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  1. Member rhegedus's Avatar
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    Due to a lack of cerebral function, I've managed to blow a PSU by accidentally switching it to 120v when it should have been 240v

    When the smoke cleared, I took the PSU out of the case and opened it up.



    By lineing up the smoke on the case, I think the blown component is a ?transistor? circled red.

    How easy would it be to replace the part and would this fix the problem?


    psu.jpg
    Regards,

    Rob
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  2. Member holistic's Avatar
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    As comfortable as i am with my electronic skills, I wouldn't bother fixing it. I don't know about your part of the world, but a decent 400+ watt PS can be had for $80. Is it worth the time ?
    What other components were stressed ? Finding the correct transistor may be challenging,
    And where is the fuse and why didn't it blow? (or did it)

    Salvage the fan (s), thank the electrical gods you lived to buy a new one.

    just my 2
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  3. Member rhegedus's Avatar
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    Originally Posted by holistic
    As comfortable as i am with my electronic skills, I wouldn't bother fixing it. I don't know about your part of the world, but a decent 400+ watt PS can be had for $80. Is it worth the time ?
    What other components were stressed ? Finding the correct transistor may be challenging,
    And where is the fuse and why didn't it blow? (or did it)

    Salvage the fan (s), thank the electrical gods you lived to buy a new one.

    just my 2
    Easier said than done.

    It's a small form factor 105W PSU and even official sources are out of stock.
    Regards,

    Rob
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  4. Member holistic's Avatar
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    OOPS!! I thought it looked small, thinking it was the angle of the picture.
    Well.... how confident are you that the other components didn't get stressed?
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  5. Member
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    Actually the part you circled looks more like a capacitor. But in truth i would think it's more likely the transformer burnt out too. Both could cost you $5 to $50 to change out, depending on if you have the tools allready or not.
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  6. Digital Device User Ron B's Avatar
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    The circled item looks like an older style capacitor to me as well. Without a schematic and if you can't read the side of the capacitor to determine what the values are, you might have a problem. Looks like a couple of your connector terminals are a little toasted as well. A burnt transformer wouldn't be out of the question either. Too bad there was no fuse or fuseable link.
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  7. i dont think its the transformer because most psu are designed to take in ac as low as 85vac and as high as 270vac. it is more likely a varistor or fuse. if you can remove the device to expose the reference designator i can tell you wat it is... however without a schematic with values it might be very hard to fix.
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  8. Member
    Join Date: Feb 2003
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    Looking at the Picture it looks like you damaged the plug, 24pin, that powers the Mobo... Try a generic PS and I'll bet you have bigger problems than just a power supply. The ATX plug won't get that hot under normal conditions. I'm guessing to much current flow through it to the Mobo = Toasted Mobo and possibly other parts too. If AC flowed over the DC lines then most likely you toasted everything. Last time I saw thast the Drives, memory, mobo, Video card etc. All history.

    Good Luck
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  9. Member
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    Very true the whole comp might be dead. That is definitely a burnt out power plug. after looking out a pin out it looks like maybe the GND got the brunt of the damage.
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  10. Mod Neophyte Super Moderator redwudz's Avatar
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    I would have a hard time trusting that PS after that sort of damage. In truth, I once switched one and it caused no damage, but I may have been lucky.

    I suspect that may be a Varistor device, which is made to limit a over voltage. If so, it may be worth repairing. It's tough to tell when they are burned up, though. A Varistor would be across the AC power leads at the power input. It looks like one power lead hooks into the board near it. You may be able to see the underside of the board if it is across the power leads.

    Here's a link to a schematic of a 200W PS that may give you an idea how the power flows through the device. You may also be able to get a better idea of what that device is by comparing the schematic to your PS.

    http://www.pavouk.comp.cz/hw/en_atxps.html

    Good luck.
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  11. Member rhegedus's Avatar
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    The mobo and the comp are fine - I tried a separate PSU.

    What you're seeing on the plug is artefact/shadow.
    Regards,

    Rob
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  12. Member pchan's Avatar
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    @rhegedus,
    Maybe it's time to replace the small form factor(SFF) case since there is no guarantee that replacing the cap and x'former will fix the problem.
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  13. Member ahhaa's Avatar
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    rob-
    just a thought, but if it happened to be an VIA Epia ITX mobo...
    there is an adapter made for carputers- a tiny circuit board that snaps into the ATX main connector & adapts the system to 12V DC.
    Dunno if the same available for other mini boards.
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  14. Member
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    What are the dimensions of your PSU. Komplett have this.http://www.komplett.co.uk/k/ki.asp?sku=303993
    Dont know if its any good but was worth a shot.
    (Edit) Forget that its only 20 pin connector
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  15. Member
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    Clarify for us - Did you have the PS set for 120V, then plug it into a 220 socket?

    If so, then your blown device is probably a capacitor or a transorb, but without a better photo, that is just a guess.

    Here's a schematic of the input of a typical ATX power supply. With the input switched for 220V input, the part circled in red is at virtual ground. Same when switched for 120V. However, if you input 220V when switched to 120V, this part is across the "mains" and will probably blow up (as you have found out).



    ICBM target coordinates:
    26 14' 10.16"N -- 80 16' 0.91"W
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  16. Member oldandinthe way's Avatar
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    As a long distance diagnosis - you are likely to have properly identified the failed part. The power supply is a single layer board so soldering in a replacement should be straight-forward if you can identify what replacement part you need.

    Since you have not removed the board from the chasis, we cannot see if the etch on the underside has been damaged. You should check that before going further.

    When replacing the part be sure to use an appropriate heat sink while soldering.
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  17. Member rhegedus's Avatar
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    Originally Posted by SLK001
    Clarify for us - Did you have the PS set for 120V, then plug it into a 220 socket?

    If so, then your blown device is probably a capacitor or a transorb, but without a better photo, that is just a guess.
    Originally Posted by oldandinthe way
    As a long distance diagnosis - you are likely to have properly identified the failed part. The power supply is a single layer board so soldering in a replacement should be straight-forward if you can identify what replacement part you need.

    Since you have not removed the board from the chasis, we cannot see if the etch on the underside has been damaged. You should check that before going further.
    Yes - I'll get some better pics when I get home tonight.


    Originally Posted by oldandinthe way
    When replacing the part be sure to use an appropriate heat sink while soldering.
    I think I'm going to need a soldering lesson.....
    Regards,

    Rob
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  18. Member rhegedus's Avatar
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    The scaled CPU:




    The damaged part:

    Regards,

    Rob
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  19. Member
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    Break out your soldering iron and remove that part. If the part number in on the outside of the heat shrink tubing (which I doubt), then take a pic of that. If it's not on the outside, cut off the tubing with an X-acto knife and take a pik of the numbers there.

    Also, once the part is removed, take a pic of the PCB (same view as the one above, 'cept w/o part). It appears that the part numbers are on the top. It will help clue in to the kind of part.

    And try to post pics that are more legible.
    ICBM target coordinates:
    26 14' 10.16"N -- 80 16' 0.91"W
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  20. Member rhegedus's Avatar
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    Originally Posted by SLK001
    And try to post pics that are more legible.
    Sorry?
    Regards,

    Rob
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  21. Member Zukeeper's Avatar
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    I think that all of us have had a case of brain fade at one time or another...

    Here's what I would do:
    Check the printed circuit side of the board for burned traces.
    If there are no burned traces, check the fuse on the board. I don't see it in your pictures but I do see the standard warning to "replace with same type of fuse etc."

    The burned component appears to be a capacitor. Note that there is a similar one to the left of the burned one. Judging from its location, I'd say that it's a filter capacitor and not part of the switch-mode circuitry.

    If you have no burned traces and the fuse is good, remove the burned capacitor. Just cut the leads if you can, or wiggle it back and forth until it breaks off. For testing purposes only, the power supply should work without the filter cap in place. This is where you have to steel your nerve and apply AC power. Probably a good idea to use a power strip with its own circuit breaker just in case something goes pop.

    If the power supply doesn't work, or if there are burned traces, I would consider it a write-off and throw it away (after salvaging the fan as was previously mentioned).

    If it DOES work, then replace the capacitor and you should be good to go.

    Kent
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  22. Mod Neophyte Super Moderator redwudz's Avatar
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    Probably more help than you need, but I would be afraid of using the computer to test the PS. You can turn on a ATX PS by jumpering pin PS_ON and any GND:


    But you would need a Voltmeter to read the outputs.
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  23. Member
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    Originally Posted by rhegedus
    Originally Posted by SLK001
    And try to post pics that are more legible.
    Sorry?
    I mean pics that are more detailed. As for needing a heatsink, this isn't necessary. Just don't dwell too long on the part and everything should be okay. And look at the board underneath the part. Is there a reference designator there that you can see? If you look at the board, you can see writing on the component side (these are the component designators).

    Ultimately, you are going to have to get more information about that smoked part and give it to us.
    ICBM target coordinates:
    26 14' 10.16"N -- 80 16' 0.91"W
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  24. Member Capmaster's Avatar
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    The part looks like a transzorb (transient suppressor). Two leads, they look a lot like a large ceramic cap. I'm almost positive it isn't a transistor. That would have 3 leads.

    It probably kicked in, then shorted out and got smoked.

    You could probably remove it and run the PS just fine without it. It's there to intercept lightning spikes and other overvoltage conditions. Just make sure you have it plugged into another surge suppressor strip. A good one, like the one in a UPS. Not those cheapo $15 strips you get at Walmart
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  25. Member rhegedus's Avatar
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    I had a look at the back of the board and it seemed OK. There was no schematic

    This is the offending article:



    Through the soot, I can make out:

    TVR
    10241
    632

    Any ideas?
    Regards,

    Rob
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  26. Member Capmaster's Avatar
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    The same thing happened to this guy with the same part:
    Hi,
    I've been given a friends PC Power supply to repair. It's a Enermax EG651
    (550W) model. It was damaged when he plugged it into a 240V supply while
    the voltage select switch was on 115V (Doh!!).

    Anyway a quick visual shows that two large ceramic disk capacitors are
    blown. The capacitors are mounted next to where the wire from the voltage
    select switch joins the pcb. They are marked Z1 and Z2 on the pcb and TVR
    10241 on the components themselves, they are about 10mm diameter.

    Does anyone know what rating these are?

    Also if anyone knows what further damege may have been done (hopefully none
    http://sci.tech-archive.net/Archive/sci.electronics.components/2004-07/0196.html

    He's wrong about the part. It's a transient suppressor, which look just like large ceramic caps.

    This guy did the same thing:

    The component is a green capacitor or resistor I think (numbers TVR 10241) wrapped in black heat shrink tubing. The tubing says R116075 125C on it. I burned that up when I plugged it into 220V/50HZ. Looking at the power supply with the wires away from you and the 2 prong cord jack toward you the component lies just to the left of the *big* 200V 680microfarad capacitor (C31 i believe) and just to the right of the white and black "boxes". Also, what is the value of the fuse? Mainly I need to know the value of the capacitor or resistor. Please help and don't just turn your back on this one.
    http://forums.xbox-scene.com/index.php?showtopic=243098

    He didn't correctly identify the part. It's a varistor, another name for a transient suppressor. Here's the datasheet for it (it's about the 12th one down the list):
    http://www.nawani.com/electronics/ntcptc/zov_highsurge_protection_tvrd_series.pdf

    You can buy them online. Just make sure the one you get has the same specs, of course
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  27. Member
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    Before you proceed to obtaining this replacement part, see if the power supply will power on. If nothing else is dead, it should turn on and run. If it doesn't, then there's no use in expending any more effort to fix it, because most likely many of the ICs and transistors could be dead (surges caused by this thing blowing can do severe damage).
    ICBM target coordinates:
    26 14' 10.16"N -- 80 16' 0.91"W
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  28. Member Zukeeper's Avatar
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    Indeed, that is a transient supressor (MOV or Metal Oxide Varistor). If all the other components are good, the power supply will operate without the MOV.

    I have an IBM computer that is more than 12 years old that took a power surge many years ago. The MOV in the power supply literally exploded, all that was left were pieces and the two pins sticking up out of the board. I clipped the pins and replaced the fuse. The power supply worked fine then and still does.

    So, you'll probably have at least a blown fuse and if the MOV didn't act quickly enough there's a possibility that the rectifier is damaged. Hard to say just from looking at the top but I'd bet that the black rectangle to the left of the electrolytic capacitor is the rectifier bridge. I'm sure there are many sites online that will explain how to check a bridge rectifier (in or out of the board, no power applied). I suppose that a quick way to check for a shorted bridge is to apply power and see if the fuse blows. If the bridge is open then the power supply will have no output. Be aware that if the bridge is shorted, the fuse will blow rather...um, enthusiastically. Take the proper precautions.

    I'd not hesitate to replace a bad bridge since they are not very expensive. Just be sure that the voltage and current ratings are equal to or higher than the one being replaced.

    To sum up, I'd say that the chances are high that only the fuse is bad, a moderate chance that the bridge is bad, and a slight chance that the power supply is dead (and not simply pining for the fjords).
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