HP Forum Archive 06

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HP-85 power supply problem Message #1 Posted by Chris Hoaglin (Boston, MA) on 10 Aug 2001, 5:34 a.m. I managed to misalign one of the flexible strip cables on my HP-85, and something seems to have shorted out. I appear to be missing every single power supply output except for the +36V output, which measures +32-34. I'm figuring that the +32 is the unregulated voltage from after the bridge rectifier, since the transformer is 24V center-tapped, (24V (RMS)*1.414=33.96VDC(peak), and that the fault is somewhere early in the supply if it killed all the other rails, but a schematic would be great if anybody's got one, to save me from having to draw it out, or any ideas of where to look first. -Chris

Re: HP-85 power supply problem Message #2 Posted by Chris Hoaglin on 11 Aug 2001, 5:13 p.m., in response to message #1 by Chris Hoaglin (Boston, MA) I went back and solved this problem.. a PCB-mount fuse in the power supply had blown, and replacing it did the trick. All supply voltages are back to normal now.

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