Antec AR300 psu, loud squeal, no power

[momaka]

Re: Antec AR300 psu, loud squeal, no power

Mo, Some thoughts on your schematic. R34 is R34; 4.99K. C19 measures 100nF. The unmarked diode is a Schottky SB540, D10. L2 measures 5.1uH. To me it looks like ZD3 does not connect to ground but to where R25/EC3 connect to the transformer. It measures 2.9V (not sure of this yet).
Jon

Cool.
Thanks for double-checking these. I updated the schematic and attaching it below. Does ZD3 and R71 look to be correctly connected now (that is, one side to primary ground / negative lead of big bulk cap?) At least going by your description and what I've seen before, it makes much more sense for ZD3 to be connected this way... though the only reason why I originally drew it where it was on the previous schematic was because that's all I could see from the provided pictures. And yes, 10V for ZD3 seems a lot more like it than 2.9V. The idea behind ZD3 is to protect U3 E-C junction from overvoltage... and I'm sure even a higher-rated voltage Zener will probably work fine here, so long as it's rated less than the V_ceo voltage of U3.

Updated schematic:

[need_info]

Re: Antec AR300 psu, loud squeal, no power

I finally got the PS powered on and measured ZD3, it did measure 10V. So my earlier post was incorrect in this regard.

[need_info]

Re: Antec AR300 psu, loud squeal, no power

Mo, Some thoughts on your schematic. R34 is R34; 4.99K. C19 measures 100nF. The unmarked diode is a Schottky SB540, D10. L2 measures 5.1uH. To me it looks like ZD3 does not connect to ground but to where R25/EC3 connect to the transformer. It measures 2.9V (not sure of this yet).
Jon

[need_info]

Re: Antec AR300 psu, loud squeal, no power

Mo, great schematic and accompanying notes. And just from the pictures. Jon

[momaka]

Re: Antec AR300 psu, loud squeal, no power

Awesome!

Below is a schematic of the Antec AR300 5VSB circuit I was able to draw from the pictures provided so far.



To anyone reading, please note that I don't have this PSU in front of me, so don't assume the schematics are 100% accurate. If anything, I drew the secondary side in a rush, so some components may not be placed right (R34, R31, C19.) The primary side should be mostly right, though. It seems to resemble the circuit of the HEC Orion PSU I linked to earlier in post #31 and some other 5VSB circuits I've drawn before.

Some interesting observations:
This 5VSB circuit has two (2) primary-side auxiliary outputs - one for its own feedback loop (generated by D8 and filtered by EC3), and one for the PWM controller of the main PS (generated by D9 and filtered by EC4, with ZD4 serving as OV protection), which I labeled "Pri. Aux." on the above schematic.
Note that you don't need to have the Pri. Aux. circuit working to have the 5VSB working. In other words, for anyone troubleshooting this PSU's 5VSB, you can still get 5VSB output, even if R29 & D9 are completely removed from the circuit. In fact, it's preferable to have those components removed while troubleshooting the 5VSB. Once 5VSB operations has been successfully restored, then R29 and D9 can be replaced back in the circuit.

Regardless of the repair steps taken, make sure EC3, EC6, and EC7 are in GOOD HEALTH before powering on the 5VSB circuit. EC3 is the startup & "critical" cap of the 5VSB circuit. If it goes high ESR, the voltage on the output may start rising... or alternatively, ZD4 may get burned out, along with resistor R29.

As always, I recommend to use an incandescent / halogen bulb in series with the PSU's live AC input to prevent component damage if something was missed and/or not replaced by mistake.

[need_info]

Re: Antec AR300 psu, loud squeal, no power

Mo, here is the way I read the components requested:
R22 red, black, green...gold: 2M 5%
R23 green, blue, orange...gold: 56K 5%
D7 LT 5323/UF1007
C16 TL/222M/1KV: 2.2nF
Q5 KN/2222A/438
Q6 UTC/2SA684/RJ0A
R28 violet, green, silver...gold: 0.75 5%
C17 J525/222/XCK: 2.2nF
TO-222 FB F02/FQPF/5N60C
if these don't make sense or you want something else, please let me know, Jon

[need_info]

Re: Antec AR300 psu, loud squeal, no power

hi,
I have attached my shot (hold the laughter please) at a schematic fragment and my spreadsheet of relevant parts. (The transistors attached to the heatsink are hard to see; I'll work on it and the other parts for identification.)
thanks, Jon

[momaka]

Re: Antec AR300 psu, loud squeal, no power

It appears that ZD3 is trashed. However, I have no idea what it's value is either. Maybe this is a hopeless idea to make it whole again?

Nah, can't let that stop us (yet.)

According to post #21 by kc8adu, ZD3 = 10V, 1W Zener
... which sounds about right.

Anyways, I drew a schematic (finally) and will scan it tomorrow when I get a chance, then upload it here.

Meanwhile, if you could provide part #'s for the following below (so I can complete my schematic a little more), that would be awesome
R22
R23
D7
C16
Q5
R28
C17
TO-220 transistor on the heatsink

[need_info]

Re: Antec AR300 psu, loud squeal, no power

It appears that ZD3 is trashed. However, I have no idea what it's value is either. Maybe this is a hopeless idea to make it whole again?

[momaka]

Re: Antec AR300 psu, loud squeal, no power

Hi Jon,
Thanks for the good quality pictures, they really help trace the circuit out.
Give me a day or two, and I'll try to draw out a schematic for this 5VSB circuit, based on your pictures. Hopefully that might make it easier to understand some of the values.

But in any case, it looks like C18 is indeed a low-value capacitor, somewhere in the low nF range (again, 0.47 to 2.2 nF likely.)

R29 also seems to have obliterated, taking the trace along with it. But I think the 5VSB can be tested without R29 and D9 for now, as it appears these are for the primary side aux. supply (which provides power to the main PS PWM controller on the primary side.)
D8 and the burned Zener diode next to EC3 need to be replaced, though.

[need_info]

Re: Antec AR300 psu, loud squeal, no power

hi,
Took a couple of photos. Not sure what you were looking for so ask away.
The two missing diodes are: D9 FR103, D8 1N4004. Some other components have not been replaced yet. Most of the ECnn have been replaced.
Jon

[need_info]

Re: Antec AR300 psu, loud squeal, no power

Hi momaka, thanks for all of the help/information. I would like to answer your questions with some confidence; so I am looking at the pcb and trying to see exactly how c18 fits into the picture. I will get back when that work is done. Jon

[momaka]

Re: Antec AR300 psu, loud squeal, no power

Hi Jon and welcome to BCN!

Given this thread has last had a reply in 2011 (12 years ago), there's probably a slim chance anyone still participating here would have this PSU... but who knows, of course.

Do you have a multimeter at your disposal? If yes, we may be able to deduce the value of C18 simply by knowing how it's connected in the circuit. Looking at pictures earlier in the thread and also this one, C18 appears to be on the primary side, connected to the optocoupler through resistor R26 (470 Ohms) and then goes through a few resistors and connects either to small transistor Q5 or the Gate/Base of the larger transistor on the heatsink (it's a bit hard to tell from the pictures from other posts... so if you could provide further pictures, that would be very helpful. Just please attach them to the forum using the built-in attachment feature, so the images are hosted here and not on an external website.)

With your multimeter, can you verify if one side of C18 connects to primary-side ground (the negative lead of the big capacitor on the primary side)?

If yes, I suspect C18 may not be entirely critical (probably there for when the 5VSB circuit is running completely unloaded.)

This PSU appears to be made by Channel Well Technology (CWT), but the 2-transistors 5VSB self-oscillating circuit they used here does not seem too similar to their ISO -line designs. However, looking at my collection of 5VSB schematics, the closest that might resemble something like your 5VSB circuit is from a HEC Orion HP585d I posted here:
https://www.badcaps.net/forum/attach...1&d=1578459617
^ On that one, your C18 would likely correspond to the 0.47 nF ceramic capacitor connected to the Base of the smaller PN2222A transistor in the above schematic.

Now, I also have a Deer DR-250ATX PSU's 5VSB schematic (that I have not posted on BCN yet), which also appears very similar to the HEC Orion HP585d 5VSB circuit. On that one, the capacitor has a value of 2.2 nF... but the series resistor corresponding to R26 is only 100 Ohms. So I suspect the higher capacitance used in the DR-250ATX 5VSB is due to the lower series resistance (100 Ohms) after the optocoupler... whereas on the HP585d, it's the same 470 Ohms as your R26.

That being said, I think there's a good chance a value of 0.47nF to 1 nF should work OK... or maybe even up to 2.2 nF.

Either way, just beware that if everything is not perfectly right with these 2-transistor 5VSB circuits, they tend to blow up a lot of parts. So double-check all of the other parts in the circuit before powering it up. I'm sure you probably already found many other parts bad. The main take-away is to make sure the output capacitors on the secondary side of the 5VSB (EC6 & EC7), as well as the "startup" / "critical" capacitor (EC4) are all good.

And even if everything checks out OK, it would still be a good idea to use a series incandescent light bulb in series with the PSU's AC Live to limit the current / power going into the primary side, in case there is still something wrong with the 5VSB circuit. This could save you from blowing up fuses and many other parts.
The series incandescent bulb "trick" is detailed here:
https://www.badcaps.net/forum/showpo...51&postcount=6
and here:
https://www.badcaps.net/forum/showpo...4&postcount=70
Use 40-60 Watt bulb at first... and if needed, then maybe jump to 100 Watts.

Since incandescent bulbs can be hard to find above 40 Watts, you could also use something like a 60-72 Watt Halogen... or 2x 35W halogen bulbs in parallel (equivalent to a 70W Halogen)... OR, 2x 40W appliance incandescents in parallel (equivalent to 80 Watts incandescent.)

Let us know what you find.

[need_info]

Re: Antec AR300 psu, loud squeal, no power

Here we are a few years later and AR300 power supplies still need help. I am rebuilding one and need help in identifying the value of SMD capacitor C18. The cap is open and since they are "unmarked", well I am stuck. I am hoping someone still has a working supply that they can measure C18's value. I know it is somewhat of a big ask; and I wouldn't if I could find another way to get the value. Jon

[ukvince]

Re: Antec AR300 psu, loud squeal, no power

PSUtech ...
That info is very useful .... thank you for taking the time to post it.

[PSUtech]

Re: Antec AR300 psu, loud squeal, no power

I know this an old thread but if any one needs this info:

CWT-300TLP REV B

EC11 4700UF 6.3V 10X30MM FUHJYYU
EC6 EC7 1000UF 10V 8X15MM TEAPO
EC12 3300UF 6.3V 10X20MM TEAPO
EC18 1000UF 16V 10X20MM FUHJYYU
EC15 EC16 2200UF 10V 10X20MM KOSHIN
EC17 330UF 16V 6.2X13MM KOSHIN
EC14 470UF 16V 8X15MM FUHJYYU
EC13 330UF 25V 8X15MM FUHJYYU
EC3 22UF 50V 5X10MM FUHJYYU
EC4 100UF 50V 8X13MM TEAPO

R29 5.6 OHM 1206

ZD4 1N4746 18V 1W ZENER

U11 7912CV -12V LINEAR REGULATOR

I just got in a bunch of these in with problems so if anyone needs other part values let me know

[Brian C]

Re: Antec AR300 psu, loud squeal, no power

You may try to draw the schematic and figure out the resistor value.

[Sylvester]

Re: Antec AR300 psu, loud squeal, no power

I think I can blow the R29 picture up a bit more.

The psu did do some damage to the mobo after all, it took out the sound chip.

[lucky13]

Re: Antec AR300 psu, loud squeal, no power

Yep, that R29 is going to be a problem.

Can you do a macro shot of it?

You should also post a pix of the Antec label here. In case someone come axross this post, they can compare their label against yours to see if there is a match.

Then, they still need to open it up and look at the solder side if they are into recapping.

Just come in and bump the post once in awhile to attact attention.

[Sylvester]

Re: Antec AR300 psu, loud squeal, no power

Think my biggest problem is R29's value.