Raidmax RX-600 ringing noise and 0ms PG

[Agent24]

Re: Raidmax RX-600 ringing noise and 0ms PG

According to that datasheet, your PS224 PGO pin is an open drain. So that burnt resistor and diode may be a pull up? It should be to 5v though...

Maybe they use 12v to pull up PGO and that transistor you find connected to PG wire is a level shifter circuit. Why the heck they would do that though...?

Anyway, if the resistor burnt, something may be shorted on that PG line, or it was plugged into a faulty motherboard.

[Dannyx]

Re: Raidmax RX-600 ringing noise and 0ms PG

According to that datasheet, your PS224 PGO pin is an open drain. So that burnt resistor and diode may be a pull up?

Yes, but it's strange the brown PG wire is not connected there to make that a pull-up resistor. However....

Maybe they use 12v to pull up PGO and that transistor you find connected to PG wire is a level shifter circuit

This might make more sense, though I could not, at least so far, find a trace which connects the two "halves" of this PG circuit: the wire and the transistors are on one side, while the area in the picture is on the opposing side. Another thing I forgot to mention is that there IS what appears to be a pull-up resistor on the PG wire connected to the bunch of orange 3.3v wires !

Anyway, if the resistor burnt, something may be shorted on that PG line, or it was plugged into a faulty motherboard.

There's no immediate short that I could find, plus the supply starts up fine and outputs are perfect, but no MB is going to start with a 0ms PG signal. The possibility of an external factor killing the resistor remains though, which would be a best-case scenario since it would mean replacing it may solve the problem....or not....:|

[Agent24]

Re: Raidmax RX-600 ringing noise and 0ms PG

That diode looks like it's got a burn spot, too?

If there was a short, it could have blown clear and you can't find it now. You mentioned a capacitor. Perhaps it works to provide a delay on PG line. Maybe the transistor circuit works as a buffer to provide a clean signal to the motherboard.

If that capacitor shorted, and blew, the diode/resistor could be damaged and now the capacitor is open-circuit, leading to the instant PG signal.


With regard to connecting the circuits, there could be top-side wire links etc hidden under other components or under blobs of glue?

[Dannyx]

Re: Raidmax RX-600 ringing noise and 0ms PG

That diode looks like it's got a burn spot, too?

I measured it and seems fine - 0.6v drop across it in only one direction.
It could be a cap, though I've never seen small ceramic caps like this failing open, though I'm not saying it's not possible...
I shall do more digging, mostly for fun and because the supply seems decent enough to keep. I shall attempt a circuit diagram when I have the time.

[Agent24]

Re: Raidmax RX-600 ringing noise and 0ms PG

It's almost always when I'm convinced that "this component can't possibly be faulty" that it turns out to be the problem. Murphy's law, or some variant thereof.

But yeah, draw up a schematic, this design sounds fascinatingly bizarre!

[Dannyx]

Re: Raidmax RX-600 ringing noise and 0ms PG

There HAS to be some connection between that PG pin and the PG WIRE....otherwise why would the PG pin even be connected ??? I was thinking it may be a simple time-delay using those transistors and cap(s) and no "real" PG indication....will have to see.

[Agent24]

Re: Raidmax RX-600 ringing noise and 0ms PG

It IS Raidmax, wouldn't surprise me...

Back in 2006 a couple friends of mine bought a few Raidmax supplies for themselves and family, all the same model PSU, and every single one had the primary capacitors go up in smoke within a month.

[Dannyx]

Re: Raidmax RX-600 ringing noise and 0ms PG

Here is a close-up of the side which has the PG wire and those two transistors. One of them is actually an AS341 IC (the one on the left), so we've got some regulator action going on ??

The device on the right is a PNP transistor, but I forgot the model right now - it's like B773 or something along those lines (has an UTC logo at the top of the can), but there's very little info on it. Still, I WAS able to find a pinout somewhere, though not an official datasheet...

There's also two diodes between the middle pin (collector) of the transistor and the GND plane....

It seems to me like they're using this setup to pull the PG wire low when the 3.3v rail has stabilized ???? Would this make that small electrolytic cap a culprit (red symbol) ??

[Agent24]

Re: Raidmax RX-600 ringing noise and 0ms PG

The electrolytic could if it were open-circuit, or if the TL431 was shorted.
Or even if the transistor were shorted B-E the capacitor may charge too fast through it. But that seems unlikely.

This circuit makes no sense though. If the values of R314 and R312 are indeed 10 and 909 ohms respectively, that would produce a voltage divider that could never pull PG below 3.2v...

Unless the pad you've marked as GND is not GND, but actually some negative rail.

And also, why didn't they just use the PGO pin on the PS224?! It may be their PSU design isn't actually stable at the point where the PS224 outputs PGO so they had to make their own circuit with a longer delay?? Who knows....

[Dannyx]

Re: Raidmax RX-600 ringing noise and 0ms PG

D'oh ! I think Danny just made a colossal screw-up with this whole story - too much work, not enough pay or lay
I had a look at the pinout of a 24p connector online, since it made no sense indeed and it just occurred to me that is NOT the PG wire there The PG wire should be gray and that's a brown one if I remember correctly I have no idea why I was so convinced PG is brown...brown is that 3.3v sense wire crimped together with one of the 3.3v ones, I guess for some sort of compensation to account for losses across the wires as close to the load as possible ? Come to think of it, this is most definitely a mag-amp regulator, since there's clearly no separate DC-DC regulator for the 3.3v rail, or ANY rail for that matter, since it's your run of the mill ATX.... With that out of the way, we can still analyze how this sense wire works, since we've gone that far

I'll definitely need to go back to the PS224, identify the gray wire and see what the deal is with that busted resistor...

[Agent24]

Re: Raidmax RX-600 ringing noise and 0ms PG

LOL that would explain a lot.

[Dannyx]

Re: Raidmax RX-600 ringing noise and 0ms PG

Ok, PSU is working now. I replaced the burnt resistor with a thru-hole one, since I didn't have a proper SMD one on hand, and the problem persisted: PG was still 0.

I checked to see what voltage I get on that resistor and it was very low and unstable, bouncing between 1v and 2.5v. This led me to believe there was something wrong with the diode which comes before it. I measured it in circuit and the drop was very high - like 1.3v or more. I measured a similar one further up the board, also in circuit, for reference, and the drop was more what you'd expect, at around 0.6v, so my first diode seemed faulty at this point.

I removed it and I got the same high reading out of circuit too. Again, not having an SMD one readily available, I botched an 1n4148 in series with the resistor and tried it out. This time it worked - PG was now at 290ms Since this is for my own personal use, I dug no further to find proper SMD replacements and simply threw that black piece of heat-shrink over the solder joint there so it wouldn't come into contact with anything.

Picture turned out really bad due to 50Hz banding from the light of my illuminated magnifier I shot through. I can't seem to mitigate the effect on my SG S10+...the first picture I took a while back turned out crystal clear though...

[Agent24]

Re: Raidmax RX-600 ringing noise and 0ms PG

Nice job!
The photo isn't bad, I can see everything okay.

But yeah, I was pretty sure that diode didn't look so good. Always a good idea to investigate anything that looks physically damaged.