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FrozenGate by Avery

Omnichrome 171 repair

ultimatekaiser

ultimatekaiser

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Tried to turn on my omni-171 supply today. Turned to the 'ON' position OK, but when I tried to move it to 'start' the key switch broke and the silver core came out on the key! Anyone know a way to fix this or have a dead related PSU that I can pull one from to replace this one? Or perhaps I can send it to someone to fix?

Top down view:
IMG_1251_zpsad5c5771.jpg


Closer inside:
IMG_1252_zpsc9e51611.jpg


Front panel key switch:
IMG_1253_zps24986bd3.jpg


Right side:
IMG_1254_zpsa02ebdfa.jpg
 
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I'd just open her up and replace the key switch with a standard switch. Everything else will be a really involved process.
 
unfortunately I don't know much about working in these huge high voltage supplies. I know you have to wait at least 5 minutes. but as they are line operated, I'm not too experienced with them, and I'd rather not fry myself on the huge supercapacitor array on the top, let alone the rest of the supply. and i's a multi-stop switch....I don't know what I could replace it with that would meet the requirements to run it. I'd prefer it to remain all original. :/
 
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Can you take a pic of the front where the key broke off inside?

Generally you need to extract the key part and then use a new key. If the tumblers were damaged then you need to replace the switch mechanism anyway.

Standard HV operating procedure. Wait 30mins after unplugging. Get a pair of chicken sticks, electrode on each, wire between them. You can put a series resistance in that wire of 10k if you want. Short out the caps with the chicken sticks and LET THE STICKS STAY SHORTING THE CAPS FOR SEVERAL MINUTES. Electrolytics have charge memory. Keep one arm behind your back when you first poke around if you're still nervous. The idea being no cross-chest discharges. You shouldn't have anything to worry about once you short that cap bank though from the looks of it. That's all low voltage cable and PCB in the vicinity of where you'll be poking around.

Once you remove the switch you can probe with a multimeter and see which contacts connect where, then just replicate it with one or more standard switches. Usually two switches at most are needed to replicate a key switch: one for standby and one for enabled.
 
Yeah that's what I figured. Though it still powers up as is. Got a couple ticks from the head and something went "plang!" Inside. I think something blew. :(

Looking it over.
 
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Eww. Plang is not one of my favorite sounds. That's right up there with "crackle", "sizzle", "BRRZZZ-PAP!", and "PLINK!".
 
ok, now that its been a few minutes...though it takes a bajillion screws to open it...propped it carefully open again, and nothing seems different. but after the noise, and very faint smoke having managed to escape before I cut the power, something is obviously wrong. it smells too, so i suspect a capacitor somewhere probably took a dump. I wonder if it's stuck in the 'start' position and something overloaded.
 
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You're going to have to do a full autopsy it sounds like. First would be to remove the switch and map it's connections (unless you find a schematic). Second would be to scour the boards for busted caps, resistors, and diodes. Hope that no active or magnetic components took a dump.
 
Just looking at the photos the key switch just acts as a DPDT switch, but after the tumbler broke it may have connected both outputs at the same time or bridged one pole to the other, neither of which are good.

Unfortunately these power supplies are switchmode and a fair bit more complex to troubleshoot
 
It's line connected, switching is likely but unknown... I'll just have to short it and look when I get home in a few hours. It agree with what happened though. I think it dumped too much power somewhere.
 
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You guys are courageous. When the plang happened is when I would have tossed my figurative monkey wrench to the side and searched ebay for a new one.

Plang sounds like shit wot could mess me up. I shock myself enough with small 6inch HeNe tube the last thing I need is a legit HV PSU in my hands lol.

Good luck on the repairs!
 
IsaacT said:
You guys are courageous. When the plang happened is when I would have tossed my figurative monkey wrench to the side and searched ebay for a new one.

Plang sounds like shit wot could mess me up. I shock myself enough with small 6inch HeNe tube the last thing I need is a legit HV PSU in my hands lol.

Good luck on the repairs!
Click to expand...

Optimally that would be best, but few are around, and fewer I can afford. Most run $500+ and hell if I can afford that anytime soon. Often times it's not too hard to fix I'm told, it's just a matter of figuring out what broke. I'm just not well equipped for this. I honestly wouldn't mind paying for repairs. But either way, it still needs diagnosis.
 
Depending on diagnosis I may be able to execute the repair if you're unable to, but I seriously doubt it's beyond you. Usually it's just a couple of parts at most, cascade failures are very rare.
 
I know what you mean... Usually a small handful of parts at most and you're back in biz. Assuming its a part still made. It's fairly old for an old PSU. It's paired with the tube I'm sure. Built in 94 both of them. Tube hasn't run in a while though, but with only 1113.4 hours on the clock IIRC.

I just need to come up with a way to discharge everything slowly. I don't think I have a big enough resistor wattage wise. Fast shorting that cap array would be bad for the caps.
 
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Even a 1/2 watt resistor can discharge safely if you use a high enough resistance. 5RC and all that jazz. =)
 
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