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+--- Thread: HP-32E Power supply -> HP-37E (/thread-16305.html)
HP-32E Power supply -> HP-37E - ytterligare - 02-12-2021 09:31 AM
How likely I can use a working HP-32E power supply in a HP-37E ?
Need to cannibalize a 32E ( power supply, display ) to revive a 37E....
Tnx
RE: HP-32E Power supply -> HP-37E - AndiGer - 02-12-2021 04:53 PM
If both are solderless models - can't you just switch the chips inside? I think everything else inside is the same.
RE: HP-32E Power supply -> HP-37E - ytterligare - 02-12-2021 10:26 PM
(02-12-2021 04:53 PM)AndiGer Wrote: If both are solderless models - can't you just switch the chips inside? I think everything else inside is the same.
I had the same thought, but I suspect that the PCB layout might not be the same : just look at the position of the "2nd function" yellow button...also, the 37E has two switches, "ON/OFF" and "BEGIN/END", while the 32E has only one.
I recently repaired a 32E, and saw that on the PCB the layout for a second switch was in place and unused...maybe it is the CPU that decide whether it is being used or not...
Anyway, the 37E will arrive in few days and I will then compare the PCB's...if they will be similar, then it is likely that switching the solderless chips and the front shell+keyboard, should be enough.
A.
RE: HP-32E Power supply -> HP-37E - PANAMATIK - 02-13-2021 04:10 PM
(02-12-2021 10:26 PM)ytterligare Wrote: I recently repaired a 32E, and saw that on the PCB the layout for a second switch was in place and unused...maybe it is the CPU that decide whether it is being used or not...
Indeed the firmware decides whether it is being used or not... , it tests the status bit 4 as the slider position. If you analyze the HP-32E firmware you will find, that this status bit is never been tested. Therefore changing the RAM ROM Chips will transform a HP-32E into a HP-37E, you even don't need to change the CPU.
The three RAM ROM chips can be placed randomly, only the C models need to place the RAM chip in the upper location, because battery plus powers only this chip when the calculator is switched off.
Bernhard
RE: HP-32E Power supply -> HP-37E - AndiGer - 02-13-2021 04:20 PM
Addition to Bernhard: you can place the chips in the E models randomly as I read formerly but must put them in respecting the right orientation ...