The 5V standby high voltage side is toast. Looks like the surge suppresion and snubber parts have cooked over time for some reason. That 4 legged lone transistor looking chip on the small heatsink is probably bad now. The opto isolator on the feedback cracked in half is a bad omen. Other parts on the high voltage side might have failed also since they have their voltage supplied from the same standby transformer through the aux circuit. Even if the failed components are replaced the burnt/carbonated circuit board has to be cleaned or sanded thoroughly also. I can look up the components by position if you need info about them.

I guess its worth a shot at reparing then...
And yes, if you could tell me the specs of those two resistors which ill post later as I don't have the psu at hand

Alright. I just need to dig out my psu from storage so we can identify the parts.

Overheated copper loses current capacity, so unless you are gonna replace almost everything and the PCB it's never going to be a 300W PSU again, you'd have to de-rate it 30% or so. In my shop I'd probably be picking parts off to upgrade or repair "alright but crappier" stuff. Also might be a case of "fully restored to a value of $40 with only $60 in parts" ... and I personally count shipping, so it's 5 $2 parts you gotta get from 5 different places with $10 in shipping a pop, that's $60 in parts. If I still want to go forward on things like that I shelve them for years and see what turns up... just scoring one here and there while you're ordering other things and the desirability of the thing itself going up tips the math the right way eventually.

The parts are one thing but the carbonized PCB is going to be a problem. If it doesn't clean up I'd probably not risk it. Quite frankly unless these PSUs are extremtly difficult to find in OPs location I would most likely bin it. Maybe remove the input filter chokes and test them, for transplat to another PSU. But only chokes, all the X/Y caps are now suspect and have to go. The output diodes might also be good, and the rest is very suspect even if it seems to be OK-ish during low voltage testsing.

As someone who worked in electronics repair, toss it, or keep it for parts. Unless it's something unobtainable or weird form factor from a specific system that absolutely has to be repaired. Those things are a rabbit hole once they fry. The only thing I MAY bother with is replacing the odd capacitor if that's all the issue is.

If you don't have any prior experience with soldering, specially high voltage components then just bin the psu as Deunan suggested or try to completely disassemble it as practice.

Before the standby circuit repair attempt check F1 fuse ( T6.3AL250V) for open circuit, TH1 thermistor (SCK 2R58) for higher that 4 Ohm resistance or open circuit. BD1 (KBL405g) bridge rectifier for short circuit.
Q1, Q2 transistors (E13009L) on the heathsink. If any of the transistors measure short on any legs you can forfeit the psu I guess you can. Part of the EMI filter CY1, CY2, (472M) X1 type ceramic capacitors and the .47J 250V film capacitor between the pfc coils leads are most likely ok.

On the low voltage side check D10 (SF504) for short circuit or low voltage drop on both directions and/or leakage current. If this component has failed then the FSP7528 pwm/supervisor combo IC has most likely be bad and the repair is just not wort it.

Before you start working remove all components in the standby ciruit and clean the pcb of all charred/carbonated areas. If the burn damages are too deep better forfeit the repair. The carbonated areas are conductive and it ill result in catastrophic failure again if psu is powered.

Standby circuit components:

R14: 0.46M Ohm
R16: 4.6Ohm
R61: 22K Ohm
R15: 0.46K Ohm
R54: 16K Ohm
R62 50 Ohm (next to D27 and the opto isolator)

Q7: C945 NPN BJT
Q3: 4N60B N FET

C6: 103 500V ceramic disk capacitor
C7: 2A222J polyester film capacitor
C10: 2A223J polyester film capacitor

D5: PS106R diode
D6: 1N4148 diode
D7: FR102 diode
D27: 1N4148 diode

IC2 PC817 opto isolator
2A102J unmarked polyester film capacitor between the anode and cathode of the opto.

My take: it doesn't look that bad and could be repaired somewhat easily if you know your way around electronics (or are stubborn and just want to do it for learning purposes 😉 ).

I don't think a power surge caused this damage. More likely, the caps on the 5VSB circuit went bad (either the small "startup" cap on the primary or the output caps on the secondary), causing the 5VSB circuit to go haywire and blow up, as this appears to be a 2-transistor self-oscillating 5VSB circuit, which are pretty barebones when it comes to protections. Actually, that's putting it lightly - 2-transistor 5VSB circuits like this pretty much never have any protections. So when a component fails, the damage is cascaded and multiple other components in the 5VSB circuit are taken out.

So as Dave86 suggested above, start by checking all of the primary-side input components as well as taking out all of the 5VSB components and checking each one out of circuit. While the components are out, try to see if the charred parts on the PCB can be cleaned up. IPA + lots of scrubbing (and maybe some sanding/chisseling) should get the carbon off the PCB. If the charred PCB *cannot* be cleaned... well worry not! - I'll share a little secret of how you can still get one of these PSUs up and running quickly... and probably be safer than it was before. 🤣 In short: you will need two power adapters - one rated for 5V and 2 Amps (the same as the 5VSB of the PSU) and another for 12-15V capable of 0.5 Amps or more. You then wire the 5V output of the 5V adapter directly to the 5VSB output (and connect the ground of the adapter to secondary-side ground of the PSU.) Essentially this now makes the 5V adapter's output de-facto your 5VSB supply. Then, you take the 12-15V power adapter and wire that the same way, but to the secondary side auxiliary rail (it's the one that supplies the PWM chip with power.)
The good about this method is that it can be a quick short-cut to see/test if the main part of the PSU is still OK without having to deal with any troubleshooting on the 5VSB.
However, before doing this test (or really any type of power test with the PSU), I strongly suggest you wire a 100 Watt incandescent bulb in series with the PSU's AC input. This will limit the current (and power) should something else be failed on the PSU - you will get a brightly lit bulb. If you're not sure about this method, look up "testing with series incandescent bulb". I had a brief writeup on badcaps.net somewhere, but I don't have the post bookmarked on this PC to show it. It's really a must-do when working with a PSU that has had primary-side damage (be it on the 5VSB or the main PS circuit.)

Now, should you consider to not bother fixing this PSU, make sure to take out the two big 200V electrolytic caps from the primary. These are by far one of the most expensive parts in the whole PSU. If you do ever get into PSU repairing/re-building, you will find that having some spares of these (especially the larger capacity ones - i.e. anything 470 uF and over) will come in quite handy. On PSUs that use these and not a single 400V/420V/450V cap, these 200V caps rarely fail. However, BitWrangler mentioned a good point in his post - sometimes you can use PSUs like this one for parts to upgrade/fix up more crappy (but otherwise OK) PSUs. In my case, I have several not-too-badly built "no-name" PSUs that could use an upgrade on their tiny input electrolytic caps (only rated for 330 uF). Luckily, I do have a few parts PSUs like this that I can pull parts from. So like I said, it's handy to save these parts. The input filters and output toroid are also valuable parts... as can be the output rectifiers... and sometimes even the main transformer (if you match its pinout to the donor PSU.)

Anyways, have fun and keep us posted what you find.

Hmm. I could also upgrade the shittier casecom "400w" psu, but unsure. As of now ig its gonna be put on hold until I get the excellent power fixed up.

momaka wrote on 2025-02-10, 23:10:

Now, should you consider to not bother fixing this PSU, make sure to take out the two big 200V electrolytic caps from the primary. These are by far one of the most expensive parts in the whole PSU. If you do ever get into PSU repairing/re-building, you will find that having some spares of these (especially the larger capacity ones - i.e. anything 470 uF and over) will come in quite handy. On PSUs that use these and not a single 400V/420V/450V cap, these 200V caps rarely fail. However, BitWrangler mentioned a good point in his post - sometimes you can use PSUs like this one for parts to upgrade/fix up more crappy (but otherwise OK) PSUs. In my case, I have several not-too-badly built "no-name" PSUs that could use an upgrade on their tiny input electrolytic caps (only rated for 330 uF). Luckily, I do have a few parts PSUs like this that I can pull parts from. So like I said, it's handy to save these parts. The input filters and output toroid are also valuable parts... as can be the output rectifiers... and sometimes even the main transformer (if you match its pinout to the donor PSU.)

Anyways, have fun and keep us posted what you find.

I too have canibalized a few FSP units for parts. There are better topology FSP units from 2003- 2005 where standby high voltage side is switched by the TNY2xx or Viper22 or something. Of course these too tend to blow up in certain cases.
I don't have a schematic or boardview of the 60GTF just a crappy photo were component locations are visable:

DAVE86 wrote on 2025-02-11, 08:41:

There are better topology FSP units from 2003- 2005 where standby high voltage side is switched by the TNY2xx or Viper22 or something. Of course these too tend to blow up in certain cases.

Agreed, I also consider PSUs with 5VSB circuits with such ICs "better" in that even if they blow up or if something goes very wrong, at least they (almost) never cause any damage on the secondary side. Most of the time, it's just the IC blowing up and maybe taking out with it the Source resistor and PSU fuse. Meanwhile, 2-transistor 5VSB circuits can do quite a bit of damage, both on the primary side and secondary side... and occasionally burn out its transformer too. So they are harder to repair in that regard. On the plus side, there's no proprietary or hard-to-find parts that go into a 2-transistor 5VSB circuit, so even 10-20 years from now, it should be possible to rebuild one without having to worry that there won't be parts available for it anymore.

DAVE86 wrote:

I too have canibalized a few FSP units for parts. There are better topology FSP units from 2003- 2005 where standby high voltage side is switched by the TNY2xx or Viper22 or something. Of course these too tend to blow up in certain cases.
I don't have a schematic or boardview of the 60GTF just a crappy photo were component locations are visable:

Could you read the value of resistor R63 and the one near Q7?

I also done some probing and it looks like the zener diodes are shorted in the burnt arena, so I guess its worth a shot.

kotel wrote on 2025-02-12, 10:16:

DAVE86 wrote:

Could you read the value of resistor R63 and the one near Q7?

I also done some probing and it looks like the zener diodes are shorted in the burnt arena, so I guess its worth a shot.

I'll report back the values. I don't have the psu at hand right now.

I hope this helps.

Before I have done anything on this PSU I have checked the secondary heatsink and guess what? All of the diodes on it are shorted together!
Final verdict for this PSU:
Broken, dead, unrepairable.
What's weird is that no of the rails are shorted to ground. All of them show correct resistance.
Although this one reminds me of my tagan PSU which has half of its diodes appear shorted on the secondary heatsink with 5v rail, albeit this one was working before with 3.3v being out of spec low (2.4v no load, 2.2v loaded).

Bummer... Though I've had given up on psus for less. A rare few times the main pulse transformer has developed a short on some secondary windings. Into the spare parts bin it went.

I might actually revisit this one due to the tagan having shorted primary driver transistors and as my luck would have it I don't have any 2sc3320's at hand.

Okay so for fun I've pulled out the secondary heatsink and the diodes, are infact, not shorted. The short is on the PCB it self... I'll probably go down the rabbit hole when the tagan repair is gonna halt due to missing parts.

Quick update.
Since the tagan and excellent power repairs went into a standstill I came back to this one and removed the damaged resistors and diodes. Now the secondary short is gone. Gonna put it together just to see if it makes my dim bulb tester light up as an Christmas tree.

DAVE68, could you tell me the specs of that weird yellow cap labled r1? If you can that is. I lost mine and don't know where ot is on the workshop floor.