HP67 Voltages on Card Reader IC 1826-0322 (card reader sense amplifier)

[TI59]

(01-04-2024 11:56 PM)teenix Wrote:  The voltages seem ok. The motor only runs at about 2.4V

Did the motor change speed when using the trimpot? If not, there may be a fault with the sense chip. Otherwise if the motor is running at speed and the card is still slow moving, check that the coupler that connects the spiral worm gear to the motor shaft has not perished like the drive wheel. If so, the motor will slip and not turn the gear properly.

cheers

Tony

Hello Tony,

Thanks for the quick reply - I have managed to fix the issue by disassembling the whole motor/gear unit of the card reader. I assume the main show stopper was some really hardened gunk from the old rubber wheel plus a to long, pre-cut new silicon rubber tube I purchased from someone one eBay - this worked as sort of brake - cutting a tiny slice and lube the gear with special lube (polyurea (PU) grease - I can recommend this stuff - does not harden over time, does not harm plastic) the card reader now works perfect - even if the speed is definitely slower (-20%) compared to be driven with 2,4 VDC using my DC Power supply. The potentiometer is definitely working - operating from 0 - 10k linear. So I assume the 1826-0322 lost maybe the full amplification capability over the last 44 years - since I'm 55 years old I'm not as fast as I was with 18 years :-D

Kind regards,
Frank