HP-65 Card Reader

[albertofenini]

Hello everyone,
I have searched thru the forum but I haven't been able to find the inner and outer diameter for a silicon tube that can work on the card reader.
I recall somehow outer : 6 mm, inner : 3 mm
Anyone can please tell me what the correct size is ?
Thanks for help in advance Alberto

[Massimo Gnerucci]

(11-26-2018 03:02 PM)albertofenini Wrote:  Hello everyone,
I have searched thru the forum but I haven't been able to find the inner and outer diameter for a silicon tube that can work on the card reader.
I recall somehow outer : 6 mm, inner : 3 mm
Anyone can please tell me what the correct size is ?
Thanks for help in advance Alberto

Have a look here Alberto.

Geoff says:

Quote: silicon tubing or small o-rings (inner diameter smaller then
outer diameter of post).

silicon tubing: ID 2.55 mm
OD 5.60 mm
Fuel line hose for model aircraft. Specify
military specs as the hole is dead centre and
therefore usable for pinch roller
o-rings ID 2.55 mm
OD 6.50 mm
Hardware store.

[burkhard]

(11-26-2018 03:02 PM)albertofenini Wrote:  Hello everyone,
I have searched thru the forum but I haven't been able to find the inner and outer diameter for a silicon tube that can work on the card reader.
I recall somehow outer : 6 mm, inner : 3 mm
Anyone can please tell me what the correct size is ?
Thanks for help in advance Alberto

I don't recall the exact specification myself, but I do recall that that silicone tubing commonly sold in hardware / DIY stores does not typically have very good concentricity between in the inner and outer diameters which can cause problems with uneven feed.

You might want to watch Geoff Quickfall's video on doing the card reader repair on YouTube. I recall he recommended getting some high-specification tubing from someplace to avoid this trouble.

Please let us know what you find.

[EDIT: It's looks like as I was typing this, Massimo had already sent the answer, which I didn't see until later]

[AndiGer]

I once ordered standard o-rings 2.90x1.78mm. Work fine

[burkhard]

(11-26-2018 03:35 PM)Massimo Gnerucci Wrote:  Geoff says:

Quote: silicon tubing or small o-rings (inner diameter smaller then
outer diameter of post).

silicon tubing: ID 2.55 mm
OD 5.60 mm
Fuel line hose for model aircraft. Specify
military specs as the hole is dead centre and
therefore usable for pinch roller

o-rings ID 2.55 mm
OD 6.50 mm
Hardware store.

Please look at the two items I have made bold above. Shouldn't the OD dimension be the same whether silicone tubing or o-rings? It seems as if one might have digits switched, no?

[Massimo Gnerucci]

(11-26-2018 08:46 PM)burkhard Wrote:  

(11-26-2018 03:35 PM)Massimo Gnerucci Wrote:  Geoff says:

Please look at the two items I have made bold above. Shouldn't the OD dimension be the same whether silicone tubing or o-rings? It seems as if one might have digits switched, no?

Yes, the link refers to repairing the battery posts. I think OD doesn't mean much there...
Geoff uses the same tube as used for card reader repair. So let's say ID 2.55 mm, OD 5.60 mm.

[albertofenini]

Hi Massimo, Hi Geoff, it's good to hear from you guys again,
may be you guys remember me from old posts.

Well, I was wondering why tube and o-ring have different sizes when the final result must look the same, is that because of the different elastic behavior of the two materials ?

I must say that I had done some repairs with o-rings back in 2013 and now I have found the o-rings melted, is that normal after only 5 years for a calc left sitting in a drawer ?

That's why I would like to go for the silicon tube now.
Massimo do you have any links where I can buy in Italy these pieces ?

Thanks in advance to everyone
Alberto

[AndiGer]

I think it should be 6.50 mm.
O-ring 2.90 + 2 times the string's diameter 1.78 adds up to 6.46 mm.

[Massimo Gnerucci]

(11-27-2018 11:02 AM)albertofenini Wrote:  Hi Massimo, Hi Geoff, it's good to hear from you guys again,
may be you guys remember me from old posts.

Well, I was wondering why tube and o-ring have different sizes when the final result must look the same, is that because of the different elastic behavior of the two materials ?

I must say that I had done some repairs with o-rings back in 2013 and now I have found the o-rings melted, is that normal after only 5 years for a calc left sitting in a drawer ?

That's why I would like to go for the silicon tube now.
Massimo do you have any links where I can buy in Italy these pieces ?

Thanks in advance to everyone
Alberto

Turns out dimensions should be 1/4" OD x 1/8" ID; so something like 6.4x3.2mm

Alberto, I've always read that a source for the tubing is from air modelling shops. The only important thing is that the hole has to be concentric; hard to check online...
O-rings should be safer from this point of view (and what I usually used).

HTH

[albertofenini]

Thanks everyone,
I'll post more measures tomorrow of what I have found in our toolbox
take care Alberto

[wallyt]

Hello, I have just completed a repair of the card reader drive wheel on my HP65 and this is what I have found. I used O-rings that I purchased in a "kit" on ebay. This kit also included a small length of silicone rubber tubing. I found that the tubing's inside diameter was a bit too wide to fit snugly on the drive wheel shaft, so I used the O-rings. Both the rings and the tubing appeared to have the same outside diameter. These rings were the "square" type with flat sides.

The good news is that the card reader now functions and pulls the cards through quite nicely. The bad news is that it does not seem able to write anything to the cards. Also, the reading of the cards is problematical, sometimes it reads okay other times I get the flashing 00 display. I tried a variety of pre-recorded cards, sometimes they work other times they don't.

One last point, before I started any of this I manually keyed-in both of the diagnostic programs from the Standard Pac listings. Both of these indicated that I had a completely functioning calc (except for the reader). Now, I am getting errors in Diagnostic program II. I was really careful during my repairs and I do have experience working as an electronic tech. Anybody have any thoughts on any of this. Thanks.

[brickviking]

(12-17-2018 03:31 PM)wallyt Wrote:  ...
One last point, before I started any of this I manually keyed-in both of the diagnostic programs from the Standard Pac listings. Both of these indicated that I had a completely functioning calc (except for the reader). Now, I am getting errors in Diagnostic program II. I was really careful during my repairs and I do have experience working as an electronic tech. Anybody have any thoughts on any of this. Thanks.

Did you run the Diagnostic program with, or without the card reader plugged in? If there's a difference, I'd suspect the card reader. If there's no difference, I'd suspect something that you may have jiggled when putting the card reader into the port. Just one more step to look at.

Disclaimer: I know nothing about the 41C family except that it has four ports, and that it's certainly old hardware these days.

(Post 323)

[Craig Bladow]

I repaired several card readers last year, for HP-41C, HP-97 and an HP-65. The "not writing" behavior could be the write protection switch not making contact. I believe I had to clean the contacts (gently) with DeOxit a few times before this worked on the HP-65.