Toshiba 26LV61K Wont power on

[landyboy]

I picked up a Toshiba 26LV61K that wont power on. It doesn't do anything. I checked the main fuse and it is good with the correct AC voltage but I can not find any DC voltage present anywhere on the board.

[landyboy]

Re: Toshiba 26LV61K Wont power on

Also checked Fuse 3802

[JonathanAnon]

Re: Toshiba 26LV61K Wont power on

Could just be an optical illusion, but that main filter capacitor (the big cap on the left side of the power board) looks awful strange... Can you take a closer picture of it..

[landyboy]

Re: Toshiba 26LV61K Wont power on

Sure Here you go,

[budm]

Re: Toshiba 26LV61K Wont power on

Check that big white 1.2 Ohms resistor to see if it does show 1.2 Ohms or so.
Do you get any voltage on the that big cap at all?

[landyboy]

Re: Toshiba 26LV61K Wont power on

Resistor reads 1.5 and no voltage at Large Cap

[budm]

Re: Toshiba 26LV61K Wont power on

OK, time for good clear pictures of the board both sides, and also in 1/4 sections (both sides) so I can trace out the connections.

[landyboy]

Re: Toshiba 26LV61K Wont power on

Ok I re-checked the large cap and I do have 169vdc across the cap.

[landyboy]

Re: Toshiba 26LV61K Wont power on

More Pics

[budm]

Re: Toshiba 26LV61K Wont power on

OK, just to be sure, you are getting 0V on all connector with black wires, same on the connector with white wires?

[landyboy]

Re: Toshiba 26LV61K Wont power on

Yes correct 0V on all white and black connector wires

[landyboy]

Re: Toshiba 26LV61K Wont power on

I test 170vdc between these two points

[budm]

Re: Toshiba 26LV61K Wont power on

OK, there is a 6-pin IC next to the small transformer, that is the standby power supply IC. Can you read the numbers as printed on it? We need to get the spec sheet so we can check the resistance and voltages on its pins.

[landyboy]

Re: Toshiba 26LV61K Wont power on

MIP2K4 .998 IC3802 but it appears to be a 7 pin?

[budm]

Re: Toshiba 26LV61K Wont power on

Sorry, you are correct, it is 7 pin for the creepage and clearance of the Source and Drain pin they had to remove one pin. That part number does not come up right.

[landyboy]

Re: Toshiba 26LV61K Wont power on

[landyboy]

Re: Toshiba 26LV61K Wont power on

I'm not sure if this matters but there is no voltage on the source pins.

[Ryu74alpha]

Re: Toshiba 26LV61K Wont power on

Did you manage to fix the set? If not yet hope this helps.......Replaced The Mosfet, usually numbered 10n60,8n65,16n60 and so on..
this mostly solves this problem.
make sure to disharge the large filter cap first... goodluck.

[JonathanAnon]

Re: Toshiba 26LV61K Wont power on

I'm not sure if this matters but there is no voltage on the source pins.

You need to check the voltage on the Vcc pin, not the source pin. I've never liked testing the pins on those small chips, I usually check the voltage on the startup cap to confirm there is no fault with the startup resistors.

The next step I would take would be in line with the above post.. I would power off and plug out, discharge the main filter cap, and test for shorts on the main MOSFET. If there is no voltage AT ALL on the secondary side, there must be a problem with the oscillation circuit, and correspondingly no voltage is induced in the secondary side of the SMPT (Transformer)

[budm]

Re: Toshiba 26LV61K Wont power on

First thing first, you need to get the standby power supply working first, as you can see in the spec sheet, check the Drain pin of the IC, it should have 160VDC on it since it is not switching, then check the Source pin of the IC which should be around 0V.
The start up cap as mention also should be check or just replaced.
I need better pictures of the bottom side around the area of this IC, straight shot, not at an angle.
There is snubber Diode at the Drain circuit area that need to be checked. Then you need to report the resistance reading of all the pins of the IC against the Ground pin of the IC.
By the way, since you are working in the Primary side (Hot side) of the circuits, the negative leg of that large filter cap is the ground ref point, also do not touch any part of the hot side with you hands or body.