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HP-42S battery drain
07-18-2020, 04:36 AM
Post: #11
RE: HP-42S battery drain
Thanks for the tips on the IR detector!

About the dim LCD issue, I don't think this is the case, the LCD is good as far as I can tell, and I tried two different LCDs (borrowed one from the 17bII), and got the same result.

About the RAM and IR led: as I said in the initial post, I desoldered all components, including RAM and IR led, battery drain still happens.

But today I got to a point where I have to give up: I located the GND processor pins. They are two adjacent pins at one of the corners. I physically cut the PCB trace where these GND pins are soldered, and the current got to 0mA, so it's confirmed it's indeed the processor. I resoldered the cut, got back to 17mA. Calculator on or off, contrast high or low, calculating or idle, current is always about 17mA. The only situation where it's less than 1mA, is in some self tests messages, but I couldn't find the reason.

Well, it's sad, but this 42s will go to the parts box. Thank you all for trying to help, I learned a lot about this model in this fixing attempt!

Eduardo
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Messages In This Thread
HP-42S battery drain - Marcovecchio - 07-09-2020, 01:48 AM
RE: HP-42S battery drain - jebem - 07-09-2020, 05:38 AM
RE: HP-42S battery drain - Marcovecchio - 07-09-2020, 12:24 PM
RE: HP-42S battery drain - Allen - 07-09-2020, 01:45 PM
RE: HP-42S battery drain - Marcovecchio - 07-09-2020, 06:09 PM
RE: HP-42S battery drain - Marcovecchio - 07-13-2020, 02:55 AM
RE: HP-42S battery drain - Dave Shaffer - 07-14-2020, 04:04 AM
RE: HP-42S battery drain - KF6GPE - 07-14-2020, 05:25 AM
RE: HP-42S battery drain - GreyUser - 07-17-2020, 02:25 AM
RE: HP-42S battery drain - Marcovecchio - 07-18-2020 04:36 AM
RE: HP-42S battery drain - ijabbott - 07-18-2020, 02:24 PM
RE: HP-42S battery drain - Marcovecchio - 07-18-2020, 08:29 PM
RE: HP-42S battery drain - Marcovecchio - 08-05-2020, 02:56 AM



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