i'm on a roll... the kgsshv

[kevin gilmore]

disconnect all wires to the transformer and measure the transformer for shorts between the windings.

[El_Doug]

no shorts between windings

[spritzer]

How much voltage is the transformer putting out? If it runs too hot then it might develop a short and boom, way too much voltage for the parts.

[El_Doug]

How much voltage is the transformer putting out? If it runs too hot then it might develop a short and boom, way too much voltage for the parts.

the 450v windings are putting out 506v unloaded, seems a tidge high, but nothing too bad. the 30v (CT) winding is putting out 34vac unloaded, again doesn't seem out of the ordinary

[spritzer]

Yeah, that's not out of the ordinary but the true test is under load to to the heat rise. One thing I wouldn't rule out is a short on the board. One of my HV amp boards is going onto the trash heap since the PCB has a short somewhere.

Edited March 23, 2012 by spritzer

[El_Doug]

I wouldn't rule that out, as I spent roughly 30 hours of error testing on one of my B22 boards just to find out the board itself had a short... but I'm having a hard time getting over the fact that both the HV and LV supplies don't seem to be working :/

I guess what bothers me the most is that newbs who solder the transformer directly to the inlet with giant globs of cold joints and no heatshrink have working units on their first go

Edited March 23, 2012 by El_Doug

[spritzer]

All of the PSU's acting up does point to the transformer or something wrong with the ground. They are the only shared elements.

That's indeed the rub. There is something to be said about beginners luck....

[El_Doug]

The transformer seems to be working just fine. Thankfully i have 2 more PSU boards to try out.

Should be a fun evening of desoldering...

[Kerry]

Good luck Doug. When you power up the new board, you can check each supply independently. Just the +/-15V, then just +HV, then just the -HV. If you can put each under load that would be a good thing as well.

I agree, that you should be looking for a failure condition that is common to the affected supplies.

As far as beginners luck goes, it only goes so far and then you need to learn how to debug these beasts. It's a great skill to have so as un-fun as it is to desolder parts, there is a reward to getting everything up and running again.

I took care to blow up my first power supply which lead to countless hours of research, etc. It was a good thing in retrospect.

Edited March 23, 2012 by Kerry

[Victor Chew]

I am also pretty afraid of future shorts that may be caused by whatever reasons. As a precautionary measure, I cleaned the boards to deflux them. Infact after I did mine and I checked all the joints, I found a few cold solder joints and also a couple of unsoldered ones. I also wanted to remove potential shortings due to bridges caused by small pieces of solder. I use acetone (nail polish remover), followed by denatured alcohol to clean off the stickyness caused by the acetone.

[El_Doug]

Thanks, Kerry. Indeed, I knew from the schematic that the two supplies are literally separate circuits, and I only had the +/-15 hooked up to the transformer. I was actually afraid that I somehow destroyed the board by powering it separately, so I'm glad that wasn't my issue

I look forward to the learning process!

Good luck Doug. When you power up the new board, you can check each supply independently. Just the +/-15V, then just +HV, then just the -HV. If you can put each under load that would be a good thing as well.

I agree, that you should be looking for a failure condition that is common to the affected supplies.

As far as beginners luck goes, it only goes so far and then you need to learn how to debug these beasts. It's a great skill to have so as un-fun as it is to desolder parts, there is a reward to getting everything up and running again.

I took care to blow up my first power supply which lead to countless hours of research, etc. It was a good thing in retrospect.

[livewire]

I took care to blow up my first power supply which lead to countless hours of research, etc. It was a good thing in retrospect.

I can relate.

[spritzer]

Flux shouldn't cause shorts under any circumstances but it won't do any harm to clean the boards.

[eggil]

I have a healthy PSU with pretty much identical voltages on both sides, -504/+504 and -15/+15

Edited March 27, 2012 by eggil

[justin]

needs more mailing tape

[spritzer]

...and reversed caps and some solder blobs.

[eggil]

Done, thanks.

I am getting only 393 V in the Bias.

I did not populate C10, D12, R27, R28, D13 and C15 and installed the jumper.

I do have 504 V per side.

Edited March 28, 2012 by eggil

[cobra_kai]

Where are you measuring the bias voltage?

[ujamerstand]

If you are measuring the bias after the 5M resistor, that would be the reason why.

[spritzer]

Yup, that would do it. We really should add a bias test point on one of these PSU's...

[eggil]

Yes I think I am measuring it after the 5M resistor in the Bias connector. I will try again when I get home this evening.

[blubliss]

That is the correct voltage for after the 5M resistor.

[spritzer]

Since you are dealing with 600V only mm from the ground plane it would be a good idea to make a small loop on the PSU side of the 5M resistor to make measuring easier. The PSU is regulated at +580V so it should just work.

[n_maher]

Everyone working on projects like this should have a set of these (or similar).

[kevin gilmore]

I modified the kgsshv power supply and batepower boards for the next board run.

Bias is now a 3 pin connector, TST which is the 580v direct, 580V which is after the 5M resistor

and the ADJ which is the center of a resistor divider for any other voltage.

If you have a 10 meg input resistance dvm, then the correct voltage measured

after the 5M resistor would be 386V.

Edited March 28, 2012 by kevin gilmore