LN32B360 No power after a certain place on the power board

[zdsh07p9]

As the title states, I have no power after a large yellow thing on this power board. pics are below. Power goes into the H2-32-VM piece (to the left of the huge Yellow Capacitor) but does not go past that point. I need some help - I am a learning smd troubleshooter so please be basic

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

I replaced a lot of diodes today in a kit from ebay (repair kit) but still no luck

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

They were installed correctly (polarity-wise)

[budm]

Re: LN32B360 No power after a certain place on the power board

OK, was this unit worked by someone else before, what is the original problem.
What DC voltage do you get on that large yellow main filter cap (rated at 450VDC)?
What do yo use for ground ref for your meter?
Board is BN44-00289B, see SCH attached.

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

I don't believe anyone else has worked on this TV before, besides me. The original problem is the TV had no power to it. (no standby light) I have been looking at the other posts about it and they all say somethings wrong with diode 803-804 but I replaced those today. They also said to possibly lift one leg of the diodes out and test standby (I haven't done that yet). What should I use for the ground reference for my meter? I cant read the schematic. if you could help me with that? I want to learn, please.

Does 169 VDC sound correct for the big main yellow cap? I put my meter on 600V test DC and put the negative on the black side of cap and positive on the other leg.

[budm]

Re: LN32B360 No power after a certain place on the power board

For checking the standby output voltage which is on the secondary side ( cold side) of the circuit, you can use the chassis as the ground ref point for your meter, the standby should be present the minute you apply 120VAC to the board.
When you work on the primary side (hot deadly side) of the circuit, the negative leg of the main filter cap, the big 450vdc yellow cap) will be the ground ref for the DC primary side of the circuit.

"Does 169 VDC sound correct for the big main yellow cap?" that is correct when TV is plugged in but the power switch is not activated, once the power switch is activated, the main board will send out the PS_ON signal to turn on the PFC Voltage booster and the rest of the main power supply, the voltage on the yellow cap should be >360V for the rest of the power supply to function.
If you have standby voltage and have PS_ON but the voltage on the cap is still stuck at 170VDC, then the next thing to check will be the PFC section.

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

Oh okay, I used the chassis to measure the standby output voltage but what should the multimeter be set to, DC ?

Ah I understand. everything on the hot side the neg. leg of the yellow cap is what I need to use. cold side is the chassis.

[budm]

Re: LN32B360 No power after a certain place on the power board

"Oh okay, I used the chassis to measure the standby output voltage but what should the multimeter be set to, DC ?" 20VDC scale.
There are two standby voltages on this board, 13V (CN802 PIN 10, 11) and 5.3V (CN802 PIN 7, 8).
If the power suply is OK, if you disconnect the cable between the power supply and the main board, the backlights should come on the minute you plug the TV into the 120Vac OUTLET.

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

Well I just screwed up trying to test some more voltages. While doing that my hand slipped and the positive and negative of the main cap were put together for a second. it has a burnt spot near the positive side of the main cap.... Did I screw something up now? I don't get a reading of 169VDC from the main cap anymore

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

WAIT! Blew the fuse, checking measurements right now after putting in new fuse

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

Damn it blew it as soon as I put power to it.

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

Okay hahahaha, what do I do past that mistake to fix that mistake- DOH

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

The main and the 2 amp fuse blew

[budm]

Re: LN32B360 No power after a certain place on the power board

You probably blown the main AC fuse and hopefully the bridge rectifier will still be OK.
You should build the box to put the lamp in series with what you are working on so when you accidentally cross the connections, the lamp will protect the circuits.
https://www.badcaps.net/forum/showpo...&postcount=112

[budm]

Re: LN32B360 No power after a certain place on the power board

You need to check the bridge rectifier.

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

Can you tell me how to check that? its the blue boxes?

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

I Just found a piece that was blown into two pieces... its NT811s

[budm]

Re: LN32B360 No power after a certain place on the power board

That is the inrush current limiter. Did you check the bridge yet?

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

I don't know how to check the bridge sir, please instruct

[zdsh07p9]

Re: LN32B360 No power after a certain place on the power board

shoot I looked it up and I get:

neg. probe on positive, pos. probe on neg leg: .505

pos. probe on neg. leg, neg. probe on ac legs... like nothing (supposed to be around .505) I think shes a goner but I am glad im learning. its fun.

other way around its .505 on each AC leg (with neg probe being on positive and pos. probe being on AC legs