HP-65/67: Strange AC-Voltage on plug-in supply type 82002A - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: General Forum (/forum-4.html) +--- Thread: HP-65/67: Strange AC-Voltage on plug-in supply type 82002A (/thread-19932.html) |
HP-65/67: Strange AC-Voltage on plug-in supply type 82002A - TI59 - 05-10-2023 02:32 PM Hello, I got two HP-67 and a HP-65. The first HP-67 came with a plug-in supply type 82002A (PSU #1) same with HP-65 (PSU #2) Since all there calculators working (card-reader fixed, resoldering, tantalum-capacitor "cure") I got a odd behavior on PSU #1 Socket / Front ####################### # # # 1 ( ) 2 ( ) # # 3 ( ) # # # ####################### -------- PSU #1 ------- Voltage u13 : 1,06 VAC 50Hz Voltage u23 : 1,57 VAC 50Hz Voltage u12 : 1,55 VAV 50Hz The DC amount is Voltage U13 : -0,678 V Voltage U23 : 0,061 V Voltage U12 : -0,001 V --- PSU #2 -------------- Comparing this to PSU #2 which looks to work DC: Voltage U13 : 16,3 V Voltage U23 : 5,3 V Voltage U12 : 10,9 V AC Amount Voltage u13 : 0,115 VAC 50Hz Voltage u23 : 0,112 VAC 50Hz Voltage u12 : 0,030 VAC 50Hz -------------------- So the PSU #2 has instead of the 4,5 V printed on the PSU 5,3 V - this should be OK since one Jacque Laporte's Page https://www.jacques-laporte.org/HP3520power20unit.htm The circuit diagram figure 8 shows a Zener-Diode of 5,1 V - so I assume the Pins 2 and 3 are for the calculator while the 16 V charging the battery with Pin 1 and 3 Which is in my taste at least 3 times to high going through the circuit diagram which shows 4 Volts for both pins. So PSU #2 maybe usable but I prefer go load the batteries wirth an external charger to avoid damaging something I replaced in PSU #1 the electrolyte capacitor with 400 mikro Farad - no remedy Since working PSU #2 has only minimal AC ripples PSU #1 consist only of AC which is strange. I can only imagine that a Diode of the rectifier is broken - but as far as I can see they work (I don't have an oscilloscope - only LCR-Meter and a Fluke 289 Multimeter) - next thing is Zener-Diode but this would explain one one strange VAC voltages at one output - but not the second Anyone facing the same issue ? Kind regards Frank P.s: I started programming with TI59 in 1981 in school - that's why I choose the Alias :-) --------- UPDATE According to EBay auction Vintage Hewlett-Packard Battery Charger 82002A for Calculators w/Box the measured Voltage of U12 is 10,94 VDC which matches my findings for PSU #2 - so should be OK. RE: HP-65/67: Strange AC-Voltage on plug-in supply type 82002A - teenix - 05-10-2023 09:42 PM Is there any AC voltage coming out of the transformer? RE: HP-65/67: Strange AC-Voltage on plug-in supply type 82002A - Johnboy - 05-10-2023 10:58 PM What's the tantalum-capacitor "cure" ? do you have a link to more info on that ? Thanks John |