Chinese DRSSTC driver woes...

[Platinum]

Hello everybody, recently I purchased a Chinese DRSSTC driver from AliExpress, 10days later I recieved it. I'm am sure it is faulty and wondering if anybody can help find the fault. There is no oscillations at all with various primary coils, I have checked the voltage regulators for the drive ICs so far and are correctly working, supply voltage is up to 311v and the seller recommends a variac rectified with stleast 2kw output. I have so far tried up to 90v (seller says 40v produces 30mm arcs, 150v 300mm) 90v is supplied by a boost converter and the full bridge of 500v 20a FETs don't pull any current, even when disconnected the capacitors from my boost converter don't even drain so no current pull at all

Any recommendations as to find what's going on? Thanks

https://www.aliexpress.com/i/32913086209.html

[petespaco]

I was hoping that many Tesla enthusiasts would jump in on this one.  I haven't played with a Tesla coil since 1956, so I know  nothing.
But----  Isn't that little toriod  that is hanging off the side of the board supposed to be the "feedback" element?  Shouldn't the power wires or something make one turn through it, as in one of the pictures show in the "details" link in the aliexpress ad?
  I attempted to add a picture of the feedback setup on their earlier model, but I don't see it here.

[Platinum]

I was hoping that many Tesla enthusiasts would jump in on this one.  I haven't played with a Tesla coil since 1956, so I know  nothing.
But----  Isn't that little toriod  that is hanging off the side of the board supposed to be the "feedback" element?  Shouldn't the power wires or something make one turn through it, as in one of the pictures show in the "details" link in the aliexpress ad?
  I attempted to add a picture of the feedback setup on their earlier model, but I don't see it here.

Hi Pete, thanks for the reply as I thought at least a few would give me some pointers, yes that toroid is a feedback CT which uses the ground side of the secondary coil to sense frequency and I assume the control circuitry locks the coil in time by continually adjusting to it, I have also checked the full bridge and half the bridge is seeing input voltage and the other half just over 2 volts (input was 70)

I really don't know what's going on as the board seems fine, I've also tried flipping the feedback but nothing, surely there would be some output even if the feedback wasn't used, no output at all

[voltek]

Heloo
Desolder big cap and look for connections with TVS-s. I have the bad PCB trace with the first TVS.
Remove varnish and solder with contact.

M.

[Platinum]

Just checked them they are okay, none of the ICs get warm too but the 5 and 9v regulators are working

[voltek]

I will take the photo of my pcb to show you where was a problem.
I yust connect bad trace and pcb working with max input pover 150V DC.
I was trying plus but I blew up igbt-s.
Have you try to change  the direction of feedback wire?

M.

[Platinum]

Thank you, yes I have changed feedback, also I only have 95v power supply, and there are 2 LEDs orange and blue but the blue one never illuminates, does yours? On less than 150vdc

[voltek]

When I turn up it blinking.
Maybe 555 ic is problem.

m.

[Platinum]

I don't think it uses 555, only 74hc08 and 74hc14, does yours work on less than 150vdc?

[voltek]

Yes is working at low voltage . At 15V is 1cm spark at 42 like in movie 6cm.

[Platinum]

I see, ohh well I guess mine will go in the bin.

I get nothing at any input voltage

Well modulation is working as i can hear the tone changing when I change frequency potentiometer (the one you turn in the video) by checking the diode by the feedback ct



Got it working, bad SMD capacitor on the back, now an IC has shorted I will replace it

Any idea what this IC Is? Boards says 555 under it

[voltek]

Ufff strange IC. I can t find data hor this.
Mayby it is alternative for 555 IC.
M.

[Platinum]

Yes I found out that it is, the other identical boards use NE555 from Texas Insutruments, so I've ordered the same ones in the same package SOIC8, the left hand 555 gets very hot I saw arcing from the strong RF output of the coil which was close by

[petespaco]

I can't see why a 555 would ever run hot.