PC PSU - Octigen LC-8400BTX - dead

[tmcw]

I'm wondering if anyone has had any experience of this brand of PSU, this is the first one of theirs that I've come across. I found it in a dumpster, inside a tower case, seemingly with all other necessary parts.

CPU fan comes on for a split second on power-up, but is dead otherwise. I opened up the PC case and took out the PSU, and the first thing that struck me was how light it is, I have some older Dell PSUs, GX280 vintage that are smaller but twice as heavy.

Anyway, opened it up, and instantly can see a couple of bulging caps, the two nearest the big yellow choke, a 10V/1000uf and what looks to be a 16V/1000uf.

Unsure of the manufacturer of the caps, have taken a snap of the logo.

I'm wondering if anyone has come across this one before, or similar, and is it worth swapping out all the green caps in that area? The other thing that concerns me is the glop of something that bridges between the big yellow choke and the transistor on the heatsink beside it. Is that something that has happened at manufacture, or due to use? A cause of concern? There is also a bit of scorching on the board around the choke. Maybe it's a poor design?

The PSU is a 400W, but the other parts in the case don't point to it having been stressed too much, the usual SATA HDD and DVD-RW, E2200 CPU, one stick of 2GB DDR2, all on a G31M-GS motherboard. No other cards inside, and to be honest, it doesn't look like the back plates for expansion cards were ever off.

[selldoor]

They appear to be YC (YANG-CHUN) caps if they are as in pic.
I will leave you to research them but I doubt if they are good.

The scorching may be due to the choke working overtime because of the
faulty cap- replace them and see how the heat is then. I would remove the gloop.

Great Find!!

[dmill89]

Actually I have this exact PSU although mine is labeled as a Rosewill (came with a case) but has the same LC model# . This PSU is made by L & C (AKA DEER). Honestly I wouldn't waste my time recapping it unless you plan on replacing the switching transistors and the primary caps. I load tested the one I had at 150w and the primary overheated in about 10 minutes. The secondary is decent although the 12v rail is overrated on the label, I believe actual capacity is around 20A where the label claims dual rails with a higher combined rating than that. Also all capacitors are undersized. The primaries are marked 330uf but I tested them brand new and they are actually 220uf. The secondary caps are grossly undersized most of them are marked 1000uf and should be 2200uf or 3300uf, and as with the primaries the markings are a lie most of those "1000uf" caps tested between 600uf and 800uf. I'd recommend just replacing it with a good 250-400w PSU, You can usually find good (Delta, HiPro, LiteOn, etc.) used OEM PSUs from old PCs relatively cheap (My local computer shop sells 250-350w pulls for around $5) and these would actually be worth recapping if necessary, you can also get decent new 300-400w units for $30-$40.

[mariushm]

Those capacitors YC are a bit above the crap no-name capacitors... had a dead power supply with them and all that were far from the minimum load resistors were ok, tested good for capacity and esr with the meter.

They just don't handle heat.

I agree with the "don't fix it" answer, everything else about these is undersized so they can't handle much - it's probably at best 250w psu.

Rather than spending 10$ on capacitors and whatever else is burnt there, spend 20-25$ (maybe after mail in rebate) on an acceptable psu.

[everell]

I have a MSI MS-4460-010 (LC-4460BTX) power supply with same symptoms. If you remove the psu from the computer and turn on the psu (short green and black wires together on main computer plug) it will power up and spin the fan, voltages look normal. So far I have not found the culprit causing the problem.
Check your power supply and see if the main pwm chip is a 2008Z "chip of the year". The 2008Z is a 20 pin chip but is NOT pin for pin compatible with the SG6105.
Some pictures showing the rest of the psu (top view) would be nice.

[Th3_uN1Qu3]

Originally Posted by everell

I have a MSI MS-4460-010 (LC-4460BTX) power supply with same symptoms. If you remove the psu from the computer and turn on the psu (short green and black wires together on main computer plug) it will power up and spin the fan, voltages look normal.

Check powergood signal.

[tmcw]

I've attached a more complete photo of the board. The chip in this one is 16-pin, has the markings:

2005AZ
C3110627838A

Grounding the power-on button doesn't generate any response from the fan (I didn't check voltages).

In fact, the fan is extremely stiff, it doesn't rotate freely a couple of revolutions like a good fan would if you flick it, it doesn't continue rotating at all. And there are only 2 wires to the fan (red and black), so does that mean the PSU isn't smart enough to know if the fan is or isn't working? I tried applying 12V directly to the fan, but it overloaded the power supply I was using, so it's probably shot too. So as Marius says, it probably couldn't stand the heat. You can just imagine the cascade of events that brought about its demise.

Anyway, if you want any specific details about this PSU, just ask. Going by the other comments, I'll probably just mark it appropriately, and toss it into a box where I may come back to it, or use it for parts (or maybe neither). On the plus side, it did have a Molex to SATA power adaptor, and it also has an on/off switch, both of which sometimes come in useful.

Was a great find all the same, included a nice 2009 Sony Optiarc DVD-R/RW, 160GB WD drive (full XP Pro and Office 2007 and other applications installed), and from what I've read, the MB and CPU are decent enough too. And all in a humongous tower case which has 5 internal and 2 external 3.5" bays, and 4 5.25" bays.

Appreciate the comments and advice, thanks everyone.

[ben7]

Originally Posted by tmcw

I've attached a more complete photo of the board. The chip in this one is 16-pin, has the markings:

2005AZ
C3110627838A

Grounding the power-on button doesn't generate any response from the fan (I didn't check voltages).

In fact, the fan is extremely stiff, it doesn't rotate freely a couple of revolutions like a good fan would if you flick it, it doesn't continue rotating at all. And there are only 2 wires to the fan (red and black), so does that mean the PSU isn't smart enough to know if the fan is or isn't working? I tried applying 12V directly to the fan, but it overloaded the power supply I was using, so it's probably shot too. So as Marius says, it probably couldn't stand the heat. You can just imagine the cascade of events that brought about its demise.

Anyway, if you want any specific details about this PSU, just ask. Going by the other comments, I'll probably just mark it appropriately, and toss it into a box where I may come back to it, or use it for parts (or maybe neither). On the plus side, it did have a Molex to SATA power adaptor, and it also has an on/off switch, both of which sometimes come in useful.

Was a great find all the same, included a nice 2009 Sony Optiarc DVD-R/RW, 160GB WD drive (full XP Pro and Office 2007 and other applications installed), and from what I've read, the MB and CPU are decent enough too. And all in a humongous tower case which has 5 internal and 2 external 3.5" bays, and 4 5.25" bays.

Appreciate the comments and advice, thanks everyone.

It overloaded the testing PSU? I bet the fan seized, then the mosfet in the fan shorted, making the psu go into shutdown. Replace the fan and see if you can get the PSU to run at all and/or replace the caps.

[everell]

Originally Posted by Th3_uN1Qu3

Check powergood signal.

I also thought of that. Here is a drawing of the 2008Z chip of the year in this psu. The pictures show what the signal looked like originally. I changed R44 from 3K to 20K and C28 from 101 to 103 (pfd). The signal is now about 3 volts DC while trying to turn on, and the filtering is greatly improved.