High Voltage Trouble shooting.

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1 year 8 months ago #9972 by Malugalugalugalugaluga
Continuity on the 7805 mosfet or the 840?

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1 year 8 months ago #9973 by Ty_Eeberfest
The IRF-840. (The 7805 is not a MOSFET, it's a linear regulator)

Look into it later when the dust is clearing off the crater.

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1 year 8 months ago #9974 by Malugalugalugalugaluga
Thank you for the reply. Getting further, I traced it out and there was a break continuity on pin 1. The light for the clock memory and the main light on the board light up but the nixies still don't turn on.

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1 year 8 months ago #9975 by Ty_Eeberfest
Do you have approx. 180VDC at the high voltage test point now?

Have you done a factory reset (hold down the button while powering up) since you repaired the Pin 1 problem?

Look into it later when the dust is clearing off the crater.

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1 year 8 months ago #9980 by Malugalugalugalugaluga
I wrote down the wrong pin It was actually pin 3 that had the continuity issue. The tubes light now but they flicker and pulse and don't do anything. The HV reads 201 and 306, jumps back and forth.

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1 year 8 months ago #9981 by Ty_Eeberfest
You said you replaced the IRF-840 at some point, Is there any chance you replaced it with an 840A instead of a plain 840? I'm asking because I remember somebody said they had a problem with their HV going wildly unstable when they tried to use an 840A. I'm not sure why it should matter (the specs of the teo parts are very similar) but for at least one guy it did.

Other than that, well, I'm not sure. Just the usual advice: look again for bad soldering, "tails" of leads sticking out, crud on the solder side of the board, etc. Try a factory reset if you haven't already.

Look into it later when the dust is clearing off the crater.

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