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hp-91 transistor substitution
09-22-2014, 07:51 PM
Post: #9
RE: hp-91 transistor substitution
(09-22-2014 06:36 PM)joseaem Wrote:  LOCATED THE PROBLEM!!!
Main item, display the minus sign...
Due a transistor shorcuted in U3 anode drivers, tomorrow I will replace with a 2n2222 transistor.
Second item, the transistor break: The calculator is functional, because is a secondary energy element, making resitance lower at power demand increasing.
All thanks to HP 97 service manual.

Thanks for your interest, Jebem, Paul And Cruff

Excellent! Thank you for sharing your work.
Un Saludo,
Jose

Jose Mesquita
RadioMuseum.org member

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Messages In This Thread
hp-91 transistor substitution - joseaem - 09-20-2014, 05:10 PM
RE: hp-91 transistor substitution - jebem - 09-20-2014, 07:17 PM
RE: hp-91 transistor substitution - cruff - 09-21-2014, 11:32 PM
RE: hp-91 transistor substitution - jebem - 09-22-2014 07:51 PM



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