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41CX was 95% working - now 100% working - Printable Version

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41CX was 95% working - now 100% working - Russell Dobson - 03-24-2012

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv020.cgi?read=210829

Just wanted to share that I've managed to fix this. The very small silver capacitor on the bottom right of the board had a lot of flux around the solder, similar to the display.
When I cleaned the solder near the display, there was no change, but after cleaning around this little capacitor - it works 100%. Over the moon now, I have a working CX and my original C working 100%. Now its time to do the gummy wheel on the card reader...

Re: 41CX was 95% working - now 100% working - aurelio - 03-24-2012

BRAVO! keep us informed about CR fixing!
Regards

Re: 41CX was 95% working - now 100% working - Luiz C. Vieira (Brazil) - 03-24-2012

HI.

First of all, congrats! It is always good news when someone here gets these little beasts back to normal life.

Second, thanks for sharing the information. It is also always good to know that some simple, easy yet hard to figure solution would solve such an annoying problem.

Cheers!

Luiz (Brazil)

Re: 41CX was 95% working - now 100% working - Randy - 03-24-2012

FWIW, the "capacitor" you describe is the crystal for the CX timer chip (the long IC above it). Any crud on it or the 22 meg resistor below it can cause timer issues.

Re: 41CX was 95% working - now 100% working - aurelio - 03-24-2012

Quote:
FWIW, the "capacitor" you describe is the crystal for the CX timer chip (the long IC above it). Any crud on it or the 22 meg resistor below it can cause timer issues.
When Colombo discovered America they believed to have reached "India"!
By the way it was the most important discovery, maybe the greatest enterprise till the first man on ther moon , what do you think?

Edited: 24 Mar 2012, 7:01 p.m.

Re: 41CX was 95% working - now 100% working - Russell Dobson - 03-27-2012

Thanks Randy. I had no idea what that part was - too small to see anyway, but I had a good feeling that it might be the problem and it turns out it was!
Now running my 41C against the 41CX in a simple counting loop, the old 41C is about twice as fast as the CX...