HP41C Card Reader Problem



#5

I got a pretty nice HP41C incl. a Card reader. I repaired the card reader (I used thermo shrink hose to create a rubber wheel instead of O-Rings), and now the reader works perfect - almost. When i try to store a program, it shows "PROTECTED" on the Display. So i analysed and found that mit must have something to do with the Optical circuit which detects wether the cards are clipped or not (I know about setting flag 14, but that's not what i want). To understand more: Which one is the LED? Which one is the Photosensor? Does the LED emit visible light or invisible?

Any ideas?

Thank you in advance,

Andy.


#6

The LED is in the bottom half, the sensor is on the small circuit board attached to the removable motor module.

The most common problem is to have accidentally bent the LED so it no longer aligns properly with the sensor when assembled. If they are aligned properly, check for fractured solder connections of the LED.

You'll have to remove circuit board for access - start by gently prying off the cap the covers the 12 contacts that mate with the 41 when plugged in. Once the cap is off, you can lift out the card reader electronics module.

The LED is non-visible infrared.


#7

Randy wrote:
> The LED is non-visible infrared.

however, it can be viewed through the (LCD) viewfinder [1] of a digital camera or a video camera.

**vp

[1] obviously optical viewfinders will not work.


#8

Quote:
Randy wrote:
> The LED is non-visible infrared.

however, it can be viewed through the (LCD) viewfinder [1] of a digital camera or a video camera.

**vp

[1] obviously optical viewfinders will not work.


Thank you for your help. I could see the LED Flashing up, and i could find that it is the Photosensor who is making trouble. Will go and buy a new one. I think of an SMD Phototransistor... That maybe will do.

Thanks again

Regards from Switzerland

Andy.


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