Shuts down, found short on vcc of driver board right top as looking at back
nec on board
lifted all vcc points no cap or ic shows short,triple layer board?
looking for part numbers of boards and source to order
thanks jim s
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Re: RCA PHD50400 PLASMA
If that board has three connectors going to it (10 pin, 9 pin and 41 pin) then it is the PDP Module but no luck on finding a source for it. RCA is bad about parts supply on thier TV's the past several years.
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if is a lcd tv the issue could be the inverter board or one of the lcd bulbs has stop or vcc which is 24 to 30volts that goes to the inverter is not found if its there check the fuse on the inverter if its a plasma the y-sustain board may be out there is a chip called the pmc (power modulator chip ) if is shorted the first sign would be a blown chip on the vcc side 180volt if thats the case the board is shorted needs to be replaced
CHECK FUSE AT Y-SUSTAINER PCB. IF BLOWN, DO NOT REPLACE IT! LOOK AT SCAN CONVERTORS BOARDS. THEY ARE CONNECTED BETWEEN Y-SUS AND PLUGS FROM DISPLAY(LEFT SIDE WITH FACE DOWN, BACK OPEN). SCENARIO: SCANS GOT BURNED(LOOK FOR A SIGNS AT THOSE LONG BOARDS: UPPER&LOWER).FIND ANY IMPERFECTIONS: REPLACE ALL 3 BOARDS: Y-SUS, UP/LOW SCANS.LAST THING: IF FUSE IS OK, CHECK POWER SUPPLY FOR BLOATED CAPACITORS(BIGGEST BOARD IN A MIDDLE OF THE SET) SAME SERVICE POSITION. GOOD LUCK, LET ME KNOW HOW TI GOES. ALEX'S TV?PHILADELPHIA, PA.
THE UNIT NEEDS 2 DRIVER BOARDS TYPE PKG50C2J1 AND " J2.LABEL # JP275852,JP273734,JP275887. MADE BY NEC. I CAN NOT FIND THE BOARDS. THOMSON/RCA TECH SUPPORT SAID I WOULD HAVE TO REPLACE THE PLASMA PANEL BECAUSE THEY DO NOT STOCK BOARDS.THE PRICE IS OUT RAGEOUS. ( $8,200.00 ) END.
These types of problems are allways hard to diagnose.. If you were to power on the set and preform tests, you would think that everything was fine until the moment it shuts off.
Look on the main power board and see if you cant find the thyristor (thermal switch), those are the things that when heated will cause the set to power off for safety reasons.. They are normally placed where ever a large heatsink is. That may give you a location as to the problem and you can put a meter around its 2 pins with the set off and unplugged a couple of min after failure, if its short (0 ohms) thats not the problem, if its open, it triggered the event.
Second, you can run the set for a while and check the voltages and Ve, Va, VCC, Vsetup etc and compair to the markings on the plasma PDP sticker. If you see one is falling down over time (volts will be lost as heat) then you can isolate that portion of the supply.
Third and allways the best way to go about these problems is buy a thermal gun and moniter various spots for heat.
Its just vary hard to say, resistance could be off somewhere, diodes could be overheating as well as fets and caps. Thats why a good thermal gun can point you to exactly where the problem is.
Hope this info helps, but I would suspect the problem is on the main power supply itself and not the y sus and z sus boards side boards.
1. Remove the rear cover 2. remove the perforated large shield on the
main board housing (almost in center). 3. Unplug the right top fan and
temp sensor plugs ( two small plugs at the top of the main board). 4.
Remove screwsthat secure the main board housing, there is also four
screws by the video inputs. Do not unplug the board, just gently pull
it away 6 to 8 inches. 5. Remove the cover with the Top fan attached
(more screws). 6. Now the scan board for the top half of the screen is
exposed. The board has four large heat sinks with two large
Electrolytic aluminum caps next to each heat sink. 7. The problem caps
are at the very top right side of the scan board C192 Nichicon 220 uf
next to the IC, the other cap is C120 100UF on the lower side of the IC
next to a heat sink. I replaced them without taking the board out. C192
is the one that failed, the other one tested OK but I replaced both.
I got the caps from Mouser.com they are 69 cents each, the Mouser
part number for the 220Uf is: 647-UUD1C221MCL1GS (Nichicon 220uFm 16V
6.3x7.7 mm surface mount); the 100uF is:647-UUD1E101MCL (Nichicon 100uF
25V 6.3x7.7mm), both are 105 degree C. I bought two extra spares in
case I need them for the future.
Reassemble the unit in the reverse order and you are done. Note if
you test it without closing everything, make sure you have the main
board shield back on, otherwise the screen will bleed due to the noise
from the board. good luck! mine has been working fine.. just like new..
Check the +170 volt test point on the power board (not the power filter board, the one that the plug comes into) but the one to the right of that board. It has a 5v test point (TP +5v) , a +170 and a +70. I've found that the +170 transformer goes bad, and won't allow you to adjust the voltage using the pot screw.
I am having the same problem with my TV. I believe that the Y-Buffer Driver IC's are bad. There are two small boards on the left hand side(looking at the TV from the back) with 6 small heat sinks on each of them. If you look closely at the boards, it ill say Y-BUFFER on them. There are ribbon cables that run from them to the Plasma screen.
In my TV, several sections of the screen do not have lines in them. These driver IC's are not hot, however the sections of the screen that have lines in, the drivers are hot to the touch. In order to verify that the chips are indeed bad, I am going to swap one that I think is bad with a good section and see if the problem moves. If this is the case, the boards can be swapped out, or chips replaced depending on what kind of parts I am able to find. The chip that they use is SN755867. I haven't been able to locate a source for the chips yet.