Re: HP 1905 No power. No led. No output voltage.
To test the mosfets Q701 and Q705 for shorts:
With your DMM set to resistance and referring to the schematic :
On Q701, place one probe on S1 and the other probe on G1, record measurement, reverse probes, record measurement.
Testing should look like this:
S1-G1
D1-G1
S1-D1
S2-G2
D2-G2
S2-D2
Perform same test on Q705
To test regulators you must reassemble everything.
Looking at the regulator with the metal tab on top and numbering the pins from left to right as 1-3:
pin1 = ground
pin2 = Vout
pin3 = Vin
Power up system and measure output voltage for each regulator.
Originally posted by newbie1
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To test the mosfets Q701 and Q705 for shorts:
With your DMM set to resistance and referring to the schematic :
On Q701, place one probe on S1 and the other probe on G1, record measurement, reverse probes, record measurement.
Testing should look like this:
S1-G1
D1-G1
S1-D1
S2-G2
D2-G2
S2-D2
Perform same test on Q705
To test regulators you must reassemble everything.
Looking at the regulator with the metal tab on top and numbering the pins from left to right as 1-3:
pin1 = ground
pin2 = Vout
pin3 = Vin
Power up system and measure output voltage for each regulator.
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