PC Power & Cooling Silencer 400 ATX Question

[jpyerry]

I have a PC Power & Cooling Silencer 400W ATX PSU that I am attempting to repair.

I have replaced every electrolytic cap in the thing with mostly Panasonic FC capacitors, I used Nichicon HE for the two 1000uF 6.3V caps and Nichicon LS for the two 1000uF 200V big caps.

Yesterday, I re-assembled it and tried it out. The voltage seems to fluctuate with a periodic regularity. On the 5V side it dips down to 4.8V and then comes back up to 5V. And, on the 12V side it dips to 11.8V and climbs back up to 12V. It does this at a pace that is slightly faster than once per second. As an additional observation, I hear a faint click that occurs at about the same pace, slightly faster than once per second. This noise is not coming from the fan, but I haven't been able to locate its origin.

I know that the voltage dips are within the normally acceptable 10% range, but I am concerned because every other PC Power & Cooling supply I have has always had rock solid stability at the voltages it supplies.

I don't know where to go from here. Any thoughts or suggestions? Do you think this supply is repairable, or should I just desolder the caps and other parts and just chalk this one up as a loss?

Thanks,
Justin

[jpyerry]

Re: PC Power & Cooling Silencer 400 ATX Question

It's been almost a week now and I haven't gotten any responses yet. So I am just trying to bump my thread.

Is this behavior similar to anything anybody has seen before? If anybody wants to see pictures of the supply, I can snap off a few, I just didn't think it would have been helpful in troubleshooting this problem which is why I didn't post any in the first place.

If nobody has any suggestions for me over the next week or so, I guess I will just tear the thing apart and salvage my caps and other miscellaneous parts. But, I'm really hoping somebody might be able help me get what should be a really good piece of hardware back to a stable condition once again, I think it would be a shame if this one ended up in a landfill.

Once again, thanks in advance,
Justin

[c_hegge]

Re: PC Power & Cooling Silencer 400 ATX Question

Does it have any load on it? You could try connecting some old fans and disc drives.

[jpyerry]

Re: PC Power & Cooling Silencer 400 ATX Question

I did try it with a resistor across the 5V and 12V rails (2kΩ 5W wirewound). Same result. I will grab an old hard drive and a fan or two and see what result I get with them attached. Unfortunately, I work the entire weekend normally starting Saturday, but got called in early, so further testing will have to wait until Monday, which is when I will get back to you on the results.

Probably the biggest thing I am curious about is what on Earth could be causing the ticking noise. It really sounds like the way a high quality mechanical watch sounds when you listen to it, clicking slightly faster than once per second.

Thanks,
Justin

[momaka]

Re: PC Power & Cooling Silencer 400 ATX Question

If anybody wants to see pictures of the supply, I can snap off a few, I just didn't think it would have been helpful in troubleshooting this problem which is why I didn't post any in the first place.

While you seem to know what you are doing, members here at BCN (myself included) still like to see pictures of the actual item. It helps because someone may see something that you perhaps overlooked.

Given the problem, it just seems as if the power supply doesn't have enough load. A 2 KOhm resistor is not going to put a significant load on the PSU. Something like one of those 12V light bulbs for track lights works much better (5 to 40 Watts recommended). A hard drive or two will in many cases work too (actually only some very very picky and/or high power PSUs won't start with just that).

[Th3_uN1Qu3]

Re: PC Power & Cooling Silencer 400 ATX Question

A 2 KOhm resistor is not going to put a significant load on the PSU.

Especially since the minimum load resistors internal to these things are on the order of 100/47/10 ohms, on 12v, 5v and 3v3 respectively.

[jpyerry]

Re: PC Power & Cooling Silencer 400 ATX Question

I know this is a very old thread, but I thought I would let you guys know I made progress on this project today. I am moving in about a week, so I've been trying to finish up a lot of my backburnered projects.

I took a second look at the supply, rechecking my solder work and polarity of capacitors. I managed to find that one of the capacitors, a 3.3uF 50V capacitor had a torn trace leading to the negative side. So, I made a new trace and epoxied it down to the board and resoldered it in place.

I turned on the supply, and it still had fluctuations on both the 5V and 12V rails with the associated ticking noise, but this time it was much smaller, in the realm of .2V fluctuation on either rail.

I decided this is more acceptable, so I decided to risk installing it in a system. Now that it is connected to a motherboard, the voltages are absolutely rock solid, 5.04V +/- .002V and 12.05V +/- .003V. And, the ticking noise is gone.

I think I am going to declare this one a repair, and I am quite happy about it, I really didn't want to see such a nice supply go into the trash.

Thanks for the help,
Justin

[senz_90]

Re: PC Power & Cooling Silencer 400 ATX Question

may i see the pict?

[jpyerry]

Re: PC Power & Cooling Silencer 400 ATX Question

may i see the pict?

I am in the middle of moving and my camera is packed. I will post a few pictures in a couple of weeks after I am done with the move.

Justin

[joshnz]

Re: PC Power & Cooling Silencer 400 ATX Question

I think you had a minimum load issue not enough load to keep it stable.