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Old 1st Jun 2019, 9:23 pm   #50
OldTechFan96
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Join Date: Jul 2017
Location: Newcastle Upon Tyne, Tyne & Wear, UK.
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Default Re: Hameg HM307-3 Cleaning and Repair

I've made sure that the diode is the right way around by looking at old photos I've taken and looking at the surface manual. Cathode faces the IC. Pot is fine too. Marked 470K and is definitely connected up OK. I even put the old parts back in and the -1000V rail was still low!

I've lifted the wire link that connects the HV to R357. The voltages present here are the same as in post 48. Since there is no change I imagine that the fault is in the -1000V section of the PSU. There is a BF459 in my other Hameg scope.
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