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Author Topic: G07 R902 Voltage HALF what it should be  (Read 348 times)

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G07 R902 Voltage HALF what it should be
« on: September 09, 2021, 02:09:04 pm »
Been a bit.

Got one I haven't run into before.  I have to boards that won't power on their CRT's.  Following the normal flow chart for troubleshooting, when I pull voltage at R902, I'm only getting 61ish Volts.  I pulled both C904's and both test fine.  Any idea what would be creating a scenario where I'm only getting half the volts on R902?



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Re: G07 R902 Voltage HALF what it should be
« Reply #1 on: September 14, 2021, 05:56:40 pm »
check your rectifier bridge and see if you have an open diode. also open F901 and just measure the voltage there, that way you aren't running the chassis.

you should have over 130vdc ish (depending on your actual line voltage level.) if it's 60 ish there, you have an issue in your line input and/or bridge rectifier

check the B+ pot, sometimes they get crud in them. note it's position then spin it back and forth a few times and get the crunchys out.