rca model l37wd12yx1

[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?

I read the datasheet for tda16888, and checked the voltages on pins 1,2,9,10,13,19. They all seemed good except for pin 19. It should be somewhere between 80-400 volts. I was getting 5v. Less than 11v shuts the chip off, 11- 14 puts the chip in standby.

So I replaced the capacitor C27, off of pin9. Now I get -70volts at pin19, but it only lasts 10 seconds or so. Could this be caused by the main filter capacitor?

Any help much appreciated.

[ropiemasta]

Re: rca model l37wd12yx1

Do you have the service manual for this TV? If so where did you get it.

[PlainBill]

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?

I read the datasheet for tda16888, and checked the voltages on pins 1,2,9,10,13,19. They all seemed good except for pin 19. It should be somewhere between 80-400 volts. I was getting 5v. Less than 11v shuts the chip off, 11- 14 puts the chip in standby.

So I replaced the capacitor C27, off of pin9. Now I get -70volts at pin19, but it only lasts 10 seconds or so. Could this be caused by the main filter capacitor?

Any help much appreciated.

It could be. Are you measuring the voltage properly? You should NEVER get a negative voltage.

First step: Reread the rest of this thread carefully.

Second step: Measure the voltage across the main filter cap.

PlainBill

[ropiemasta]

Re: rca model l37wd12yx1

Made any progress on this??

[ropiemasta]

Re: rca model l37wd12yx1

Just thought of something... Should I always have the standby 5V?

[PlainBill]

Re: rca model l37wd12yx1

Just thought of something... Should I always have the standby 5V?

Yes, if you have AC voltage applied to the power supply.

PlainBill

[ropiemasta]

Re: rca model l37wd12yx1

Thanks. So correct me if I'm wrong in my thinking... (I've only had bout an hour and a half of sleep) When the tv is turned on, Power goes from the SMPS 1W board to the scaler board. From there it sends the on/off "signal" to the SMPS board to get the 24/12V going. Is my thinking correct? I'm looking at the Interconnect pdf that was previously attached. Thanks for the help.

[PlainBill]

Re: rca model l37wd12yx1

Thanks. So correct me if I'm wrong in my thinking... (I've only had bout an hour and a half of sleep) When the tv is turned on, Power goes from the SMPS 1W board to the scaler board. From there it sends the on/off "signal" to the SMPS board to get the 24/12V going. Is my thinking correct? I'm looking at the Interconnect pdf that was previously attached. Thanks for the help.

Exactly right.

PlainBill

[dhack61]

Re: rca model l37wd12yx1

I have the same problem Red standby light on. Measured 3.6V on standby voltage from bp600 smps 1w board to scaler board. Anyone have the schemaitcs on the SMPS 1W board or can tell me what generates the 5v standby voltage?

Dhack

[PlainBill]

Re: rca model l37wd12yx1

I have the same problem Red standby light on. Measured 3.6V on standby voltage from bp600 smps 1w board to scaler board. Anyone have the schemaitcs on the SMPS 1W board or can tell me what generates the 5v standby voltage?

Dhack

It's discussed above and in other threads. The SMPS board contains two power supplies. The first is the standby supply and is always on. This powers the standby processor (on the main board). When the power button on the remote or the control panel is pressed the standby processor pulls the PS_ON signal high, which turns on the main power supply portion of the SMPS board.

Initial troubleshooting is easy. Check for output (typically 5V) from the standby connector. If present, see if the PS_ON signal goes high. If PS_ON goes high, check the outputs of the main supply.

PlainBill

[dhack61]

Re: rca model l37wd12yx1

Thanks Bill
understand what you are saying but this set ( I think) has its own standby SMPS. Its the board in the upper right hand corner of the Pics of the entire back of the set. It is SMPS W1 and from what I can tell, its only putting out 3.6V to the Scaler board. Cant find this board anywere in stock so Guess I'm gonna have to fix it.

[PlainBill]

Re: rca model l37wd12yx1

Thanks Bill
understand what you are saying but this set ( I think) has its own standby SMPS. Its the board in the upper right hand corner of the Pics of the entire back of the set. It is SMPS W1 and from what I can tell, its only putting out 3.6V to the Scaler board. Cant find this board anywere in stock so Guess I'm gonna have to fix it.

I have never seen a TV designed that way. The main power supply definitely has two sections; usually these are standby and main.

PlainBill

[dhack61]

Re: rca model l37wd12yx1

OK
Then what the purpose of the SMPS W1. CON2 on the main SMPS isnt used on this set and if I am reading the SMPS(1).pdf correctly that would be the 5V stand bye, if it was used. So I'm really confused now.

Anybody know where to get a cheap service manual?

Dhack

[hd77shovel]

Re: rca model l37wd12yx1

What is the "common problem" that causes the red light to stay on?