RCA L32HD35D not turning on

[bell7526]

I was given an RCA L32HD35D with a built in DVD player. When pluged in the green light will come on in the front but nothing else. I can not figure out what is wrong. I am new to this and need help.

[PlainBill]

Re: RCA L32HD35D not turning on

I was given an RCA L32HD35D with a built in DVD player. When pluged in the green light will come on in the front but nothing else. I can not figure out what is wrong. I am new to this and need help.

Well, we all have to start somewhere. I have it on good authority that even PCBONEZ wasn't an electronics expert when he was born.

Thank you for the pictures of the power supply and the main board. They were large enough, and sharp enough to be a big help. The tcon and inverter - not so much.

The significant question is 'does the main board fail to ask the main supply to come up, or does the main supply receive the command, and fail to respond, OR does the main supply respond, and the main board hangs in the start process. Unfortunately, the connectors do not appear to be labeled with their pinouts, so we will have to do this the hard way.

I would like two additional pictures. One is of the back of the TV with all the boards in their proper position, and all cables at least laying on their connectors. That will help me get an idea of the layout and signal flow.

The second picture should be of the back of the power supply.

PlainBill

[bell7526]

Re: RCA L32HD35D not turning on

Thank you for the help. I have attached the pictures. The board are attached to the back plastic not the panel.

[PlainBill]

Re: RCA L32HD35D not turning on

Thank you for the help. I have attached the pictures. The board are attached to the back plastic not the panel.

Thanks, that must have been a lot of work. It gave me the information on what connector is for what purpose. Unfortunately, it doesn't tell me what the function of each pin is, so we (and by 'we', I mean 'you') are going to have to do it the hard way.

It's an interesting layout. I'm alternating between "That was very clever" and "What a beast that is to troubleshoot."

CP3902 and CP3903 connect the power supply and the main board. Unfortunately, the only way I can see to do this will require either the control panel or the IR receiver be hooked up. Jumper W044 on the front of the board is ground. A number of the pins on CP3902 and CP3903 will be tied to that, there is no need to check them repeatedly. For the rest, with power hooked up, measure the voltage on each pin. While measuring the voltage hit the power button on either the remote or the control panel several times at 5 second intervals. The information I need is the voltage on each pin, and if it changes when you hit the power button. If you wish, you can identify adjacent pins that are tied together and only check one of them.

PlainBill

[bell7526]

Re: RCA L32HD35D not turning on

Thanks I will try to check the voltage tomorrow. Ran out of time today.

[bell7526]

Re: RCA L32HD35D not turning on

I not very good with a multi-meter yet, but these are the readings I got from my analog meter.
CP3902
Pin 1 - 0 on 15AC Setting
Pin 2 – 0 “
Pin 3 – 0 “
Pin 4 – 0 “
Pin 5 – 0 “
Pin 6 – 0 “
Pin 7 – 0 “
Pin 8 – 0 “
Pin 9 – 0 “
Pin 10 – 0 “
Pin 11 – 0 “
Pin 12 – 0 “
Pin 13 – 0 “
Pin 14 -13 “
Pin 15 – 13 “

CP3903
Pin 1 – 7.5 on 150AC Setting
Pin 2 – 11 on 15AC Setting
Pin 3 – 11 “
Pin 4 – 0 “
Pin 5 – 0 “
Pin 6 – 0 “
Pin 7 – 0 “
Pin 8 – 7.5 “
Pin 9 – 7.5 “
Pin 10 – 6 “
Pin 11 – 7.5 “
Pin 12 – 7 “
Pin 13 – 7.5 “
Pin 14 – 7.5 “
Pin 15 – 0 “

The ones that read 0 were tested by repeatedly hitting the power button at 5 sec intervals. They did not change at all.

[PlainBill]

Re: RCA L32HD35D not turning on

These are DC outputs. Set the meter to the DC range.

PlainBill

[bell7526]

Re: RCA L32HD35D not turning on

As I said I a newbie to the multi-meter. These are the readings on setting 50 DC. I know I need to invest in a digital meter. I use the analog meter to test underground dog fences for breaks.

CP3902
Pin 1 - 0
Pin 2 – 0
Pin 3 – 0
Pin 4 – 0
Pin 5 – 0
Pin 6 – 0
Pin 7 – 0
Pin 8 – 0
Pin 9 – 0
Pin 10 – 0
Pin 11 – 0
Pin 12 – 0
Pin 13 – 0
Pin 14 - 2
Pin 15 – 2

CP3903
Pin 1 – 10
Pin 2 – 2
Pin 3 – 2
Pin 4 – 0
Pin 5 – 0
Pin 6 – 0
Pin 7 – 0
Pin 8 – 1
Pin 9 – 1
Pin 10 – 1
Pin 11 – 1
Pin 12 – 1
Pin 13 – 1
Pin 14 – 1
Pin 15 – 0

The ones that read 0 were tested by repeatedly hitting the power button at 5 sec intervals. They did not change at all.

[PlainBill]

Re: RCA L32HD35D not turning on

Well, it looks like pin 1 of CP3903 is the output of the standby supply. The main board shows what is obviously a pair of voltage regulators in that area. It's not going to be a fun thing to troubleshoot. If you want to take that approach, there is a 5 pin IC (pin 3 missing, and the IC has a tab) on the bottom side of the board directly above pin 1 of the interconnect. What is the part number of that IC?

As an alternative, this eBay auction is selling the main board.

PlainBill

[bell7526]

Re: RCA L32HD35D not turning on

One other thing is their is a DVD in the player and I turned the TV on and tried to eject the DVD and nothing happen. I don't think the DVD player is getting power is does the main board control that as well.

[PlainBill]

Re: RCA L32HD35D not turning on

One other thing is their is a DVD in the player and I turned the TV on and tried to eject the DVD and nothing happen. I don't think the DVD player is getting power is does the main board control that as well.

Yes. I've been over this many times on other sets. The basic design is the same on all of them. The power supply is actually two supplies in one board. The first is a standby supply, which is on whenever the power cord is plugged in. That provides power (usually 5 volts) to the standby processor (or in this case, probably the standby section of the main processor). When the standby processor sees the power button is pressed, either on the control panel, or on the remote, it pulls a control line high, which turns on the main power supply. This typically will provide 12 or 24 volts for the inverter, and may also provide additional power to the main board. In this case, it will also provide power for the DVD player. Your tests did not show any control line going high.

On many sets, this would not be a problem because the power supply connector is clearly marked. The control line can be forced high to verify the power supply is good. That isn't the case here. Not only that, there are coatings that make it extremely difficult to trace the lines.

PlainBill

[bell7526]

Re: RCA L32HD35D not turning on

Replacing the Main Board should hopefully fix it then. Right?

[PlainBill]

Re: RCA L32HD35D not turning on

Replacing the Main Board should hopefully fix it then. Right?

The operative word is 'hopefully'. It is much easier to trace circuits with board in hand than it is on a picture. Some of the results are ambiguous.

One not so secret clue is if you search for a particular model TV on eBay and see 5 main boards and 0 power supplies, it indicates the power supply fails more frequently than a main board. Unless the 5 main boards are all 'refurbished', and you see someone selling a repair service.

I am reluctant to say 'buy this' unless I have a high expectation that 'this' will fix it.

PlainBill

[bell7526]

Re: RCA L32HD35D not turning on

I found several power boards for around $40 on ebay. Is there any other suggested circuits, you would recommend before I guess at which board to buy. It is never just a simple decision.

[PlainBill]

Re: RCA L32HD35D not turning on

I found several power boards for around $40 on ebay. Is there any other suggested circuits, you would recommend before I guess at which board to buy. It is never just a simple decision.

While composing a snarky reply, one idea DID come to mind. It's a long shot, but try disconnecting all cables from the DVD player.

And thinking about it some more, there are a few tests we can try to eliminate simple faults with the power supply. First, do the DVD player thing.

PlainBill

[bell7526]

Re: RCA L32HD35D not turning on

I disconnected the DVD player. But also didnt test CP3903 properly. I only power cycled the pins that registered 0 and they didnt move. I went back and power cycled the pins on CP3903 that register something above 0 and when the power turned off they went to 0 and with power on they register what I listed above.

[PlainBill]

Re: RCA L32HD35D not turning on

I disconnected the DVD player. But also didnt test CP3903 properly. I only power cycled the pins that registered 0 and they didnt move. I went back and power cycled the pins on CP3903 that register something above 0 and when the power turned off they went to 0 and with power on they register what I listed above.

OK, it's been a long day for me, but let's see if we can move forward. What are the DC voltage ranges on your VOM? It would be nice if we could get better resolution on these readings without risking bending a needle. If you can determine when the TV is on and off you won't have to hit the power button repeatedly. Also, if you look at the bottom of the connector, it is obvious some of the pins are connected together

What I would like to see is something like this:

Pins ,, Off ,, On

1,2 ,,, 0 ,,, 0
3,4 ,,, 0 ,,, 5

And so forth.

Also, D3822, D3826, and D3827 are almost certainly the rectifier diodes for the main supply. Check them for shorts.

PlainBill