chances of reviving a Philips plasma tv?

[kikkoman]

hi guys

i have the chance to get 1 or 2 philips 42" plasma tv's. i'm currently trying to find out the model number(s) and if someone has attempted to fix them before.

according to the seller they show the picture for 1 or 2 seconds when turned on and then go dark.

he's asking 60€ apiece so if there's a chance of reviving them i'd be definitely in.

IIRC there was something about a recall of some of their 42" and 50" sets a while ago (due to bad caps???)

any help appreciated....

[PCBONEZ]

Re: chances of reviving a Philips plasma tv?

Philips/Magnavox LCD's are now made by Funai who seems to also be (directly or through subsidiaries) the OEM behind all the Walley World (Walmart), CostCo, Best Buy, Circuit City, and such "House Brand" TVs.

A lot of boards are common between the 'brands' which makes them more readily available.

I have an Emerson 19" LCD TV (Funai) out in the shop I haven't gotten too deep into yet. That one blows the fuse straight away. [I ran out of fuses,,, which wasn't hard because I only had one spare on hand in that size..]
It has crap brand caps but none bloated. That one is almost new. Mfr date April 2008.

Been working on an Element 22" LCD TV (Funai/Circuit City OEM I think but not sure) that won't stay on for more than 10 seconds. Same-same, it has crap brand caps but none bloated. It goes COMPLETELY dead. Not just video or back light, power light goes out too vice just flashing some odd color like the 'usual' problem they have. I suspect an IC in the PSU section is bad but I haven't started desoldering and checking yet.
- This one is cream of the crap. PSU PCB is marked for 2 fuses but those positions have jumper wires where the fuses should be. DANGER! WILL ROBINSON!

So far as what to expect...
My guess is it will be more involved than just caps.

Even still, even if you can't fix them...
If the LCD's themselves are good then just those sold alone may be worth more than the whole TV as broken. - So before you tear it down get a quick snap shot of the screen working [for your ad] in case you don't feel like putting it back together later on.

.

[PCBONEZ]

Re: chances of reviving a Philips plasma tv?

Oops...
http://www.funai-corp.com/support/default.aspx

[PCBONEZ]

Re: chances of reviving a Philips plasma tv?

I guess the Element isn't much older. August 2007.

[kikkoman]

Re: chances of reviving a Philips plasma tv?

Even still, even if you can't fix them...
If the LCD's themselves are good then just those sold alone may be worth more than the whole TV as broken. - So before you tear it down get a quick snap shot of the screen working [for your ad] in case you don't feel like putting it back together later on.

.

it's not an LCD, it's a plasma.
form what i've read so far it uses a Digitalview controller board () which works with plasma and LCD units, so issues might be similar to those with LCDs. just guessing here.

[PCBONEZ]

Re: chances of reviving a Philips plasma tv?

I've looked up the main board for various LCD TVs and found there are plasma's they also fit. I don't think LCD vs Plasma makes a lick of difference in the video sections other than maybe in the inverter.
[I'm just guessing too.]

MOST of the problems will probably be in the power supply section anyway and I know the PSU's don't care what kind of screen is out front. Compared to PC SMPS they are pretty simple. In them I'm seeing a lot of GP caps where low ESR caps should be used. [In odd-ball brands I've never heard of too. Some are funny: "Decon", "Procon" - Rat Poison and a Professional Con.]
Anyway,
For those that I've been able to find specs on, Panny FC easily exceed the original specs.
Decent caps won't be hard to find for them.

.

[Wizard]

Re: chances of reviving a Philips plasma tv?

most common issue is blown YSUS. Usually best to change as as set on YSUS, and logic board, both upper and lower YSUS driver boards. Not very much bucks if it is V7 LG panel and it is a kit.

Cheers, Wizard

[PCBONEZ]

Re: chances of reviving a Philips plasma tv?

wassa YSUS Wiz?

[kikkoman]

Re: chances of reviving a Philips plasma tv?

i hear philips offers repair kits, so i take it a blown YSUS should be fixable. i even found a german repair forum with a workaround (diy YSUS driver chip) for blown ysus boards on LG (and other) units, don't know if philips is similar there.
let's see what the seller says, but i might have a new toy next week. or two.

[PCBONEZ]

Re: chances of reviving a Philips plasma tv?

This might be of interest
http://www.scribd.com/doc/7580885/LG...raining-Manual
Looks like Plasmas have a lot more junk in them than LCD's.
Either that or it's that the biggest I've look at so far is 27".
All seems to be related to the actual screen though.
Tuners and Video boards could easily be the same.

[Wizard]

Re: chances of reviving a Philips plasma tv?

YSUS is what it say. There is a design flaw in the STK IC (cannot obtain this) that breaks solder (it is a overlap on the edge sitting on pads, dumb to do and it will crack for SURE is what blow the MOSFETS arrays in that same STK IC, this also sometimes takes out the YSUS drivers boards. And there is fixes in the logic board so it was came out as a kit for the Philips-LG using V7 panels.

Many of them eventually dropped STK and went distcrate drivers instead. Far more reliable. Samsung included.

YSUS big board is for horizontal lines individually addressable with 2 narrow boards on left side while other ZSUS board is common tied to all other horizontal lines so each cells have 2 lines in parallel. That are the neon electrodes.

While the boards at bottom of the panel are address lines running vertically up and down. YSUS and ZSUS set up the cell charge just to the point it sparks off into excition if kicked off by the address line. This pre-firing charge is what cause cells to glow. Hence you can't get high enough constrast with this panel and another reason for the smoked glass placed in front of panel itself also to protect it and to protect customers from the high voltages and heat.

With all the high voltages and large area of capacitanace coupling to everything, plus neon current making some heat, that is reason take tremdeous power to run. The 42" panel I see has wattage printed on the back on the panel itself along with few voltages is around 300W for whole white, at full brightness typically. Hence the back of the plasma panel is metal (panel glass is bonded to this, early ones were diecast potmetal then stamped steel, with mounting fixtures riveted to this), and lot of driver ICs and transistors heavily heatsinked.

Newer plasma panels now have driver ICs on the TCP so the circuit strips is simply bus circuit. If the IC dies, panel is junk and must go back to panel repair factility.

This link is about LCD but newer plasmas utilizes TCP of their IC dies pressed between metal plates and thermal pads for heatsinking.

http://www.fps-europe.com/repair.html

These are more likely to fail compared to LCDs due to termendous power and high voltages involved.

Cheers, Wizard

[Wizard]

deleted

[Krankshaft]

Re: chances of reviving a Philips plasma tv?

Great more STK ICs I've had enough of those on both my RPTVs. After some Arctic Silver 5 though and subbing them for the newer revised ICs they've been rock solid.

From my knowledge Sanyo discontinued them in 06 or 07. Sanyo said it was because of the fall of RPTVs and also probably because as you said plasma manufacturers moved to discrete components.

So basically the YSUS is the display driver?

This might be of interest
http://www.scribd.com/doc/7580885/LG...raining-Manual
Looks like Plasmas have a lot more junk in them than LCD's.
Either that or it's that the biggest I've look at so far is 27".
All seems to be related to the actual screen though.
Tuners and Video boards could easily be the same.

Very nice link PC I'm reading all of this.

[Wizard]

Re: chances of reviving a Philips plasma tv?

The logic board (connected by LVDS cable from mainboard) do all the directing and timings to the power transistors and drivers ICs to fire them off at correct timings/sequences.

Logic board is much like a music director telling players to play their instruments at correct sequences (power transistors and drivers ICs).

There are 2 big boards, YSUS and ZSUS using power transistors or a BIG STK ICs that is where real power is. Merely brute power, the sub circuits (board strips along the two edges of panel do the final channeling to correct lines (scanning).

YSUS board on left side is channeled to the invdividual lines as directed by the logic board while ZSUS board on right side is tied to all the lines like a tree. Both YSUS and ZSUS has to cycle the different voltages line by line rapidly. It has "discharge voltage to snuff out the cells, charge up the cell to the level where small trigger set neon off into ionization; light up the cell and surstain voltage to have cell lit without excessive current. Etc. Very, extremely complicated signal. Not simple blink on and off.

And LOUD in radio radiation, this is major reason the plasma units have metal back. I see this static on CRT TVs when we test run and adjust plasma units with their back removed.

Cheers, Wizard

[i4004]

Re: chances of reviving a Philips plasma tv?

>Both YSUS and ZSUS has to cycle the different voltages line by line rapidly.

line by line?
like crt scan?

doing all lines at once would be too much voltage?

complex, yeah, but i bet not as complex as ntsc vertical blanking...hehe...

[i4004]

Re: chances of reviving a Philips plasma tv?

some other goodies from there
http://www.scribd.com/tag/training%20manual
sanyo lcd manual seems interesting

other categories
http://www.scribd.com/browse/Manuals/

[Wizard]

Re: chances of reviving a Philips plasma tv?

Pixel addressing one by one, hence high KHz, even near MHz.

CRT scanning STUPID simple, that was easily done with tubes back then.
But plasma panel is most complicated to do especially trying to dim a neon action that is nearly impossible to dim to begin with, hence the complications.

Cheers, Wizard

[kikkoman]

Re: chances of reviving a Philips plasma tv?

i found out the model number. they're 42PD1609 's - professional units (no tv tuner, just monitors) and most likely come from an airport. this probably means they're somewhat burnt in.
guess i'll back out.
thanks for your replies though.

[Wizard]

Re: chances of reviving a Philips plasma tv?

Good idea!

Cheers, Wizard

[PCBONEZ]

Re: chances of reviving a Philips plasma tv?

i found out the model number. they're 42PD1609 's - professional units (no tv tuner, just monitors) and most likely come from an airport. this probably means they're somewhat burnt in.

May also mean they were installed outdoors in a box on a pole.

.