LF501EM5F No Power, Chirping/Beeping Transformer

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

I check all the diodes. None were shorted. check as many of the surface mount diodes on the back side as I could and they all seemed fine too

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Have never had 3.3vdc. Doesn't matter if the ribbon cable is plugged into the board or not. 3.3 is not present. As far as the chirping that only happens when the ribbon cable is plugged in. I have not tried to plug the ribbon cable in with the resistor soldered in place.

OK, then we need to look at the ALL+3.3V standby power supply section first then, we know we do have the main DC 160V to run the standby power supply section, we will be working on the power supply board without any other board connected to it at this point and try to get the 3.3V working first.
I will have to look at the diagrams. BTW, did you do any testing of the Diodes on that power supply board?

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

checked all the surface mounted caps you mentioned on the back side of the power supply and the all measured over 3k ohms and above.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

slk001 I'm assuming you are talking about the surface mounted caps on the back side?

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Have never had 3.3vdc. Doesn't matter if the ribbon cable is plugged into the board or not. 3.3 is not present. As far as the chirping that only happens when the ribbon cable is plugged in. I have not tried to plug the ribbon cable in with the resistor soldered in place.

[SLK001]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

If you are only getting 160V on your main caps, then C605, C606 or C607 is probably shorted.

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

So you do not have 3.3VDC at the ALL+3.3V then without connection to the main board? And how about the chirping and beeping of the transformer? It does that without the main board connected to the power supply board or connected to the power supply board?

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

that is with the main board unhooked

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

The 165 remains steady but the 3.3 is only 1.9mv basically nothing

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

OK, remove the cable between the main board and the power supply board, you are going to solder a resistor (anything between 330 Ohms to 1000 Ohms 1/4 or larger will be fine) between the ALL+3.3V jumper (J151??) and the P-ON-H2 jumper to force on the power supply, when you plug the TV into the outlet, the 3.3V should be steady and and then you should have >160VDC (the diagram shows 230V, not sure if that is correct or not) on the main cap.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

If I unplug the cable to the main board it is steady 166

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

seems like just as the main cap starts to discharge it tries to restart. It holds at 165 volts for proably .8 sec and then starts to drop and at roughly 145 volts it starts back up and shoots up to 165 volts. Kind of hard to measure

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

You mean the TV is powering on and off but the 160VDC on the cap is steady?

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Ok with the main board plugged in I'm getting 2.79mv and that was using the min max on volt meter because it cycles on off on off about every 1 to 1.5 seconds.

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Check the DCV between the chassis and the jumper J189 (P-ON-H2, it is next to the black connector of the power supply board) when the TV is turned on, we need to find out if the power supply board is getting this turn on command signal from the main board or not.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

ok, so now what?

[CapLeaker]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Budm how about we start right where pillit83 quit. I have 168vdc

168V is only rectified mains, like with the TV turned off. If you have the TV turned on and still get 168V, that means your PFC (Booster circuit) isn't working, which should read over 360V DC on the main filter cap. No boosted voltage, no 12/24V DC rail.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Yes, the psb is BA3AUOF0102 3, Same board same voltages

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Ooops, I gave the wrong link:
https://www.badcaps.net/forum/showthread.php?t=54078

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

So your board is exactly the same as shown in this thread and the link to the other thread I provided?