Sceptre32 MegMeet mp116 Solved

[gravesent]

Re: Sceptre32 MegMeet mp116 Solved

Are any of you able to give me the values of D13 / D15 located against the heatsink closest to the connectors on the edge, also Q15 and Q16? Any help is greatly appreciated!

[goop]

Re: Sceptre32 MegMeet mp116 Solved

I don't have it available. If you find nothing else, maybe worth trying to ask the manufacturer: http://www.megmeet.com/siteen/ywlx/1635.html

[haychis]

Re: Sceptre32 MegMeet mp116 Solved

I know it's an old thread, but I had the same problem as other in this thread. Thought I'd share my experience.

Vivid 32" tv from Aldi with mp116 v1.0 ps. Not used much, but suddenly the screen would turn on and off. Same problem as others. Went out and bought the caps, pulled the power supply off and was ready to solder.

But before I did that, I saw that the board was a tad warped. Brought memories back of my old xbox 360 repairing days. Got the liquid flux, applied all over to the back of the board. I heat gunned it for a good 5 mins. Enough for the solder to re-flow. It heated up nicely, but was careful not to pop the caps (which looked ok). Let it cool. Plugged it back in. Working ok.

Has been a few days now, and all good. Not sure how long it will last. So problem may not be the caps (if they look ok), but solder joints. Might look at securing it better to keep it from warping.

[Martinizhr]

Re: Sceptre32 MegMeet mp116 Solved

I recently had this power-supply board repaired.
When I first got it PFC transistor was blown Q2 (MDF13N50), fuse and resistor from mosfet to ground R42 (1 ohm). Replaced all of them and it didn't work. The problem was when you turn the tv on, back-light was flickering, it would power on, stay on for a second, then turn (back-light) off for 2 seconds and repeat. I thought capacitors were bad. Replaced them all. Still the same problem, then I saw that board was warped (probably form prolonged heating), I suspected some cold joints and resolder whole board. The problem was still there..
It was time to do some deep investigation. My suspect was L6599 and current feedback loop. It made sens that power-supply was going into current protection mode..
To make long story short, recently mentioned resistor was the problem. Originally?? there was 1 ohm resistor. I changed it to 0.47 ohm (that was the first one I found. ). And now it works! I do not know why there was 1 ohm resistor there, I found some schematics for this board and there were 1 ohm parallel to 0.1 ohm. So guess I pfc wasn't able to step up voltage if there was big load on the output.