Sanyo DP42647 - No Picture - Sound and Backlight OK

[Frimp]

Sanyo DP42647 LCD TV - No picture

I joined the forum a few days ago and have tried to read everything regarding this problem.
I have downloaded the Service Manual and tried to follow the troubleshooting information but I have been unsuccessful. I feel I have done my homework over the last 4 days and hope one of you can help me figure this out. I was hoping to just find the bad board and replace it. I am not an electronics wiz and I am not to sure of my soldering abilities.

My problem.
My wife turned on the set and it came on fine. Five minutes later the screen went dark but the sound was still working. She turned it off and back on but it still was dark with sound working, and the backlight is on. Next day I turned it on and it had sound but no picture. I tried to change inputs using the remote control to see if it worked with the DVD but got nothing. I tried to change input back to the cable but with no screen I was unable too.

I tried entering the Service Menu mode by unplugging and holding the Vol - button and plugging it back in but still nothing.

I found this forum, read all the threads on a DP42647, I read Retiredcaps write up on 2 seconds to black and decided it did not match my problem since I get no image at all when it first starts.

I have checked the screen with a flashlight to see if anything was displayed but saw nothing.

I have removed and inspected the Power board, Main Board, and Control board, but did not find any obvious problems.

I followed one thread where Tom66 suggested using a MultiMeter to checked the voltage on the Power Board at the 24V pin and it read 23.75. I think that means the power board is ok but I have been wrong before.

I read the Service Manual and followed the troubleshooting flowchart. It suggested looking at IC5500 but it is under a metal shield and soldered to the board. I did check wire K5LV from the Main board to the Control board (the small board at the top) and it looks fine.

So - Should I attempt to remove the solder on the shield and check IC5500 or are there some other test I can do to isolate the problem to a board or an easy repair?
Thanks in advance

[budm]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

The picture 7 is the T-CON board, check that fuse F1 (white fuse with 'K' on top) to see if it shows <1 Ohm of resistance, TV not plugged in of course.
Then with the TV turned, then check the DC Voltage on both ends of the fuse with ref to the chassis ground.

[Frimp]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

Budm - ohms <1 on the fuse and I get 11.75v & 11.74v readings when tv is on

[dixydo]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

hi was it the Tcon board at fault?

[Frimp]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

dixydo - Don't know yet - fuse checked out ok and I don't know about the voltage, I'm waiting on Bud to get back on it.

[selldoor]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

Fuse looks ok - really need a new picture for the Tcon Pic 5 so we can read what it says on it
On the top left just below the connector there is a row of 14 testpoints I cant tell if there is any labels but if there are tell us what they are.
Then below that there is a square IC - what is the part number
Then below that there are more test points but scuppered without a good picture.

Anyway for starters test the 14 in a row meter on vdc20 black probe on a ground screw

[budm]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

There should be some voltage test points and some voltage regulators and switchers on the T-CON that needs to be checked. Need good clear closed up pictures of the T-CON or may have to go to shopjmmy to see if he has good pictures of the board.

[Frimp]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

Here are 3 pics of the board, left side, right side, and test points/IC chip.
I only had time to upload new pics - I will test the points later.
Thanks

[selldoor]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

Thanks- when you get back to it those 14 testpoints then at the bottom of pic 3 there is VGH VGL and VGMA-ref

[Frimp]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

Selldoor - thanks for taking the time to help - I checked the test points with my multi meter set on VDC (it is auto-ranging) and the settings kept changing. I called a friend and he said to test with it set on VAC (I hope that was the right way to test), and all 14 points read .006 volts. I can try again with VDC as you asked if I was wrong.

I am confused because the LVDS out pin shows 12v and I checked it on VDC and it read 11.87v and held steady. I apologize for my ignorance, I have never studied electronics.

I checked the VGL using the VDC setting and it was 6.02, VGH was 26.87, and VGMA ref was 6.1.
Thanks again

[selldoor]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

Test is using VDC I think U304 may be a voltage regulator but cant read the part number.
Try using a different ground? copper hole surround at top of pic one should be good.
Test also LVDS IN , V205 V303 V303-F to see if they are stable

[fading fast]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

I have had bunches of sanyo with no video coming out of main control

[selldoor]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

I have had bunches of sanyo with no video coming out of main control

Thanks - that is a really useful bit of information? What did you do about it?

[fading fast]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

sorry had to buy main, believe many-pin flat pack chip bad

[fading fast]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

look at tuner to see 4 or 5 letter and number / like n7ee yours look like a n6 or older n4**

[Frimp]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

Selldoor - LVDS In reads .1mv
I have checked the 14 testpoints many times and cannot get consistent/good readings.
I get readings showing the polarity is reversed and then change to .7mv and then back down. I did not get any voltage using my old analog multimeter but it is not reliable.
I changed batteries and checked my fuses in my MM and rechecked the TP and came up withe same garbage.
Then I checked:
LVDS In = 0v
V2D5 = 2.482v
V3D3 = 3.3v
V303 - F = 3.33v
Then I rechecked:
VGL = -6.08v (rev polarity)
VGH = 26.86v
VGM-Ref = 4.4mv
VGHC = 26.8v
I did not know VGL was reversed the first time I gave you readings and did not catch VGM-Ref being 4.4mv not v.
Thanks again

[Frimp]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

I just remembered to look at U304.
It has J403 950T65 printed on it.

[selldoor]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

Ok must have missed this -sorry - have had a few projects on the go.
U304 is a 2.5v regulator if you can test it
Its odd that you have those voltages but none on the 14 gl test points - there is usually
a range of voltages so unless you can find out why or where the volatages you have peter
out it looks like a new board - I think it was on here the Max chip was faulty or unsoldered
- perhaps check that out.

[Frimp]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

Selldoor,
I'll look into the Max chip - gotta do my research on that.

I read Retiredcaps post on testing voltage regulators and based on that, I got the following U304 Voltages:
Top pin on left is 1 and read top down:
1 - 3.324
2. 0
3. 2.486

[Frimp]

Re: Sanyo DP42647 - No Picture - Sound and Backlight OK

[QUOTE=Frimp;474312]Selldoor,
I'll look into the Max chip - gotta do my research on that.

I read Retiredcaps post on testing voltage regulators and based on that, I got the following U304 Voltages:
Top pin on left is 1 and read top down:
1 - 3.324
2. 0
3. 2.486

Aug 15:
Well I have checked the board and the net and I need to ask if the "Max Chip" is the 200 pin AUO - 016K1 0723 T002 5K102 chip on the control board?