Sceptre32 MegMeet mp116 Solved

[tom thumb]

Sceptre x320bv-hd megmeet mp116 rev 1.4-- 2010.03.02

Weird Intermittent Problem

Tv would work fine for hours on end but if turned off
When Left in standby for any amount of time and turn on
it would startup and then lose both picture and backlights
for a second, and then come back on. In other words on off on off on off indefinately.
Unplug and leave cool down and it would work for hours again.

Found out it was Losing both 12 and 24 volts 5 volts always there
Hard to trace as I thought it was going into protective shut down
But it wasn't.

I also thought something was drawing too much current so
I unplugged inverter board and tv would stay on but
plug inverter board back in and unplug T-Con board and
TV would also stay on.

So power board could not handle the full current load to run tv.
Maybe cold solder joint or something shorting out but in the end I replaced one switching Transistor 2n4401 (Q8) which is connected to the opto-isolaters and it works great now.
I am out of desoldering wick so I just clipped the leads of the old transistor and soldered the new transistor on the bottom of the board

Meter was no help reading the transistor voltage as the on off cycle was too fast for the
Meter to stabilize. So I figured it might be bad and gave it a shot

Hope this info might help someone in the future

[rohanu]

Re: Sceptre32 MegMeet mp116 Solved

Thanks for sharing this info. I had the same problem, tried what you suggested and the lctv is no longer headed to landfill. I originally suspected bad caps for this power board. You saved me a ton of time!

[merrayz]

Re: Sceptre32 MegMeet mp116 Solved

I have a vivid tv from Aldi australia doing similar things however mine flashes on off when cold if I turn all picture settings to zero the tv will eventually stay on, once warmed up all good. I am heading off to get the transistor now and will replace with fingers crossed.All the caps look ok on the board ,no bulging or leaks so hope this works.

[merrayz]

Re: Sceptre32 MegMeet mp116 Solved

couldn't get a 2n4011 at the shop so I used a 2n2222A that was supposed to be the same or near enough anyway seems to have solved the problem so thanks "tom thumb" for your post .Why would this be a common issue with these power boards

[merrayz]

Re: Sceptre32 MegMeet mp116 Solved

spoke to soon still going on off as before,off to the tip I guess

[nomoresonys]

Re: Sceptre32 MegMeet mp116 Solved

spoke to soon still going on off as before,off to the tip I guess

make sure you got good solder joints, could still be a bad cap, they dont have to bulge to be bad.

[budm]

Re: Sceptre32 MegMeet mp116 Solved

Yo have two startup caps, the EC7 black, and the blue one to the right of the transistor that should be replaced or check the capacitance and the ESR.
You can also heat up those two caps with hair dryer for a few minutes to see if the Voltage will become normal.

[merrayz]

Re: Sceptre32 MegMeet mp116 Solved

ok thanks I will replace the 2 caps and see how I go.

[selldoor]

Re: Sceptre32 MegMeet mp116 Solved

ok thanks I will replace the 2 caps and see how I go.

Get good quality low esr caps- panasonic FR or FM or nichicon/rubycon equivalent.

[merrayz]

Re: Sceptre32 MegMeet mp116 Solved

would the ones from Jacar be ok or would I have to buy these brands online.Im in Brisbane Australia jaycar is the only place I know for this kind of stuff

[merrayz]

Re: Sceptre32 MegMeet mp116 Solved

Its ok found somewhere RS components only 10 min.drive from home.

[merrayz]

Re: Sceptre32 MegMeet mp116 Solved

replaced the caps still no good so gave up and vented my anger with ball pane hammer, actually I feel good now. The tv is for the caravan so rarely gets used so I will just pick up a used one some where seems to be plenty of 32" lcd about. Any brands to stay clear of other than this model.

[rohanu]

Re: Sceptre32 MegMeet mp116 Solved

I had the same problem again after a nasty brown-out so I did what bdm suggested and replaced the blue (or black on my power board)100uf 35v capacitor (next to the transistor in question)with a better quality cap and it's back to normal again. Yesterday, another savage brown-out and the TV's fine. Another thing I noticed with my tv is that I no longer have to point the remote straight on at the censor to operate, now that I have replaced the suspect caps and transistor. Yeh! I hope all this helps with everyone that is having problem
s with this particular power board model. Good luck.

[budm]

Re: Sceptre32 MegMeet mp116 Solved

Thanks for the repair feedback.
Any one can supply good clear pictures of the top and the bottom side of the board so I can figure out what the function of that transistor is?
There are many version of this model MP116.
The MP116A, that transistor is the switch for supplying the B+ to run the PFC and the 24V power supply when PS_ON is applied to the board.

[rohanu]

Re: Sceptre32 MegMeet mp116 Solved

Thought I'd mention that the 100uf 35v cap I replaced was a SAMXON. Say's it all really!

[rohanu]

Re: Sceptre32 MegMeet mp116 Solved

Sorry budm, my tv is now back where it belongs, in the wall unit. If it craps out again I will post the clear pics you ask, before I bin it. I'm glad you know your stuff. You've been a great help and it's good to know that other's might benefit and not have to buy a new tv because a company goes cheap and uses bad caps. This has been a process of elimination and requires a little patience. Good learning curve, right here. Thanks all.

[rohanu]

Re: Sceptre32 MegMeet mp116 Solved

Hi all, the problem kept persisting. The only cap I had not replaced off this power board was the largest of them all, the 68uf 450v. I bought a Rubycon cap of the same value to replace the Crapxon. I'm happy to say now, that I can start the tv from standby without the picture cutting in and out. The only way I could prevent this from happening before was to cold start the tv from the power switch. All I can suggest to anyone reading this thread and has this problem, you might just save time by starting from where I ended. Replace the 68uf 450 cap first. Good luck.

[rohanu]

Re: Sceptre32 MegMeet mp116 Solved

The inverter board is the problem. F*$

[amxman]

Re: Sceptre32 MegMeet mp116 Solved

Hey all... this is my second time needing to fix my sceptre TV. I do have a question... at the bottom of this post.

Here is a link to my thread from the first failure... that fix worked a good 2 years. I had 2 bulging caps and I decided to replace 4 in the row the 2 were in.

https://www.badcaps.net/forum/showthread.php?t=33144

That time around I did not see any other failing caps.

This time I have a different problem. I have no stand by light(red) or power on light(blue), it is almost like I just unplugged it just nothing lit and doesn't respond to any tricks.



SO... I took it apart and found the large cap has a bulge in it. My question is can I or should I upgrade the cap with a larger uF I read somewhere that it can be "upgraded" would anyone recommend this??? What would be the benefit or what could it hurt?? If I should upgrade what is a good uF for a 450V cap? From what I can see it is a 68uF 450V KM 105 degree C.



Thanks,
amxman

[goop]

Re: Sceptre32 MegMeet mp116 Solved

Here's the Megmeet MP116A, Rev 1.0, 2010/09/28:





(I don't know why the forum ruins the links to the large images, so here they are plainly: top, bottom, left, middle, right.)

On the top, U1 and U2 are AZ431 (adjustable shunt regulator).

On the bottom, IC1 is probably NCP1606B PFC controller from On semi. The unlabled 16 pin IC is ST L6599D high-voltage resonant controller. There's also IC2 which is a small 6 pin one, and Q10 which is 8 pin and reads ...(6?)3652.

Another top view of a very slightly different MP116A board (date code 1147, above it's 1131), from this thread:
https://www.badcaps.net/forum/attach...8&d=1381571466

The model, revision, and date are the same, but there are minor differences, like the presence of C68 at the bottom, or a place for D17 below the output capacitors.