Thermaltake Pure Power 600W +5VSB problem

[JohnStark]

A few days ago I found my PC shut down though as usually I put it in standby. First thing I found the green power LED on motherboard was blinking fast. After some inspections I found that the problem is in PSU. I have a Thermaltake Pure Power 600W PSU and till that day it worked perfectly.
When I checked voltage on +5VSB wire there was ~3.4V. After shutting down PSU and connecting to power after a while it has normal 5V on the line, but once there is some load (~0.5A) voltage drops and a LED connected to this line will blink with about 20Hz rate and there will be a low frequency ticking in the PSU. Turning on PSU with PS_ON wire starts it with all voltages in their normal values under load (still +5VSB will behave in the same way).
I started to dig up the problem, but I couldn't find some reference point. Another problem is that PSU have a compact parts placement, dual layer PCB and a high temperature melting solder and is not quite easy to take out parts from PSU to check them or to see how components are connected and I don't really want to disassemble it completely if the problem can be found without that.
Can you give some directions on what can be the problem of this behavior?

[Khron]

Re: Thermaltake Pure Power 600W +5VSB problem

Is it just my imagination or a shadow, or is the 5Vsb filter cap bulging? Second picture, to the left of the uppermost red-heatshrink-wrapped common-mode inductor, right next to the small transformer. What brand is it, by the way?

[JohnStark]

Re: Thermaltake Pure Power 600W +5VSB problem

Is it just my imagination or a shadow, or is the 5Vsb filter cap bulging? Second picture, to the left of the uppermost red-heatshrink-wrapped common-mode inductor, right next to the small transformer. What brand is it, by the way?

It's a SAMXON 2200uF x 10V and, yes, it's a little bulged...

[JohnStark]

Re: Thermaltake Pure Power 600W +5VSB problem

Well, is seems that the problem was in that cap. I changed it with a new one and now PSU and PC is working as usual. Is it possible that it went out because of many USB devices were connected to PC and it was mostly in standby?

[Khron]

Re: Thermaltake Pure Power 600W +5VSB problem

That may well have been the case, but it also depends how the mainboard was configured to supply power to USB devices, either from the main 5V rail or the 5Vsb rail. Check either the BIOS settings or the manual (in case that's set via jumpers near the USB ports/headers).

[Pentium4]

Re: Thermaltake Pure Power 600W +5VSB problem

Hmm, what series is that Samxon? It doesn't look like GF or GL, which are the ones I know are bad. Also, what did you replace it with?

[c_hegge]

Re: Thermaltake Pure Power 600W +5VSB problem

Ive had a similar power supply do the same thing (although in my case, it killed the motherboard). The fact is, it's a junk Samxon GF cap, and it's gonna fail regardless of how it is treated.

[TELVM]

Re: Thermaltake Pure Power 600W +5VSB problem

Is this the critical +5VSB cap you guys always talk about that can kill the mobo when it fails?

[Wester547]

Re: Thermaltake Pure Power 600W +5VSB problem

^ No, that's the output filtering capacitor for +5VSB, or at least the one before the ferrite coil in the output filter as a whole. The critical capacitor is found on the primary side, after the +5VSB transistor. It is much smaller and is usually a 2.2uF (minimum) to 220uF (maximum) GP capacitor or somewhere in between (usually the case).

[TELVM]

Re: Thermaltake Pure Power 600W +5VSB problem

Thanks Wester!

[senz_90]

Re: Thermaltake Pure Power 600W +5VSB problem

^ No, that's the output filtering capacitor for +5VSB, or at least the one before the ferrite coil in the output filter as a whole. The critical capacitor is found on the primary side, after the +5VSB transistor. It is much smaller and is usually a 2.2uF (minimum) to 220uF (maximum) GP capacitor or somewhere in between (usually the case).

is there any way to prevent this critical 5VSB caps to kill motherboard? or just replace it with a well known caps?

[c_hegge]

Re: Thermaltake Pure Power 600W +5VSB problem

You can either replace it with a reliable Japanese part, replace the whole 5vsb circuit with a PWM IC driven one, or put 1W 5.5V Zenner diode across the output, with the stripe facing the positive. If the output goes higher than 5.5V, it will conduct the excess over to ground. If it really goes south, the Zenner will short and blow up the switching transistor, but it won't take the motherboard out.

[senz_90]

Re: Thermaltake Pure Power 600W +5VSB problem

You can either replace it with a reliable Japanese part, replace the whole 5vsb circuit with a PWM IC driven one, or put 1W 5.5V Zenner diode across the output, with the stripe facing the positive. If the output goes higher than 5.5V, it will conduct the excess over to ground. If it really goes south, the Zenner will short and blow up the switching transistor, but it won't take the motherboard out.

I miss this thread and just realize it now!! sorry.
it will be easier to use zener diode. but im curious about pwm ic that you have mention. does it mean attach a new circuit on new pcb that driven by new pwm ic or just from the psu pwm ic itself?

[c_hegge]

Re: Thermaltake Pure Power 600W +5VSB problem

^
https://www.badcaps.net/forum/showthread.php?t=6680

I meant something like this. everell has done it plenty of times.

[senz_90]

Re: Thermaltake Pure Power 600W +5VSB problem

^
https://www.badcaps.net/forum/showthread.php?t=6680

I meant something like this. everell has done it plenty of times.

Thanks c_hegge. I will see it.