rca model l37wd12yx1

[garciaj]

So I got this tv thinking it would be an easy fix. Im wrong and don't have a clue, I have changed out all the caps on the main power board. It also has secondary power board that. someone else tried to fix but they did a really bad job and I almost wonder if they didn't fry it in the process or anything else for that matter.

I did find a replacement part for it that I think will work for all the models but im not quite sure.
http://www.shopjimmy.com/catalogsear...price&dir=desc

The first picture is the bad soldering job,thrid should be were the board sits

Think that's about it, thanks very much in advance for any advice.

[PlainBill]

Re: rca model l37wd12yx1

So I got this tv thinking it would be an easy fix. Im wrong and don't have a clue, I have changed out all the caps on the main power board. It also has secondary power board that. someone else tried to fix but they did a really bad job and I almost wonder if they didn't fry it in the process or anything else for that matter.

I did find a replacement part for it that I think will work for all the models but im not quite sure.
http://www.shopjimmy.com/catalogsear...price&dir=desc

The first picture is the bad soldering job,thrid should be were the board sits

Think that's about it, thanks very much in advance for any advice.

Wow!!! Almost more problems than I want to contemplate.

First of all, the good news. One or two of those pictures were clear enough to be useful. And it should be possible to repair the power supply. Plus you did attach the pictures, rather than post inline. The third picture DID give an indication of something BAD happening.

Now for the problems. Most of the pictures were so badly out of focus they were useless. The glare from the flash doesn't help either. That's not surprising; I consider myself fortunate if 1/3 of the pictures I take are useful. I just don't post the failures. One other clue - most boards have an orientation. I go by the major lettering. If you position it so most of the legends are right side up, it's easier to decipher.

Bad news, no service manual available from my favorite site.

Here's what would make it easiest to help you: Take new pictures. The first one should be an overall picture of the back of the set with all boards in place. (Don't bother putting in the screws, but cables should be at least near their connectors.) This gives me an idea of the power flow.

Next, I would like to see two pictures of each of the boards. The first is of the top side of the board with the majority of legends oriented for easy reading. The second is of the bottom of the board, with it flipped from left to right. That way if I'm trying to identify a component in the upper right corner of the top picture I know the leads appear at the upper left corner of the bottom picture.

After viewing those pictures I will be identifying points I wish you to measure. And of course, a brief description of the problem would help.

PlainBill

[garciaj]

Re: rca model l37wd12yx1

Major problem is theres no power at all. theres 120 going in, but the power button wont do anything, no lights, no sounds.

[PlainBill]

Re: rca model l37wd12yx1

Major problem is theres no power at all. theres 120 going in, but the power button wont do anything, no lights, no sounds.

That's what I suspected. With pictures I can point out where to measure voltages to identify the area of the failure.

PlainBill

[ropiemasta]

Re: rca model l37wd12yx1

So was this ever taken farther. I've got the same TV with the same exact issues. I can take the pics of the TV with all cards in place and close ups of individual cards as well. I'm at a lose as to what I should be reading...

[PlainBill]

Re: rca model l37wd12yx1

So was this ever taken farther. I've got the same TV with the same exact issues. I can take the pics of the TV with all cards in place and close ups of individual cards as well. I'm at a lose as to what I should be reading...

Take clear pictures of the top and bottom of the power supply board as I described above. That will make it easy to identify test points.

PlainBill

[ropiemasta]

Re: rca model l37wd12yx1

This is the back:


Front:


And overall view:


In the overall view the colors:
Red - I measured 120V coming in.
Cyan - Measured 5V
Purple - Nothing.

So that being said, the problem should be between the red and purple. Just can't figure out the flow. Thanks for the help. If you need bigger pics, let me know and I'll put bigger ones up.

[PlainBill]

Re: rca model l37wd12yx1

0. If you have 5 volts, the standby supply is probably working.

1. I'm multitasking and have a headache.

2. Please don't post pictures inline.

3. While I can (with difficulty) read upside down, I've never mastered reading sideways. If the pictures aren't large enough and clear enough to read the labels, they don't help me help you.

4. Note the links in my signature on taking and attaching pictures. PLEASE, as close to 2000 x 2000 as possible, and oriented so the test is right side up.

PlainBill

[ropiemasta]

Re: rca model l37wd12yx1

Hopefully these are better. Thanks

[PlainBill]

Re: rca model l37wd12yx1

Hopefully these are better. Thanks

The quality of those pictures is excellent, thank you. Unfortunately, what I thought was printing in the earlier pictures - isn't. These guys didn't give many clues to help.

Still, we will work with what we have. It appears the 4 pin connector on the output is the standby supply. The focus isn't sharp enough to enable me to read the legend, but I suspect it is 5V standby and Gnd. Please confirm that. CON3 is definitely the main power supply output, and it has both 12 and 24 volt outputs. And what is of more interest, pin 1 is the control input. Typically, pin 1 will be low (0V) when the TV is in standby, high (3-5V) to turn the main power supply on.

Your job is to verify voltages out of the standby output (and what the tiny printing says), and check the voltage at pin 1 of CON3. If it switches from low to high (and back again) as the power button is pressed repeatedly, but there is no change in the output of the supply, you have a power supply problem. If CON3, pin 1 never changes voltage, you have a problem on the main board.

If it does turn out to be a supply problem, what is the part number of IC1?

PlainBill

[ropiemasta]

Re: rca model l37wd12yx1

Okay, I measured everything and here are my results:

Con3:
Pin 1 ~.4VDC off
~.7VDC on

Pin 2/3 - 0VDC on and off
Pin 7 - 3.11VDC on
- 0VDC off

As for Con2 there was nothing ever connected to that. However there is 5VDC at Pin 1 and 2.

IC1 is an Infineon TDA 16888. Based on the Datasheet, it says pin 2 is a 7.5V reference but I'm getting in the range of 70-80V.

[PlainBill]

Re: rca model l37wd12yx1

Okay, I measured everything and here are my results:

Con3:
Pin 1 ~.4VDC off
~.7VDC on

Pin 2/3 - 0VDC on and off
Pin 7 - 3.11VDC on
- 0VDC off

As for Con2 there was nothing ever connected to that. However there is 5VDC at Pin 1 and 2.

IC1 is an Infineon TDA 16888. Based on the Datasheet, it says pin 2 is a 7.5V reference but I'm getting in the range of 70-80V.

Oy vay!!!! This gets more confusing the further things go.

Reference the third picture on post 7 - the picture of the entire set. It appears to me the AC input connector for the set is at the bottom middle of the picture. Is that correct? The red and black wires may carry AC to the board in the upper right corner of the picture. Is that right?

If I was right about that, could I have a good picture of the board in the upper right corner?

You're reading the voltage at pin 2 of the TDA16888 using the wrong ground. For measurements on the hot side, use pin 7 of the TDA16888 (or points connected to it) as ground.

PlainBill

[ropiemasta]

Re: rca model l37wd12yx1

Thanks for making realize I was using the wrong ground. Using Pin 7 I got a perfect 7.5VDC. From what I can see, AC enters the connector at the bottom middle of the unit. From there follows the red and black line to the small card in the upper right hand side of the unit. From there it is picked off and sent to the main PS via the black and red lines and enters the card where the red circle is. Then makes its way to the 7 pin connector (CON3). I think I might have found a copy of the service manual for the TV so hopefully that will clear things up.

[ropiemasta]

Re: rca model l37wd12yx1

So I found schematics for the PS. Here they are. Hope they make a lil more sense to you.

So far I have measure CON3 and got this

Pin.....Actual...."Good"
1.......~.6........11.9
2-4.....0..........0
5-6.....0..........23.39
7........3.11......3.1

I've started measuring back trying to find either 24 or 12VDC but have yet to find anything. Of course I could be using the wrong ground. If you look at the schematics Ref B37 is where I'm assuming where 24VDC "starts." I measured CS4 but got nothing. BUT should I measure across the cap or use a ground somewhere?

[PlainBill]

Re: rca model l37wd12yx1

So I found schematics for the PS. Here they are. Hope they make a lil more sense to you.

So far I have measure CON3 and got this

Pin.....Actual...."Good"
1.......~.6........11.9
2-4.....0..........0
5-6.....0..........23.39
7........3.11......3.1

I've started measuring back trying to find either 24 or 12VDC but have yet to find anything. Of course I could be using the wrong ground. If you look at the schematics Ref B37 is where I'm assuming where 24VDC "starts." I measured CS4 but got nothing. BUT should I measure across the cap or use a ground somewhere?

You are going at it from the wrong direction. The On/Off signal comes in on CON3, pin 7 and goes through the area where you were working, and eventually to IC2 (one of the opto isolators). Make sure the signal is getting through there.

To use an analogy, if you just replaced the spark plugs in your car and now it's lacks power, you wouldn't start troubleshooting at the differential.

PlainBill

[pelota]

Re: rca model l37wd12yx1

I have got the same model TV, with the same symptoms.
CON3

Pin.....Actual...."Good"
1.......~.6........11.9
2-4.....0..........0
5-6.....0..........23.39
7........3.11......3.1

I checked the opto isolators and found IC3 (P421) to measure about 17 Kohms between pins 3-4 in either direction. IC2 was about 750K. Would this cause no voltage on the 12 and 24 volt lines?

Thanks

[ropiemasta]

Re: rca model l37wd12yx1

Hey pelota, how did you get that white gunk covering IC2 and IC3 off? Any type of cleaner or just plain scraping it off?

[ibanez1357]

Re: rca model l37wd12yx1

By any chance does the red standby light come on?

[ropiemasta]

Re: rca model l37wd12yx1

Yes my standby light is on. When I try to turn on the TV I get a click from the relay on the smaller power supply and the red light turns off.

[ibanez1357]

Re: rca model l37wd12yx1

Yes my standby light is on. When I try to turn on the TV I get a click from the relay on the smaller power supply and the red light turns off.

Ah never mind then there is a common problem with the red light staying on with this model. Any time the standby LED goes out after you hit the button it's usually something blowing the fuse on the main power supply.