Eric, The Ti-59 cardreader does not use a optical detector. The SR-52 uses a switch to detect the card insertion and after that the 'opto' for card edge detection and write protection. I suspect there should be some delay in the motor drive circuitry , to ensure that card is pulled out far enough, to get it free from the capstand. But I need the schema to find this out. So ik some one has a copy or a scan of it, I would be very happy. -Rik -----Oorspronkelijk bericht----- Van: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org] Namens Eric Smith Verzonden: woensdag 3 september 2008 20:08 Aan: General Discussion: On-Topic and Off-Topic Posts Onderwerp: Re: Slightly OT: SR-52 Service manual Rik Bos wrote: [...] I had a paper copy around 1979, which wasn't too hard to get at the time. IIRC, I just called TI's Lubbock, TX office and asked for a copy, and they sent it to me. I doubt that they have them any more, but if they were easily obtained (unlike HP calculator service manuals), there are probably people out there that still have copies. The TI-58/59 service manual is more commonly available. It's possible that the card reader is similar enough for that manual to be useful to you. Eric