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Carl L
Carl L, Master Technician
Category: TV
Satisfied Customers: 4009
Experience:  Current Electronics Shop Owner and Master Technician in FL.
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Pioneer PDP-503PU 50 plasma with a power problem

Customer Question

I have acquired a Pioneer PDP-503PU 50" plasma with a power problem. Before I got the interface cables, the screen would go through the following sequence on power up: 1) in a darkened room, I saw about 1 full second of faint snow 2) in a darkened room I then saw about 1 full second of a faint pink field 3) moments later I heard some relays kick in and the power LED went to flashing 2 times over and over. I then got some original interface cables and a Y-sustain board on eBay. The board was reported as having come from a working unit that suffered a broken screen. With the interface connected, I get the same results if I turn on the interface first. The interface LED remains green. If I turn off just the interface at this point, the screen LED flashes continuously and slower. When I turn the interface back on, I get the snow/pink/relays sequence again and 2 flashes. Now, if I turn the screen off/on, I get a brief green LED, no snow/pink/relays, but soon the LED changes red and flashes a sequence of 5 times and repeats. I have a copy of the service manual and that was what prompted me to replace the Y sustain board. Two red flashes suggest this is the bad board. The part numbers are an exact match. My problem is unchanged. On page 83, the service manual suggests that I test several nodes for logical low values that initiate the shut down relays. I cheated the safety interlock, turned on the unit and tested these with a DVM and got .001 VDC for all 5 of them. The manual also suggests removing the P3 cable from the PS and in the ‘conditions’ column it says “When P3 connector disconnected, P.D. does not occur.” I did this and it did Power Down and I got 5 red flashes. I also noted that a red LED lights up on the power supply board and stays on once the PD relays click.. I am inclined to try another Y sustain board from someone who guarantees testing. I have not inspected the scan ICs as they are very difficult to access. They are under the aluminum frame and I would have to do considerable disassembly to reach them. I presume that they are also attached to the plasma glass somehow and I really don’t want to disturb them if I don’t have to. Also, I saw on a blog that I can test the unit without the control box attached, that it is essentially just a video switcher. One note - the control box gets fairly hot if I leave it on with or without the plasma attached/turned on. The green light stays on as long as both the controller and the plasma screen are turned on, regardless of the protection being activated on the screen panel. I have not tried feeding the plasma panel a video signal directly from the DVI input. That seems irrelevant until I solve the power down problem. What next?


Download service manual for free from:  http://dl.dropbox.com/u/35219914/Pioneer%20PDP503PE.pdf  This version does NOT include schematics, though.

Submitted: 2 years ago.
Category: TV
Expert:  Carl L replied 2 years ago.

Hi and welcome to Just Answer. My name is XXXXX XXXXX have been repairing TV's Professionally for over 7+ years and currently own a Shop in FL.

 

Remove the Y-Buffers that contain IC's from the Y-Drive (Y Sustain) Board and try to power up the unit. When one or more of those IC's short out it will give out an error that the Y Sustain is faulty.

 

Remove the Y Sustain and fold out the Y Buffer Board and reinstall the Y Sustain and power the unit on making sure that the Y Buffer Board doesn't touch anything.

graphic

 

Let me know if the unit stays on just with no picture.

Customer: replied 2 years ago.

Hi Carl,

The disconnect is easier than you describe. There is an inline connector between the Y sus board and each of the scan boards (Y3 & Y5). There is no other connection other than a floating ground. I disconnected these and the system still shuts down just as quickly. Let me know if this is a sufficient test or if I need to actually lift out the scan asemblies. Does this mean that the scan assemblies are no longer suspect?

 

 

Expert:  Carl L replied 2 years ago.
I would just actually take then out just to be 100% sure.
Customer: replied 2 years ago.
Done. Scan assemblies laid to the side of unit. PD still happens just as quickly. All scan assembly components look okay - no fried ones. Does this eliminate the scan assemblies from suspicion?
Expert:  Carl L replied 2 years ago.
It sure does and it a good sign. Who did you purchase your Y Sustain Board from? I would hate to be on a wild goose chase when you received a bad YSUS this whole time. I know a lot of dealers and can tell you if where you purchased was a good place.
Customer: replied 2 years ago.
If that was a difinitive test, it is helpful to eliminate the scan boards. I alfrready put them back anyway. Yes, I agree that the source of the board is suspicious. The two red flashes and no change when I disable the scan chips pretty much screams Y-sus board (according to the service manual). Check out this eBay auction - 180660768364. The board is an exact match in appearance and model number although he pulled it from a PDP-433. I researched it and found them (PDP-433, PDP-503, PDP-800) to use the same board. No guarantee, however. I am watching several other auctions starting around $60. I seasrch the original part number: ANP1984-F. There are offerings that claim to be tested and others who say they are from 'working units' or 'broken screens'.
Expert:  Carl L replied 2 years ago.

You best option is to buy it from an ebay store with a DOA warranty. My supplies are selling this board for around $180 so ebay with DOA protection would be the way to go. Here's one that I like and would buy myself http://www.ebay.com/itm/ANP1984-F-Y-DRIVE-ASSY-PIONEER-PDP-433PU-/150569405898?pt=LH_DefaultDomain_0&hash=item230ea2cdca.

 

Customer: replied 2 years ago.

That one was on my watch list. I bought it. Been down this road before, though. Eliminating the scan boards makes all he difference. Let you know in a couple days, I guess...

Expert:  Carl L replied 2 years ago.
Ok no problem. I'm here everyday to help with any questions along the way even after an accept.
Customer: replied 2 years ago.
2nd Y-sustain board came today. Installed it. No change.
Expert:  Carl L replied 2 years ago.

If its not the Y Sustain then its the Digital Main Board which is the brains of the unit and processes all the Video. Its replacement is $89.16 at http://www.shopjimmy.com/tvs/pioneer-awv1903-digital-video-assy.htm.

 

I would place those other 2 YSUS Boards on ebay to get back what you've put into it my friend.

Customer: replied 2 years ago.
You are fairly certain that this is all that is left? Is this based on the two flashes PD status?
Expert:  Carl L replied 2 years ago.
The problem with the error codes is that it comes from the Logic Main Board and isn't always accurate. If you dont have video or audio and have already replaced the YSUS Board, its usually always the Digital Main (Logic) Board.
Customer: replied 2 years ago.

I never had audio because the set goes into protection right away. My strongest clue is the 2 red flashes after PD. When I connect the controller (I have not used it since contacting JustAnswer and doing the tests you have suggested) I sometimes get 5 red flashes. Remember that I get a brief, evenly distributed snow then pink field before the unit powers down.

 

Okay... This is why I am contacting JustAnswer in the first place. I have now spent what I wanted to invest in this repair and another $100 puts me at or past what the TV is probably worth. Assuming that this board solves the problem (VERY important), I can use the environment to test the others and proclaim that they are good on my eBay ad, but regaining any of what I spent is still a gamble.

 

I also googled JustAnswer and this particular TV model and of the several attempts I saw, none of them were resolved to produce a working TV. My confidence level is not real high. I am gambling that you have strong direct experience in this area - your answers seem to have been informed so far.

 

By the way, the last board I got had rust on the screws and metal plates attaching it to the scan boards. Perhaps this is enough to return it once the dust settles.

 

Bottom line: Do you really feel confident that this last purchase is all that is left to do?

Expert:  Carl L replied 2 years ago.

I have years of direct experience in CRT, Projection, DLP, LCD, & Plasma TV's. LCD's are easier to repair than Plasma's as Plasma's have more boards in them. As with all Plasma TV's some repairs are set in stone and some can be caused from 1 of 3 boards and there is not always a for sure "This is definitely your problem". Thats why we'll sometimes recommend taking the set to a repair shop as they have the spare boards to swap out in stock and can only charge you for the one that fixes it.

 

If it were the X Drive going out, you would have audio. If it were shorted IC Buffers you would have half a screen or nothing at all. A bad Main Board will cause issues with external inputs but the OSD will still work. A bad Power Supply will cause clicking sounds, no video or Audio at all. A Bad Logic Main Board will cause scrambled Video, No Video, No Power On, No Audio, etc.

 

 

Customer: replied 2 years ago.
I ordered the part.
Expert:  Carl L replied 2 years ago.
K. Let me know how it turns out.
Customer: replied 2 years ago.
I got the part in today. The processor board is under the power supply and one of the main frame supports. The frame support blocks the version number from easy view. When I went to change it out, I found that it has a different version number. Mine says AWV1979D. The replacement I just got and the board name on page 3 of the service manual for my machine is AWV1903. I looked up the 1979D and it seems that it might be from a Runco CW50MC or an RCA PD50500 (according to online sellers). Presumably a few Pioneer models as well. Since there are different designations for different screen sizes, how much does this matter? I have not yet tried the part.
Expert:  Carl L replied 2 years ago.
It should be fine. We may have to do a Factory Reset so that the New Board initializes the other boards.
Customer: replied 2 years ago.

Factory reset?

 

I put in the alternate board and the results are the same: plasma alone - 2 red flashes; plasma w/ controller - 5 red flashes.

Expert:  Carl L replied 2 years ago.
What are all the Voltages coming out of the Power Supply? The VA, VS, etc.
Customer: replied 2 years ago.
Would the readings be valid if it has shut down?
Expert:  Carl L replied 2 years ago.
During immediate startup you should be able to see the Voltages.
Customer: replied 2 years ago.
Hi Carl,
Got busy for awhile, but wanted to revisit this incomplete repair. Here is what I got when I tested the power connector on my Y-sus board. Refer to pg. 36 in the manual - power connector. Voltages read:

Between VSUS (11) & (13) SUSGND / approached 220vdc at PD.
Between D.Gnd (2) & (1) +15 / tested steady +15vdc until PD
Between D.Gnd (2) & (3) +13.5 / tested 0v
Between D.Gnd (2) & (4) -9v / tested 0v
Between D.Gnd (2) & (5) YDRIVE_PD / tested +4.9vdc until PD
Between D.Gnd (2) & (6) Y_DC_PD / tested 0.6vdc until PD
Between D.Gnd (2) & (7) VOFS_ADJ / tested 3.18 until PD

The HV of the main power supply seems okay, but the low voltages are off. Do you think this is repairable without replacuing the entire PS?
Customer: replied 2 years ago.
More info: I went to the PS board and found several test points for selected voltages. The +15 and +12 were normal, but the +13.5, +8.5 and -9 were low or off. This was with the V-SUS power connector disconnected. More indications that the PS is to blame...yes?
Expert:  Carl L replied 2 years ago.
If you dont have anything connected to that line to drag down the voltage and your readings are much lower than they should be while insulated, then that could indicate a bad PSB. Replacing it is really the only way to tell like I mentioned before. I find myself at times having to use spare boards to play the swap out game just because cases such as these can't be set in stone sometimes.
Customer: replied 2 years ago.
I guess I'm off to try to find a decent price on a AXX-1064 (the replacement for my AXY-1059), I understand these were well known for failure, but never found out what output was indicative of the classic problem.
Expert:  Carl L replied 2 years ago.
You can get one at http://www.shopjimmy.com/pioneer-axy1059-power-supply-unit.htm but it's not that cheap. Shop Jimmy is about the best place to find good parts with a warranty for the cheapest price.
Customer: replied 2 years ago.
I see warnings to stay away from the original part number (AXY-1059) and seek out the more stable upgrade (AXX1064).
Expert:  Carl L replied 2 years ago.
Their is one out there for the other but is much more expensive.

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