Toshiba 32AV502U fuse blows

[pop70458]

Hi, I would like to thankyou for allowing me to join this forum.

I have a Toshiba 32AV502U and the power supply fuse blows as soon as the power is connected. The power supply is an FSP145-4F03 or 75012927. I have a dmm that i can use for testing and i am a novice.

Thanks,

Barry

[awyatt2]

Re: Toshiba 32AV502U fuse blows

check bd101 for a short it is a bridge rectifier. dmm set on diode test, if unsure how to do it google how to test bridge rectifier.

[pop70458]

Re: Toshiba 32AV502U fuse blows

I tested the bridge rectifier with the directions i got from the first google result and it tested good. The directions were from a youtube video by aerodurbanite.

[awyatt2]

Re: Toshiba 32AV502U fuse blows

the short is somewhere on the primary side if it blows the main fuse . check the caps for shorts and any diodes as well. usually the bridge when the fuse blows but not always.

[retiredcaps]

Re: Toshiba 32AV502U fuse blows

Check Q101 and Q102 to see if there is a short. Number the pins 1, 2, and 3. Measure the resistance between pins 1-2, 1-3, and 2-3. Any reading under 30 ohms suggests it is shorted and should be desoldered and verified out of circuit.

[awyatt2]

Re: Toshiba 32AV502U fuse blows

had to go look at the pic, check q1d1 and q1d2 c116 c118 and 6102, q1d1 and q1d2 are probally diodes as well there should be a diode symbol on front of the case if it is. probally two diodes in one case. you should find something shorted to ground.

[pop70458]

Re: Toshiba 32AV502U fuse blows

Hi, when i measure q101 and 102 does the negative or postive have to be in a certain position. The legs on the botttom are marked g, s and d.

Thanks for the help.

[retiredcaps]

Re: Toshiba 32AV502U fuse blows

For resistance measurement, it doesn't matter.

If you are new to multimeters, see this tutorial

http://www.youtube.com/watch?v=bF3OyQ3HwfU

[awyatt2]

Re: Toshiba 32AV502U fuse blows

these are fets if gat source and drain. they may be shorted if so they should read the same (low ohms) both ways. i usually pull them and test with analog meter and finger. you can find the way to test on google, you will also need to know if n or p channel, so look up the part number first.

[pop70458]

Re: Toshiba 32AV502U fuse blows

I am going to pull the fets and test them out of the circuit. How would i test c116 and c118? What would these be called also?

Thanks

[budm]

Re: Toshiba 32AV502U fuse blows

Since the shorted circuit is bad enough to blow the main fuse, all you have to do is to look for real low Ohm reading, your meter does not even has to be in Diode mode, just set to 200 Ohm range, since what is/are ever shorted out become just like a piece of wire instead of semiconductor.
So take the resistance reading on those two pair of points as shown in the picture.

[pop70458]

Re: Toshiba 32AV502U fuse blows

The reading on q101 is 14.17 and q102 is 13.78. The dmm i have is set to auto mode is there any setting i need to change? I had the positive on the s terminal and ground on the d.

[budm]

Re: Toshiba 32AV502U fuse blows

Set the meter to 200 Ohm range instead of auto range. We are looking for short, so polarity of the probes do not matter.

[pop70458]

Re: Toshiba 32AV502U fuse blows

The meter only changes from ohm, kilohm and megohm. When it is set to ohm it just gives me OL. I have a extech 22-816 meter.

[budm]

Re: Toshiba 32AV502U fuse blows

OK, I see the user manual for your meter. Set it to Ohm mode. See page 11 how to set it to manual mode.

[pop70458]

Re: Toshiba 32AV502U fuse blows

It just says OL.

[budm]

Re: Toshiba 32AV502U fuse blows

OK, it is not showing dead shorts. See more test points first, then we need to recheck the bridge next

[pop70458]

Re: Toshiba 32AV502U fuse blows

It measures 000.3

[budm]

Re: Toshiba 32AV502U fuse blows

Ok, that is dead short, may be you did not properly test the bridge rectifier since those two points are the AC inputs for the bridge., the board also has two surge suppressor devices that are connected to those two points of the bridge also. It is easier to lift one leg of the suppressor than trying to remove the bridge. See the pictures.
By the way, did your house got hit by any power surge?

[pop70458]

Re: Toshiba 32AV502U fuse blows

It may have been a power surge but this was the only tv that stopped working. I lifted the legs and measured and i go OL on the meter.