Have open diode T2D 93

[Don Umphrey]

I have a LG power supply/inverter board in a Vizio model VO320E TV that has an open diode. The only marking is T2D 93 with a line under the 3. Having no back ground in electronics I would like to know if this something that Radio Shack would sell and what would I be asking for? I don't seem to be getting any where by Googleing this part. I could use some help please. Thank you

[tom66]

Re: Have open diode T2D 93

It is quite possible "T2D 93" is a zener diode, and would appear open under normal test conditions.

[budm]

Re: Have open diode T2D 93

More likely to be snubber diode like in this post: https://www.badcaps.net/forum/showth...609#post274609
Zener diode will still read like diode when you forward bias it, but you cannot tell its Zenning voltage using the meter, you will have to use variable DC power supply and a current limiter resistor then aplly the reverse bias voltage until it reaches the Zenning voltage point of the zener diode.

[tom66]

Re: Have open diode T2D 93

Of course, silly me. I was thinking of a TVS, or similar device.

OP - How big is the device? Whereabouts is it on the circuit? It may be possible to guess the value or part.

[budm]

Re: Have open diode T2D 93

It may be something like this (TVS Diode):
http://pdf1.alldatasheet.com/datashe.../ST02D-82.html
I cannot find ST02D-93. I have a feeling it will be part of the snubber circuit of the transformer primary side drive section.
Pictures of both side of the board and the location of the parts will help.

[Don Umphrey]

Re: Have open diode T2D 93

I have a couple of pictures. One with a black arrow showing the location and the diode is on a white piece of paper setting on the heat sink. The other picture is just a close up. I hope this might help. I will take a picture of the back side and post it.

[Don Umphrey]

Re: Have open diode T2D 93

It may be something like this (TVS Diode):
http://pdf1.alldatasheet.com/datashe.../ST02D-82.html
I cannot find ST02D-93. I have a feeling it will be part of the snubber circuit of the transformer primary side drive section.
Pictures of both side of the board and the location of the parts will help.

sending pictures

[tom66]

Re: Have open diode T2D 93

OK, that diode forms RCD network, it should not appear open, so I would guess that's one possible fault.
Are you using the diode test range on your meter to test it?

[Don Umphrey]

Re: Have open diode T2D 93

OK, that diode forms RCD network, it should not appear open, so I would guess that's one possible fault.
Are you using the diode test range on your meter to test it?

I do have a cheap meter but watching a you tube site on how to use a meter I think at I am using the right setting. I checked the diode out of the board and the meter reads OL in both directions. I was hoping to be able to identify this diode so I could replace it to see if it was my problem.

[tom66]

Re: Have open diode T2D 93

The diode will be something similar to MUR460.

[budm]

Re: Have open diode T2D 93

OK, that is the snubber diode for the 5V tsnaby power supply to protect the SMPS IC. Proably similar to the PDF attach, it will read open when check with the meter, you have to have power supply taht puts out high enough voltage to reach the break down voltage of this TVS Diode.
If it is ST02-200, it will read open due to back to back diode setup.
If is is ST02D-170 (Unidirectional TVS Diode), then it will read like diode which I think that is what you have:
Since this is part of the 5V Standby power supply, so you are not getting the 5VSTBY?

[Don Umphrey]

Re: Have open diode T2D 93

OK, that is the snubber diode for the 5V tsnaby power supply to protect the SMPS IC. Proably similar to the PDF attach, it will read open when check with the meter, you have to have power supply taht puts out high enough voltage to reach the break down voltage of this TVS Diode.
If it is ST02-200, it will read open due to back to back diode setup.
If is is ST02D-170 (Unidirectional TVS Diode), then it will read like diode which I think that is what you have:
Since this is part of the 5V Standby power supply, so you are not getting the 5VSTBY?

Yes I have 5volt stand by. I think I am way over my head as I have very limited electronic skills. Worked for Heath Kit for 33 years and built many kits but that is far as my skills takes me.

[budm]

Re: Have open diode T2D 93

If you do have 5V then that snubber diode is OK, If it is bad, the 5V power supply will not be working since that snubber diode is for the 5V power suuply section.

[ankit007]

Re: Have open diode T2D 93

please tell me how to check for 5volts stand by

[budm]

Re: Have open diode T2D 93

please tell me how to check for 5volts stand by

You should start the new thread and provide a lot more information including the pictures so we can see what we are dealing with.