Toshiba 42LX196 Troubleshooting

[cequil32]

I have come across a Tosihba 42lx196 that has the 3 red blinking lights. I thought I had narrowed it down to the power supply but I am not so sure now. I bought a power supply board (Board# PE0071) from ebay supposibly from a working tv but wanted to know what to do to test it to make sure it is ok. I put the "new" board in the tv and I don't get the red lights anymore but the power supply just continues to click, like the relay keeps clicking on and off and I have no lights or signs of power at all. I haven't let the power supply click too long for fear of damaging something else or itself if it proves to be another board that is causing the problem. I have checked some of the pins like the AC Detect and such and I can see the voltages at the right levels for the second that the relay kicks on and then it goes to zero when it kicks out. I am lost...really don't want to buy another board if the power supply board I bought is bad already.

[tom66]

Re: Toshiba 42LX196 Troubleshooting

The "three red blinking lights", is that the power LED or some other light?
As far as testing, can you take any photos of your power board?

[cequil32]

Re: Toshiba 42LX196 Troubleshooting

I believe the blinking light is for the Timer Record not the power LED but I have the "new" board in the tv right now that doesn't flash so I would need to swap them to verify.

I am trying to attach a picture...hope they come out well.

T820 is the relay that is clicking on and off I belive...I have circled it in one of the pictures. It continues to click on and off in almost second intervals. I don't believe it is giving the other boards time to "start-up" before it kills the power because I have tried to go through a Toshiba flow chart and it seems like I am getting the right voltages but it just flickers on and off.

I have had a similar situation in a previous tv I fixed and it ended up being a resistor on the power board that had shorted out similar to the white ones on this board, I have also circled those in the picture.

[cequil32]

Re: Toshiba 42LX196 Troubleshooting

I still believe there is something wrong with the power board that I purchased and not totally convinced, even though the ebay seller insists, it came from a working tv and was tested.

[tom66]

Re: Toshiba 42LX196 Troubleshooting

Along the connector going to the low voltage boards in the set (such as the main board, inverter, etc.) you'll have a listing of the pin voltages, what do each measure? Compare to the label. Try testing your old board as well. Board should be installed in set & the set should be powered on in the fault condition.

[cequil32]

Re: Toshiba 42LX196 Troubleshooting

"NEW BOARD (NO FLASHING LEDS, again these voltages turn on and off)
30V = 0
30V = 0
GND = 0
GND = 0
GND = 0
24V = 0
5V-1 = 5V
GND = 0
ACDET = 0
PROTECT = 0
POWER_SIG = 0
POWER = 3V

"OLD BOARD (BLUE POWER FLASHING LED)
30V = 0
30V = 0
GND = 0
GND = 0
GND = 0
24V = 0
5V-1 = 5V
GND = 0
ACDET = 0
PROTECT = 1.5V
POWER_SIG = 0
POWER = 0

I thought it was the timer rec light flashing before, I looked at it again and the STR W6765 component is loose so that may be a problem...I may try to solder it back on good and see if that makes a difference.

There are no other voltages on any of the pins but I may go back and check again to be sure.

[tom66]

Re: Toshiba 42LX196 Troubleshooting

Looks like the old board was fault with PROTECT output, but some other damage may have been done elsewhere.

[Joelito Maderazo]

Re: Toshiba 42LX196 Troubleshooting

Agree with tom. your previous board was in protect since you got 1.5v
Since your new board was on & off the relay..Im not sure but looks like theres a problem on the load side.

[cequil32]

Re: Toshiba 42LX196 Troubleshooting

Yeah..that is what it looks like to me that the old one has went into protection mode. For the new one...I have tried trouble shooting based on the Toshiba Service Manual Flow chart and it points to changing out the A/V Board but I still think there is a problem on the "new" power board because it continues to click on and off like it is trying to turn on but maybe there is something wrong with the circuit protection on the Power Supply itself.

[cequil32]

Re: Toshiba 42LX196 Troubleshooting

When you say load side do you mean on the Power Supply itself?

[cequil32]

Re: Toshiba 42LX196 Troubleshooting

This did turn out to be the power supply...faulty from the seller and had to get another.

[budm]

Re: Toshiba 42LX196 Troubleshooting

This is how I test the board: similar to LX
https://www.badcaps.net/forum/showth...196#post371455

[mrgcav]

Re: Toshiba 42LX196 Troubleshooting

Replacing only one regulator is not recommended. Toshiba recommends replacing all three regulators
STR-X2039
STR-Z4479
STR-W6765


This is NOT a job for beginners and amateurs. Improper installation technique Will damage these regulators, the PC board or both. This is a difficult job for a pro of 38 years, like myself. IT is dangerous in thinking anyone can do this type of work without prior skills.

Call a Pro if you are not a veteran technician.


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[mrgcav]

Re: Toshiba 42LX196 Troubleshooting

Since this is not a capacitor related issue... Why is this being posted on this site ?

[budm]

Re: Toshiba 42LX196 Troubleshooting

Since this is not a capacitor related issue... Why is this being posted on this site ?

Because it is not just about bad capacitor related problems, we have many people here with many fields of experience in electronics.
BTW, the set I repaired is still working after a year pass so far.