I have 2 main caps on this psu. The board is completely out of circuit and the caps are still soldered in. I'm getting 145V across one and 145mV across the other. Should I get the closer to 145V across both? They are 200V 390microfarads.
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Re: Main Filter caps
Sounds like the bleeder/voltage-equalizer resistor in parallel with the cap reading 145V is open. You should read zero volts across both caps within a minute or two of removing power. These resistors serve two purposes:
1) Form a voltage divider to ensure the two series input caps share voltage equally.
2) Provide a high impedance path to discharge the input capacitors relatively quickly when power is removed.
High value resistors like these (they're usually several hundred thousand ohms) that have high voltage across them, often fail open circuit. -
Re: Main Filter caps
Thanks for the lead I appreciate it. I will apply this knowledge.Comment
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Hi and thanks in advance for any input you might provide!
I have a Sceptre U550CV-UMRD8POTV83BB 4K LED (this is a dumb tv) that I bought new in August 2021, so It's just completed 3 years.
Main power board model: TP.MS3683.PC821 T-Con board: N4TP546UHDPU2L_BO
Last Sunday I was watching a dvd and fell asleep for about half hour, when I awoke the tv screen was black and couldn't get the dvd menu to show, so I changed the input to antenna and had sound but no picture, turned it off. I then got online and found this great site! ....read many troubleshooting tips and this... -
Hello I have a Marantz sr5012 that I have been repairing. After I have replaced the 2 main filter caps the 2 fuses for the power amplifier blows. The original capacitors are ELNA LAO 10,000uF 71V and the replacements are Nichicon LKS 10,000uF 80V.
I assume a short circuit connection has occurred so I set my multimeter to measure ohms across the 2 fuse connections and both read 55 Kilo-ohms so I assume that is ok.
I am certain that I do not have any bridges on my soldering and after probing around I do find a temporary 0 ohm reading when probing across the positive and negative... -
I know I've been a little scarce lately (like the last 2-3 years), but I'm still here and still doing my thing with fixing PSUs.
For today's considerations, I have a Seasonic B12 BC-550 [A551bcafh] 550 Watt ATX power supply for you (click on links for full size images).
https://www.badcaps.net/filedata/fetch?id=3591771
https://www.badcaps.net/filedata/fetch?id=3591772
It's a modern ATX unit with fixed (non-modular) cables and an 80-plus bronze certificate. Here's the label:
https://www.badcaps.net/filedata/fetch?id=359177... -
Normally, I never post repairs this quick after I do them, because… I am usually very slow.
But today, I’m making an exception here. Why? No idea. Perhaps only because the repair details are still “fresh” in my head… which is ironic, given this is a 16 year old monitor that hardly anyone will care about today. It is new to me, though. 
I picked it up last November from someone on my local Craigslist. It wasn’t very close to where I live, but was close to a family friend that I had to go visit anyways. So after watching the posting on Craigslist for a few weeks and seeing it getting...
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This one should make @Pentium4 smile
(if he is still reading BCN forums) – I got a new old stock / open box Casing Power MPT-301 PSU on eBay for $4 total. 
Yes, it’s a very generic-looking box, but the manufacturer isn’t (at least not back in the days), which is…
Macron Power Technology Co. LTD.
Let’s look at the PSU itself.
The shell/case also appears quite generic, like many “sold-with-the-PC-case” units. However, the shell is well-formed and has decent steel thickness. In terms of...
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