Hyena wrote:Awe, the fried guinea pig award, now I HAVE to investigate further
OK as requested here's the pics.
Firstly, here's where mine let the magic smoke out!
mwkeefer wrote:Yes R25 should open the range on the top end... when you say you added the zener of 19v... you wired them properly (direction) and in series right? check your caps voltage rating too.
Thanks for the report back.. What was your current maximum before removing a shunt?
Connecting 2 of them in series is okay... what target output voltage / current do you want... you may be able to do it with your existing units.
Also, are your units identical to the ones you post the link image to? If not, you know the drill - open it up, remove the PCB and scan the trace side + photo the component side... plus, what version is it (should be stamped on the board or have a date at minimum).
Oh - one last note... the Diode and Transistors which use the case as a heatsink require that thermal coupling paste to work correctly (and the shims so they don't short out)... a cheap and available alternative which Radio shack should have is ceramic polysynthetic thermal compound, commonly known as "Arctic Silver". Be sure to re-apply some if you damage it. I use this same stuff on the Infineon controllers and have never had an issue with it.
Hope this helps!
Vanquizor wrote:Maybe I missed it, but what was the final verdict for this failure? Bad bits or related to Hyena's mods?
Hyena wrote:I did this on my passively cooled 145w meanwell. Why not just pinch 12v from somewhere in the power supply itself though ???
I had a poke around with the multimeter while powered up and found 12v off the back of a zener diode and much to my suprise found that when under load and supplying alot of current the voltage actually increased, so I ended up with a variable speed fan that increased with current draw. BONUS!
Cool graphs Mike. Why does it cut out at ~ 38, 47 and 54 minute ? Is it going into hiccup mode or did a lead come off or something ?
does the fan have NEON?
Hyena wrote:My buzzing ONLY came from the R37 resistor mod. The second I touched another resistor across in in parallel the current dropped and it started the arcing/buzzing sound. Remove it and the current shoots back up and the arcing stopped. The packs I was charging are also brand new, but as I said they happily charged silently at the full current output from the power supply so in my case atleast its not the packs causing the buzzing (and probably less likely in your case too, unless one cell is madly sucking current or something ? )
Oh and yeah I have the earth connected - well, the earth connector to the AC power lead earth. I haven't physically run a lead from that earth terminal to the side of the case. to the I have a CFL light over my work bench that buzzes quite loud sometimes, but a sharp whack fixes it. Hmmm, maybe I should try that with the PSU next time...
heathyoung wrote:Have you post-mortum'ed the old PSU's? I wouldn't mind a look at some of your dead-'uns to see what happened...
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