HP-41CV Card Reader "Memory Lost"

[fpatton]

Hello!

TL;DR - Both before and after replacing the gummy wheel in a card reader of unknown state (thanks to everyone on this forum for the amazing tutorials!), powering up the HP-41CV results in "Memory Lost" when I try to insert a card. I'm wondering if this is a known issue, and if so, how to fix it.

Full version -
I recently picked up a "parts-only" pack of a non-working HP-41CV, some modules, a nice case, and a card reader. I mainly wanted the modules to go with my 41CX, and figured the rest was gravy if I could get it working. The modules seem to be fine, so that's good.

Following excellent tutorials here and elsewhere, I fixed the calculator's various broken posts and it's fine now, too. (Hurray! Cost easily recovered.) However, that card reader...

I plugged the reader into my 41CX, powered it up, and tried to run a card through it. The calculator turned off, and it took removing the batteries and waiting several minutes before it would turn on. Panic! All was well, as it recovered, and I won't make that mistake again. However, the CV was a bit more expendable, so...

I figured it might be an overcurrent draw from the motor if the wheel was gummy, so followed tutorials here to recover it. I successfully replaced the wheel with some fuel tubing I had on hand, carefully checking the diameter against the recommended 005 O-rings. With the motor removed, the geared wheel spins freely on its axle, yet nicely pulls a card through. After careful reassembly, I still get the "Memory Lost" error, and occasionally some really screwy characters on the display.

So - am I out of luck with this reader? No big deal if so, but if it's repairable, I'd love to have a working card reader.

Thanks for reading this far!

Fred

[BillBee]

Its possible the reader is screwed but I would test the ports first with a known working module. Sometimes when the ribbon cable is not "fully" connected the calculator will appear to work normally but have odd errors.

-Bill

[Xorand]

(05-31-2022 11:03 AM)BillBee Wrote:  Its possible the reader is screwed but I would test the ports first with a known working module. Sometimes when the ribbon cable is not "fully" connected the calculator will appear to work normally but have odd errors.

-Bill

I had this happen on my previous CV fullnut. Everything else was working fine, but if I stuck a module in port 3 or 4, the calculator wouldn't turn on, or would provide strange characters on the display. Plug the module in 1 or 2 and all was fine.

I pulled it apart and cleaned and adjusted the ribbon cable near the module ports. Put it back together (with much effort due to crumbling plastic posts, etc.) and it worked fine afterwards.

[fpatton]

I checked port 4 on both the CV and the CX with a working "Securities" card, and they both seemed to read it just fine. I hadn't thought about the port being bad, since I had tried it on both calculators, but it was worth a shot. CV edge connectors got a very good cleaning with DeOxit during the rebuild.

Oh well, it happens! We'll consider this a source of spare parts if I ever pick up a card reader. Thanks for the input!

Fred

[BillBee]

The only other thing I could suggest is to check the connectors on the card reader. Internal color coded little plugs and the port connectors themselves.

We are past my depth after that.

-Bill

[Craig Bladow]

My suggestion is to check the batteries. I got the same error with my original 41C and card reader on alkaline batteries that were not completely fresh and ultimately went to NiCad batteries and now NiMh batteries which handle the card reader better.

[BobVA]

After you overhauled the card reader did you try it again in your CX?