Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

[bznhvx]

I see that the typical problem with this board (used in a Sharp LC-52E77UN) is the loss of the 5V standby and there is a kit for the replacement components. I checked those components and they are good, and I have a solid 5v standby. I have a schematic for the CPU board, but not the Delta DPS-286AP board. There is a lot of voltage error checking (monitoring) done from the CPU, and the LED blink codes indicate no UR10V or AV9.

If I bench test the Delta board and use a 1K pull-up resistor between the 5v and PS_ON signal pin, I can hear the enable relay click on. I've checked the accessible diodes and TIP31 and found them all to be functional.

There is a PQ30RV31 4 terminal regulator that is not getting voltage to its input. I could really use a schematic of this board before I go poking around on the primary side. Anyone familiar with this board or have a schematic?



Mac

[R_J]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

If you are asking about IC7121, it is the PNL12V, switch. You need another resistor from stby5v to the PNL_POW line to turn on this regulator
I think you have the pin numbers wrong for the regulator Do you have 13.5v on PD pin1,2?

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Thanks R_J. Yes, you are correct on the PNL_POW. I do not have 13.5v on PD 1,2. I think that power is supposed to feed the PNL12V switch as well. Pin 1 is input, pin 2 is the output I believe, but since I'm not getting the 13.5V to it, the problem looks to be upstream.

I started tracing from mains direction and I have 170VDC out of the Bridge, but the circuit gets a little confusing between there and the isolation transformer bridging the primary and secondary parts of the PS. I assume they are chopping the 170VDC and feeding the resulting A/C to the transformer? Going to put a scope on it and look for movement.

[R_J]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Don't connect your scope to the primary side unless you have an isolation transformer, or your scope is not line powered (battery powered or powered by adaptor)

Check R7641 (locate on the bottom) it is hiden under a heatsink. If it is open, check Q7601 & Q7602

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Check R7641 (locate on the bottom) it is hidden under a heatsink. If it is open, check Q7601 & Q7602

R7641 is not open... must be a very low ohm resistor (0.4 or so?). Q7601 and Q7602 seem good. Looking for my isolation transformer... I know I have two, but where did I leave them...?

[R_J]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Check the voltage on the main filter in standby, (160VDC) and then when the power supply is turned on, the voltage should increase to (380VDC)

Because of the heatsink, You can use:
J7030 Hot ground
D7908 (anode) Check for PFC voltage (380vdc)

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

I found one of my isolation transformers... will look to see if the PWM is going on the primary side in the morning.

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Will check for the 380vdc as well.

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Check the voltage on the main filter in standby, (160VDC) and then when the power supply is turned on, the voltage should increase to (380VDC)

Because of the heatsink, You can use:
J7030 Hot ground
D7908 (anode) Check for PFC voltage (380vdc)

I'm getting 170VDC in standby, and when I pull up the PS_ON to the 5vBU, I hear the relay engage, but the voltage from J7030 Hot ground to
D7908 (anode) goes to 168vdc instead of 380vdc.

[R_J]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

That means the PFC circuit is not working, once the power supply is turned on the pfc should boost the B+ to 380+ volts.
It looks like Q7808 & Q7805 are the pfc outputs, the driver ic looks like IC7801, Post the numbers of IC7800 & ic 7801.

[budm]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

https://assets.shopjimmy.com/media/c...jqz-bottom.jpg

Check the resistance of the PFC Diode D7805.

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Measurements of 7801:

Pin
1 - 1v
2 - 6.3v
3 - 0.85v
4 - 0v
5 - 1v
6 - 0v
7 - 0v
8 - 13.5v

After taking the above measurements, I was re-checking, and heard the relay turn off. The line fuse had blown. I'm pretty sure I didn't short anything, but the noise injected from my probe might have caused a problem. Found a shorted K3569 (Q7808 or Q7805... not sure which one). Also observed that a fair amount of lint was present between the legs of both drivers... I wonder if that could have been providing a path to disturb gate drive?

Anyway, the K3569 looks to be obsolete. Mouser shows TK10A60D as a sub.

Thoughts?

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Check the resistance of the PFC Diode D7805.

Thanks Bud. D7805 tests normal.

Would you have a schematic for this Delta board? That would help me a bunch.

Mac

[R_J]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

No schematic for this board, the sub for the fet should be TK750A60F
I asked for the numbers from the ic's, you did not need to check the pins, as they are very close together and as you found out, easy to slip and cause more problems. The best way to check the ic's voltage would be to follow the trace and check on the nearest component.

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

No schematic for this board, the sub for the fet should be TK750A60F
I asked for the numbers from the ic's, you did not need to check the pins, as they are very close together and as you found out, easy to slip and cause more problems. The best way to check the ic's voltage would be to follow the trace and check on the nearest component.

That's exactly what I did... not on the IC. The numbers on the ICs are very difficult to see, but under double magnification, at an angle, I believe the numbers are:

D26Z3 and ETR23

Mac

[R_J]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Could this be it? I suspect it is a L6562DTR, the etr23 are likely date codes. If you happened to short pin 8 to pin 7, that would have damaged the mosfet, It may have only damaged one as they are in parallel, I would also check if ZD7807 & ZD7811 are shorted, You would need to lift one end to check them as they likely have a low ohm resistor in parallel.

It does look like you had a proper vcc voltage on pin 8.

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

...It may have only damaged one as they are in parallel, I would also check if ZD7807 & ZD7811 are shorted, You would need to lift one end to check them as they likely have a low ohm resistor in parallel.

It does look like you had a proper vcc voltage on pin 8.

ZD7807 & ZD7811 check out as good. With the shorted MOSFET out of the circuit, would it be OK to power back up to continue troubleshooting? If the shorted MOSFET was in parallel for load capacity, then it would seem that I could operate without the loads (inverters, CPU board) without an issue? I should have a replacement MOSFET in a day or two.

Thoughts?

[R_J]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

It might work, as long as when the fet shorted it did'nt damage the ic's output, sometimes this happens when the drain shorts to the gate in a fet.

[bznhvx]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

OK, replacement MOSFET installed and we are back to where we were. Getting 168VDC but not doubling when the PS_ON is activated and the relay clicks on. What next?

[R_J]

Re: Delta DPS-286AP (RDENCA336WJQZ) Troubleshooting

Check the VCC sources, using hot ground (J7030 Hot ground) check the voltage on:
D7910 (cathode)
D7904 (cathode)
D7919 (cathode) (should be 18v)
J7801 (should be 15v)