Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

[CapLeaker]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

and what is it doing with the PSU on?

[momaka]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

My “feeling” is that these main caps are still ok. But I know feeling does not rule out facts. But I would like to rule out some other things in the 12v circuit before touching the big boys. Any suggestions on how to trouble shoot for the next steps?

If you have a means to check caps (cheap tester is fine) for ESR and capacitance, just check the primary caps anyways. They are CapXon's, after all. Because if they are bad, they can cause the PSU to misbehave in very strange ways and possibly make you chase after problems elsewhere on the board that don't really exist.

One step forward the 5V circuit is now stable. If I push the on button the on board relay is switching. Unfortunately still no output on the 12v. The boosted power is rising from 350 when the psu is off up to about 390 when the psu is on.

Good.
Looks like at least the primary-side and 5VSB is working OK (aside from still having to check the primary caps.)
I'll try to take a look later to see how the 12V rail is being generated. Looks like a synchronous rectifier design (with MOSFETs.) Makes it considerably more complex to analyze and troubleshoot.

[Dynamite76]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

A “cheap” ERS tester is on its way…but it will take a couple of days to fly from China…. It the mean time I will focus on the rest of the circuit. At the high power side there is also this chip..? What does this chip do? Could not find a data sheet.


I was also trying to find any similar schematic but so far I was not successful…

[Dynamite76]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

and what is it doing with the PSU on?

Supervisor readings are: pgi pgo 0V fpo and pson 5V when psu off all 0V when psu is on

So when the psu is turned on both fpo and pson drop from 5V to 0V for the rest no changes in value

[Dynamite76]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

Any hint to further troubleshoot would be welcome… I a bit clueless where to debug further… ear I will check once the meter has arrived…

[Dynamite76]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

Anybody can help me further, my options have stalled a bit

[CapLeaker]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

On what are you stuck now? Did you get the new meter? Is the PFC working?

[Dynamite76]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

On what are you stuck now? Did you get the new meter? Is the PFC working?

I have no output on the 12V rail... and I am not able to trace the root cause. I think the main circuit is working as it is also supplying power to the 5V circuit, which looks stable now. Unfortunately the ESR tester is on it way and has not arrived so I can not check the main caps. When I push power on button the relay is activated and voltage level at main supply goes up from 350 up to 390. On the 12v side I have measured at many points but there is no voltage level at all, also the 5V supply to various chips is not there so it must be somewhere at the start of the system. The voltage to the control chips for the 12v circuit is seperated from the standby 5V circuit as far as I can tell from tracing lines.

[Dynamite76]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

If you have a means to check caps (cheap tester is fine) for ESR and capacitance, just check the primary caps anyways. They are CapXon's, after all. Because if they are bad, they can cause the PSU to misbehave in very strange ways and possibly make you chase after problems elsewhere on the board that don't really exist.


Good.
Looks like at least the primary-side and 5VSB is working OK (aside from still having to check the primary caps.)
I'll try to take a look later to see how the 12V rail is being generated. Looks like a synchronous rectifier design (with MOSFETs.) Makes it considerably more complex to analyze and troubleshoot.

I am still waiting for equipment to test the main caps... In relation to the 12V side, any input?

[momaka]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

I am still waiting for equipment to test the main caps... In relation to the 12V side, any input?

I haven't been able to trace much, since the PSU uses a double-sided PCB and there are too many components in the way to see how things are connected. But all I can tell you is that the 12V rail uses synchronous rectification. There are 2 N-ch MOSFETs located between the main transformer and main output toroid. You can see them on this picture of yours here (see towards upper left corner):
https://www.badcaps.net/forum/attach...6&d=1692212985

One of these MOSFETs is Q152. The other one I can't read the PCB designator. Both are attached to long aluminum heatsinks. Their connection is probably the same as the output of this PlayStation 3 PSU that I posted here:
https://www.badcaps.net/forum/attach...1&d=1526486481
In particular, your MOSFETs should be connected similar to how Q201 and Q202/Q203 are connected (Q202 and Q203 are in parallel, so you can regard them as one larger MOSFET.) However, please verify if that is true or not. To do that, use resistance measurement on your multimeter. If true, both MOSFETs on your PSU should have their Source pins connected to ground (you'll get 0-1 Ohms of resistance when checking between ground and the Source pin of each MOSFET) and their Drain pins should also show very low resistance to the 12V rail.

Now also verify that neither of the MOSFETs have a short-circuit between their Source and Drain pins, Source and Gate pins, and Drain and Gate pins. Let me know what you find.

When I push power on button the relay is activated and voltage level at main supply goes up from 350 up to 390.

Good. That means at least the APFC circuit is working and that none of the main power-handling components are shorted.

[Dynamite76]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

One of these MOSFETs is Q152. The other one I can't read the PCB designator. Both are attached to long aluminum heatsinks
In particular, your MOSFETs should be connected similar to how Q201 and Q202/Q203 are connected (Q202 and Q203 are in parallel, so you can regard them as one larger MOSFET.) However, please verify if that is true or not. To do that, use resistance measurement on your multimeter. If true, both MOSFETs on your PSU should have their Source pins connected to ground (you'll get 0-1 Ohms of resistance when checking between ground and the Source pin of each MOSFET) and their Drain pins should also show very low resistance to the 12V rail.

Now also verify that neither of the MOSFETs have a short-circuit between their Source and Drain pins, Source and Gate pins, and Drain and Gate pins. Let me know what you find.
.

I have tested both the mosfets Q152 and Q154 and indeed the Source in conneted to ground and the Drain to the 12V rail.
I have only measured the mosfets in circuit so the readings on the pins are bit jumping arround. In diode mode i get 0,5V between S->D, about 20 KOHm between G and S (20K resistor) The rest of the measurements are jumping a bit, but no direct sign of shortcut...
Both the Gates are routed via a 0 Ohm and a parallel restistor 5.4 Ohm to the controller chip PM8834 - EZ141
There is no Power supply on this chip, measured between VCC and Ground...

The VCC is leading via a 27kohm resistor to pin 1 of a chip 19 M8P TJ?



I have measured at some other location but it looks like there is no volage on the control circuit.

[momaka]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

I have tested both the mosfets Q152 and Q154 and indeed the Source in conneted to ground and the Drain to the 12V rail.
I have only measured the mosfets in circuit so the readings on the pins are bit jumping arround. In diode mode i get 0,5V between S->D, about 20 KOHm between G and S (20K resistor) The rest of the measurements are jumping a bit, but no direct sign of shortcut...
Both the Gates are routed via a 0 Ohm and a parallel restistor 5.4 Ohm to the controller chip PM8834 - EZ141

OK, at least that eliminates the MOSFETs as the culprit.

There is no Power supply on this chip, measured between VCC and Ground...

The VCC is leading via a 27kohm resistor to pin 1 of a chip 19 M8P TJ?

That's strange. Seems unlikely to me to have a 27 KOhm resistor in series with the Vcc, so perhaps that's not where the Vcc is generated from?

Does the 5VSB transformer have one or two outputs on its secondary side? If there are two outputs, the 2nd one could be used for Vcc of the controller chip (though likely won't be connected directly to it and probably would be gated by the supervisor chip at the same time the primary side is enabled via optocoupler.) And even if there is no 2nd output from the 5VSB traffo, perhaps the controller chip is powered by 5V via 5VSB. Though my hunch is that the Vcc should be higher than 5V, likely to drive the output MOSFETs a little harder for lower R_ds On state.
It could also be the Vcc is produced by a separate rectifier from the main transformer... though that also seems unlikely to me, since it would take at least a few cycles through the main transformer before Vcc is established, so maybe not the case.

If you have a datasheet of the controller chip, maybe try giving it something like 12V directly on the Vcc pin and try to power on the PSU immediately to see what happens. I'd save this experiment for a latter point or almost last resort, as you'll have to analyze first what would be the consequences of feeding 12V into the Vcc of the controller IC. To do it safer, you can use a 100 Ohm resistor in series, so in case something goes awry, the 100 Ohm resistor will limit the current to 120 mA.

Another experiment would be to feed the PSU's 12V rail with a 12V source (a small 2-3 Amp adapter should do, though using another ATX PSU should be fine too.) For this one, first power the 12V source (ATX PSU or adapter) and check if there's a high current drain going into the 12V rail. If none, then power On the PSU by connecting PS-ON to ground. Now try removing the 12V source and see if the PSU continues to run OK.

[leetrung]

Re: Dell D635EF DELTA DPS-635AB PSU with blown TNY280PN

A “cheap” ERS tester is on its way…but it will take a couple of days to fly from China…. It the mean time I will focus on the rest of the circuit. At the high power side there is also this chip..? What does this chip do? Could not find a data sheet.


I was also trying to find any similar schematic but so far I was not successful…

Please look at https://pdf1.alldatasheet.com/datash...P/CM6502S.html