RCA RLED2845A Red Led No Power Up

[Icitte]

Hi all,

I am pretty new at TV/Monitor repair. I repaired around 10 lcd monitor, mainly bad cap and some fuse/bridge rectifier problem.

Someone give me a 28'' LED TV and I am a bit lost for the diagnos procedure....

The red LED turn on when plugged but nothing happen when I press power button on the TV or on tne remoteé

The logic en power board is the same. Fuse not burst, every cap seems fine, no burned welding. If you have any advise for me it would be appreciate!

tanx a lot

p.s.: sorry for my bad english!

[dskall]

Re: RCA RLED2845A Red Led No Power Up

Does red light blink when you push buttons? Sorry I do not know how to troubleshoot integrated power/mainboard

[Icitte]

Re: RCA RLED2845A Red Led No Power Up

No blink the light still solid red

[dskall]

Re: RCA RLED2845A Red Led No Power Up

Check your button/ir sensor cable for voltage and voltage change when pressing buttons

[dick_barton]

Re: RCA RLED2845A Red Led No Power Up

Any voltages on the board??? where it says 5V, 3V etc???

[Icitte]

Re: RCA RLED2845A Red Led No Power Up

ok here some update

here my testing result at the connector on the logic/power board

the wires come from the ir board and button board

from left to right, result (VOLT) in stand by mode and when power button pressed

1 GND 0 0
2 K7/N - -
3 K6/P 3.3 0
4 K5/M 3.3 0
5 K4/V- 3.3 0
6 K3/V+ 3.3 0
7 K2/C- 3.3 0
8 K1/C+ 3.3 0
9 K0/S 3.3 0
10 GNS 0 0
11 IR 5 5
12 GRN 0.088 0.088
13 RED 1.67 1.67
14 5V 5.12 5.12

I saw a little resistor or cap on the bord just at the left where its written R12V

measure resistance = 0

thanks again for your help

[dskall]

Re: RCA RLED2845A Red Led No Power Up

Looks like pin 3 K6/P is power button. Others are vol, chan, menu. Do they change voltage when you press button? R12 maybe a 12v point.

[Icitte]

Re: RCA RLED2845A Red Led No Power Up

I think that when you press power it is suppose to send signal to a pin often call PSON. Am I right? If yes which pin is it so I can try to bypass the system!

[Icitte]

Re: RCA RLED2845A Red Led No Power Up

R12v has 12v only on one side

[dick_barton]

Re: RCA RLED2845A Red Led No Power Up

It is a 0 ohm resistor which should have 12V on both sides. Power down the set and measure using your meter set to ohms.

If it's the white connector you mean then one pin will be 12V the other 0V

[Icitte]

Re: RCA RLED2845A Red Led No Power Up

Ok yeah finally 12v on each side of the resistor so here is not the problem

[dskall]

Re: RCA RLED2845A Red Led No Power Up

When you press power button It sends input to mcu. You should get voltage changes when you press buttons

[Icitte]

Re: RCA RLED2845A Red Led No Power Up

When you press power button It sends input to mcu. You should get voltage changes when you press buttons

is mcu this chip?

http://www.datasheet-pdf.info/attach...3393LU-DI1.gif

I've got this on my board and I saw that pin 59 in on/off, will try to test this

**update pin 59 1.2v nothing change when I press power button

[Icitte]

Re: RCA RLED2845A Red Led No Power Up

Anybody?

[Icitte]

Re: RCA RLED2845A Red Led No Power Up

ok! I give up!

who want it? lol seriously, anyone can tell me which pin is the on/off and how the voltage should be on this pin? like 0 when off and 5 when on?

thanks...

[attainteddragon]

Re: RCA RLED2845A Red Led No Power Up

i am not very good at these intergrated main and ps boards, but i'll try to help a little.

check dcv (black probe on chassis ground) on ul1, and ul2 (from left to right) looks like a fixed regulator, but i cant read it.

also check the opto (there is only 1 that i can see). i believe that is where your on signal is transferred to the hot side to activate the pfc circuit.

[ddollard]

Re: RCA RLED2845A Red Led No Power Up

I have the same problem. No power and no response from buttons. 5v standby good. Anyone have any advice. There was a post that said to check the optocoupler. What should values be?

[neilc6]

Re: RCA RLED2845A Red Led No Power Up

Every RCA TV I've looked at either has bad backlights (turns on with no backlight or flash of backlights) or bad EEPROMS (has standby light but doesn't turn on). Freeze the eeprom (8 pin SOIC by the main processor) with an upside down can of duster before plugging in. If it turns on, its the EEPROM. If it doesn't, it still could be the EEPROM.

RCAs are low end TVs with very little value and not worth putting any money into repairing IMHO.