Testing transistor on power supply

[Trueburton]

Sorry if this is in the wrong topic. Im testing a panasonic power supply board with 10 blinks. This is my first time testing circuit boards. I am trying to test the transistors currently. I believe I have an PNP transistor. With my meter in diode mode, I get OL on every pin no matter how i test them. If I switch to Ohms I get a reading only on the middle and right pins. Is this a bad resistor? They are out of circuit. Getting the same readings on three transistors.
Thank for the help

[budm]

Re: Testing transistor on power supply

Uploading good clear pictures of the whole top and bottom side of the board and the suspect Transistor will help.
What is this product any way? TV?

[dick_barton]

Re: Testing transistor on power supply

There are quite a few Youtube videos that can help you.

https://www.youtube.com/watch?v=b0jCUsenNsY

[Trueburton]

Re: Testing transistor on power supply

Yes, 2008 50" panasonic TV. I have Youtubed as much as possible but Im not seeing anyone show the same results I am getting. I apologize Im very new to this so I may be overlooking something very obvious.

I can upload pics if you'd like, Nothing looks burned or obviously bad to me. Only testing these transistors cause a few youtube videos said these can go bad.
Thanks for the quick replies.

[martino]

Re: Testing transistor on power supply

post model number,clear pictures of all boards together and separate and a detailed description of what the tv is doing will greatly help people here to help you solve this

[Trueburton]

Re: Testing transistor on power supply

TH-50PZ85U It seems to be a common 10 blink no power issue that a lot of people have, I replaced both IC's on MC301 MC201 and caps. Still no power and 10 blinks. If i leave the TV unplugged for a day or two it will turn on but when you turn it off it wont come back on.

[budm]

Re: Testing transistor on power supply

You are getting some of the power otherwise you will not be getting any blinking LED.
What dcv did you check and have so far on the board components and at the connectors?

[Trueburton]

Re: Testing transistor on power supply

not sure where to even begin

[martino]

Re: Testing transistor on power supply

Not to interfere,but I remember doing a few of these and remember the polarity of the caps clearly.As a general question to not overlook the obvious: Are those the right caps used? Also,those look like big blobs of solder,you sure its not shorting pins on the Ic?

[Trueburton]

Re: Testing transistor on power supply

Its the caps that came with the kit for this exact part number on the board. The are the same value as the polarized ones. From what I understand, theses are just not polarized. Yes my soldering skills and tools are subpar but I do not believe there are any solder bridges.

[martino]

Re: Testing transistor on power supply

kk,I would double check the soldering for sure.

Disclaimer: not trying to doubt your work or skill,just trying to help avoid a long goose chase for a fault if it's a simple mistake,as the 10 blink is such a common thing for these tv's and you did replace the parts that have always solved the 10 blink for me. (I only replace the caps,never the chips)

Getting off stage now and give you back to budm,you're in very good hands with him

[Trueburton]

Re: Testing transistor on power supply

Ill go over the solder points again. Also one other possible culprit, There are a few small surface mount resistors, at least i think thats what they are. About the size of an ants head. Very small and on one of the boards i got too close to one and unsoldered it. I attempted to resolder it but was impossible. Then lost the resistor due to the small size. I need to replace this yet i believe but not sure what size or rating i need to get and how to reinstall. Thanks, again!

[martino]

Re: Testing transistor on power supply

http://www.toms-service-manuals.com/...h=Submit+Query

[vinceroger69]

Re: Testing transistor on power supply

https://www.youtube.com/watch?v=LjpGKaBt8hg

did you replace the moduls back in the rite places as they are diffrent. mc201 mc301

there is a repair service for these on ebay maybe if you message the shop they will advise/know the value of the missing resitor theres no harm in asking i guess.

[Trueburton]

Re: Testing transistor on power supply

Yes i did one at a time as not to switch them around.
Thanks

[Trueburton]

Re: Testing transistor on power supply

First off, getting a little side tracked, no one has answered the first question about my transistors im testing. Please advise. Secondly here is a picture with what I believe is a 1K Ohm resistor that i need to resolder to the board. can anyone confirm the identity of this?
Thanks for all the help!
PS please ignore the solder of the capacitor as i have cleaned that up since taking the photo.

[budm]

Re: Testing transistor on power supply

I still do not see the pictures of the Transistor, and how did you figure out it is PNP Transistor? May be it is MOSFET?

[vinceroger69]

Re: Testing transistor on power supply

some very good information in this thread maybe worth a read
http://www.avsforum.com/forum/167-pl...urning-46.html

[Trueburton]

Re: Testing transistor on power supply

There are two of these mounted to the heat sink in first picture. You can see the three points where it attaches to the board.
Thanks for the help

[vinceroger69]

Re: Testing transistor on power supply

i think thats a mosfet this video may help you test it correctly
https://www.youtube.com/watch?v=RkWy1EirEu8