Simplistic MosFET HV Shunt Regs

[merlin el mago]

I used & worked OK red board the issue comes when I changed the power Tx, before 240VAC unknown power but surely 50W ore less now 200VAC 100W.

 

[Salas]

Remove R10 so the on procedure will sync faster, just in case there is a rapid high charge.

 

[merlin el mago]

Remove R10 so the on procedure will sync faster, just in case there is a rapid high charge.

I put a jumper instead R10?

 

[Salas]

No, just leave the RC broken.

 

[merlin el mago]

And after removing R10 I have to measure voltage across R3 56K?

 

[Salas]

The leds must light up, nothing must poof, and the voltage across R3 should be ~279V for ~5mA through the leds, in case of success. You did not tell me if you have no continuity between Mosfet tabs and sinks. Your sinks touch and its dangerous if there is a leak there.

 

[Salas]

Also there is some weird grey thing between your MJE transistor and a sink in your photos, what is that? Clean that area. MJE's back should not touch anything around it.

 

[merlin el mago]

No continuity between any pin mosfet & screw, also no continuity between tab (mosfet hole) & screws, that's OK?

 

[merlin el mago]

Also there is some weird grey thing between your MJE transistor and a sink in your photos, what is that? Clean that area. MJE's back should not touch anything around it.

Removed and soldered a new one, see attached pic, it's OK?

 

[Salas]

No continuity between any pin mosfet & screw, also no continuity between tab (mosfet hole) & screws, that's OK?

Scratch the sinks a little so you have some shiny scratch. Put the Ohm meter between metal tab of each Mosfet and its exposed sink's metal. Must read very high (open circuit).

 

[Salas]

Removed and soldered a new one, see attached pic, it's OK?

Looks much cleaner. From that angle seems it does not touch the sink although very near.

 

[merlin el mago]

Gotcha, there is continuity between metal tab IRF9610 & his own heatsink also IRF840

 

[merlin el mago]

After hard work, OK now no continuity I must used nylon screws & nuts, can I fire up?

 

[Salas]

Give it a try, stay back.

 

[merlin el mago]

If LEDs don't lit when fire up inmediately I power off

 

[Salas]

I see a hit 5k6 on the photo, is that working?

 

[merlin el mago]

LEDs lit a few seconds, R1 burned again

While connected I read 140V at the dummy load but fixed Vout value can not adjust with trimmer inmediately R1 burned.

 

[Salas]

Solder the Vin cables directly under Vin capacitor electrolytic.

 

[merlin el mago]

I see a hit 5k6 on the photo, is that working?

Yes it's R5 between MJE350 and GND.

 

[vgeorge]

Have you taken out and measure ALL the semiconductors and make sure they are OK? Do that before next try.