KVX2982U Sony Trinitron TV - No remote functions

[ant12345]

Hi, I have a Sony Trinitron KVX2982U TV. For some reason, the remote functions work intermittently. The actual remote control is fine. It's the TV that has the problem.

Can anyone advise on what I can look into.

Thanks Ant

[torbjorn]

First, check wheter you have anything in the room that can disturb the IR communication from the remote to the tv. Some modern low energy lamps can be very nasty as they have a switched mode ballast operating at roughly the same frequency as the modulation frequency of a typical IR remote (30-50 kHz).

I have had problems with a low energy lamp that blocks the remote for my heat pump, that's very annoying as the indoor temp sensor is located in the remote. I had to put up a piece of black plastic to blind off the heat pump's IR sensor from the light from that lamp.

[ant12345]

Hi, Thanks for the repsonse. Apart from the sky box and the ceiling lamp (and the TV of course), there are no other electrical items in the room.

The 'no remote functions' does occur in the day (with the lights off) and so I suppose I can rule that out.

I have noticed that when the red LED light on the front of the TV lights, the remote works, otherwise it doesn't. Sounds like a TV remote receiver problem ; perhaps a dry joint some where on the board.

I have an electrical/ electonic backgound (CEng) and so do have come awareness of electical systems.

Thanks

[minnie]

I'd start by resoldering the IR sensor.

[ant12345]

Hi, I've opened the TV & check the IR board. All seems ok - no dry joints. Cleared the tracks etc.

Upon looking into this more, I notice that the LED light on the front of the TV, which is ON when the TV goes into standby mode goes off after an hour or so. This should stay on.

When the remote function does work, this RED LED blinks which i think is normal.

Perhaps a power issue to the IR board ???

By the way, the LED & IR components are on the same board connected via a 6-7 pin connector to the main board.

[Leadfoot]

.
ant12345,

Here is a suggestion:

1. Remove the batteries from your remote.

2. Carefully open up the remote clamshell.

3. Pull out the PC board and peel off the elastomeric keypad.

4. On the back of each and every key is a small conductive button.
If the power button is pressed, the small conductive button
needs to make contact with the conductive trace on the PC
board. If there is any dirt, oil or liquid on the conductive button
or the PC board trace then there will not be any closure on that
PC board switch and the microcontroller chip will not detect a
key press during the keypad array scan.

5. Suggest you clean the elastomeric keypad and that portion of the
PC board that the elastomeric keypad rests on using Isopropyl
Alcohol and a small brush. Try not to get any IA on the micro-
controller chip. Once you have cleaned the keypad and PC board
use a paper towel to thoroughly dry the keypad and PC board.

6. Place the keypad into the plastic clamshell so that it fits into the
corresponding holes. Place the PC board on top of the keypad,
component and conductive trace side down.

7. Carefully attach the other half of the plastic clamshell so that it
snaps together with the other half. Make sure that the coil springs
for the batteries are visible and protroding into the battery tray.

8. Insert batteries into the tray and your done.

Let me know if this helped you or not.

Cheers,

[Guest]

Take your camera phone to the front of the remote and see if the led lights. This will tell you if it's a remote problem or micro problem.

[ant12345]

Hi,
First of all, thanks to leadfoot & 'guest' for your advise.

1. The remote is fine. I have 3 remotes which all work. I've tested them on other sony TV's.

2. I tried the mobile phone suggestion. This doesn't make the LED blink; even on another TV I have which works perfectly.

Since poking around the other day, the reliablity of the remote functions has improved. I suspect its a dry joint on the main board, however I don't really want to fiddle around with the TV incase something else malfunctions.

Does anyone know where the power to the IR / LED board comes from the main board.

Thanks

[kenray]

you might want to resolder the connections even though they may look good. sometimes cold solder joints are hard to detect without a microscope.

[ant12345]

Thanks for the posts. I've resoldered all the parts on the IR board. The problem still exists i.e. intermitent remote functions.

Any other suggestions ? Thanks