No high voltage, no help from the seller...

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2 months 1 week ago #11032 by jonboy
I am having the same problem with my kit.
I have changed the irf640, changed the mc34063 twice, changed the 1n5819, the 2n3906, both capacitors (100nf and 680pf) the uf4007.
I only have the inductor and 0.18 resistor to go!
If the mc34063 is in or out I still get the same basic reading of about 5v.
It’s driving me mad!
Is it because I am only using a 5 volt out put?
I did change the pot to a 10k instead of a 5k and the picture had a 10k in it, but it wasn’t working with the 5k pot either.
Any other ideas?
Thanks

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2 months 5 days ago #11046 by Ty_Eeberfest
Okay, now that we have a schematic to look at I can assure you the the unprogrammed WeMos has nothing to do with your power problem. The schematic shows that there is no interaction between the WeMos and the High Voltage Generator.

I don't understand what you mean when you say "Is it because I am only using a 5 volt out put?". It looks to me like the circuit wants to be powered by 5V.

Remember... the reason these boards were free is because the silk screen is messed up / backwards. With that in mind, are you SURE you have all the components in the High Voltage Generator installed the right way around? The silk screen can not be trusted for polarity markings and other orientation matters!

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

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2 months 5 days ago #11047 by Ty_Eeberfest
Also - since you are reading 5V on the 50V test point I'm pretty sure your inductor is okay. Look at the schematic. The way that 5V can get to the 50V test point is by flowing thru the inductor and diode D2, therefore it follows that those parts are likely okay.

Have you got a scope? If so what do you see on the gate of the IRF640, or in other words at the node consisting of D1 cathode, Q4 emitter and Q3 gate? Also what do you see on Pin 2 of the MC34063?

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

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2 months 4 days ago #11048 by Ian
OK, guys, sorry this is causing such a lot of problems, here's how you should go about building it:

1) Power connector header (J1) and/or USB connector (J2)
2) ENTIRE HV circuit. Missing ANY component will cause it to not work at all! Note that the timing capacitor is 360pF on the schematic. I'll check to make sure that is really what I installed on the prototypes. At the end of this, you should be able to get up to 70V at the test point. Set it to 50V for the moment.
3) Controller and shifters
4) Separators - I put these here because it is a good test to see if the shifters are working.
5) Optos
6) NeoPixels
7) Tubes, IN TWO GROUPS of 3 tubes, note that the heaters are in series with the dropper diodes. If any of the tubes in the group is missing, none of them will light!
8) finally, RTC.

After you have the NeoPixels installed, you can do a startup test, and you should see the NeoPixels light up and change colour.

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2 months 4 days ago - 2 months 4 days ago #11049 by Ian
Ty, yes, the silk screen for Q4 *might* be the wrong way round. I had a second batch of boards made that were corrected, and honestly, I don't remember what I sent out to people, so please, lots of extra attention around Q4.

For reference:



The section around the board:



So, according to my calculations, the transistor has to go in rotated through 180 degrees, i.e. with the flat on the right hand side, not the left.
Attachments:
Last edit: 2 months 4 days ago by Ian. Reason: Clarification in description

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2 months 4 days ago #11050 by jonboy
Okay, to try and answer a few questions.
Q3 the irf640 might be the problem.
The instructions said “ Q3 should be orientated with the metal tab closest to the board.” I read this to mean the metal tab on it lies onto the board
So from left to right the pins would be 1,2,3.
However on the above schematic the pins are 3,2,1
Should I take it our and turn it around to match the above pin out?

I have Q4 flat side facing right as you look at the top of the board.

I don’t have a scope, but can test around with the multimeter later

I also wonder if I have now installed Q1 and Q2 the wrong way. At the moment I have the flat edge facing the bottom of the board.

Thanks guys

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