ILO PDP4210ea1 unstable Buffer Voltage from Ysus

[ZnsaneRyder]

I am trying to repair an ILO PDP4210ea1 42 inch LG-Based plasma.

Panel LG PDP42V7 is on the panel.

Power light turns on green like normal, but I get no picture.

When I disconnect one, or both buffer boards from the power output terminals of the Ysus board, (leave the fine wires to the buffers connected) I get 120V out from the Ysus. When I connect EITHER the upper OR lower buffer boards, still get 120V, but when BOTH boards are connected, I get unstable voltage between 40-75V jumping up and down.

If I disconnect the fine wires on the buffers, or completely remove one or both of the buffer boards, I get no output from Ysus, which I assume is normal.

I am wondering, if this is caused by a bad buffer causing overload on the Ysus, or is the Ysus itself need to be further diagnosed?

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Update, I found a blown fuse on the Ysus board and replaced it. I measured no shorts on the MOSFETS or the big IPM IC CHIP.

I now keep good voltage (120V) on the buffers and the VS is 187.8 (188v) like it is supposed to, but I still get no image. You can hear the normal buzzing like you hear when the TV is working, but I still get no image, or menu.

I am trying to figure out why the Ysus fuse was blown, but no signs of failure from the Ysus or buffer boards.

I am wondering if a power surge hit this TV.

[ReeceyBurger123]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Pictures ?

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Pictures of inside of TV. Inside is similar to other TV that uses the same LG panel.

[Alastair E]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

I'll bet one of the IPM's is open....

--Prob the Y-SUS one, seeing there's nothing on screen.....

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

If the IPM is open, would the TV still produce good voltage to the buffers? Looking at the board, it seems power flows from the IPM, to the MOSFETS, to the buffers.

Is it possible it could be a mainboard not working, because all the voltages seem good makes me wonder if it's that and not really something relating to the display.

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

UPDATE on this TV.

Just ordered a new Ysus board (this one looks better and is not discolored)

The TV is doing the same thing. Turns on fine with no picture! Standby LED red, turns to green when turned on like normal. Will turn back off like normal. NO PICTURE!!! I can hear Ysus buzzing like normal, just like the original board did when I replaced the fuse.

I am stumped! Any ideas? This is an LG-based Plasma ILO TV.

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Is it possible it is a bad screen? Or even a bad eeprom?

The old Ysus board was badly discolored and had a blown fuse.

I had some previous experience last week with a Sanyo 50"Plasma because I had to swap an eeprom chip that corrupts the firmware. The Sanyo Plasma TV was power cycling, and using a heatgun and kingbo flux to replace the chip with an ebay kit flash chip worked for THAT TV. I am starting to wonder if an eeprom may have failed in the Ilo too.

[ReeceyBurger123]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Checked Y buffer ? The screens themselves almost never ever fail unless cracked.

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

I checked both Y buffers none are shorted.

I see through online research this TV has this issue a lot and there is also an AKAI branded version of this TV, (PDP4273M1) so I am now looking up its twin to see what else I can find.

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

I was able to short the LG Logic board R406 to attempt to get test patterns, no test patterns will show.

The TV will come on fine, but still no picture. I am suspecting the Logic Board (TCON) is failed since I cannot get a test pattern, and the main board turns the TV on and off properly.

[Nick's Tvs]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Not sure if this is one of the models you can do this for, but have you tried to disconnect the top buffer board, and run the set see if you get the lower half of the screen to prime. If not place it back in and try disconnecting the lower buffer and then see if the top portion of the screen primes.

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Not sure if this is one of the models you can do this for, but have you tried to disconnect the top buffer board, and run the set see if you get the lower half of the screen to prime. If not place it back in and try disconnecting the lower buffer and then see if the top portion of the screen primes.

I did that early on and tried it again, no difference. Thanks.

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

I was listening to the "BUZZ" that the Y and Z boards make, and I hear a timed difference in sounds, almost like if it was really running the test pattern but I cant see it!

I didn't get that before, just a regular buzz before jumping R406 to get the test pattern.........

I already ordered a logic main board.

I'm really hoping this is not a bad screen............Already got parts in it.....

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Will a Plasma TV run with a broken screen???

The buttons on the bottom show signs of jarring or mishandling. The "input" button is stuck in. I am wondering if the owner dropped this TV before bringing it for repair.

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Got replacement Logic Main Board ((Tcon) or video board) and TV does the same thing. All voltages good, mainboard responsive, and you can hear differences in the sound emitted from the Y/Z boards when the video is disconnected. I am PUSHING HARD for the owner of this shop to get an O-scope it would make things a LOT EASIER, but I am working with what is available!

I'm sure its the screen, but IF I AM WRONG, feel free to school me, but the TV comes on and works, just no image!

The owner seemed rather brash that brought in the TV, could barely speak to him or get a word in when you went to tell him what you discovered about the TV without him pushing out the ignorance ("I don't know nuttin 'bout that stuff"), I think they dropped it and know it and won't admit it!

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

OK, found something that measured short! The Parallel row of MLCC Caps are measuring 0 ohms. So I will try to shake this frustration, maybe it just may be the Z-SUS the only one board I didn't change!

The Capacitors are coupling the AC output from the output of the IPM to the output coils right? So there should be no short across them right? I wonder why I hear the board buzzing as if it is working? The IPM seems to measure fine with no shorts..............but if I measure from ER_UP_OUT OR ER_DN_OUT to the output of the Z-SUS board, I get a 0 ohm reading.

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

I just removed the output inductor coils to ensure the IPM isn't shorted!

The capacitors are shorted for sure!

Does anyone know the value of the capacitance of these MLCC caps? I want to replace them with POLY caps of the same rating. I have a BUNCH of 3.3uf and 1uf poly HV caps from plasma TV that should work. If not, I'll just replace them with like parts.

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Here is a photo of the failed rows of MLCC capacitors...............

There are actually 20 of these caps (10 per output) but I had to crop the pic to fit the forum size using a photo editing program in Linux I am still getting used to.

Sorry about part of the pic being cut off

[ZnsaneRyder]

Re: ILO PDP4210ea1 unstable Buffer Voltage from Ysus

Anybody know the value of the MLCC caps used on the output of the Zsus chip?