Haier Power Supply Board AY090D-4SF01

[Nicktronic]

Hey Everyone,

I have this Haier 43" TV Power Board that is not supplying enough voltage to turn on the LED Backlights. When the TV is powered on, I get about 60 VDC at the connector for the backlights (CON3F) and this is regardless of the backlights being connected or not. I've tested the backlights with a tester and they all work (about 120 VDC for full illumination). So it appears I'm getting half the supply voltage. I've changed out the 22uF 200V cap (C25F) with a 22uF 450V that I had kicking around. No change and the original cap tests good and discharges normally.

I've confirmed all voltages on CON2 are present and stable.

I'm not sure on how to go about testing components further up the line from C25F, and I'm hoping for some advice!

See attached pictures of the board.

Thank you!

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

Try checking CON 4, on-off, check it in standby, leave probe where it is hit power, what are the voltages both ways?

[lotas]

Re: Haier Power Supply Board AY090D-4SF01

Rather, you have a faulty backlight (a break, even one LED is faulty and the LED garland circuit will be broken) and there will be no current consumption at the output and the led driver will not raise this voltage.

[Nicktronic]

Re: Haier Power Supply Board AY090D-4SF01

Try checking CON 4, on-off, check it in standby, leave probe where it is hit power, what are the voltages both ways?

Ok, I will do that on the bench and let you know.

[Nicktronic]

Re: Haier Power Supply Board AY090D-4SF01

Try checking CON 4, on-off, check it in standby, leave probe where it is hit power, what are the voltages both ways?

Is that voltage supposed to generated on the Power Board or is it supplied by the Main Board? I don't remember if anything was connected to CON4, and I'm at work and the TV is home, so I can't check right now.

For what it's worth, though, I measured 0 VDC in both standby and when I provide the PS_ON signal to fully turn on the P.S.

[Nicktronic]

Re: Haier Power Supply Board AY090D-4SF01

Rather, you have a faulty backlight (a break, even one LED is faulty and the LED garland circuit will be broken) and there will be no current consumption at the output and the led driver will not raise this voltage.

Thank you for your reply, but as I stated initially, the backlights were tested and all work....

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

Is that voltage supposed to generated on the Power Board or is it supplied by the Main Board? I don't remember if anything was connected to CON4, and I'm at work and the TV is home, so I can't check right now.

For what it's worth, though, I measured 0 VDC in both standby and when I provide the PS_ON signal to fully turn on the P.S.

Not exactly sure on this one but I believe thats the backlight on signal that goes to that pin and it comes from the mainboard.

[lotas]

Re: Haier Power Supply Board AY090D-4SF01

Con4

[jsdffxf]

Re: Haier Power Supply Board AY090D-4SF01

power on produces 5sb motherboard working on/off, then after 10 seconds, the remote control press power, the motherboard first produce on/off normal work, (if the motherboard fails to start, then stop working) no longer produce blon and adj. The power board needs 3 operating voltages to work alone. on/off blon adj loading 5vsb at the same time can light the LED

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

so procedure is probably use three 1k ohm resistors to jump ps-on, adj and on/off all 3 to 5sb, make sure that ALL mainboard to powerboard cables are unhooked, then plug in power cord and see if backlights come on and stay on while it's jumpered.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

Thought that should be the procedure but really have not dealt with this exact model.

[Nicktronic]

Re: Haier Power Supply Board AY090D-4SF01

Ok, so had a chance to hook the power board back up to the TV.

In Standby;

CON4

ON/OFF - 0VDC
ADJ - 0VDC

CON1

5VSB - 5.09VDC
PS_ON - OVDC

All supply voltages - 0VDC

TV Power Button Pressed (LED lights did not come on):

CON4

ON/OFF - 4.87VDC
ADJ - 3.12VDC

CON1

5VSB - 5.09VDC
PS_ON - 4.88VDC

All supply voltages - 12VDC, 12VDC, 5VDC, 5VDC

CON3F - 72VDC

LED Backlight Tester - 114VDC minimum voltage to turn on backlights.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

Can you very carefully check the dc voltage of C2 and C3 with tv powered on, probe on each leg, careful not to touch it with your hands could be around 400 volts which can be DEADLY.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

Not sure about CON 3F but the rest looks ok, did you check all the diodes on top of the board?

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

Maybe try heating those electrolytic capacitors with a hairdryer for a couple few minutes then try it, see if it acts any different, don't wait for them to cool off, try it while it's still hot.

[Nicktronic]

Re: Haier Power Supply Board AY090D-4SF01

C2 and C3 have 161.3 VDC each across them. Are those the ones you are suggesting to heat up? I have a heat gun.

D4, D5 and D20F are all about .4 VDC one way and open the other way. So good I think?

[Nicktronic]

Re: Haier Power Supply Board AY090D-4SF01

I tried heating up the board with the heat gun and the only reaction i got was a slow decrease in the 72VDC output to the LEDs as i heated up the board in that corner (see attached picture 3). It dropped as low as 67VDC and when i removed heat, it climbed back up to 72 VDC.

[Rajnhl]

Re: Haier Power Supply Board AY090D-4SF01

check backlight supply while tv is booting. if it goes up (more then 114 volt in this case) and drops then back lights are problem. if this is not happening then give 3v to 5v to Bl on and Bl adj pin on connector.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

I tried heating up the board with the heat gun and the only reaction i got was a slow decrease in the 72VDC output to the LEDs as i heated up the board in that corner (see attached picture 3). It dropped as low as 67VDC and when i removed heat, it climbed back up to 72 VDC.

No a heat gun could potentially get them too hot, a hairdryer for a couple minutes is all that's needed, heat them all, be sure to get the ones near CON 3F too, it's just a test that can temporarily lower the esr and make a weak cap work for a bit, usually just heat all the electrolytics and try it, it won't work if a cap is too far gone but your caps may be ok.

[nomoresonys]

Re: Haier Power Supply Board AY090D-4SF01

C2 and C3 have 161.3 VDC each across them. Are those the ones you are suggesting to heat up? I have a heat gun.

D4, D5 and D20F are all about .4 VDC one way and open the other way. So good I think?

Is the 161.3 in standby, is it the same when powered up? I would expect it to go up to about 400 volts or so when powered up.