of usage and/or "expectations".

**rprosperi** · 07-24-2019, 12:52 PM

(07-24-2019 09:02 AM)Namir Wrote:
(07-24-2019 07:31 AM)NoEqualsButton Wrote: I just scored a HP 65 in immaculate condition. Cosmetically near perfect and works perfectly with the exception of the card reader. I have replaced the batteries and fully charged them. When a card is inserted the motor does not start. No noise. The display just blinks 0.00.

Any ideas? I know the gummy wheel needs replacing anyway, but I'd expect it to at least try and read the cards.

Your HP-65 needs a gummy wheel repair job. This happens due to age and regardless of usage and/or "expectations".

What Namir said! The old rubber can degrade enough that it has literally glued the roller to the surface preventing any movement at all. And it's best to stop trying as doing so is stressing the tiny motor, trying to turn rollers that can't move.

burkhard · (This post was last modified: 07-24-2019 01:03 PM by burkhard.)

(07-24-2019 09:02 AM)Namir Wrote:
(07-24-2019 07:31 AM)NoEqualsButton Wrote: I just scored a HP 65 in immaculate condition. Cosmetically near perfect and works perfectly with the exception of the card reader. I have replaced the batteries and fully charged them. When a card is inserted the motor does not start. No noise. The display just blinks 0.00.

Any ideas? I know the gummy wheel needs replacing anyway, but I'd expect it to at least try and read the cards.

Your HP-65 needs a gummy wheel repair job. This happens due to age and regardless of usage and/or "expectations".

Well, yeah, but he acknowledged that. He was asking why the motor wouldn't turn on.
There are several reasons why this could be --
a) Problem with switch that detects card insertion
b) Problem with motor itself
c) Problem with wiring for a) or b).
d) Something related to the display just blinking zero -- some greater brain damage?

I think you will need to investigate once you get in there to fix the certain gummy wheel anyhow. With a DMM you ought to be able to check out the switch function and continuity throughout. Directly power the motor with 3.6 VDC and verify that works as well.
The display blinking 0.00 I am more at a loss on... At the very least, when you have it open, clean all the contacts with IPA and DeOxit. Oh, does it ONLY blink zero when you insert a card, but otherwise works fine? Maybe it is detecting a stalled (gooed / glued up) motor?

There are lots of posts here about removing and reattaching that foil label without ruining it. Be sure to check them out in advance! I'd then leave the label off until you are sure everything is working 100%.

Good luck!

[kby] · (This post was last modified: 07-24-2019 05:04 PM by [kby].)

Assuming it doesn’t immediately blink zero, that is normal behavior once the calculator decides the card didn’t read correctly.-kby

(07-24-2019 12:58 PM)burkhard Wrote:
(07-24-2019 09:02 AM)Namir Wrote: Your HP-65 needs a gummy wheel repair job. This happens due to age and regardless of usage and/or "expectations".

Well, yeah, but he acknowledged that. He was asking why the motor wouldn't turn on.
There are several reasons why this could be --
a) Problem with switch that detects card insertion
b) Problem with motor itself
c) Problem with wiring for a) or b).
d) Something related to the display just blinking zero -- some greater brain damage?

I think you will need to investigate once you get in there to fix the certain gummy wheel anyhow. With a DMM you ought to be able to check out the switch function and continuity throughout. Directly power the motor with 3.6 VDC and verify that works as well.
The display blinking 0.00 I am more at a loss on... At the very least, when you have it open, clean all the contacts with IPA and DeOxit. Oh, does it ONLY blink zero when you insert a card, but otherwise works fine? Maybe it is detecting a stalled (gooed / glued up) motor?

There are lots of posts here about removing and reattaching that foil label without ruining it. Be sure to check them out in advance! I'd then leave the label off until you are sure everything is working 100%.

Good luck!

NoEqualsButton · 07-25-2019, 01:04 AM

Many thanks for the input!

I have "bitten the bullet" and pulled back the label revealing the screws. I am going in now.

Wish me luck!

NoEqualsButton · 07-25-2019, 02:35 AM

Okay. I got in there. As expected the gummy wheel was VERY gummy and adhered to the reader body, probably preventing the motor from turning at all. I have removed all that material from the roller. Can anybody suggest what size o-rings I need to replace it with? Thanks.

NoEqualsButton · 07-25-2019, 02:46 AM

Found some o-rings on eBay with inner diameter 3mm and outer diameter 8mm. Seems VERY close. I'll give those a try.

NoEqualsButton · 07-25-2019, 04:18 AM

Tested the motor with a 3.6v power supply - works fine. Ordered some 3mm inside and 5mm outside diameter o-rings as a plan B.

Will do some cosmetic maintenance while I'm waiting. I can see how this stuff can get addictive.

burkhard · 07-25-2019, 01:09 PM

(07-25-2019 02:46 AM)NoEqualsButton Wrote: Found some o-rings on eBay with inner diameter 3mm and outer diameter 8mm. Seems VERY close. I'll give those a try.

There are a number of people selling HP card reader o-ring kits for only a couple dollars. It's possible you could do slightly cheaper on your own, but to me, going with a proven part many others have had success with would be prudent.

Some kits use standard looking round profile black rubber (some sort of rubber, who knows what) o-rings. Others square cross section o-rings. Others silicone tubing. I have read (I think from Geoff Quickfall) that common big-box-store silicone tubing can have varying wall thickness and imperfect concentricity of the ID and OD. For that reason, a MIL-SPEC silicone tubing was recommended instead.

Geoff has a really nice video up on YouTube somewhere (maybe HHC Conference page) where he rebuilds an HP-65 card reader on the spot and points out things to be careful of. There is a tiny ball you don't want to lose...

Good luck!

teenix · 07-25-2019, 02:13 PM

(07-25-2019 02:46 AM)NoEqualsButton Wrote: Found some o-rings on eBay with inner diameter 3mm and outer diameter 8mm. Seems VERY close. I'll give those a try.

If you like, I can send some O-rings to you, I have plenty and they work. I also have some home made couplings for the motor shaft to worm gear if yours has perished inside the aluminium sleeve.

Just need an address.

cheers

Tony

NoEqualsButton · 07-27-2019, 12:21 AM

I have been overwhelmed by the amount of support you guys have supplied. Thank you very much. This is my first restoration project so I really need all the help I can get.

I'm taking my time and photographing EVERYTHING before and after disassembly. So far, so good, no lost or broken parts at this stage.