PC P&C Silencer 420W

[Colt45ws]

This little bastard ran my newly recapped Biostar P4M900 for all of 20 minutes before making a sound like someone opening a beverage can and shutting off.
I opened it up, checked it out, no obvious burning, no open caps.
The fuse is open, so something definitely shorted, though I dont know how or what to test for.

That burned glue on the PFC coil is the only burnt spot Ive found on the entire apparatus. How likely is it that killed it?
http://colt45.ws/misc/silencer3.jpg
http://colt45.ws/misc/silencer4.jpg

[Colt45ws]

Re: PC P&C Silencer 420W

I should clarify; the supply is 2 or 3 years old at this point. It just so happened it failed 20 minutes after I finished recapping the board of the machine it was in.

[c_hegge]

Re: PC P&C Silencer 420W

OST Caps! I expected better from PC P&C, although probably not the cause of the problem

[Toasty]

Re: PC P&C Silencer 420W

>>making a sound like someone opening a beverage can and shutting off.<<

Was it a hiss-pop sound, or just a hiss?

Caps can (and do) vent out the bung without deforming the top, nor blowing the bung out. Also have been know to have pinholes in the can under the plastic wrap.

Check all components from fuse to mains cap and switchers. VISUALLY inspect all the MOSFETS and dual Schottky's for hairline cracks. Get the plastic away from that coil and inspect the coil for burns. Sometimes it's just the glue that has darkened from heat. Be sure to remove and replace all that kind of glue everywhere with silicone caulk. The glue can become conductive when it gets hot and darkens.

Check that F.U. mains cap, especially for open. Should charge up one way on the ohms scale, and read infinite on reverse polarity. If it opens, it will take out the PFC or switcher FETs.

The fuse is a fast acting 7 amp "pigtail" type. Replace the fuse, or temporarily jumper it with a strand or 2 from a piece of stranded wire. Use a table lamp (100 watt) inline with the Line (L) side of the mains. Test leads with alligator clips are useful.
( See: https://www.badcaps.net/forum/showpo...2&postcount=23 )

When you plug the PSU in, the lamp should pulse once or twice and go dark. If it stays illuminated, the input side is shorted and you'll need to find what component(s) is at fault.

If it flashes and goes dark, then try jumpering the PSU on by jumpering Green to Black on the mobo plug. Again, it may pulse and go dark. If it stays on, then the output side is shorted some where.

Report findings please.

Toast

[370forlife]

Re: PC P&C Silencer 420W

Check that Hitachi mains cap, especially for open. Should charge up one way on the ohms scale, and read infinite on reverse polarity. If it opens, it will take out the PFC or switcher FETs.

Knew Fuhjyuu was good at copying Hitachi's logo.

[Toasty]

Re: PC P&C Silencer 420W

LOL!

Yeah, my bad. It's a Hitachi. It just made sense to see a FU in with OST's....

The really odd bit is the HP series. It's the same series as Capxon that has failed in the Apple Samsung PSU's at over 90%

Toast

[Colt45ws]

Re: PC P&C Silencer 420W

>>making a sound like someone opening a beverage can and shutting off.<<

Was it a hiss-pop sound, or just a hiss?

I wanna say hiss-pop along with the lights dimming at the same time.

Caps can (and do) vent out the bung without deforming the top, nor blowing the bung out. Also have been know to have pinholes in the can under the plastic wrap.

Check all components from fuse to mains cap and switchers. VISUALLY inspect all the MOSFETS and dual Schottky's for hairline cracks. Get the plastic away from that coil and inspect the coil for burns. Sometimes it's just the glue that has darkened from heat. Be sure to remove and replace all that kind of glue everywhere with silicone caulk. The glue can become conductive when it gets hot and darkens.

Check that F.U. mains cap, especially for open. Should charge up one way on the ohms scale, and read infinite on reverse polarity. If it opens, it will take out the PFC or switcher FETs.

The fuse is a fast acting 7 amp "pigtail" type. Replace the fuse, or temporarily jumper it with a strand or 2 from a piece of stranded wire. Use a table lamp (100 watt) inline with the Line (L) side of the mains. Test leads with alligator clips are useful.
( See: https://www.badcaps.net/forum/showpo...2&postcount=23 )

When you plug the PSU in, the lamp should pulse once or twice and go dark. If it stays illuminated, the input side is shorted and you'll need to find what component(s) is at fault.

If it flashes and goes dark, then try jumpering the PSU on by jumpering Green to Black on the mobo plug. Again, it may pulse and go dark. If it stays on, then the output side is shorted some where.

Report findings please.

Toast

Im on lunch so I just really quickly checked the mains cap. I have 5.5ohms both ways, does not change. Does that mean the short is on the input side? I feel silly for not checking earlier. Ill do some more after I get home from work.

[Toasty]

Re: PC P&C Silencer 420W

Light dimming is not a good sign. I'm betting on the PFC or switcher FETs.

The low ohms on the mains cap -probably- means something nearby is toasted.

[Colt45ws]

Re: PC P&C Silencer 420W

D304 which is closest to the mains cap shows shorted. Q302 which is the next on over shows short on all three pins and Q301 is shorted on two pins.

[Toasty]

Re: PC P&C Silencer 420W

You have to desolder them (not necessarily remove them) to test correctly. One could be bad and the rest are reading that short.

[Trinite]

Re: PC P&C Silencer 420W

Light dimming is not a good sign. I'm betting on the PFC or switcher FETs.

The low ohms on the mains cap -probably- means something nearby is toasted.

I'm betting the PFC FET, since it would be inline with the PFC coil and would cause it to overheat in a failure, thus the burn mark (assuming a buck-boost configuration).

[Colt45ws]

Re: PC P&C Silencer 420W

You have to desolder them (not necessarily remove them) to test correctly. One could be bad and the rest are reading that short.

The diode D304 and FET (?) Q302 are both shorted.
Also the little diode D303 sitting on the board is shorted as well.

[Toasty]

Re: PC P&C Silencer 420W

Best to replace both FETs. What are the numbers of the bad parts?

[Colt45ws]

Re: PC P&C Silencer 420W

The FETs are 18N50, D304 is STTH8S06D, and D303 is 1N5406
Any idea as to what caused the initial failure?

[Toasty]

Re: PC P&C Silencer 420W

About $7.50 + shipping from Digikey.

I would check the SMD components nearby. Q303/304 and the 4 diodes (2 glass, 2 flat pack D301/302) as they are providing the drive signal to both FETs gates. A leaky transistor or diode could be altering the drive waveform causing one or both FETs to stay on too long. One is off when the other is on and vice versa. If they both or one is on when the other comes on, it will overload (eventually) and pop.

Are the FETs physically damaged? Cracked or cratered? If not, you still need to find the noisemaker...

If everything checks good, then follow the SMD transistors drive back to the middle of the board and that daughterboard. There's another 2 SMD transistors there. The daughterboard probably has the PWM/PFC chip(s) on it.

Toast

[Colt45ws]

Re: PC P&C Silencer 420W

No, physically all the components look to be 100%.

[Toasty]

Re: PC P&C Silencer 420W

Keep looking at all the caps then, even output side. Something did that.

[weirdlookinguy]

Re: PC P&C Silencer 420W

I thought PCP&C was supposed to be the holy grail of PSUs? This thing looks very plain. Like a run-of-the-mill Delta with crapcaps.

[370forlife]

Re: PC P&C Silencer 420W

Run of the mill seasonic with subpar OST's. About sums it up for PC P&C. They do, or well did, have better units with better caps, but at the price point no. Too many other companies selling the same performing, or even just the same units with 120mm fans and modular cabling for cheaper prices.

Their new units are okish performing High Powers.

[Trinite]

Re: PC P&C Silencer 420W

I thought PCP&C was supposed to be the holy grail of PSUs? This thing looks very plain. Like a run-of-the-mill Delta with crapcaps.

Depends on what unit you get. PC P&C has some absolutely superb units as well as some that are fairly mediocre. I have a 610W Silencer that is rock solid. But some of their cheaper units (at least the older ones) I'd avoid. It really depends on who they contract their units out to.