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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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HP59864B vacuum gauge info, Micro-ion gauge controller
Had to repair one of these HP/Agilent HP59864B units. It's very similar to Granville-Phillips 340 series. Usually the three big obvious 470uF filter caps get baked out over the years, which lets 100KHz ripple get onto the op-amp +12VDC rail, then shorts out a couple of protection zeners.
SCHEMATICS: most of the unit is just variations on suggested circuits app notes in the spec sheets for various chips. Also, you can run the unit with a "fake gauge tube" test jig made from some resistors. For lots of info see: http://staff.washington.edu/wbeaty/chem_granv.html My measurements: Gauge tube filament: 2amps, 1.2V ( about 0.6 ohms) Gauge tube emission current: 10uA across 135V Gauge tube collector electrode: +7.0pA to +7.0uA at 0.0 volts AD input volts, pressure, collector current: -?5V? = 9.9 x 10-2 Torr = 7.0uA -2.79V = 1 x 10-2 Torr = 0.70uA -1.39V = 1 x 10-3 Torr = 70nA +0.0V = 1 x 10-4 Torr = 7.0nA +1.4V = 1 x 10-5 Torr = 0.70nA +2.4V = 1 x 10-6 Torr = 70pA +2.78V = 1 x 10-7 Torr = 7.0pA |
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