Pioneer Plasma PDP427XDA 10 red blinks

[dkneyle]

The service manual says this is "X DCDC", the checkpoint is the X Drive Assy, and the main cause is "Abnormality in VC_15 power" or "Abnormality in VXNRST power"
I'm yet to open her up, but thought I might be able to shortcircuit the process by seeking any blinding insights of what to look for, process of fault finding, etc.
(I've worked on this set before and replaced the power board for a separate problem. Unfortunately the owners just see it go into power down 2 seconds after it begins its start-up routine, and it looks "just the same as when you fixed it last time!")

[tom66]

Re: Pioneer Plasma PDP427XDA 10 red blinks

XDCDC would be the Reset pulse generator for the X-drive, about 100V. Could be short on X-drive, or in the reset pulse ckt. If you post a picture of your X-drive, some test points can be located.

[dkneyle]

Re: Pioneer Plasma PDP427XDA 10 red blinks

The owner said that the issue got progressively worse until it no longer would operate, by then always dropping back into power down mode. To me this suggests that it's not a semi-conductor failure but more likely a capacitor failure.
Caps all visually look OK. But this is a 10 year old set, and I already exchanged the main power supply board 12 months ago because of a failure. (It was my first foray into flat screen repairs and I didn't chase that one down to component level, but I did notice the big main caps in that case were ever so slightly bulged.) That suggests to me that maybe the heat of the TV is drying out the caps?
I recall reading a post somewhere that I can't track down which was about failure of the 16.5V to 15V DC/DC converter on the X-Drive board.

[dkneyle]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Here's a close up of the test points for the 15V and 5V rails. I'll see if I can get a measurement before the set shuts down (challenging). I notice there are two 47uf/16v electros in that vicinity. What are the chances they might be the culprits? Going to change them over and see.

[dkneyle]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Changed those two caps without any change in behaviour of the TV.

I notice that the VRN DC/DC converter appears to generate a fairly high voltage and that this must be the reference in the troubleshooting guide to "Abnormality in VXNRST power". Those big electros might be suspect then even though they don't show signs of failure?

[tom66]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Bottom right of board. XNRST test point. Check the voltage there.
Refer to service manual & panel for voltages.
For example: Panel may have XNRST=031, use service manual to convert this to a voltage.

[dkneyle]

Re: Pioneer Plasma PDP427XDA 10 red blinks

I replaced the high voltage filter caps: no change.
Measured the 15v line, it's measuring at 16.7 volts prior to power down.
The XNRST test point measures 97 volts prior to shutdown.
Can't interpret the expected value of XNRST because the panel seems to require specialist knowledge to interpret the code. I tried using a QR Reader but it won't read that code. I have attached an image.
From these measurements it would appear the 15V DCDC converter is not doing its job. Looking at the board I can't immediately determine which part of the circuitry that is, and unless it is a pretty easy component change I think I'm looking down the path of a board replacement.
Also attaching the Service Manual for reference.

[dkneyle]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Pioneer PDP427-XD service manual

[tom66]

Re: Pioneer Plasma PDP427XDA 10 red blinks

97V sounds reasonable for that test point, can't help you much with the sticker either unfortunately. I was hoping it would be like a 9G Kuro.

[dkneyle]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Yes I thought 97V seemed about right. But not 16.7V on the 15V point. It's all SMT components from this point on. Looks like it's time to just invest in a new X-Drive board.
I don't know why it doesn't have the usual voltages stuck on the panel that we are used to seeing? I looked hard to see if it was hidden anywhere. I would have liked to have found a component-level repair to save costs, but I guess it wasn't meant to be.
I guess this TV is about 8 years old. As I said, it's had a new power supply. Now it looks like a replacement X-Drive board. Why do I feel the Y-Sus might not be a long away from failing? It's probably going to cost more to keep repairing than it's worth, but I just can't see good technology just going onto landfill.

[tom66]

Re: Pioneer Plasma PDP427XDA 10 red blinks

The reason the voltages aren't printed directly on the panel is the control board constantly adjusts them to keep up with panel ageing. Panasonic also do this. So there isn't really a fixed voltage - just a base, plus some ageing control and temperature control. You can get fairly close by just measuring the voltage, if you know the translation. I'll have a look for the translation table.

[tom66]

Re: Pioneer Plasma PDP427XDA 10 red blinks

According to page 80 of the SM, XNRST should measure -180V. I have to admit, that is bizarre. I have never heard of an X-main using a negative reset voltage...

Perhaps test across those two points?

[dkneyle]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Yes Tom, I did the test across the two points. It would appear that was the intention since they are side-by-side. I too saw that value of -180V in the manual and thought it very odd. I think the measured value of 97 volts is far closer to the value of ~100V that you and I would have expected. Just going to see if I can work out how the 15 Volts DCDC converter is generated before giving up.

[dkneyle]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Recapped the X-Drive board with exchange electros but no change. I have ordered a replacement 2ndhand board from the USA. Will take about two weeks to get here.

[dkneyle]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Changed over with 2ndhand X-Drive board; all works brilliantly again. Would have liked to have solved down to component level but it wasn't to be. Board was surprisingly cheap. About $60 landed in Oz, most of that was P&P.

[vinceroger69]

Re: Pioneer Plasma PDP427XDA 10 red blinks

thanks for posting the fix thats not a bad price i have a panasonic 42in myself great picture imo.

[kenebusma]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Hello, i have a pioneer pdp lx 6090H and i need help.

Since yesterday, it's stuck on standby mode, when i turn the power on i have the blue light for two seconds and then when a series of 8 red flashes. I don't know what to do. There is no pioneer repairman in my country so i have to do it myself. Please i need advice or testimony of people with the same problem.

Thank you very much

[tom66]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Hello, i have a pioneer pdp lx 6090H and i need help.

Since yesterday, it's stuck on standby mode, when i turn the power on i have the blue light for two seconds and then when a series of 8 red flashes. I don't know what to do. There is no pioneer repairman in my country so i have to do it myself. Please i need advice or testimony of people with the same problem.

Thank you very much

Nice choice of TV!

This is a very easy fix. I have a PDP-LX5090 on my wall that I fixed with the same fault. I'm watching it now, it's been working great for months.

You need to replace a regulator on the audio PWB.
https://www.badcaps.net/forum/showth...-LX5090&page=2

Cost about £2 for the part. I do recommend you have someone with some surface mount soldering experience to do this if you have not done such a repair before. If you need help locating the part post a picture of your audio PWB (this is the board with the speaker connections, component video, SCART, etc.)

[kenebusma]

Re: Pioneer Plasma PDP427XDA 10 red blinks

Hello and thank you tom66,

is it this one: NJM2846DL3-18-TE1 Regulator IC LDO 1.05A 1.8V TO252-5.

Thanks again

[tom66]

Re: Pioneer Plasma PDP427XDA 10 red blinks

That sounds like the right one.