Corsair GS800 Power Supply Problem

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Re: Corsair GS800 Power Supply Problem

".237 nF" seem correct for this capacitor (C15)? When removed the voltage is WAY more stable around 4.2v.

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Re: Corsair GS800 Power Supply Problem

Decided to chase the voltage. Applied 15v to riser board. Maybe one of these two caps that are in parallel? Update:First two caps where the voltage drop begins are fine.... Gotta be getting close. Any ideas?

D4 testing odd in circuit. D2 testing fine. D4 look bad to anyone-goes to PFC driver output on cm6800 controller? Hard for me to tell when in parallel with other components. if D4 I don't understand why a drop at the two capos where the 3.7v drop begins. Why not after the diode? Or maybe it is one of the two caps where the drop is first noted? I don't have an EST just doing a simple capacitance test with DMM.

* voltage unstable bouncing from 3.7-4.2v

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Re: Corsair GS800 Power Supply Problem

Tagged some jumper wires directly to the original controller while still in-circuit and got a stable 7.5vdc for Vref and a stable 1.766vdc for Vfb. Consuming 21mah. Maybe surrounding SMDs causing the erratic readings?


New-out-of-circuit consumes 0mah during testing.

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Re: Corsair GS800 Power Supply Problem

Removed riser board on primary side again to get to the PFC controller (CM6800tx).

Traced the riser board to Vcc of this PFC controller (in-circuit) and applied 15vdc (typical) to the riser board which results in 10.1vdc to pin13 of the cm6800. Reasonable voltage drop? datasheet states min. is 10vdc.

Pin 14 is Vref and should be 7.5vdc. It does go to 7.5dc but is extremely unstable, drops out completely then jumps back to 7.5vdc.

Pin 15 Vfb Is typical 2.5vdc and is actually .0663.

All of the above testing is in-circuit.

I put a new CM6800TX in breadboard applying 15vdc to vcc. Vref gives a stable 7.669vdc and Vfb provides a stable 2.18vdc.

Question: original controller faulty or just normal in-circuit? Interesting...that Q12 PNP that RJ found was shorted causing PSU to be in constant-on state traces to VCC on riser board. Is it likely that Q12 being shorted damaged PFC controller (CM6800TX)?

Thanks for any help.

Top Photo: Third pin from top is ground 6 is Vcc for controller.

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Re: Corsair GS800 Power Supply Problem

Connected oscilloscope (TDS 320) to 12v and there is no response. Did same for 5v and 3.3...no signal.

Primary side detecting a problem and not trying to startup secondary side optocouplers maybe? Could the Q12 short have caused other damage along the same circuit maybe? It seems Q12 is controlled by pin 5 of the CN1 riser board. Has 160vdc to positive terminals of Q12, but negative terminal is no being grounded by the CM6800 riser card as it was shorted before and constant on state. Reference. post 82.

- U10 oc controls appears to control 5vstdby
- U3 and U5 maybe signal for large transformer.

U3 and U5 trace back the the vertical riser board (CN1) on primary side. Controller IC on this riser is a CM6800TX.

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Re: Corsair GS800 Power Supply Problem

Supplied corresponding power to each rail (secondary side; 3.3, 5 and 12) to see current draw-PSU tester not connected:
1. 12v - 137mah
2. 5v - 61mah
3. 3.3v - 1mah

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Re: Corsair GS800 Power Supply Problem

Sleep helps.

Power supply tester is applying a 329mah load to 5v+ rail. 15 ohm resistance I have been chasing is in the power supply tester itself. UGH again! Without PSU tester in place and 12v applied to daughter card w/bench power supply current is 137mah. This sound right?

Applied 12v to daughter board with a thermocouple attached. U1 temp rose from 77f to 96f and settled there in about in about one minute-draw at 307mah. Removed PSU tested and current dropped to 136mah but temp stayed at 99-100f.

Current state in this Corsair PSU SAGA is 5v stdb that does not power on. That is serious progress from where this thing started.

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Re: Corsair GS800 Power Supply Problem

Pulled Q6, Q7 and Q8 15 ohm short remains. D/S diodes checked out OK out-of-circuit.
Pulled U1 short remains. UGH

red dot to green dot is 128ohm in image below. This is the same for the 3.3v, and 12v rail to ground, but 15ohm to the +5v rail and open circuit when power supply tester is removed.

red dot to yellow dot is 15ohm in image below.

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Re: Corsair GS800 Power Supply Problem

In-circuit PH1 (8) is grounded (15 ohm) to daughter board ground.

Pin PH1 (8) to PGND (10) is 15 ohm in-circuit

Pin PH1 (8) to GND (4) 15 ohm in-circuit.

I'm no EE...just an unhealthy obsession with fixing "stuff." This appear problematic? Maybe LG1 or UG1 shorted as you suggested?

Pic shows PHL circuit. Sure seems the short is in this region.

Looks like alibaba is only source. Emailed mouser and digikey for availability.

Q 6, 7 and 8 are identical. Probing Q7 and Q8 in-circuit from D to S is 15 ohm. surrounding CCs are not showing short in-circuit.

Pulled D2 short remains. Diode good.

[R_J]

Re: Corsair GS800 Power Supply Problem

Without the ic driving UG & LG the vcc current should be around 5~10ma @12v. Check that the mosfets are not shorted. As for a source, likely China

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Re: Corsair GS800 Power Supply Problem

Applied 12v to daughter board and it drew 300mah (PS set to 800mah). U1/uP3861P did get warm. Any ideas on testing this 20-pin to confirm? Thanks for any help. PS tester makes a very interesting high frequency noise/squeal not made when connected to other power supplies.

Anyone know where would I find these uP3861P? OrderNo. uP3861PSAF SOP-20L

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Re: Corsair GS800 Power Supply Problem

When I plug in this power supply tester I have 15ohm on +5v rail. If I simply jump green-ground at 24-pin for power on signal this short is not present. Verified PS tester works on another known good PS.

Pulled the only +5v signal from this daughter board to the main PCB which runs from this daughter board and the 15 ohm short remains. Will dig around on the daughter board.

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Re: Corsair GS800 Power Supply Problem

Catching up (almost a year)...Power supply was constant power-on state. We found Q12 (primary side PNP transistor shorted collector to emitter out-of-circuit and possible (actual) cause for constant on state. Replaced w/ PBSs5350t as R_J stated to me repeatedly-THANK YOU! No longer constant on when replaced. PSU now only gives +5vsb. Main cap is 160vdc.

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Re: Corsair GS800 Power Supply Problem

Found another ZD SOT 23

Testing the replacement out-of-circuit:
1. collector-emitter: no drop both directions (diode test)
2. collector-base: .6v and 0 drop (diode test)
3 base-emitter: .6v to 0 drop

Seemingly functional? If so, I will install. The original is definitely shorted from collector to emitter.

[R_J]

Re: Corsair GS800 Power Supply Problem

Thanks...will source this'es.

Would these work? I can get these within a reasonable time frame and if that fixed this PS I could acquire an original for a final solution. Can't seem to find the 5350ts in USA.

Specs:Collector-Base Voltage: 40V
Collector-Emitter Voltage: 40V
Emitter-Base Voltage: 5V
Collector Current: 200mA
Mfr: ON Semiconductor
Package: SOT-23
DC Current gain: 30-300

Not going to work, only 200ma, you need 2amp
Digikey has the originals

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Re: Corsair GS800 Power Supply Problem

"these" won't work. you need "this"...PBSs5350t PNP transistor

Thanks...will source this'es.

Would these work? I can get these within a reasonable time frame and if that fixed this PS I could acquire an original for a final solution. Can't seem to find the 5350ts in USA.

Specs:Collector-Base Voltage: 40V
Collector-Emitter Voltage: 40V
Emitter-Base Voltage: 5V
Collector Current: 200mA
Mfr: ON Semiconductor
Package: SOT-23
DC Current gain: 30-300

[R_J]

Re: Corsair GS800 Power Supply Problem

I have "these" and "these".

"these" won't work. you need "this"...PBSS5350t PNP transistor

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Re: Corsair GS800 Power Supply Problem

Do you need to order them or do you have "these" if you need to order them, order the originals

I have "these" and "these" Dang...cant wait a month from china....Will dig through my bin and see...maybe I will find something on a scrap PCB. Will update the thread as soon as I find something.

old roomba board is loaded with W2T W2Xs and A7Ws....?

Will re solder pin 5 to riser card and remove that transistor and see if it stays off. Safe test?

[R_J]

Re: Corsair GS800 Power Supply Problem

Will these or these work as replacements?

I knew I remembered the ZDW: https://www.badcaps.net/forum/showthread.php?t=83465

They won't work, "these" are N channel mosfets, you need a PNP transistor

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Re: Corsair GS800 Power Supply Problem

The ZD is a PBSs5350t, here is the pinout. I suspect the transistor is shorted emitter to collector, that would explain why the ps won't turn off.
W = made in China
19 = date code

Will these or these work as replacements?

I knew I remembered the "ZDW": https://www.badcaps.net/forum/showthread.php?t=83465