Kaiju driver [resolved]

[nmatlin]

Hi all,

I have greatly been enjoying the Kaiju build. I’ve passed all my voltage tests up to the driver testing. I am getting all correct voltages save on OA on the left board, which is reading around 70V-80V and the right two LEDs are not lighting. Previously, though, I measured correct voltages on the left side. So I suspect a cold joint. Do you have any suggestions on where to look?

I should note that, on my first test, I had issues with the right board OA node, but upon fixing a cold joint there, that resolved. But when I went back to test the left (which had been formerly correct, OA was 70-80v and the two LEDs were dark.

An update (which will require me getting a replacement driver board): I looked through all the joints, tried again, and the left side started working as expected: IA at 510V and OA at 298V, but then the right side had IV at 510V and OA at 0.00. After a few minutes of running as I checked over things, there was an audible snap and the 90.9 ohm resistor in R1 on the A side burned along with the LED diode on the A side that is on the side away from the pot. I'm quite sure that all the polarities were right--but if anyone has any insight on the postmortem/what could have gone wrong, please let me know.

Thanks for your help!

[Paul Birkeland]

That could well be a cold joint or there might be debris on your socket causing problems.  What are the Kreg voltages on that board?

[nmatlin]

Hi Paul and Forum Folks,

I just updated the top one, as I didn't see your response. The end story is that something shorted and the R1 resistor on the A side burned up (along with one of the LED diodes)--so that's a new one for me (and quite unfortunate). So that board is, regretfully, toast. But want to try to figure out what went wrong--I had checked the wiring quite meticulously, but I could always have missed something. I've attached postmortem photos.

Nick

[Paul Birkeland]

I've had this happen from pins touching each other on the board that shouldn't be, backwards or improperly installed zener diodes on the 5 lug terminal strip at the socket, or from a miswire at the socket itself.  Typically though it is two pins of the PN2907 touching.

[nmatlin]

Hi all,

I have replaced the board. Nothing is up in flames (phew). I also found that I had bridged D4 and D5 with a small piece of wire--so I clipped that. So now things are getting closer.

A board measures perfectly.

B board measures fine on on IA, but OA is high (~350V). Kreg voltage is 4.7. Any suggestions?

[Paul Birkeland]

The Breg/BB jumper may be missing.

[nmatlin]

It is on there--matches the other board exactly.

[Paul Birkeland]

What does the pad with the X next to it on the B side measure?

[nmatlin]

I found it--the white wire from Kreg to D2 was not soldered well. Thank you!