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ROB! Or anyone: How can I fix my Toshiba 40WH08B?

The reason I put "ROB" in the question is because the same problem was solved here by someone called Rob:

http://www.howtomendit.com/answers.php?id=43421

Although, no solution was posted :(

The problem in brief:

The TV will switch on for a second then instantly back off, this is due to the protection circuit.
If the green light gun is unplugged from the circuit board with the two large heat sincs on it works fine, no problem. If the green gun is then plugged into the red socket again it switches on fine without any problems, asside the obvious colour/image issues. Therefore the light guns and corresponding boards are fine!
I have so far fixed one diode that had come unsolodered from the aformentioned board and am still experiencing the same problems.

Has anyone seen this before? Or even got some ideas?

If anyone has any ideas I would be REALLY greatful as I don't want to see this TV go.

Joey
March 2009

Toshiba Video, Televisions Rob Anyone Toshiba

My answers above are in the wrong order but hey ho!

One last thing I should mention. The white paste between the ics and the heatsink is silicon thermal compound. Without this the heatsinks will not take heat from the ics effectivly and the ics will burn out!

I recommend that you clean all of the old paste off the heatsinks and apply new to the whole of the metal plates on the back of the ics before you screw them to the heatsinks. You can get the thermal compound and the desolder pump from the same supplier I recommended for the ics.

Good luck

Regards

Kelvin

Kelvin Harley
May 2009

Hi Joey

I have a fix for you that has worked perfectly for me.

On the convergence board PB 9487 (the one with the 2 large heat sinks that the r, b & g guns plug into) you will see two STK392-110 ics connected to the large heat sinks. Replace both of these and readjust convergence in service mode if necessary.

I obtained the replacement ics from Charles Hyde & Sons Ltd (see link below). I ordered the general ics not the Toshiba ones as these are identical as far as I could see and they cost £17.19 each instead of £36.68 each.

http://www.chsinteractive.co.uk/search.html?query=stk392-110

You will need to desolder the heat sinks as well as the ics as access to the ic mount screws are obstructed by the conv.dig board (metal cased). Buy a good quality desolder pump if you dont have one.

Let me know how you get on.

Regards

Kelvin

Kelvin
May 2009

Hi Joey

This seems from these posts to be a common problem with the 40WH08B. I also have the problem but mine works if I unplug the red gun from the board with the 2 big heat sinks.

When I plug the red gun back in and power up, the TV works fine again for anything up to a week before I have to go through the same process again. This has now happended 4 times.

Have you sorted your problem yet?

Kelvin
May 2009