FSP400-60GLN worth fixing?

[Per Hansson]

Re: FSP400-60GLN worth fixing?

It's connected directly to Vstr pin on the DM311

[ben7]

Re: FSP400-60GLN worth fixing?

Perhaps the large capxon cap started to go bad, and the PFC circuit worked harder to maintain the voltage, overheating the PFC coil and shorting out the DM311 from high voltage spikes?

[Behemot]

Re: FSP400-60GLN worth fixing?

Than it should be more than 70 V. The DM311 datasheet specifies 20 V at 3 mA max. So there should be some 300 V drop with zener dropping it further to 20 V. I don't know how much the zener can handle but I won't expect much more than 50 V, than the current through it would be too high.

That is under normal operation though, if the DM311 draws more than 3 mA than it should, there can be higher drop on it than on the resistor. Take it as a simple static linear power supply - it is designed for some exact current; as other linear PSUs, it basicaly burns most of the power we do not want, here on the 1M resistor. Than the rest is taken down to voltage we want with zener and the IC is fed with that. That's how I understand it anyway.

ben7: there must be some zener, there always is and I remember some in the design…it should smooth the spikes together with a capacitor. However, what usually goes bad because of excessive overheating due to using that GP diode and no cooling, and because of poor quality, is the cap. Than the zener is supposed to do all the work and can go short…

[Per Hansson]

Re: FSP400-60GLN worth fixing?

Behemot: 20v is not on Vstr, it can handle 650v according to the datasheet.
That's why I was surprised at first, I assumed I would be reading 330v here and that the resistor was bad.
But digging further it looks alright.
But I don't understand the purpose of the resistor, why have it there at all if the DM311 can handle up to 650v on Vstr?

[Behemot]

Re: FSP400-60GLN worth fixing?

Oh my bad, I've been talking about Vcc…the Vstr should consume 100 uA. So I think huge resistor is there to ensure slow enough charging of the Vcc cap otherwise there would be huge spike through the IC, auxiliary transformer windig and to the cap.

[everell]

Re: FSP400-60GLN worth fixing?

The Vstr resistor is a current limiter. It also drops the 330 volts to something useful. Vstr only STARTS the chip, it doesn't maintain operation of the chip. To sustain operation, it depends on the feedback voltage from transformer T2 thru diode D41 to provide Vcc voltage on pin 2 of the DM311 chip.

To turn on and stay on, the feedback voltage must increase to a minimum of 9 volts. Typical operation on this power supply, it should reach and maintain 12 volts. If Vcc drops to 7 volts or below, the chip turns off. Also, if the Vcc goes above 20 volts it turns off. Check the voltage on pin 2. To operate it must be above 9 volts.

To complicate matters more, the feedback winding of T2 and diode D41 also provide Vcc to the 6800 chip (PFC control and PWM control). It also provides voltage to the PFC driver transistors Q12 and Q13, and to the PWM driver transistors Q70 and Q71. If the 6800 chip or any of these four transistors short, it can load the feedback winding voltage such that it never goes above 9 volts.

Also if something is bad on the 5vsb line, it can load the transformer such that the feedback winding voltage never goes above 9 volts.

Hopefully this information helps. The voltage on pin 2 of the DM311 must be above 9 volts, typically 12 volts. Measure it and let us know what you get.

I did a comprehansive study on this power supply board a few years ago. It is the same board under the Sparkle brand. I am including some photos of that power supply and the drawings I made. Hopefully they will help you to understand the circuits better.

[everell]

Re: FSP400-60GLN worth fixing?

And here are some drawings

[Behemot]

Re: FSP400-60GLN worth fixing?

Everell, this is very common design, an OEM version of BlueStorm II, ranging usually from 300 to 500 W but designed up to 600 or maybe 700. It has ended as quite many PSUs of many brands as it was main FSP design for quite some time. No wonder it also ended as Sparkle as it is FSPs brand, a try for independet retail brand IIRC.

Anyway, thanks for your valuable input, I see these PSUs quite a lot, but never had time to dive so much much into these tanks of shit...

[everell]

Re: FSP400-60GLN worth fixing?

PerHansson: did you get your Fortron FSP400-60GLN fixed?

[Behemot]

Re: FSP400-60GLN worth fixing?

Oh, I just found a Blue Storm II 500 W I had here for some time, also with burned R44. There is also shorted Vcc zener and I measure very low resistance between +380 V and ground. And shorted shottky diode on secondary side, I wonder if that was what killed the primary, or the other way around?

As for the SB driver, there is not DM311, but some Fairchild 270 something IIRC. Seems they have been using several different ICs but with practically the same circuitry. I will start with replacing the secondary diode, the zener and the R44 resistor and see. There is chance the PWM is bad as well.

[goodpsusearch]

Re: FSP400-60GLN worth fixing?

Please keep us posted. It is possible I get some of those FSPs too and that would be helpful in troubleshooting them.

[Behemot]

Re: FSP400-60GLN worth fixing?

In like 90 % cases the capacitors just get baked, throughout the whole stand-by rail, beginning with Vcc cap and ending with output caps in Pi filter. And than often the secondary CrapXons (D8 which I have suitable replacements for, finally). So you need to replace them all, every time. Everells idea of replacing 1N4007 with some fast diode together with quality caps should keep them alive for much longer.

Than I have also encountered baked PFC coil as well as Per Hansson did, which actually started this thread :-) This is (for me) the first one which encountered some explosion So far we managed to get good amount of information here so that is what actually made me even try to get it running again, a year back I would just scrap this one, which is what it was shelved for, I just did not have the time.

[Per Hansson]

Re: FSP400-60GLN worth fixing?

PerHansson: did you get your Fortron FSP400-60GLN fixed?

Yea, I'll look into it later.
Weather has been too nice to play with this shit PSU, plus the little time I've spent inside has been on the Dell monitor in another thread.

a year back I would just scrap this one, which is what it was shelved for, I just did not have the time.

Yea I'm actually kind of regretting not using this one for target practice aswell.
TBH I just hate this design, idiotic cramped PSU with small 8mm caps that just cooks themselves.
I should have gone with my original gut feeling: .30-06

[Behemot]

Re: FSP400-60GLN worth fixing?

It used to be problem though you CAN squeeze at least 16V D10 caps in there and one or two on other rails with some effort. It is not such a problem to get 1200-1500uF 6,3V caps but it was to get D8 16V/1000uF (IIRC only Panny FJ with quite short life and almost too low ESR). Now I have 5000 h@105 °C NCC KZH so no problem from now on

[selldoor]

Re little brother FSP350-60HLC

Starter for 10 newbie question
I have tested the DM311 using primary ground - neg leg on Big cap.
I am now going to test CM6000 ( well some pins)
Do I still have to use primary ground for this?

[everell]

Re: Re little brother FSP350-60HLC

Do I still have to use primary ground for this?

Yes

The first thing to troubleshoot is the 5vsb. It must work for everything else to work. From your earlier comments, it does seem to be working.....but.....you need to look for the two diodes that can cause trouble. The feedback diode AND the snubber diode both need to be high speed switching diodes. On the last power supply of this type I found that they used 1N4007 diodes in both places. With time, this will cause trouble. Wouldn't hurt to replace both 5vsb output capacitors. Bad 5vsb circuit means trouble for the rest of the power supply.

Once you have the 5vsb fixed properly, you need to look at the PFC (power factor correction) circuit. This power supply uses the 6800 chip which has both PFC and PWM (pulse width modulator) functions. To work properly, the PFC part of it MUST turn on and work properly or the PWM section will not turn on.

A quick test for the PFC circuit: hook your voltmeter across that big capacitor. Apply power to power supply. You should read about 165 volts in countries using 120 volt power or about 320 volts for countries using 240 volts. Now short the green wire to the black wire to turn on the power supply. Watching the meter, you should see the voltage increase to 400 volts. If the voltage increases to 400 volts, your PFC circuit is working. If it does not increase, the PFC circuit is bad and must be fixed before the power supply will work.

Let us know what you find.

Safety warning: Danger, this test means you will be working with high voltage. I take the pc board out of the case to work on it....to prevent it from accidently making contact with the case and causing sparks. Next, I recommend soldering a resistor to the positive side of the big capacitor, and another resistor to the negative side of the capacitor. Then use these resistors as a place to clip voltmeter leads. Using this technique, your hands are away from the high voltage AND you won't have the voltmeter leads accidently slip and touch something else......causing sparks and additional damage. And....wear safety glasses during the test. If you don't have safety glasses....get a pair. The cost of safety glasses is cheap compared to the cost of losing vision.

[Behemot]

Re: FSP400-60GLN worth fixing?

If the secondary caps are bad (I have seen at least one bloated in selldoors pics) than surely the +5 V SB are as well. I have not seen a PSU of this type where they were not so replacing them is a must. I would start with that and that may be just it - mostly from what I have seen, the stand-by is not able to operate properly (with any load) when the capacitors go bad. It may start with no load making an impression it is actually OK. Bad PFC/PWM part is mostly in minority in these PSUs.

[everell]

Re: FSP400-60GLN worth fixing?

Bad PFC/PWM part is mostly in minority in these PSUs.

First GLN I worked on had two FETs in the PFC shorted AND the booster coil was shorted. What a nightmare to troubleshoot.....I was just beginning to learn how to troubleshoot power supplies......it was one of the first power supplies I worked on. And I thought I knew something about electronics! Very humiliating.

[Behemot]

Re: FSP400-60GLN worth fixing?

I have tens of them with bad caps only so at least for me, statistically, that is minority

[everell]

Re: FSP400-60GLN worth fixing?

Statistics are great for politicians. But how come I end up with the really bad ones??? The very first power supply I worked on was the Bestec ATX-250 12E.....and it was a real nightmare! It had multiple problems. In the end, I took the basic 5vsb design using the DM311 from the Fortron GLN series, put the parts on a small piece of perf-board, and installed it on the Bestec. Worked great and no more 5vsb headaches. Now I don't fix two transistor 5vsb circuits on Bestecs. Too much trouble.