PC Power & Cooling Silencer 235 ATX

[bluto]

I bought this guy new many many moons ago. It is not dead, but I pulled apart the system it was in for other reasons. I was looking at it and thought to my self...I wonder what kind of caps it uses and if they might possibly need to be replaced after all this time. So at first I looked in through the holes in the case and I see... Teapo not good! So off the cover comes...

And so I examine it and find that amazingly, none of the caps are bulged. But there is something amiss, a large resistor that was wrapped in heat shrink that has been burned to a crisp.

Any thoughts on this? What can I do with the resistor? Replace it with a higher wattage? And I guess the Teapos should probably be replaced.

I am a little pissed given that this was supposed to be a premium power supply back in the day. The built quality looks great other than the presence of the Teapos and the huge burning resistor.

[PeteS in CA]

Re: PC Power & Cooling Silencer 235 ATX

For 235W, those heatsinks look really solid! In heatsinks, heavy metal is goodness! From another POV, between the relatively low power and the reasonable cooling, those Teapos probably weren't stress horribly. OTOH, that supply may have been built ca. 2000, so those caps might be getting near the end of their useful life. If it would be useful to you, you could replace those caps: the chances of finding modern I/P lytics that are 100uF-200uF higher in capacity and in the same case is decent; Nichicon PW or UCC LXZ or Rubycon ZLs might give you better O/P caps, improving the efficiency and decreasing the waste heat slightly. I would also suggest replacing that green disc near the I/P filter inductor, as it may have taken enough surges to degrade it some. If you can get higher capacity I/P lytics, your 235W P/S might have been converted to a 250W or even 275W P/S (the max. currents wouldn't increase - nor the max. 5V + 3.3V current - just the amount of power that could be drawn from the +12V and the +5V/+3.3V O/Ps simultaneously).

The bottom line for your decision is whether it would be useful to you, with what desired life (just a year or two might not be worthwhile).

[bluto]

Re: PC Power & Cooling Silencer 235 ATX

Yes I will probably fix it up. The green disc seems like it is a current inrush limited based on where it is located. It reads 15 ohms cold. What about the melted resistor? It reads ~7 ohms right now. Should I just replace it with a 10 watt wirewound resistor of similar value and call it a day?

[PeteS in CA]

Re: PC Power & Cooling Silencer 235 ATX

Ah, I mistook the green disc for a metal oxide varistor, which protects against line voltage spikes and surges. Your measurement means that it is a thermistor, which limits the inrush current surge when the P/S is first turned on. So it is probably just fine.

I seriously have no clue as to the purpose of that large roast resistor, unless it is a pre-load on the +3.3V. If that's what it is (you should be able to verify with your ohm meter) and the value is 6.8 ohms, then it draws about half an amp, and the power it dissipates is is about 1.6 watts. IF that's what it is, then a 10W resistor would be overkill (but quite safe), a 5W resistor still pretty conservative, and a 3W resistor would be OK. The inductance of a wire-wound resistor would not matter if it's just a pre-load.

[Rulycat]

Re: PC Power & Cooling Silencer 235 ATX

I see tiny little Fujyyhus in there. They concern me more than the Teapo.

(now - do we decide if the plural of teapo is still teapo or teapos?)

[Scenic]

Re: PC Power & Cooling Silencer 235 ATX

To be honest, that PSU looks a lot like an old modified Fortron Source (FSP) from the 200-300W range.

Those too had the minimum load resistor in that place, wrapped in heatshrink tubing which becomes brittle over time from constantly being toasted by the resistor..

Either replace the resistor with one that puts a little less load on the output (=less heat), relocate the resistor(s) somewhere near the fan or just leave it as is.

I usually don't bother to fix those old PSUs anymore. I usually run them till they die and only fix them if it's simple to do and not time-wasting..


edit: it looks like the small cap to the right of the bottom blue one is bulging a bit
https://www.badcaps.net/forum/attach...4&d=1329671070

Teapos are usually fine in PSUs, but given that this one has hot load resistors in that area for every rail and it's supposed to be a quiet unit with an 80mm fan, that probably didn't work out too well and most of the caps are
done for..

edit2: looking at that pic more closely, the bulging cap seems to be right next to a load resistor.. so much for the above theory.. lol

[PCBONEZ]

Re: PC Power & Cooling Silencer 235 ATX

Teapo generally do okay in PSUs.
.

[PCBONEZ]

Re: PC Power & Cooling Silencer 235 ATX

(now - do we decide if the plural of teapo is still teapo or teapos?)

I think it's Teapo if they are all the same size or series and Teapos if they are a collection of different sizes and/or series.
Like Fish and Fishes.
Of course I just wrote this to be smart-ass but now that I have it kind'a makes sense..
.

[b700029]

Re: PC Power & Cooling Silencer 235 ATX

Going by the dimensions of that huge resistor it probably is a 5W unit for minimum load.

This is how big a 5W is, looks about right:
http://www.gooddealchina.com/upimage...1155677265.jpg

I'm going to guess it's on the 5V rail and providing about 3.7W of load, because with 3.3V and 1.6W they would use probably use a 2W resistor instead.

It isn't exactly good looking but it seems to be ceramic so it can stand the heat. Bad idea for them to wrap it in heatshrink though.

[dmill89]

Re: PC Power & Cooling Silencer 235 ATX

To be honest, that PSU looks a lot like an old modified Fortron Source (FSP) from the 200-300W range.

That actually wouldn't be too surprising. Many of the early PCP&C Silencers were made by Sparkle (SPI) before they were acquired by FSP. It is likely that many FSPs designed / made not too long after the acquisition of SPI used many elements of the SPI designs.

[PeteS in CA]

Re: PC Power & Cooling Silencer 235 ATX

I'm going to guess it's on the 5V rail and providing about 3.7W of load, because with 3.3V and 1.6W they would use probably use a 2W resistor instead.

It isn't exactly good looking but it seems to be ceramic so it can stand the heat. Bad idea for them to wrap it in heatshrink though.

It's hard to know the scale. Personally, I would not use a 2W part to handle 1.6W of power. That puppy is going to get really hot! Ditto a 5W part to handle 3.7W! Not that my inclinations matter much. Concur that the heatshrink sleeving is a dumb idea. My guess is that it's there to prevent shorts or breakage due to shock or vibration. And of course, the heat of the resistor would shrink it on quite securely. The down-side of the sleeving that it will cook even a properly sized part (though in a machine with 3-5 years' life, the user might never notice).

I'd use a part that is double the expected wattage or higher. You may be able to find 3W carbon film or metal oxide film resistors (OK if it's a pre-load for the +3,3V). And if you use a wirewound, one whose resistance wire is wound on a ceramic core is better than one with a fiberglass core (though the latter are cheaper). There are vertical mount bathtub-style wirewounds in 3W, 5W and 10W sizes, which might be OK for the exiting hole pattern and have good mechanical stability if you want to use this P/S as a football.