Voltage level on LCD power supply board.

[just4todd]

A friend that I work with brought me his LCD TV hoping that I could fix it. I originally suspected that it had bad capacitors but after getting the back off and did a visual inspection they all looked okay. I know that the can be bad and look okay externally but I thought I would do some more research before buying all the caps and spending all that time replacing them.
My main question is the voltage levels on the output which goes to the logic board. The 5v standby levels seem to be fairly good, but when I turn it on to check the 12v levels I see what I think is a problem. The 12v pins check around 9.8v. Does this indicate that the power supply board is bad after all, and if so is it the caps or a voltage regulator of some kind? BTW this was checked with all boards connected.
The TV turns on, at least by the indicator on the power button, I hear a click coming from the board, it starts buzzing / whining for about 10 to 15 seconds them the TV powers itself off.

[Toasty]

Re: Voltage level on LCD power supply board.

Make/Model of TV? Board part number?

5 caps along the top left... can't see clearly. Is that leakage or ink markings from the factory?

Can you get the 12v to come up without other boards connected?

Visual inspection is fine, but without checking the caps ESR, you can't be sure.

Screen back lights come on?

Toast

[tom66]

Re: Voltage level on LCD power supply board.

It might be the camera angle, but from here it looks like the dipped polyester capacitor (blue) C842 may be bulging - these fail by a different mechanism to electrolytics but can also bulge. If it is bulging, it can cause low output voltages, I've seen it on Vestel TVs.

[just4todd]

Re: Voltage level on LCD power supply board.

Make/Model of TV? Board part number?

5 caps along the top left... can't see clearly. Is that leakage or ink markings from the factory?

Can you get the 12v to come up without other boards connected?

Visual inspection is fine, but without checking the caps ESR, you can't be sure.

Screen back lights come on?

Toast

The TV is an Element brand, model number is ELCHW402. Mfg board number Element 125372.
The caps along the top have what looks like a mark from the factory.
Have not tried the 12v with all boards disconnected, was not sure what that would mean anyway if it did work.
As far as checking the caps mechanically, I don't have the means.
The screen back lights are not coming on, have not tried the flashlight method yet.
I got into this because I had just started doing some monitor repairs for myself and had been doing real well with replacing caps; 3 total monitors fixed so far, and I thought what the heck I will try something bigger. So here I am.
I have attached more pics so you can get a better look.

[tom66]

Re: Voltage level on LCD power supply board.

It doesn't look normal in your first picutre, does it feel bulged at all?

[just4todd]

Re: Voltage level on LCD power supply board.

It doesn't look normal in your first picutre, does it feel bulged at all?

I have attached a better picture because I really need some help on this. I also included a stock photo of a replacement board for comparison. If the blue capacitor is bad where would I buy a replacement, the printing on the side of it is hard to read.
I want to thank you all for any and all help.

[PlainBill]

Re: Voltage level on LCD power supply board.

I have attached a better picture because I really need some help on this. I also included a stock photo of a replacement board for comparison. If the blue capacitor is bad where would I buy a replacement, the printing on the side of it is hard to read.
I want to thank you all for any and all help.

I'm about 90% certain you need a new cap. That bulging at one end really looks unusual.

Remove it from the board and take a picture of the side. The logo, value, tolerance, and voltage is probably there. Digi-Key carries them

It's hard to read, but it seems to say 1000V and 47NJ, that would be a 47 nF, (4700pF), 1000 volt, 5% tolerance.

PlainBill

[selldoor]

Re: Voltage level on LCD power supply board.

I have looked at a few of these boards on line and that cap appears knobbly /bulged on a few of them. I have put links instead of pictures as they give the names of other sets which I think use this board and may assist in discovering a schematic. I havent had time to look on Badcaps to see if they get a mention already.
http://www.ebay.com/itm/APEX-LD4068-...-/370529277379

http://www.retechtv.com/products/rsa...-42lc55s240v87

http://www.retechtv.com/products/125...2-power-supply

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=270859118919

@just4todd - can you check Does the following number appear down
one side of your board if not what number does it have

RSAG7.820.1673/ROH

[just4todd]

Re: Voltage level on LCD power supply board.

I'm about 90% certain you need a new cap. That bulging at one end really looks unusual.

Remove it from the board and take a picture of the side. The logo, value, tolerance, and voltage is probably there. Digi-Key carries them

It's hard to read, but it seems to say 1000V and 47NJ, that would be a 47 nF, (4700pF), 1000 volt, 5% tolerance.

PlainBill

Here is a close up of the blue poly cap. It is definitely not uniform in width from one end to the other. I am willing to replace this if I can find a replacement. Thanks for your help.

[PlainBill]

Re: Voltage level on LCD power supply board.

Here is a close up of the blue poly cap. It is definitely not uniform in width from one end to the other. I am willing to replace this if I can find a replacement. Thanks for your help.

Mouser 871-B32652A473J should work. Check dimensions before ordering.

PlainBill

[just4todd]

Re: Voltage level on LCD power supply board.

Mouser 871-B32652A473J should work. Check dimensions before ordering.

PlainBill

I have looked just about everywhere and I can find no one which has a cap to these specs that is the right size. The cap has leads that are about 1 inch apart. Can anyone help me by finding a direct replacement or telling me how to make a different size cap work in its place?

Attached another picture to help show the size.

Thanks again for all of your help.

[PlainBill]

Re: Voltage level on LCD power supply board.

I have looked just about everywhere and I can find no one which has a cap to these specs that is the right size. The cap has leads that are about 1 inch apart. Can anyone help me by finding a direct replacement or telling me how to make a different size cap work in its place?

Attached another picture to help show the size.

Thanks again for all of your help.

The leads were bent on the first picture. You should be looking for a lead spacing of 22.5mm. Digikey 495-3799-ND and 399-5982-ND should work.

PlainBill

[dcavman]

Re: Voltage level on LCD power supply board.

i have what seems to be the same power supply but i am thinking a different issue my educated guess is that the main 220uf 450V cap leaked can any one help pictures to come

[selldoor]

Re: Voltage level on LCD power supply board.

Ok please can you update your profile with country and mains voltage.
Can you state the make and model of YOUR Tv and the part number on the
power supply though it should be clear in the picture.

Welcome to the forum-
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
https://www.badcaps.net/forum/attach...1&d=1290283049

https://www.badcaps.net/forum/attach...7&d=1280167246

It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc.

[dcavman]

Re: Voltage level on LCD power supply board.

I am working on the same PCB i believe i can hear somthing is loading it down but am not sure what. any help would be appreciated

[just4todd]

Re: Voltage level on LCD power supply board.

I am working on the same PCB i believe i can hear somthing is loading it down but am not sure what. any help would be appreciated

The blue poly cap was the problem on my board. Once it was replaced; the TV worked normal. Have you checked the voltages on the board? That might help trace the problem.
You say that you can hear something. I was as hearing a buzzing sound, but I don't think it had anything to doi with the problem.

[dcavman]

Re: Voltage level on LCD power supply board.

I tested the polly cap with a high end cap tester it read 17nf in circuit. The power supply pcb number is RSAG7.820.1673/ROH VER.E. The tv is a Dynex model DX-L40-10A.

[budm]

Re: Voltage level on LCD power supply board.

What is printed on the cap?

[selldoor]

Re: Voltage level on LCD power supply board.

Picture are not really clear enough for trouble shooting where is the one of the back of the board. Have you replaced the BIG leaking cap. Is that white rectangular component
ok looks at an odd angle. ( may be a resistor?) You still have not told is what the problem is?

[dcavman]

Re: Voltage level on LCD power supply board.

The blue cap is a 2000v 22nj and the big cap is not leaking the problem is the television will not power up id love to tell you what it did as it died only problem is i am attempting to save it from the dump kinda wanted it for my garage