Need help ID'ing a diode - T2D85

[ngth82]

Hi all -

I have a TV SMPS with a bad diode.

The marking around the component body is "T2D85" but i haven't been able to find a datasheet for it.

The diode is a through hole axial. The body is black. The band and text is a dark red color.


Edit: I have a replacement part for U101 coming next week from Digi-Key.

[R_J]

Re: Need help ID'ing a diode - T2D85

What is wrong with the diode? It can be a TVS diode and they can check open. If it is checking shorted in circuit it could be due to the shorted ic

[ngth82]

Re: Need help ID'ing a diode - T2D85

I removed it to check for shorts in the supply circuit for U101. While i had it out, I noticed that the diode doesn't beep with the meter in diode mode - no forward drop.

[redwire]

Re: Need help ID'ing a diode - T2D85

I find the root part number for T2 diode is ST02D as a Shindengen "trankiller" TVS zener+diode inside. So a T2D85 is 85V ST02D-85 and would test open-circuit unless you can test it past 85V.

I don't think it's a rectifier diode but would have to see the schematic.

[ngth82]

Re: Need help ID'ing a diode - T2D85

I find the root part number for T2 diode is ST02D as a Shindengen "trankiller" TVS zener+diode inside. So a T2D85 is 85V ST02D-85 and would test open-circuit unless you can test it past 85V.

I don't think it's a rectifier diode but would have to see the schematic.

Thanks for the lead! I'll look into the PN you identified.

[petehall347]

Re: Need help ID'ing a diode - T2D85

check the symbol underneath it

[R_J]

Re: Need help ID'ing a diode - T2D85

I removed it to check for shorts in the supply circuit for U101. While i had it out, I noticed that the diode doesn't beep with the meter in diode mode - no forward drop.

These type of diodes don't "BEEP", they are usually two internal diodes with common cathode

[ngth82]

Re: Need help ID'ing a diode - T2D85

Thanks guys. The board symbol for this component is the same as the one immediately south of the red box from the pic in Post #1.

I just realized that i didn't post the board number information.

This is a LGIT SMPS board for a Philips TV. Board PCB PN: 2300KEG031A-F

Funny, Coppell TV Repair also mentions that U101 is a common failure (which this appears to be the case):LINK

[redwire]

Re: Need help ID'ing a diode - T2D85

I think OP's could be a ST02D-82 (note datasheet wrong 67V spec). Mouser sells them.

It looks like other people mistakenly think these T2D snubber diodes "power clampers" are open-circuit, when they are just HV zener plus diode:
looking for T2D80 https://www.badcaps.net/forum/showth...t=20211&page=2
Sony Diode T2D98 ST02D-140 https://www.badcaps.net/forum/showth...t=54016&page=2
T2D98 https://www.badcaps.net/forum/showthread.php?p=671655
T2D40 https://www.badcaps.net/forum/showth...067#post221067

[ngth82]

Re: Need help ID'ing a diode - T2D85

Also, looks like this component sits across the two terminals of the transformer that bridges the hot and cold side of the SMPS. I removed the transformer and checked for shorts across the three separate windings. The transformer to be okay.

[R_J]

Re: Need help ID'ing a diode - T2D85

That TVS (HV zener) diode (D106A) is across the primary, In some cases they use a UF4007 for D106 and have C103 and R102 populated which are in series with the uf4007 fast recover diode.

[ngth82]

Re: Need help ID'ing a diode - T2D85

Update: The FSQ510 arrived and was replaced on the SMPS.

The TV fires up and appears to work.