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joust

CE2000 High Voltage issue

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joust    0

Hello guys! Now it's my turn to seek wisdom! :)

I have this CE2000 with a HV fault: The D8 10V zener diode located in the HV circuit doesn't regulate normally : I only have about 5V on the diode when 10V should be nominal.

I've checked or swapped out D8, D6 and D7, the C1 cap, verified vertical resistors R1 (1K) and R2 (15K: yes, it is 15K instead of the 2.2K wafer in this circuit (latest design mod)!); I even swapped out R2 for a 2.2K with the same result: D8 still doesn't regulate! I do have high voltage on the zener diode and R2 but only 105V when I should have 108 to 110V. There appears to be enough voltage on the load side of R2 though.

+VCC (rail) is at 100V (It should be nominal at 98V...)

Any suggestions?

Alain

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joust    0

Thanks everyone for your input! And yes, I had already evaluated and replaced C1. :)

My original issue was that the zener diode (D7, 10V) is not regulating properly! There was also something odd with the voltage prior to the 'ballast resistor' R2, it was quite high (about 140Vdc instead of a normal 116Vdc). What I believe I was reading was the 'peak' voltage (without filtering!) of the HV. When evaluating the voltage divider R30 and R31, I discovered an open C3 cap! Replaced the 10uF 50V SMT cap and the problem was solved.

Alain

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