Tv does not power up

You answered on your own. (lol)If its suppose to be a standby 12 volt supply then whats the top voltage to be there?? 12 VOLTS!!! The value your looking for is a 12 to 13 volts 1 watt zener diode.. Im thinking your a handi man trying or attemting a repair?? please remember the HI voltage saftey issues, as these sets hold alot of HI voltage even after they are unplugged for a while. Good luck

I have found that in a lot of cases, if we are uncertain of the value of the Zener Diode, the IN 4148 zener works! It is like a universal diode, which works differently in different areas. As for rating, I suggest you put 2 IN4148s in parralel and solder. the 12V problem should get sorted out.

You my friend are a ASSHOLE

the only diode in the primary with a zener symbol on board vd509 says 1s2 on body, this crosses to a 20v 1a schottky. however this wasnt the problem on the one i fixed. nor was the only diode that checked shorted in the primary vd507, a 1n4148, which is a 100v .2 to .45a 4ns fast sw, and not a zener. it also wasnt bad only accross a ferrite bead coil l504. i was unable to find any 900 series diodes nor any designated d anything. but getting back to reality for a moment. the threee 78xx regulators all mounted on copper coated steel heatsinks wernet being powered, because the 16v from vd554 off the secondary of the swmps t511 through r569 and turn on pnp transistor v554 was lost due to cleverly disguised 1a picofuse r569 looking like a tiny white resistor, that opened. the pico fuse opened because capacitor c572 470uf 10v was a dead short on the output of 5v regulator n552, which ws fed by 12v regulator n551 which should have gotten 16 v into it when power on sig to base of turn on transistor v554 arrived i assume from the micro in response to pressing the power button. the primary was clearly good because 123v b+, 23v and 16v were good out of the secondary of the powersupply. youre right it sint complicated but haire when they got tired of making rootbeer never bothered to learn how electronic components should be designated on circuit boards or how to draw schematics. i cant find a shcematic either, but just decided not to let this one kick my a**. hope this helps you, unclejed. Doug, no title just a tech for 50 years VVL