Orion SLED4668W TV will Not Power Up.

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

Thanks guys I will check those and get back to you.

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

3.2mv on the middle legs of D3829 and D3828

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

That white fuse F3803 is blown, no readings at all.

[RCA2000]

Re: Orion SLED4668W TV will Not Power Up.

NOW...you need to find out if you have shorted MOSFETS..in the primary of the supply..(likely". ). if SO...you ALSO likely will have a bad driver chip..since it drives those FETS and when they SHORT..they spike that chip HARD..

On one side of that fuse to HOT ground..see if there is a LOW resistance. if SO..almost SURELY shorted FET's.

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

RCA2000 i'm not sure what you mean by "On one side of that fuse to HOT ground" can you be more specific please?

[RCA2000]

Re: Orion SLED4668W TV will Not Power Up.

This is an SMPS (switched-mode power supply) that has BOTH a HOT and COLD GROUND. By that I mean HOT ground is hot with respect to the AC line--COLD or "isolated ground" is NOT hot with respect to the ac line--ONLY to the COLD ground bus "tv ground" in the SET.

You see that dashed line around the bottom of the PS board--ALL inside of this line is HOT ground--or on the PRIMARY side of the supply On the OTHER side of this dashed line--is the COLD side--and it is ISOLATED from the AC line for SAFETY reasons above all else.

Looks lke the hot ground is that big trace near the fuse that ALSO goes to the ehat sink on those FET"S I spoke about. The chip I spoke about is right behind those FET"S too.

Ground the meter lead to that sink...THEN take the OTHER one and touch that fuse on the side nearest that sink. see if it shows LESS than 10K or so. If not--do the same for the OTHER side..if EITHER ONE show below that...SOMETHING is shorted.

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

Ok putting the black lead to the sink on cold side and the red to the closest end of blown fuse(right side) I get 5.9M ohms

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

Black lead to sink and red lead to left side of blown fuse shows 16.20m

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

After rereading your post: red lead on right side of fuse and black lead on sink on primary side I get 84.6 ohms and when I put red lead on left side of fuse I get 9.4k ohms and continues to drop.

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

With tv unplugged right?

[RCA2000]

Re: Orion SLED4668W TV will Not Power Up.

So...NOW...check those two FET'S on that sink by that fuse. I am SURE at least ONE of them is shorted---or VERY LEAKY.. CHeck the center lead to each of the outer ones. They should NOT read low... ON diode test..from G-S...they MAY read as a diode...but from D-S..they should read HIGH.

[budm]

Re: Orion SLED4668W TV will Not Power Up.

At this point you will need o replace those two power MOSFETs and the SMPS IC3804, you also need to check the MOSFET's GATE drive resistor capacitor network to make sure they are not damaged either.

[thoma]

Re: Orion SLED4668W TV will Not Power Up.

Please can someone tell me the name of IC3804 smd ic?!
regards thoma!

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

In diode test mode on Fet 3817 with black lead on center pin and red on G pin I get .335v, with red on S pin I get .001v
Fet 3818 with black on center pin and red on G pin I get .437v, with red on S pin I get .045v

[budm]

Re: Orion SLED4668W TV will Not Power Up.

You need to change out both MOSFETs.

[eagle00799]

Re: Orion SLED4668W TV will Not Power Up.

Thanks Budm, So both Mosfets Q3817 and Q3818, IC3804, Fuse F3803? Is that it or do I replace D3828 and D3829 also?

[budm]

Re: Orion SLED4668W TV will Not Power Up.

Thanks Budm, So both Mosfets Q3817 and Q3818, IC3804, Fuse F3803? Is that it or do I replace D3828 and D3829 also?

Do the D3828 and D3829 tested bad?
What about the P/N of IC3804? You need to check the resistors, capacitors, diodes or what ever are on the output drive pin to the Gate of the MOSFETs to make sure they are not damaged when the MOSFETs shorted out.

[thoma]

Re: Orion SLED4668W TV will Not Power Up.

Please post the name of SMPS IC3804!!!
regards thoma!