RCA L37WD12 won't power up

[ilikesteel]

I have this RCA L37WD12 that won't power on. the small 1W 5V stdby power supply is working. 5.1V stdby voltage is there.

The power on signal from the scaler board is working. the small 1W 5V supply does supply 120vac to the main SMPS after hitting the power on button.

however, at conn3, the +12 and the +24 are not reading correctly. pin 1 of conn3 reads about 1.9V instead of +12. pins 5 and 6 on conn3 read 19.0 volts instead of +24. pin 7 (blue wire) has 3.2V.

I removed the 6 caps from the main SMPS board and have decided to replace them. they are capXon caps, 3 of them are 1000uf@16V, and the other 3 are 1000uf@35V and probably original to the board.

I'd like to buy the Panasonic FR series from digikey. will the following caps be a good replacement?

http://www.digikey.com/product-detai...466-ND/2433600

http://www.digikey.com/product-detai...2CT-ND/3072212

thanks guys.

[ilikesteel]

Re: RCA L37WD12 won't power up

UPDATE:

replaced 6 caps, 3=1000uf 16V, and 3= 1000uf 35V. the caps were Panasonic FR series and I matched the exact uf and voltage ratings.

no change in the powering on of the TV.

stdby voltage 5.1V

upon power on, led goes from red to green (ps clicks) and the led continually blinks green until I interrupt the power. dead set.

AC 120V is being turned on to the main smps.

voltages out at connector #3 are 3.6V for the +12V leg, and 21V for the +24V leg. consensus is the main smps not putting out the correct +12 and +24, right?

can it be any other board of the set not allowing the voltages to come up?

scaler board on far left has a blinking red led on it that just blinks on and off at a quick rate of change.

I'd like to take a shot at troubleshooting the smps. since I have the AC going to the smps and incorrect voltages, where would I start to look for the trouble.

thanks a bunch
ilikesteel

[budm]

Re: RCA L37WD12 won't power up

Do you get close to 400VDC between the two legs of the main filter cap when TV is turned on?

[ilikesteel]

Re: RCA L37WD12 won't power up

thanks Budm.
I haven't checked that. is that the large round cap which is on the HOT side of the power supply? I will check it in the morning. it may be tight to get the leads on the cap. will do my best and report back.

thanks

[budm]

Re: RCA L37WD12 won't power up

thanks Budm.
I haven't checked that. is that the large round cap which is on the HOT side of the power supply? I will check it in the morning. it may be tight to get the leads on the cap. will do my best and report back.

thanks

Yes, we need to find out if the PFC Voltage booster circuit is working or not.

[ilikesteel]

Re: RCA L37WD12 won't power up

Budm,

180uf, 400V rated cap. looks like C3 in schematic. I got 360V across + and - leads. now what?

thanks so much
ilikesteel

[budm]

Re: RCA L37WD12 won't power up

Budm,

180uf, 400V rated cap. looks like C3 in schematic. I got 360V across + and - leads. now what?

thanks so much
ilikesteel

Next step will be tracing the circuit and checking the 12V/24V SMPS section.

[ilikesteel]

Re: RCA L37WD12 won't power up

Budm,
do I need to post more pics of the top and bottom of the board for details. I assume the +360V is ok and not too low. where do I begin to trace?

thanks
ilikesteel

[budm]

Re: RCA L37WD12 won't power up

http://www.shopjimmy.com/rca-272062-power-supply.htm
Is this the one you have?
RCA 272062 (JSK3220-007D, JSK3220-007B) Power Supply
Pictures provided by shopjimmy

[ilikesteel]

Re: RCA L37WD12 won't power up

Budm,
Yes, That's the one. I was going to try and get some voltage readings on the cold side of the T1. not sure what to expect. the schematic I have does not show voltages except for the output of the +5, +12 and the +24. just give me a place to start.

thanks,
ilikesteel

[budm]

Re: RCA L37WD12 won't power up

Budm,
Yes, That's the one. I was going to try and get some voltage readings on the cold side of the T1. not sure what to expect. the schematic I have does not show voltages except for the output of the +5, +12 and the +24. just give me a place to start.

thanks,
ilikesteel

OK, good, now I have good picture of the bottom side of the board from SJ for me to trace the circuit, but I do need good hi res straight shot of the top side.

[ilikesteel]

Re: RCA L37WD12 won't power up

Budm,
The very 1st pic on post 1 is of the top of the board. I just took some pics of the board in sections trying to get some close ups. I also tried to identify some of the components mounted to the black heat sinks on both sides of the supply.

The following are mounted on the black heat sinks. some are isolated from the heatsink.

Q2, Q4 and Q10 are all FOPF 13N50C
D4 N6D-FSU10A60
DS3, DS5 MBR-20100 FCT AKA ac0160 (?)
DS2,DS4 MBR-20150 CT AKA AC0529
could not quite read Q12, but it's marked with SIRECT MBR -xxxxxxx

most are marked with the name SIRECT

IC1 INFINEON
TDA 16888
P V0617601K15
G0610L

T1 BCK50298S

Thanks
ilikesteel

[ilikesteel]

Re: RCA L37WD12 won't power up

"bump"

[budm]

Re: RCA L37WD12 won't power up

I did not get any where with it last night, I spent over an hours looking at the pictures, the board is really crowded so it hard to trace the connections.
BTW, you can see over heated SMD resistors/cap for the snubber drive circuit.

[ilikesteel]

Re: RCA L37WD12 won't power up

Budm
oh oh, now what?

[ilikesteel]

Re: RCA L37WD12 won't power up

"BUMP"
Budm,

during this past week while bad-caps was unavailable, I went over the PS board. I took resistance measurements of most of the diodes. transformers, mosfets, and the shottkey barrier diodes. I didn't see any obvious shorts or opens.

the last useful test I made was across the main cap which showed 360V. I'd like to take more voltage readings, but I'm not sure what correct voltages should be and exactly where to check them. can I make useful tests on the secondary side of transformer T1? The output voltages haven't changed, +20V on the +24 rail and +2V on the +12 rail.

what part of the circuit would affect the +12 and +24 outputs? should be something common to both, right? this is the furthest I've checked on a PS. I'm willing to do more with some direction.

Thanks,

ilikesteel

[ilikesteel]

Re: RCA L37WD12 won't power up

Another "BUMP"

[ilikesteel]

Re: RCA L37WD12 won't power up

Another "BUMP"

[ilikesteel]

Re: RCA L37WD12 won't power up

Another "BUMP"

Thanks

[ilikesteel]

Re: RCA L37WD12 won't power up

Another "BUMP"

thanks