HP-35 Power Supply Waveforms
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04-01-2019, 08:41 PM
Post: #6
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RE: HP-35 Power Supply Waveforms
Here we go !!
Edoardo has worked very hard and the HP65 PSU has been reproduced on a breaboard ! We used mostly original spare parts, the Toroid, the transistors, the resistors, couple of capacitors are original. We replaced the 3,3 microF capacitors, with new parts very close with the value (about 3,8 microF) We replaced the 15microF with a new part very close to that We replaced the diodes, the original have a value of about 0,287 V while these new have a value of 0,347 or 0,37Volts (BTW : why the voltage value of a diode displayed on the multimeter is a 1/10 of the real value ??) We are attaching pictures and a drawing we used to check the correctness of the PSU Everything seems fine but .... Vbatt = 3,9V Vcc (expected 8.2V) is 8V (good) Vgg (expected -12,4 V) is -37V !!! (three times) Vss (expected 6.28V) is 15,8 V (more then double) Any help in finding what we did wrong or what is missing is welcome !!!! Thanks in advance !! Edoardo & Alberto |
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