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+--- Thread: Mysterious component on the HP 41C board (at least for me) (/thread-1042.html)
Mysterious component on the HP 41C board (at least for me) - Onur ILKORUR - 04-05-2014 01:19 PM
Hi,
I have just acquired a HP 41C with tall keys. I believe the board is from 1979 according to the HP Forum Archive #19, message "HP 41C and CV boards with some piggy backing from the factory" by Geoff Quickfall.
The previous owner was very brutal when he was trying to bring it back to life and "broke" the 1908-0868 diode and the component which is indicated with the red circle in the attached picture while trying to bolt the PCB back to the front half of the calculator.
I've replaced the diode and since I thought it was a resistor, I replaced the indicated component with a 100kOhm. The calculator turns on with scrabbled screen, which makes me doubt that the indicated component may not be a resistor but something else.
Any help would be greatly appreciated.
/Onur
I have just acquired a HP 41C with tall keys. I believe the board is from 1979 according to the HP Forum Archive #19, message "HP 41C and CV boards with some piggy backing from the factory" by Geoff Quickfall.
The previous owner was very brutal when he was trying to bring it back to life and "broke" the 1908-0868 diode and the component which is indicated with the red circle in the attached picture while trying to bolt the PCB back to the front half of the calculator.
I've replaced the diode and since I thought it was a resistor, I replaced the indicated component with a 100kOhm. The calculator turns on with scrabbled screen, which makes me doubt that the indicated component may not be a resistor but something else.
Any help would be greatly appreciated.
/Onur
RE: Mysterious component on the HP 41C board (at least for me) - Paul Berger (Canada) - 04-05-2014 02:55 PM
According to the service guide it is a 100K resistor between pin 12 of U2 and ground. U2 is the 14 pin chip under the piezo sounder.
There are 4 colour bands the first brown band just blends with the body colour.
RE: Mysterious component on the HP 41C board (at least for me) - Onur ILKORUR - 04-05-2014 04:17 PM
(04-05-2014 02:55 PM)Paul Berger (Canada) Wrote: According to the service guide it is a 100K resistor between pin 12 of U2 and ground. U2 is the 14 pin chip under the piezo sounder.
There are 4 colour bands the first brown band just blends with the body colour.
Exactly what I've thought. The brown color blending in with the color of the component.
I was thinking it could be an axial capacitor, but thank you for clearing it out for me.
/Onur
RE: Mysterious component on the HP 41C board (at least for me) - Drulli - 04-05-2014 08:40 PM
The board layout type it the "Initial HP-41C Three Transistor"
http://www.clonix41.org/Maintenance/hp-41_PCBs.htm
The component is the R2 Resistor - 100kOhm, 1/8 W, 10%