[41] Odd display problem
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04-21-2015, 01:45 PM
Post: #2
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RE: [hp41] Odd display problem
A pity nobody can give a clue.
In any case, I keep looking for it. I've found that, in a a working 41, the display OS1 signal stays at 0.9 V in RUN and SLEEP modes, whereas it shows a triangular waveform, between 0 and 0.9 V (at a frequency of 7 kHz) in STANDBY mode. The 7 kHz frequency is consistent with the 11 minutes timeout, as the LCD driver chips wait for the timeout 9ยท2^19 ~ 4M7 cycles. At 7 kHz such number of cycles means ~11 minutes. My faulty 41 does not show such triangular waveform, it remains fixed at 0.9 V anytime. I do not know yet if the oscillator is faulty or there is another reason for this behavior (although I am missing the hope on such). Regards. |
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