Haier Power Supply Board AY090D-4SF01

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

Maybe test the powerboard as stand alone, UNPLUG everything from it, then grab 3 resistors and jumper them as in post #10, see if the voltage on those main caps go above 161.3. trying to see if the powerboard is doing what it should.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

Some testing and tips from shopjimmy: https://www.youtube.com/watch?v=4RzuLiRTzJg

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

More simple testing from shopjimmy: https://www.youtube.com/watch?v=2pyuXwNkBMA

[Nicktronic]

Re: Haier Power Supply Board AY090D-4SF01

Maybe test the powerboard as stand alone, UNPLUG everything from it, then grab 3 resistors and jumper them as in post #10, see if the voltage on those main caps go above 161.3. trying to see if the powerboard is doing what it should.

So I did what was said in Post #10. I had a 3 multimeters on C2, C3 and the output of CONF3 and set the meters to MIN/MAX. C2 and C3 never climbed past 166.3 VDC. The output of CONF3, on the other hand, peaked at 122.3 VDC on power up and then dropped to and settled on about 59.4 VDC.

[lotas]

Re: Haier Power Supply Board AY090D-4SF01

So I did what was said in Post #10. I had a 3 multimeters on C2, C3 and the output of CONF3 and set the meters to MIN/MAX. C2 and C3 never climbed past 166.3 VDC. The output of CONF3, on the other hand, peaked at 122.3 VDC on power up and then dropped to and settled on about 59.4 VDC.

This suggests that the problem is in the backlight, as I already wrote.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

ok, so I don't know about all tvs, but a lot of the ones I mess with, if you don't have the boosted pfc voltage which boosts the voltage of those caps to more that 360 volts usually, then you don't get backlights on.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

a good rule and sometimes a real time saver, is to be sure and check for starters ALL diodes and resistors on top of the board.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

ok, so if you did not, while you have those jumpers in place, plug in the backlights and retest. UNPLUG the power then plug in backlight connector then plug power cord back in then retest.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

prolly is the backlights, AS it usually is, so tear it down and check them.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

check those 2 shopjimmy links I posted, they are simple to follow.

[lotas]

Re: Haier Power Supply Board AY090D-4SF01

Yes, on C2, C3 you have low voltage, are they connected in parallel or in series, and what is your voltage in the outlet?

[R_J]

Re: Haier Power Supply Board AY090D-4SF01

So I did what was said in Post #10. I had a 3 multimeters on C2, C3 and the output of CONF3 and set the meters to MIN/MAX. C2 and C3 never climbed past 166.3 VDC. The output of CONF3, on the other hand, peaked at 122.3 VDC on power up and then dropped to and settled on about 59.4 VDC.

There is no pfc circuit on this board so your voltage across the main caps of 166vdc is good, the fact that your voltage on CONF3 peaked at 122vdc indicates what was suggested before (post#3), You have a BAD LED in the panel.
The led boost voltage is shutting down because it detects a fault. Your backlight tester only test the circuit with low current (about 30ma) when the leds are working properly they draw about 130ma. The led drive circuit monitor over voltage as well as current and if it is wrong, it goes into protection.
This is a universal input power supply (90vac~264vac) that is why the man caps are rated for 450vdc
The LED DRIVER output is rated 85v at 530mA

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

ok, so no pfc on this one, Budm use to always tell people how to check backlight voltages by turning tv on and off, I think whats confusing a lot of people is what it should do when doing that test, I forgot and can't locate the exact procedure in Buds posts, can you explain it RJ?

[R_J]

Re: Haier Power Supply Board AY090D-4SF01

The backlight circuits are all different, some have Over Voltage Protection, some have Under Voltage Protection, and Current monitoring, some circuits use all.
The best way to test the voltage is across the + and - of the led connector (in this case) You must monitor this voltage as the tv is turned ON,
In this case the board spec is 85v under normal operation, The fact it peaks at over 100vdc suggests the led circuit is going open and the circuit detects an Over voltage and shuts off the boost circuit, the 60vdc is just the raw dc supplied to the drive circuit.
This is a very simple led drive circuit used on this board, some circuits are more complicated as in multiple strings and the circuit can check the current faster than you meter reacts and if the led current is wrong, the boost circuit may not even start.
Others have a constant supply voltage and only control the return path of the led string

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

Thanks RJ, so looks like the the over peak tells the problem, if it was ok it should be around 85vdc as rated and not spike up over 100vdc or settle to 60vdc, that's a good bit of info and will help a lot of people that don't have a meter that puts out enough ma. for effective testing.

[R_J]

Re: Haier Power Supply Board AY090D-4SF01

Guessing at this model to be a 43UG2500a it would use 4 strips with 8 led's per strip @ 3v each would be a max of 96v.

Remember when we tell people to turn down the backlight setting to see if the backlights stay on longer (if they fail after being on for a while) turning down the setting usually reduces the current through the strips, so less strain on the weak led. It only takes one in the series string to fail and trigger the protection.

[Nicktronic]

Re: Haier Power Supply Board AY090D-4SF01

This suggests that the problem is in the backlight, as I already wrote.

The backlight was disconnected though. Does it not still maintain the output voltage if the backlights are disconnected?

[Nicktronic]

Re: Haier Power Supply Board AY090D-4SF01

Guessing at this model to be a 43UG2500a it would use 4 strips with 8 led's per strip @ 3v each would be a max of 96v.

Remember when we tell people to turn down the backlight setting to see if the backlights stay on longer (if they fail after being on for a while) turning down the setting usually reduces the current through the strips, so less strain on the weak led. It only takes one in the series string to fail and trigger the protection.

I will confirm the model tonight and recheck the LED strips, but I figured when I saw the 114 VDC on my tester when I connected to the whole array that that was the minimum voltage required.

[lotas]

Re: Haier Power Supply Board AY090D-4SF01

The backlight was disconnected though. Does it not still maintain the output voltage if the backlights are disconnected?

Led Driver did not see the load on the connector, it could be the backlight turned off, a break in the LED line, ...), the driver protection worked and the voltage dropped.

[R_J]

Re: Haier Power Supply Board AY090D-4SF01

The backlight was disconnected though. Does it not still maintain the output voltage if the backlights are disconnected?

No. without the led's disconnected, the drivers boost circuit will shut down, It will see an over voltage and also no current draw. The only voltage you will see is the raw DC (60v) in this case supplied to the driver circuit.