Power Supply Toasted - Page 1
Forum section: electronics / repair

author: Savetheday
author_rank: Regular Contributor
timestamp: December 29, 2022, 04:59:51 pm
content: HiToday I powered up my desktop computer and then right away something burned. My Computer Power Supply (Jersey GE-650WS) is toasted.I take it apart. Then I saw that an unknown resistor was toasted under the induction coil and right after full bridge rectifier GBU 6J. Can some one tall me what kind of resistor is this?

author: Savetheday
author_rank: Regular Contributor
timestamp: December 29, 2022, 05:12:27 pm
content: ++

author: TheMG
author_rank: Frequent Contributor
timestamp: December 29, 2022, 06:20:58 pm
content: Where's the resistor? If there isn't enough left of it to be able to read its value (color band ls or writing), I'm afraid you're out of luck unless you can find an identical power supply to get the resistor value from.Impossible just looking at a few pictures to even begin to guess what it might be.Also, resistors don't usually go up in smoke catastrophically on their own. This means something else inside the power supply has failed (likely a shorted transistor at the very least). These cascade type failures can be quite challenging to troubleshoot if you don't have a lot of experience with troubleshooting SMPS unfortunately.

author: Savetheday
author_rank: Regular Contributor
timestamp: December 29, 2022, 06:40:01 pm
content: This one , I have to remove first of all coil and then resistor come out already but impossible to read colors.

author: james_s
author_rank: Super Contributor
timestamp: December 29, 2022, 06:48:58 pm
content: That looks like a flameproof resistor, is it in series with the input? If so it's probably a fraction of an ohm. The resistor isn't the fault though, it's a symptom of another fault. PC power supplies are usually a nightmare to work on, they're so cheap and difficult to repair that there's little point in trying unless you just want a challenge.

author: Savetheday
author_rank: Regular Contributor
timestamp: December 29, 2022, 09:48:52 pm
content: One leg connected to one of the leg induction coil other Cap 2A1 23J.There is also 1x 8DIP ST Lb5bl ?, 2x K2837 N-ch MOSFET, 1x HFA16TA60C Recovery Diode

author: Savetheday
author_rank: Regular Contributor
timestamp: December 29, 2022, 10:13:19 pm
content: hfa16ta60c Recovery 2 Diode has short circuit. I’m reading both sides 0

author: james_s
author_rank: Super Contributor
timestamp: December 29, 2022, 10:44:26 pm
content: There are probably more shorted parts, you'll have to find all of them or it will blow again as soon as you apply power. This is part of what makes repairing these so challenging.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 30, 2022, 02:34:54 am
content: find near the R or the PS input a fuse or fusible R ?Imho even if there fusible R, it's good idea to interpose/insert a glass fuse with its socket right after PS input by the googled typical limiting max current before proceeding to repairing

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: December 30, 2022, 04:04:25 am
content: I would suggest connecting a lightbulb in series before plugging it in.If the resistor is dead I believe the best way is to scrape off the ceramic around the resistor to get to the resistive material. Afterwards, you can measure the resistance to each leg and add them up.

author: TheMG
author_rank: Frequent Contributor
timestamp: December 30, 2022, 05:47:09 am
content: If it was in series with a capacitor, connected across an inductor, then the resistor and capacitor are likely a snubber network.I assume this is part of the PFC pre-regulator circuit?Wouldn't at all be surprised if not only the diode, but also the associated MOSFET and perhaps even the PFC controller IC are toast. Probably an electrolytic capacitor associated with the PFC controller went bad, causing it to malfunction and switch erratically, overheating the snubber resistor, once that went open the excess ringing from the lack of a snubber cooked the MOSFET and diode. This is a fairly typical cascade type failure I've seen a few times, one bad cap can cause the release of a lot of magic smoke!

author: Chris56000
author_rank: Frequent Contributor
timestamp: December 30, 2022, 05:46:55 pm
content: Hi!Try 4R7 1W fusible to start with!Failing that, if you have a multimeter, try scraping off the coating from approximately halfway along the resistor and see if you can get a reading from one end of it, if you do, approximately double the reading you get and order the nearest value commercially available in that size!The IC is ST L6561 – ST use horrible styled figures that make a "figure 6" look like a "b!"If there is a diode gone, there will almost certainly be other damage, very likely the 2SK2837s gone on the primary side to begin with!If you want an exact replacement power supply, this seller has one in stock :–https://computerstoreberlin.de/Jersey-GE-650WS-ATX-psu-650-Watt-322312If you do find an exact replacement, it's worth while taking a pic of the resistor in the replacement working one so you've got a record of it's value!Chris Williams

author: Savetheday
author_rank: Regular Contributor
timestamp: December 31, 2022, 12:46:40 am
content: Hi again sorry for late answer.I measure the bad Resistor 12k ohm and that part(red marked ) checked and those components are bad.Cap was 50v 47uF ESR over 0.4 ohm.Quote from: EggertEnjoyer123 on December 30, 2022, 04:04:25 amHow you do that ? Do we need to buy different sort of Extension cord?

author: james_s
author_rank: Super Contributor
timestamp: December 31, 2022, 01:16:56 am
content: Quote from: Savetheday on December 31, 2022, 12:46:40 amI don't intend this to sound rude, but if you don't know how to connect an incandescent lamp in series with something to limit the current that suggests you are not especially knowledgeable about basic electrical principals and you really should be extremely careful poking around inside a switching power supply. Again I don't want this to sound insulting or condescending, but these things can be seriously dangerous to work on and are not good beginner projects. I have decades of experience repairing things and I have still had limited luck working on ATX power supplies, they're just so densely packed and so poorly documented.