Hv question

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2 months 2 weeks ago #9717 by jonboy
Hv question was created by jonboy
Hi guys,
So I have started rebuilding my rev 5 nixie board and so far I have only I question.
I have finished the low voltage side and the high voltage side.
My problem is that I am using a 12v supply and getting 5v at the test point, so far so good.

However when I test the high volt side, I am only getting 12 v, not the 170 I thought I would.

I have replaced, the resistors, and the 22pf and 100nf’s.
All the big capacitors are the right way around according to the board print.

The instructions say that, “Especially check that the stripe on C1 is facing the top of the board (not near the 170V test point).”
But the negative stripe on the capacitors at c1 the 22uf 400v doesn’t face the top of the board, it faces to where the nixie bulbs connect. The picture shows it this way so that’s the way I place it.
But is this wrong?

What else will cause me not to get to 170v?

I am sure I will banned from here soon, with a simple questions I keep asking!!

Thanks for the help though.

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2 months 2 weeks ago #9718 by Ty_Eeberfest
Replied by Ty_Eeberfest on topic Hv question
You didn't explicitly state that the microcontroller is installed on the board, so that's my first question: is it installed? HV generator won't do anything but "leak" +12v thru the inductor without the microcontroller installed and running.

If you have the stripe side of C1 facing toward IC3 (negative lead of the capacitor in one of the holes in the white filled side of its printed footprint on the board) it is installed correctly. The usual result of putting C1 in backwards is the smoky or even explosive death of C1.

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

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2 months 2 weeks ago #9727 by jonboy
Replied by jonboy on topic Hv question
Great, so I have C1 in the correct place, white stripe towards ic3.
And, Yes I do have the atemga chip installed, it’s in a holder, so it didn’t get overheated when placed in, and have no solder bridges as far as I can see.
Two out of two so far!!
Could I have fried the microcontroller when I had problems? That’s the only bit I haven’t got a spare part for, but have asked Ian to send me one with the nixie clock bootleg programs on it, when he send me a few other bits. (Just waiting to hear how much I owe him!)

It’s only like 26 bits I have soldered on so far, and have replaced 90% of them, so it’s either the microcontoller or the IRF840 mosfet in Q1, as that’s all I am left with!!

Thanks

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2 months 2 weeks ago #9730 by Ty_Eeberfest
Replied by Ty_Eeberfest on topic Hv question
It's possible the controller chip was damaged. I'm not sure what sort of test equipment you have. Do you have a scope or perhaps a multimeter that can measure frequency? If the controller is working I'd expect to see approximately 32.5KHz signal at the gate of the mosfet and also at Pin 15 of the controller. Another way to tell if the controller is running is to measure from Pin 17 to ground. Pin 17 should be switching on (+5) and off once per second (one sec on, one sec off, repeating - it's the separator flasher pin).

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

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2 months 1 week ago #9745 by jonboy
Replied by jonboy on topic Hv question
Sorry for the delay in replying.
I am not getting a tick at all from pin 17 to ground, just a voltage of about 2.
So I guess it’s the chip that’s wonky.
I will await my new one.

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2 months 1 week ago #9746 by Ty_Eeberfest
Replied by Ty_Eeberfest on topic Hv question
Yeah, 2V doesn't sound right. Depending on whether the program is running Test Mode or normal clock mode the signal may or may not be PWMing, but regardless you should see some sort of 1 second "pulse" not a constant voltage.

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

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