Enermax Liberty ELT400AWT making clicking noise but still running

[Agent24]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Same resistance both ways.

With my Blue ESR meter I get 0.03 ohms. With my multimeter I get 0.3 ohms which makes sense since it can't measure below 0.1 ohm and besides, the test leads give 0.3 ohms when shorted anyway.

The resistor is connected in series between the negative side output of the bridge rectifier and the rest of the PSU... I'll draw out a picture to make this a bit easier...


EDIT: Same resistance (0.03 ohms) of the R14 resistor from the other PSU.

[Agent24]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

OK here's a drawing of part of the primary side

There are more connections that what I have shown, of course. Namely the rest of the pins to that primary-side sub-board. But I think you get the idea...

[Behemot]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Well if the resistor is connected directly to the -, I guess it can't be 37 ohm, due to the high voltage and current it would vaporize…so guess the little resistance (0,03 ohm) is OK.

[Agent24]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

It definitely goes in line with the negative rail, and it makes perfect sense it should be a low value as you say, but I don't understand then how the colour code is wrong. I've attached a photo of R14 and it clearly shows the gold band. Doesn't make sense.


Also, I've edited the schematic, I forgot to add connections to the resistor and sub-board, which contains an LM393 and UCC3817 PFC controller IC.

I guess R14 is basically a current shunt and helps with some kind of feedback to the PFC controller.

[ben7]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

It definitely goes in line with the negative rail, and it makes perfect sense it should be a low value as you say, but I don't understand then how the colour code is wrong. I've attached a photo of R14 and it clearly shows the gold band. Doesn't make sense.


Also, I've edited the schematic, I forgot to add connections to the resistor and sub-board, which contains an LM393 and UCC3817 PFC controller IC.

I guess R14 is basically a current shunt and helps with some kind of feedback to the PFC controller.

Wtf, its strange. orange = 3, blue = 6, white = 9, gold (multiplier) = 0.01, green = 20ppm. So I get 3.69 ohms

What does it measure out of circuit?

[Behemot]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Gold is x0,1, silver is for x0,01.

[Agent24]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Wtf, its strange. orange = 3, blue = 6, white = 9, gold (multiplier) = 0.01, green = 20ppm. So I get 3.69 ohms

What does it measure out of circuit?

0.03 Ohms is what it measures out of circuit. Sitting on the bench as per the photo is about as out of circuit as you can get

It doesn't make sense to me either, but the numbers don't lie.

PSU label says it can run from 100-240 volts and draws between 6 and 2.5 amps.


The resistor is in series with the whole PSU. Assuming the best case of 2.5 Amps, if it were the 36.9 ohms as the chart suggests, it would have to dissipate at least 230 watts, which is clearly wrong. By the size it can probably do 4 watts maximum.

[rogfanther]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

the third band seems silver to me, that would give 0.38 ohms, for a 2W resistor in the 230W consideration. Could that be ?

But that doesn´t explain why both your meters measure much lower ...

[Behemot]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Definitelly white, silver would reflect light…

[ben7]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Definitelly white, silver would reflect light…

I don't understand why the color coding would be different. But I agree, its not 39 something ohms xD

Ah, now I think I got 0.369 ohms, which is about what it reads.

Have you checked the PFC mosfets?

[Behemot]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Man, how? You have something different every time. Clearly code is for 36,9 ohm.

[ben7]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Man, how? You have something different every time. Clearly code is for 36,9 ohm.

How would a resistor go short circuit? :S

[Behemot]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Error in Matrix?

[goodpsusearch]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

:conspiracykeanu:

[Agent24]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Have you checked the PFC mosfets?

No, how should I do that?

How would a resistor go short circuit? :S

Probably from a severe manufacturing defect. I don't see how a resistor would go short circuit by itself, unless it was overloaded and somehow melted or something.

A wire-wound one could if the insulation broke down, I suppose.

I would assume some physical evidence of the latter, and for the former it doesn't really explain why the resistors from both PSUs are the same value.

[Agent24]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Didn't do anything with this since it wasn't a big priority, but I found some of that brown shit glue on the MOSFET legs and scraped it off, and blew some dust out of the PFC board.

Decided to try again and was going to swap PFC controller board from the other PSU to see what happened, but this time no clicking.

Maybe the glue was the problem, maybe the dust was full of moisture from winter... Will see what happens I guess.

[Phaihn]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Didn't do anything with this since it wasn't a big priority, but I found some of that brown shit glue on the MOSFET legs and scraped it off, and blew some dust out of the PFC board.

Decided to try again and was going to swap PFC controller board from the other PSU to see what happened, but this time no clicking.

Maybe the glue was the problem, maybe the dust was full of moisture from winter... Will see what happens I guess.

is there s good solvent that you can use to remove that glue?
would thermal paste remover work?

[Agent24]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

I don't know about solvent, didn't try. There wasn't very much on the leads, so was easy to remove with a knife.

It was bridging on some (they used it to secure ferrite beads to the leads) - I removed the bridges and cleaned up the bits sticking out. Left the rest to keep the ferrite beads on.

I have ripped bigger chunks of that glue off other things before, it seems to hold together better than it sticks to things (unless it's really baked), so probably knife\pliers might be better, less messy anyway.

[ben7]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

You might have bumped a cold solder joint too.

I guess the clicking sound could have been from the glue breaking down and arcing.

[Agent24]

Re: Enermax Liberty ELT400AWT making clicking noise but still running

Yeah, no idea at this point. Will investigate more if it happens again I suppose