Hp-41C card reader - dead

[Vintage63]

I'm having a go at it again after 2 years.
Unfortunately the coaxial cable can fit over the worm gear, I have to machine it slightly, but is too big to fit snugly on the motor axle.
I removed the gunky stuff that was on the 'big' end of the worm gear.
Can I in some way 'glue' the worm gear over the motor axle with white glue to give it a bit of flexibility?
Attached a photo of the motor and worm gear as they look right now, not secured.

   

Thank you
Marco

[Dreato]

This has been my experience with both the 67/97 and 41C card readers:

1) I check the worm gear placement on the shaft - it should have a bit of 'play' before it contacts the brass bearing at the end away from the motor.
2) I mark this location on the motor shaft, remove the worm gear and glue it to the motor shaft with cyanoacrylate glue.
3) A tiny bit of lubricant on the worm gear tip reduces motor noise considerably.
4) Card won't pull? The 41C card reader uses both optical and mechanical switches for card control. The card inserted switch is mechanical. If fresh batteries don't pull a card, you need to check the mechanical switches. Carefully clean them and test card inserted actuation with an ohm meter. I don't recall, but I don't think switch contact is adjustable, like on the 67/97. If, when a card is inserted, you don't see the contact closure with an ohm meter, you may need to remove the switch leaves, and bend them slightly. CAREFUL!

Anyone else?

Good luck and Best Regards,

Dave

[do2]

I bought a used card reader recently, and as it happens I managed to repair it just today!

It had the usual problems. At first, I thought I can get away with replacing the deteriorated rubber on the capstan, but this resulted in checksum errors and malfunctions. In the end I had to superglue the silicon tubing (I went with this solution) and the tiny aluminum sleeve on the worm wheel and motor shaft. Problem solved

I am skeptical that more elaborate solutions with thin cable insulations to mount the worm wheel would provide any significant dampening effect to justify the efforts. But I can definitely report that a rock solid mounting of the o-rings/tubing to the capstan and of the worm gear to motor shaft is mission critical for the card reader to work.

Best,
odo

[teenix]

Was the coax RG-58 type?, this should work. Inner translucent core diameter = 0.120", inner solid copper core = 0.030". The translucent core is flexible and has good friction qualities to grip the motor shaft.

Details for making one can be found in my Classic Notes here under "Gummy Repair"

Having the worm gear sitting in place like that is no guarantee that it is aligned properly to the center line of the motor shaft. Any misalignment will result in vibration and the possibility of motor damage and faulty card reading and writing.

If you glue the motor shaft to the worm gear and it is out of alignment then you have to hope it will come apart to repair again, plus remove all the hardened glue. Pulling hard on the helical gear to remove it from the motor shaft may damage the motor.

You also need to make sure the helical shaft end is positioned onto the thrust bearing located in the plastic frame which minimizes noise and possible damage to the motor bearings over time.

It is difficult for a home repair to ensure correct alignment, you can only do your best.

There are some details on card reader maintenance near the end of the 97 service manual. (June '82)

cheers

Tony

(04-22-2022 04:54 PM)Vintage63 Wrote:  I'm having a go at it again after 2 years.
Unfortunately the coaxial cable can fit over the worm gear, I have to machine it slightly, but is too big to fit snugly on the motor axle.
I removed the gunky stuff that was on the 'big' end of the worm gear.
Can I in some way 'glue' the worm gear over the motor axle with white glue to give it a bit of flexibility?
Attached a photo of the motor and worm gear as they look right now, not secured.



Thank you
Marco

[teenix]

On the subject of 41 card readers, does anyone know how to split the case, without damage, to remove the CPU board? The board is sandwiched inside the plastic part that slides into the 41 slot.

cheers

Tony

[AndiGer]

(04-23-2022 02:21 AM)teenix Wrote:  On the subject of 41 card readers, does anyone know how to split the case, without damage, to remove the CPU board? The board is sandwiched inside the plastic part that slides into the 41 slot.

cheers

Tony

Wasn't it described in the card reader service manual?
Didn't do that nor have the manual handy at the moment
Andi

[Vintage63]

@teenix, I tried with a TV antenna cable. I ordered an RG58 cable so before glueing the worm gear I'll have a go at the coax cable. Thank you

[teenix]

(04-23-2022 07:59 AM)Vintage63 Wrote:  @teenix, I tried with a TV antenna cable. I ordered an RG58 cable so before glueing the worm gear I'll have a go at the coax cable. Thank you

Happy to post you a couple if you can PM an address.

cheers

Tony

[do2]

(04-23-2022 02:21 AM)teenix Wrote:  On the subject of 41 card readers, does anyone know how to split the case, without damage, to remove the CPU board? [snip]

The upper part (I/O cover) is simply slipped over, but there is a plastic lock in the inside in the middle. The service manual recommends to insert a spatula into the I/O slot. It also warns to be careful not to damage the I/O contacts.

Best,
odo

[teenix]

Figured it out.

I used a narrow piece of metal and slip it between the contact terminal block and the surface underneath the top cover. This moves the two one way locks away from the top of the contact block and the cover slides off.

cheers

Tony

(04-23-2022 10:47 AM)do2 Wrote:  

(04-23-2022 02:21 AM)teenix Wrote:  On the subject of 41 card readers, does anyone know how to split the case, without damage, to remove the CPU board? [snip]

The upper part (I/O cover) is simply slipped over, but there is a plastic lock in the inside in the middle. The service manual recommends to insert a spatula into the I/O slot. It also warns to be careful not to damage the I/O contacts.

Best,
odo

[Vintage63]

@teenix, I've tried with the RG58. This is the right size and once removed all the threads in the central hole fits snugly on the motor axle. I read the instructions in you pdf document. I do not have a lathe nor a drill tower nor anything else apart from a Dremel.

I enlarged the hole on the otherside of the internal insulation bit so tha the worm gear fits in it. I used a driil bit that is the same diameter of the worm gear.

I placed the motor and assembly in its housing to see how much I have to cut off in order to get it to fit into its space.
After cutting it I saw that it was already skewd.
Did this three or four times with different pieces with sameresults, fortunately the cable is long :-)

Tried attaching jpegs multiple times but it doesn't show them although I resized them to 400k
They are loaded in the correct place of the forum but files are empty, I have 7 MB still available for uploads too

Ideas?
Marco

[Vintage63]

don't ask me how the photos got there because I couldn't see them with the preview post option nor in the dedicated attachement directory

[Thomas Klemm]

(04-24-2022 05:18 PM)Vintage63 Wrote:  don't ask me how the photos got there because I couldn't see them with the preview post option nor in the dedicated attachment directory

You can include them with the [Insert image] button:





I've reduced their size in the img-tag by a factor of 6 so it fits better.
But you can also re-upload the images with lower resolution.

Cf. MyCode, also known as BB Codes to add effects or formatting to your posts.

[teenix]

To me , it looks like one end has expanded so you may have used a drill size that is too small and forced the worm gear into the coupling. This may have distorted it. Also, the drill depth is too short for the length of the end of the worm gear. The coupler should butt up against the shoulder.

As mentioned this can be difficult to do at home. The best tool would be a lathe but not many would have one.

Geoff Quickfall also did a replacement using wire insulation but I can't find the link.

Still happy to make a couple and send them to you. That is - a couple of couplers ;-)

cheers

Tony

[Massimo Gnerucci]

(04-24-2022 11:36 PM)teenix Wrote:  Geoff Quickfall also did a replacement using wire insulation but I can't find the link.

Message #7.

[3p141592654]

I wonder if heatshrink tubing would be a good solution here. It would be self centering and offer some dampening.

[teenix]

(04-29-2022 01:59 AM)3p141592654 Wrote:  I wonder if heatshrink tubing would be a good solution here. It would be self centering and offer some dampening.

I don't know if it will be accurate enough, especially considering the difference in size diameters between the motor shaft and the worm gear. The motor shaft diameter is very small so you need something with good grip as well.

Can always try though :-)

cheers

Tony

[Vintage63]

Thanks to Teenix's couplers, which I can't thank enough, I have reassembled part of the card reader eager to give it a go. The motor works, the coupler and the worm gear work nicely when I give power to the motor.
I have launched 'Catalog 2' and I get the list of functions on the card reader.
If I call RDATA or VER it asks for CARD but if I insert the card nothing happens.
The first line I have when launching Catalog 2 is 'CARD RDR 1E' which casts some doubts on the integrity of the reader. Is this some kind of doomsday error?
Marco

   

[BillBee]

When I had an issue it was with the two "golden forks" being either misaligned or bent.

-B

[Vintage63]

I have 5 as you can see protruding from the 5 holes on the PCB. Are you referring to these or are they under the PCB?