Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Nope, can't find it..

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

OK, found an OC 0.1ohm resistor. So replaced that and Fets with temporary equivalent.
Vsus now powers up to the correct voltage but have since discovered there is a short on the ysus board.

[ReeceyBurger123]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Ahh dam, maybe the Ydrive killed the Vsus supply. What devices have you found blown ?

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

3x FKP300A fets.
Ybuffer seems to be OK but will double check when I've figured what's what on that PCB and the busbar.

[ReeceyBurger123]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Ok good, in all honesty might be best to just change the Ydrive for the sake of the Ybuffer as the buffer is bonded to the panel and replacing the Ics will be very hard with that set up.

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Thanks, I'm quite comfortable with surface mount rework.
Where would be the best place to purchase said ydrive board?

[ReeceyBurger123]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

You can get them off ebay for cheap buddy

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Had a look, couldn't find any..

[ReeceyBurger123]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Any luck ?

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Not yet. Power supply is fully repaired and outputting the correct voltages on power up.
The new fets have not arrived yet.
There are 8x FKP300A fets that feed the scan pcb. 3 were fault so I removed those. Then, I swapped the remaining working ones so that I have 4 in a row on the the bottom to drive the bottom half of the panel.

On powerup I get 3 flashes from the red led. I suspect (HOPE) that it detects a SCAN fault because the top half fets are open circuit (removed as they are faulty)
On repairing cheaper tvs, i was always able to drive either top or bottom half of the screen without the tv tripping.
Just got to wait for the replacement fets to arrive.
On another note, I would have rather replaced the pcb as you suggested but can't find any for sale..

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Fets arrive and installed.
TV powers up for 1/2 a second and display stuff in the top right corner then powers down and red led blinks 8 time.

[ReeceyBurger123]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Ohh dear that means there is a fault with the Y address Pcb aka Y buffer. Do any of the Ic's look physically blown apart ? Replacing them wont be easy as the buffers are bonded to the screen.

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

No shorts on the y buffer ICs.
However, there are 4 pcbs along the bottom and 4 along the top of the display with 8 way wired connectors going to each of them. All the voltages are there except the 5 volts on any of the boards.... the y main feeds the left 4 (2 top 2 bottom) and the z feeds the right 4 so there must be a common signal that kept the 5v shut off as all the voltages going in to the ymain and z sus are good.

[ReeceyBurger123]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Ok, possibly just a blown fuse some where have you checked the Smd fuses ?

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

cant find any blown fuses. Will look later on the bottom of the t-con when i get a bit deeper.
I made a bit of an assumption about the 5v feed to the 8 pcbs. Only on the bottom of the zsus does it say 5v which feeds the bottom 2 right pcbs. weird thing is, that 5v feeds (which always measures 0) are not commoned with any of the other assumed 5volts to the other 6 pcbs including the 2 bottom right pcbs. Its almost as if the label is wrong..
i.e the 2 bottom connects have the same labels which are identical and buzz out 1-1 except the 5v pin. Maybe they meant that pin is an address control line hence unique...

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Incidentally, the T-con does 8 flashes aswell (probably just mirrored onto the front red led. Strange I get a picture every time on power on for a split second.

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

OK, forget what I said about the 5V silkscreen. I was right, its wrong! The repair manual says it is NC (strange they put the bloody wire in in all 8 connector looms as well!!! Grrrr)

So, fuses or buffer ICs. Question, would the whole panel light up if any of the buffer ICs are blown?

Oh, I've re-seated all the flexis as well.

[ReeceyBurger123]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

It would light up but have distortion then shut down. Did you say you get an image ?

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

Yes, I get the channel number etc in top right corner of screen etc

[niblettr]

Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

going the bin!