Debug Help

[pascal88]

I have tested all the major signal points with DC power only and have all the proper signals. I just can't get the system to oscillate and produce HV. The secondary coil reads 255ohms, the primary has 5 turns. I tested and made sure the 2 capacitors get full and they do. I am getting the flip flop action on the primary of the gate drive transformer but the output of the gate driver transformer is zero.

Also, I have a 220v board that was modified for 110v with a wire from the negative of the two capacitors to the fuse. The fuse is not blown, The gate drive transformer does hum ever so lightly.

What should I be looking for?

[Heidi]

You should be using a 6-turn primary unless your secondary resistance is under 230 ohms. There was an issue with a batch of secondaries about a year ago where they were wound with wire having heavy-build insulation, resulting in too few turns and a skewed tuning point.

Have you tested your UCCs in both orientations?

[pascal88]

You had sent me an email before I finished the coil to check my secondary resistance which was 221. I used 5 turns in the primary because the secondary is under 230 ohms which I did.

I also swapped the UCCs and it made no difference.

[pascal88]

test-onetesla_220Vboard.jpg

(166.86 KiB) Not downloaded yet

is there a spice model or test points for the HV side? i can substitute 20VAC for 110VAC for testing but since its not oscillating, i need some reference points.

Thank you

[pascal88]

LowPowerTest_out.jpg

(420.4 KiB) Not downloaded yet

does anyone have some scope readings on this?

[Alex]

do not short the output of the bridge to ground!!!

scoping across the primary wont really show you anything.

how are you measuring the output of the GDT?

[pascal88]

The output of the bridge is not grounded or shorted.
I used a scope across the GDT

[Alex]

in your diagram you show that your scope probe ground clip was connected to the primary.

And yes, obviously you used a scope (:
but how are you scoping it? where is your ground clip? where is your scope probe?

[pascal88]

I measured the resistance of R8 and R9 before I soldered them on the PCB, they were 6.8 ohm. I soldered them on and measure them again, one was 6.7 and the other measured 1.7ohm. I also checked the C-E of the IGBTs and they measured a short. Are the IGBTs fried? How do I test to see if the Gate Drive Transformer is wired properly?
Thank you.

[pascal88]

it appears that one of the IGBT was DOA that was causing all the problems I was having. I doubled checked everything and I just hope that I did not destroy the runs unsoldering some of the components to test...