Sanyo DP50747 no video

[Tproveau]

Hi. I have read all the posts regarding this model TV and I cannot seem to figure out what is faulty on my DP50747.
mine has the Chassis # p50747-01
I have no video at all, no lighting up of the screen when switching on power. The green power led comes on and stays on.
I do have audio and the change channel seems to be working as the audio is heard switching every time I change channel.
I have photos I will be attaching to this thread.
I cannot find any faulty looking capacitors on any of the boards.
I have repaired caps before on several LCD monitors with success, but my experience is limited. I have the service manual for this model but with the p50747-00 chassis. I could not find the p50747-01 manual anywhere.
I do not know how to read schematic diagrams. I read the troubleshooting flow charts but find them a bit confusing.
I can use a voltmeter and i have one.
I guess I need to check the VS and VA voltages etc. to check if the lower board is at fault first? Does that seem correct? I tried checking them with the cable off the vs and va CN806 connector. The readings seem to fluctuate as they are being taken. The VS around 4 and the VA around0.5.
Is the main/logic board next to check, if the power board checks out ok.
Also I read about bypassing the logic board, shorting out a couple of pins and runing a video test which would test the ysus and zsus boards and the panel itself? however the photos I looked at in the post looked like it was a different chassis model than my DP50747. Not sure I should try this.

In conclusion I am looking for help/suggestions on what to test/try next to determine if this TV is repairable and if it is worth the cost.

I know from reading the other posts that my quest could be and probably is complicated. Thanks in advance for any help/suggestions.

What I have done so far besides visually checking the capacitors:
Checked all cables for wear and tight connections, all good
Tested all fuses, I could only find 4 on my chassis, one on the power board, one on the power distribution board (the board where the AC line hooks up) and 2 on the ysus board. All fine.
The green power light stays on when turned on and the click startup sound is heard. LED lights d3, d4 and d5 all turn on but d4 turns off almost immediately. Sometimes d3 and d4 come on steady and d5 turns off? Weird.

Thanks again. Hope I am posting this correctly. I am a noob to posting on forums.

[rpgruss]

Re: Sanyo DP50747 no video

Good first post.

If Vs and Va are that low, something is wrong, either with the sustain board/boards, or the power supply itself. If I'm understanding correctly, you have already disconnected power to the X and Y sustain boards and measured the voltage on the power supply? If this is the case, then there is a fault in the power supply. If I'm reading it right, you have the YPSU-J013A power supply, which is, of course, hard to come by. It looks like there is a repair service on eBay for $60 + shipping.

[Tproveau]

Re: Sanyo DP50747 no video

Yes that is the power supply.
I just tested it with all connections, connected and all the voltages are in the correct range.
VS 193.0 VA 58.0
the other 12, 24 and 5 volt connections were close like 11.7, 23.6 and 4.5
I was trying to measure them disconnected and I think the set kept turning off when the connections were unhooked so I was getting what was left in the caps I guess.
Sorry I am so new to this.
So power supply looks great actually. Set does stay on when all wires are hooked up to the power supply board.
I guess there is a main board with all the video inputs etc. made by Sanyo and then a logic board? made by LG in this chassis version as well as the YSUS and ZSUS etc going to the panel. I am not sure how to test these.
I cannot seem to find any instructions on testing the YSUS and ZSUS and panel on this chassis model p50747-01.
Thanks for your input and very sorry to give incorrect info on the power supply testing.

[Tproveau]

Re: Sanyo DP50747 no video

Further info re: testing
I found this info (1) but cannot find the corrosponding auto gen pins etc.
Also not sure what the VLDS cable is. Sould it read "LVDS" low voltage differential signaling cable?

(1) "on the contol board look for "auto gen" it could be 2 point on circuit board
or pin 1 & 2 of a 4 pin plug -- unhook the VLDS cable and short pins -- if
screen goes thru colors and checker board pattern - the y-sus ,z-sus and
control board and PDP panel are good"

[Tproveau]

Re: Sanyo DP50747 no video

Some more info. I hooked up a dvd and changed the input to AV1 which the dvd is hooked up to. Got clear audio but still no picture. All voltages on all boards where connectors hook up have been tested and are correct.
Any ideas?

[PlainBill]

Re: Sanyo DP50747 no video

That uses an LG Electronics panel, and you may be in luck. Here are two manuals to look for; they should both be at Elektrotanya.

The first is the LG Plasma Quick Reference Alignment Handbook. It covers many LG plasma panels and the LG TVs that use them (The sustains and control card are part of the panel).

The second is the LG 50PC1DRT Troubleshooting Manual 2007 VG Training. It covers troubleshooting one of the LG TVs based on this panel. It MAY show you how to put the panel in self test mode. That is what post 4 was discussing.

PlainBill

[Tproveau]

Re: Sanyo DP50747 no video

That uses an LG Electronics panel, and you may be in luck. Here are two manuals to look for; they should both be at Elektrotanya.

The first is the LG Plasma Quick Reference Alignment Handbook. It covers many LG plasma panels and the LG TVs that use them (The sustains and control card are part of the panel).

The second is the LG 50PC1DRT Troubleshooting Manual 2007 VG Training. It covers troubleshooting one of the LG TVs based on this panel. It MAY show you how to put the panel in self test mode. That is what post 4 was discussing.

PlainBill

Thanks Bill. I will get those and have a look.

[Tproveau]

Re: Sanyo DP50747 no video

LG 50PC1DRT Troubleshooting Manual 2007 VG Training was no longer on electrotanya however I found it on 4shared.com easily.
Will be reading them shortly!
thanks again Bill.

[Tproveau]

Re: Sanyo DP50747 no video

Well I unhooked the LVDS cable and shorted pins 1&2 on the 4 pin connector as seen in the LG training manual and nothing on the screen. Tried the other pins as well, still nothing. There is a slight hum sound when shorting the pins so it's probably trying.
The YSUS and ZSUS boards both have a low humming sound with the YSUS being slightly louder than the ZSUS and heat sinks are warm but not hot.
Found the surface mounted fuses now and all check out good.
So I think the power supply, filter board and sanyo main board are all fine and the problem may be in the LG logic control board, YSUS or ZSUS boards, the panel itself or the XL or Y driver boards?
I think I do not have the skills needed to test those components.
No oscilloscope and no video output, that most of the testing in the LG manuals seems to need.

Any suggestions for further testing would be appreciated.

[PlainBill]

Re: Sanyo DP50747 no video

Go through the alignment procedure in the LG Plasma Quick Reference Alignment Handbook. You can't do the adjustment that requires a scope, but check the voltages. Many LG sustain boards have an additional supply on-board. There is a fault on a 42" LG panel where one of the supplies on the Y-Sustain does not produce a correct voltage.

Edit: On the 43" panel these supplies are found on daughter boards. I see the supplies on the Sustain boards.

PlainBill

[Tproveau]

Re: Sanyo DP50747 no video

Checked voltages on Y sustain board and adjusted up a bit to specs.
Checked Z sustain board, is at 65v should be 100. Adjusted up to 85 which is as high at it will go. No change to TV still no picture. Took Zsus board out to visually check for burns, bad caps etc. Can see no problems visually. Incoming voltages to Zsus board are right on spec. Bottom of board is slightly greasy to the touch on most of the surface, eneough to hold a finger print. Could this Zsus board be the culprit. Could there be more problems as well?
I always preferred the picture on Plasma tv's but all the heat and electronic degredation showing up on so many of these sets, I am beginning to think LCD's may be better in the longevity dept. anyhow.
This TV was given to be by my neighbour but I own An LG 50inch myself that is 3 years old now.
Anyhow thanks for sticking with me through these questions Bill.

[PlainBill]

Re: Sanyo DP50747 no video

Checked voltages on Y sustain board and adjusted up a bit to specs.
Checked Z sustain board, is at 65v should be 100. Adjusted up to 85 which is as high at it will go. No change to TV still no picture. Took Zsus board out to visually check for burns, bad caps etc. Can see no problems visually. Incoming voltages to Zsus board are right on spec. Bottom of board is slightly greasy to the touch on most of the surface, eneough to hold a finger print. Could this Zsus board be the culprit. Could there be more problems as well?
I always preferred the picture on Plasma tv's but all the heat and electronic degredation showing up on so many of these sets, I am beginning to think LCD's may be better in the longevity dept. anyhow.
This TV was given to be by my neighbour but I own An LG 50inch myself that is 3 years old now.
Anyhow thanks for sticking with me through these questions Bill.

The most likely causes of the low voltage would be something presenting an excessive load, or a bad capacitor on the output.

PlainBill

[Tproveau]

Re: Sanyo DP50747 no video

Would the exsessive load or bad cap be problems on the zsus board or elsewhere? Also would the low voltage cause no video on the whole panel like I have?
Thanks
P.S. I have been building and repairing PC's for 17 years now, much easier than this plasma troubleshooting. With the PC I keep extra working components around for testing and swaping out, with this TV, I would need another whole TV of the same model at least! I admire your troubleshooting skills in such a challenging sector!
Terry

[PlainBill]

Re: Sanyo DP50747 no video

Would the exsessive load or bad cap be problems on the zsus board or elsewhere? Also would the low voltage cause no video on the whole panel like I have?
Thanks
P.S. I have been building and repairing PC's for 17 years now, much easier than this plasma troubleshooting. With the PC I keep extra working components around for testing and swaping out, with this TV, I would need another whole TV of the same model at least! I admire your troubleshooting skills in such a challenging sector!
Terry

The problem would most likely be on the Z-sustain board. A close-up of the lower end of the Z-sustain would be helpful. One thing that you can do is try to trace the output voltage. And yes, an incorrect voltage could cause this problem. In one thread here someone had a TV based on an LG panel. The screeen would be blank for some 10 minutes when first turned on. The problem turned out to be the Vsc supply which is generated on the Y-sus.

Please understand that I have never seen a decent schematic of a plasma TV and while I have read a number of training manuals, the best description I can give is 'certain drive waveforms are applied to the electrodes in the panel at precise times and amplitudes and magic happens.'

PlainBill

[Tproveau]

Re: Sanyo DP50747 no video

Would the output voltage be the voltage sent to the plasma panel?
Got to head to work now. Will try and post a photo of the bottom of the zsus in the next day or so.

[PlainBill]

Re: Sanyo DP50747 no video

Would the output voltage be the voltage sent to the plasma panel?
Got to head to work now. Will try and post a photo of the bottom of the zsus in the next day or so.

Not directly, it is probably used to generate a drive signal.

PlainBill

[Tproveau]

Re: Sanyo DP50747 no video

Sorry for the long delay posting again.
Attached are photo's of the bottom section of the Z sustain board.
Not sure if I should try spending some cash on a Z sustain or try parting out the good power board, control board etc. or just scraping the set?
From what I can tell this Sanyo model had high failure rates which makes me reluctant to spend on it.
I don't need another 50 inch Plasma as I already own a newer LG myself but my son would have liked this one if it could have been fixed by replacing a few caps.
Thanks again for your input Bill.
P.S. One photo with flash on one with no flash.

[CoppellTVRepair]

Re: Sanyo DP50747 no video

Hello,
this is some information we hope will help people seeking help with Sanyo DP50747 plasma TV troubleshooting.

For a starter it is very important to know which chassis is your TV.

This helps narrow down the list of available failure descriptions, modules for sale and repair services offerred - not just by us, not just in this forum/thread, but everywhere on Internet.

Sanyo DP50747 is one of the first 50'' plasma TV models out there and it came in so many different versions, all bundled under the same DP50747 model, it is often very confusing to figure out what you need from all the other information.


And the differences between the different chassis models is so big it is practically talking about different TVs with different failures and solutions for each individual chassis model!

At the time - and even now - many people did not know about this differences so they just referenced to their TVs as "Sanyo DP50747" and the result is that there's ton of information out there that is mixed up and misleading as it may be for one chassis model and you could have another.

The chassis is printed on the label, usually right under the model number and is very similar to it - it lacks the leading "D" from the model and has a suffix with a dash and the number of the sub-model (chassis) version.

***LINKS REMOVED BY SITE STAFF***

Hope this helps!