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HP-29C ACT compatibility
05-11-2018, 07:20 PM
Post: #5
RE: HP-29C ACT compatibility
Very interesting information about the compatibility of the ACT chip.
I have already repaired several HP calculators like; 10,21,22,25,37,55,65,67,97 and 41, and I have the tools and knowledge to do it.
But, my last purchase a HP 29c does not want to work. After cleaning the electrolyte leaks from the batteries and checking capacitors and voltages of the PS, I have concluded that the ACT, at least, is defective.
I refuse, for now, to look for a 21 or 22 to donate the ACT, and I have been looking the waves in the ACT pins. I notice that the initial RST does fine, but the output / O1 on pin 17 has only 1V amplitude, while the / O2 on pin 16 is ok with 18V.
The high threshold on both is the Vss + 6V, but in phase!
I am considering adding a small circuit with transistors to generate / O1 from / O2 and insert it into pin 17 line of the ACT.
If someone has already tried this solution, I would appreciate if can tell me if it could work, or go directly to replace the ACT.
Thanks in advance.


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Messages In This Thread
HP-29C ACT compatibility - PANAMATIK - 06-08-2017, 08:31 AM
RE: HP-29C ACT compatibility - Paul Dale - 06-08-2017, 10:16 AM
RE: HP-29C ACT compatibility - PANAMATIK - 06-08-2017, 07:15 PM
RE: HP-29C ACT compatibility - teenix - 05-23-2018, 10:00 PM
RE: HP-29C ACT compatibility - Paul Dale - 06-09-2017, 11:58 AM
RE: HP-29C ACT compatibility - biogon - 05-11-2018 07:20 PM
RE: HP-29C ACT compatibility - PANAMATIK - 05-12-2018, 11:10 PM
RE: HP-29C ACT compatibility - biogon - 05-18-2018, 10:07 AM
RE: HP-29C ACT compatibility - Harald - 05-23-2018, 03:35 PM
RE: HP-29C ACT compatibility - jjohnson873 - 05-25-2018, 12:18 PM
RE: HP-29C ACT compatibility - biogon - 06-25-2018, 01:19 PM



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