I had the same problem. To fix it 2 capacitors at 69 cents each have to be replaced on the PKG61C1F1 board or the board has to be replaced. The board is going for $162 and up.
The capacitor replacement procedure is shown at the bottom of this post. To give credit where credit is due, see http://forum.eserviceinfo.com/viewtopic.php?t=16490&highlight=nec+plasma+capacitor
"I will try and walk you through the process.
I recommend having a power screw driver (not a drill driver) lots of screws, bag and tag in ziplock bags. All References are REAR VIEW of set.
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."
I have a Runco PL-61cx 61" plasma tv and now after about 20 min. of it being on, the top half of the tv goes completely black. I have done some research and it looks from other peoples problems that it might be the upper y buffer board. I found the part believe I need... http://www.shopjimmy.com/scan-drive-pkg61c1e1-from-nec-px-61xm1a.htm
but...it is out of stock, anyone have any advice? Is this the real problem? Is this the right part? Also i noticed the top right of the tv gets a little bit warmer than the rest of the TV, and this is where I THINK the problem.