Toshiba 26LV61K Wont power on

[landyboy]

Re: Toshiba 26LV61K Wont power on

Ok first tested from neg of large cap to pin 5 (drain) no voltage. Checked snubber diode OL and .54vdc.
IC
Pin 1 .74k
Pin 2 12.3M
Pin 3 276.8K
Pin4 3.54K
Pin 5 25.8ohm
6
Pin 7&8 .2ohm

[budm]

Re: Toshiba 26LV61K Wont power on

Pin 5 of 25.8 Ohm is not right at all since that pin is connected to the one end of the Primary winding of the transformer, the other end of the transformer is connected to the + of the large filter cap. Please trace out that Drin pin connection, also see the example circuit in the IC spec sheet to see how it is used.

[landyboy]

Re: Toshiba 26LV61K Wont power on

I may be reaching the limit of my technicial abilities. It appears the Drain then goes to that snubber diode and a small 4.7nf cap which when tested to the neg of the large cap it shows the 25ohm resistance. I did test the small 4.7nf cap on my meter and it is testing 0 on the capacitor testing scale.

[budm]

Re: Toshiba 26LV61K Wont power on

OK, I am sure you are a little confused right now, but any way, it should not go the Negative leg of the cap because the Drain needs to be fed with positive with ref to the ground (negative leg of the cap). Just take a break from it for now try tracing it again later.
Your power supply is more likely to wired up as shown in this picture.

[landyboy]

Re: Toshiba 26LV61K Wont power on

Im sorry I meant I was using the neg lead of cap as a test point.

[budm]

Re: Toshiba 26LV61K Wont power on

OK, since you have indicated 0V reading at the Drain pin, then there must be an open connection some where from the Drain pin back to the positive leg of the cap. Let find out if you have that connection or not.
If your test result is correct, then you have two problems:
1- the Drain to Source has short circuit of 25 Ohms.
2_ Open traces or open winding of the transformer between the + leg of the cap and the Drain pin of the IC.

[landyboy]

Re: Toshiba 26LV61K Wont power on

Take a look at the resistor, I cant believe I missed that. Now I have to brush up on resistor values

[budm]

Re: Toshiba 26LV61K Wont power on

10 Ohms, what are the legs connected to? It may be the fusible resistor that supply the B+ the Drain pin through the transformer winding.
One end the + leg of the cap, another end to the transformer winding?

[landyboy]

Re: Toshiba 26LV61K Wont power on

If I'm correct it is a 1ohm 5%. How exact does the replacemt have to be? I have a bunch of resistors laying around.

[landyboy]

Re: Toshiba 26LV61K Wont power on

It connects to the pos lead of the small cap next to it and eventually back to the IC we have been testing other other end of it.

[budm]

Re: Toshiba 26LV61K Wont power on

It looks like Brown Black Black (10 Ohms), or Brown Black Gold (1 Ohm)? looks to be about 1/2W to 3/4 Metal Oxide fusible.

[landyboy]

Re: Toshiba 26LV61K Wont power on

Yea I think it is Brown Blk Gold Gold not sure why 2 golds? Can I use anything else?

[budm]

Re: Toshiba 26LV61K Wont power on

OK, now I see the traces how that resistor is connected to, the standby power supply B+is generated by another diodes, not by the bridge, but by two diodes D3811, D3814 in series and filter by C3818?, the positve leg then feed the blown resistor, the output side of the resistor feed the one leg of the transformer primary winding, another leg of the primary winding feed the Drain pin of the IC.
So you will need the resistor and the new IC.
Measure the body size.
http://www.digikey.com/product-detai...NCT-ND/2813224

[landyboy]

Re: Toshiba 26LV61K Wont power on

Ok I will order them and follow up once installed...Thanks!!!!

[landyboy]

Re: Toshiba 26LV61K Wont power on

Resistor and IC installed set now working perfect thanks!!

[budm]

Re: Toshiba 26LV61K Wont power on

Great, thanks for the feedback on your successful repair.