I have returned things to Mouser with no issue and full refund, even where I changed my mind. The real question is who will cover the return shipping on those bad boys - they look almost beer can sized.

use for singlepower repairs?

use for singlepower repairs?

 

If Mikhail did the repair wouldn't that mean he would just glue them to the top cover and not actually attach them to the circuit?

I'm a little surprised at spritzer didn't say as long as we've got them lets build a monster around them.

 

Thanks for catching the Mouser error. I'll be sending them back this week.  Hopefully that will get them to cover shipping because beer can size is about right and they are full and heavy!

Hey!!!  I just got home from work...   

 

400V isn't enough for any serious amp.  I have some 3900uf/550V caps here somewhere and some 3*110uf/630V film caps.  Two of them are the size of that 717... 

How much output current could one really get away with for the offboard version? I actually had my working board running at ~10mA by swapping R5 and R6 with 100ohm resistors. After nearly an hour being on the outside of the heatsink reached about 37C, also the lowest I could get the offset was 7V.

8.8mA here.

I can get within 5V.

Drift will rise the more you increase current.

Which version are you using, IXYS or the A1968?  Personally I'd only do this on the Sanyo part...  As for how much current, until there is smoke. 

 

You can also tweak the offset series resistor to give you more range.  

I'm using the 1968s. So would I lower the value of the 2k resistor then (R26)? I'll probably just leave it at 10mA though, not going to be running anything but a lambda with it for a while.

I'm using the 1968s. So would I lower the value of the 2k resistor then (R26)? I'll probably just leave it at 10mA though, not going to be running anything but a lambda with it for a while.

I was running at 34v (using ixys parts) when I ran out of turns. Lowered R26 to 1.2k and the problem was fixed. I believe that current variation is the same as the ixys parts, you may want to try dropping it to 1.5k. For some strange reason, both my on-board and off-board suffered the same problem.

Edited June 4, 201313 yr by Victor Chew

Could you not use a 2k pot instead of the 1k pot to also deal with the issue, or is that to be avoided?

There are voltage issues at play here so stick with the 1K pot. 

8.8mA here.

I can get within 5V.

Drift will rise the more you increase current.

 

Sorry s_r,

I was not clear.

I’m able to zero offset, but it drifts 5V - 0 + 5V because of the extra current.

As the guys have said R26 needs to be a lower value if your pegged at 7V.

So put in a new set of zeners, ohmed out the traces to make sure I didn't wreck something and everything checked out. Turned it on and something made a small zap. I got 750V on the output and about 320 across the zeners.

 

I'm starting to think I should just populate a new board.

Maybe not a good night for KGSShv power boards!  

 

I powered up my board for the first time and had a nice little spark at R17.  I was not able to keep it powered up to do any checks as it was giving me a nice steady snap, snap, snap.    Nothing else visually appears damaged.

 

 

After removing the resistor (which tested OK after removal) I noticed this hanging solder and wondered if I had a cold joint that allowed some arcing?  

 

Do I need to protect that board now where the arc has gouged into the copper?

 

I tried putting another resistor in and had the same result, arcing in the same spot.

 

I'm calling it a night, starting to get tired which is not a good time to start trouble shooting high voltage.  

Carbon is an excellent conductor so clean all that off and seal the exposed copper somehow.  Glue, varnish, something like that. 

It's a bad idea to solder the voltage reference in there as those are very easily damaged.

If you read previous posts, you can see that I had a strange problem with mine.

Do what Birgir said. clean those nasty stuff off and tape it up with a small piece of kapton or seal it with epoxy.

Pull all active components out and test them individually.

Also... I can see quite a few very very large balls of solder.... come on... clean those shit up.... even if they aren't arcing right now, they will in the future for sure.

I would highly recommend after the soldering job, go back and add some quality flux to every joint and reheat them to make them all nice, smooth, and shinny. If you can make the solder just seep through a little to the other side of the board all the better, but not like those balls of solder tho.

And good luck!

@shipsupt -

 

Maybe not a good night for KGSShv power boards!  

 

I powered up my board for the first time and had a nice little spark at R17.  I was not able to keep it powered up to do any checks as it was giving me a nice steady snap, snap, snap.    Nothing else visually appears damaged.

 

 

After removing the resistor (which tested OK after removal) I noticed this hanging solder and wondered if I had a cold joint that allowed some arcing?  

 

Do I need to protect that board now where the arc has gouged into the copper?

 

I tried putting another resistor in and had the same result, arcing in the same spot.

 

I'm calling it a night, starting to get tired which is not a good time to start trouble shooting high voltage.  

 

 

What are you using to insulate your 7815 and 7915?

O_o

Well alomost all 78XX and 79XX today have tab connected to ground, so it's not a safety hazard per se. Grounding problem, however, is an entirely different matter.

 

my bad, 78XX has tab connected to ground while 79XX has it connected to input.

Edited June 10, 201313 yr by jwzhan

NO, you have to use a thermal insulator on the 78xx and 79xx

tabs are not ground

non insulated parts need insulation (i.e. 4171G ceramic pads)

plus thermal paste.

and are those flat head screws?

Yeah, panhead would be better.

That snapping cracking sound must have been disturbing...

That 50k is in the negative rail though. I am not sure I follow how only that resistor blew, just by its little self.

Edited June 10, 201313 yr by eggil