I also replaced the three electrolytics on the logic board, the original specification for all three is: 100µF 35V 105C.
Before replacing these, the monitor still wouldn't turn on occasionally, it seemed temperature dependent.; heating those three capacitors with an air gun would make it work.
davidebaldini
Member
Last Activity: 11-25-2024, 12:26 PM
Joined: 02-23-2018
Location: Ravenna
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Fujitsu E19W-5 quick white flash when plugged to AC then no life
[B]Symptom:[/B] my Fujitsu E19W-5 emits a white flash from the CCFL lamps for a split second after being plugged to AC, then it behaves as if unplugged from mains: no backlight, no image on the LCD, no LED light on the front bezel; it remains in this status indefinitely. Re-pugging the AC cable repeats the behavior.
I have fixed it by replacing the four capacitors on the power supply circled in the photo. It is functional without defects now. This PCB seems identical to the Fujitsu E19-5 that was discussed [URL="https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-computer-displays/91988-fujitsu-display-e19-5-service-manual"]here[/URL]... -
Re: Corsair HX620W - dead APFC MOSFET
@Francesc V.
I think your description of symptoms so far matches the conditions of my failed ATX power supply with shorted APFC mosfets that I repaired [URL="https://www.badcaps.net/forum/showthread.php?t=114885"]here[/URL]. Maybe you can repeat the same tests I did.Re: Corsair HX620W - dead APFC MOSFET
@Francesc V.
I think your description of symptoms so far matches the conditions of my failed ATX power supply with shorted APFC mosfets that I repaired [URL="https://www.badcaps.net/forum/showthread.php?t=114885"]here[/URL].Leave a comment:
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Re: [Troubleshooting] Dell T7610, computer won't post after turning on memory mapped
Tangential note:
I have a Supermicro with two 771 sockets that also doesn't detect the CPUs. The problem begun with only the secondary socket not detecting its CPU, and over the months the primary socket became faulty too. Surprisingly, a workaround is to press both CPUs against their sockets for a few seconds during boot, before the power button is pressed, and release pressure after the power-good LED on the motherboard is lit (~3 seconds). Thereafter it all works, for me. The pressure...Last edited by davidebaldini; 03-01-2023, 03:13 AM.Leave a comment:
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Re: ATX power supply keeps blowing PFC mosfets — Cooler Master RS-550-ACAA-E3
I took this power supply out of storage yesterday to mount it back on the workstation were it blew up. Apparently it's working fine, it's been running overnight at full CPU load, no apparent problems so far, and it holds the UPS switching time. I didn't do any further bench tests the way I'd like, it would have been interesting to measure the temperature of the replaced mosfets since they have higher gate capacitance and lower slew rate, but those heat sinks are large anyway, and after a day nothing...Leave a comment:
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Re: Intel DX58SO high side VRM MOSFET keeps failing
Could anyone speculate whether this might be due to an open capacitor in the voltage regulator circuit that causes stress on its mosfet, as it happened on my [URL="https://www.badcaps.net/forum/showthread.php?t=114885"]power supply's APFC[/URL]?Re: Intel DX58SO high side VRM MOSFET keeps failing
Could anyone speculate whether this might be due to an open capacitor in the voltage regulator circuit that causes stress on its mosfet, as it happened on my [URL="https://www.badcaps.net/forum/showthread.php?t=114885"]powerLeave a comment:
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Re: ATX power supply keeps blowing PFC mosfets — Cooler Master RS-550-ACAA-E3
It works!
This is how it looks now just before I closed the chassis and called it done
I did the standby test which yielded 5.1V SB (purple wire) and 4.8V PS_ON (green wire). This time VSB remained stable and precisely regulated at 5.1V for ~30 seconds after I toggled off the wall switch, while in the previous test with the broken cap it began to drop immediately. The bulk capacitors now retained some charge for ~40 seconds past power off.
I shorted green...Last edited by davidebaldini; 01-28-2023, 03:03 PM.Leave a comment:
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Re: ATX power supply keeps blowing PFC mosfets — Cooler Master RS-550-ACAA-E3
Thanks for the suggestions. Today I prepared a "replacement kit" inspired by momaka's suggestion using components I had at hand, with a voltage divider between the two electrolytic caps and a film capacitor in parallel (see schematic) rated 100nF 630V. The 4 resistors are 220ĸΩ 1W which will replace the original 1MΩ resistor on the PCB. The corrugated cardboard box in the picture contains the two caps, which will be squeezed between the two heat sinks leaving about 4mm of clearance,...Leave a comment:
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Re: ATX power supply keeps blowing PFC mosfets — Cooler Master RS-550-ACAA-E3
I found the bulk capacitor is defective. I desoldered it from the PCB to test it independently from the circuit. I charged it to 10V with a dedicated bench PSU thru a 210Ω resistor; for as long as the bench PSU leads were clamped to the cap, the multimeter read 10V across the cap. As soon as I unplugged one clamp of the bench PSU from the cap, without first switching the bench PSU off, the voltage dropped to 0V.
I did the same test with two other used capacitors I had as spares from...Last edited by davidebaldini; 01-26-2023, 10:59 PM.Leave a comment:
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Re: ATX power supply keeps blowing PFC mosfets — Cooler Master RS-550-ACAA-E3
I ran the test you suggested. With the PSU on bench w/o any load attached, with power cord attached to mains, in standby, the 5VSB measures 5.10V and the bulk capacitor reaches 310V, equivalent to 220V rms, which is expected for the Italian grid. The mosfets don't overheat while in standby.
As soon as I switch the mains off, the 5VSB begins to drop. It reaches 3V one second after the mains is off, and continues to drop. The bulk capacitor is at 0V 10 seconds after the mains...Leave a comment:
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Re: ATX power supply keeps blowing PFC mosfets — Cooler Master RS-550-ACAA-E3
I wanted to use an incandescent light bulb in series with the PSU, but this is Italy, the incandescent ones have been illegal for 15 years, importing is troublesome and takes months for customs clearance. If I build a proper test bench I'll look into automotive halogen bulbs, which are still sold. But so far, during the short 1 second tests, the surge protection breaker in the house hasn't tripped with the new pair of IRFP460, which are larger and more robust than the original mosfets,...Leave a comment:
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Re: ATX power supply keeps blowing PFC mosfets — Cooler Master RS-550-ACAA-E3
Noted. The overheating I got after replacing only one 16N50C3 seemed exaggerate to be explainable only by a mismatch of response time between the two mosfets, as the remaining 16N50C3 exploded after less than 1 second of uptime. After I replaced this one too with another IRFP460, I'm still getting a warm heat sink after just one second....Leave a comment:
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Re: ATX power supply keeps blowing PFC mosfets — Cooler Master RS-550-ACAA-E3
Attached annotated PCB layout.
The IRFP460 G D S pins are marked. Green, yellow, purple and black circles indicate jumpers. The two PNP transistors in front of the replaced IRFP460 are marked, with two pairs of zener+resistor connecting both gates, one pair per gate. Both BJT bases are connected to the CM6800 board via the thru-hole resistor (on the PCB components layer, not visible here) that crosses over the SMD R9 on the tracks layer....Last edited by davidebaldini; 01-26-2023, 09:06 AM.Leave a comment:
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ATX power supply keeps blowing PFC mosfets — Cooler Master RS-550-ACAA-E3
This is an ATX PSU rated for 550W powering 24/7 a computer load of about 200W, fed by a line-interactive 1500VA UPS. Mains is 230V.
[LIST=1][*]First issue: the PSU blew a mosfet on what I think is the active PFC boost converter, shorting its G D S pins together causing a short across the + and - lines produced by the rectifier on the 230V mains. The surge protector of the house tripped. When this happened I found that the UPS was unexpectedly disconnected from the wires of its battery. The UPS wasn't damaged, but I suspect this spontaneous detachment of a battery wire caused a condition...Last edited by davidebaldini; 01-25-2023, 03:38 PM. -
Re: UPS ruins batteries every three months
Further tests:
I unplugged the two batteries from the UPS; in open circuit, the corroded battery (float-charged at 12.85V) reads 2.5V across its terminals, the other battery (float-charged at 14.14V) reads 12.8V. No doubt, the corroded one is broken.
I pried open the good battery; looking thru the cell caps, there's a white sponge inside each cell (fiberglass?) so these are non-flooded SLA batteries, which require a slightly higher float voltage than the flooded ones. The sponge looked dry so I added ~80ml of tap...Last edited by davidebaldini; 10-02-2019, 09:39 AM.Leave a comment:
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UPS ruins batteries every three months
[B]Problem description:[/B]
My UPS requires new batteries every ~3 months; in this time frame, an average of about 5 to 10 power flickers or short power interruptions (< 2 minutes) occur. After an average of 3 months, a new pair of batteries begins to fail to keep the UPS up during any flicker or power interruption. The load it powers is a single computer/workstation running 24/7 with a continuous consumption between 200W to 300W.
[B]UPS model:[/B]
The [URL="http://www.atlantisland.it/pub/prodotti.php?famiglia=1&l1=7&l2=24&articolo=QTAzLVMxMDAx"]Atlantis...Last edited by davidebaldini; 10-02-2019, 06:25 AM. -
Re: Worn ATX PSU still works but with reduced power peak
Thank you all, I repaired the PSU and it works fine even on high load now. Here's what I did.
I ordered Panasonic and Nichicon capacitors from [URL="https://www.ebay.it/usr/bm-electronique"]this French seller[/URL] on ebay; the caps appear legit at sight and the capacitances I measured match their nominal values. Before ebay I checked Mouser, Digikey and rs-online but their postage fee was high to Italy. The seller I found on ebay appears in good standing regarding caps as per his feedbacks.
...Last edited by davidebaldini; 02-28-2018, 05:07 PM.Leave a comment:
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Re: Worn ATX PSU still works but with reduced power peak
I could find two — and only two — electrolytic caps close to the switches, they are: 2.2uF 50V and 22uF 50V.
I don't have an ESR meter so I'm placing an order on ebay for the caps. Which other caps are likely to need replacement beside these two? I already replaced most of the larger ones.
Also, why these two capacitors are the first ones to check?
...Last edited by davidebaldini; 02-25-2018, 11:17 AM.Leave a comment:
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Worn ATX PSU still works but with reduced power peak
The model of this 500W ATX PSU is "[I]Cooler Master rs-500-psap-j3[/I]".
It appears that after an estimated 30,000 hours of mostly uninterrupted usage, its output power peak dropped below the minimum required to keep my computer on.
[B]Diagnosis:[/B] the PSU ran stable w/o issues for a few years permanently attached to the same PC hardware ([I]PC #1[/I]). All hardware remained the same up to several months before the PSU failed. I found my PC abnormally powered off without any UPS event recorded; this occurred again after ~12 hours of uptime since the previous...Last edited by davidebaldini; 02-24-2018, 04:29 PM. -
Re: New Members - please post your introductions here
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