Sceptre 32" Flashing (Video)

[tom66]

Re: Sceptre 32" Flashing (Video)

There is a cap, looks like C8... has this been replaced before? It doesn't look like it fits right.

Have you owned it since new or was it used when you got it?

[smigglet]

Re: Sceptre 32" Flashing (Video)

as DRPJ23 suggested "pins 1-5 are the 24v and pin 12 seems to be the BL_ON. Monitor the voltages by putting the red lead on the corresponding pin and the black on the chassis." See if the 24 V is fluctuating, same on BL_ON.

I did test them, i also posted the results. I believe its post #13.

If you were in Europe I would say that is suspiciously low but I heard of low PFC voltages for US-made sets.

Damn, forgot the image... I manage this somehow... Here is what I was referring to in the last post:

I measured the main cap, but how do i go about measuring the pfc?
Thank you

There is a cap, looks like C8... has this been replaced before? It doesn't look like it fits right.
Have you owned it since new or was it used when you got it?

I bought it new from newegg.com, i dont think it was a refurb.

[smigglet]

Re: Sceptre 32" Flashing (Video)

Here are closer pictures of the board. I looked at c8 maybe there is something im not seeing, i also took pics of the back. There a little solder that looks goldish brown, could it have been a replacement or is it normal?

[budm]

Re: Sceptre 32" Flashing (Video)

Sorry, I just do not have the time to look at the video yet.

[smigglet]

Re: Sceptre 32" Flashing (Video)

pins 1-5, go from 20.1 to 10
pin 12 stays a constant 3.4

the meter was set on DCV 200

[tom66]

Re: Sceptre 32" Flashing (Video)

The main cap stores the output from the PFC. There's nothing yet to measure in the PFC circuit, as it is working.

That cap does look suspicious and I have encountered backlight flickering before when those caps go bad -- on different chassis TVs though, not on this one, which I have not seen before.

If I were to shotgun this my guess would be the main cap or one of those poly (red) caps.

[smigglet]

Re: Sceptre 32" Flashing (Video)

Is there a way i can test the poly red caps? Youre talking about the one below the main cap its kinda long dark red?

i tested the main cap again and the reading seems to be fluctuating from 365-370

I can buy capacitors tomorrow, what size is the main, and the red you are talking about?

[tom66]

Re: Sceptre 32" Flashing (Video)

Do you have a capacitance meter?

The fluctuating voltage is suspicious.

For a 32" LCD, the main cap is 120-180uF, 400-450V. The exact rating will be printed on it.

The poly cap will have a code such as "565J 400V" which codes for its value (5.6uF with ±5% tolerance) and voltage rating (400V.)

Note: Do not try to buy the large cap at RadioShack or Fry's, as they will not stock the appropriate component (they do not sell low impedance/ESR caps.) The poly cap, you may have luck. You can buy the components online. Suppliers like digikey have them for a couple of dollars plus $3 or so shipping.

[smigglet]

Re: Sceptre 32" Flashing (Video)

No i only have a multi meter this one


I was planning to buy them from radioshack

i have so much bad luck. Is there anything else i can check?

[tom66]

Re: Sceptre 32" Flashing (Video)

I just had a thought:-

Do you have a hairdryer?
Can you get hold of freeze spray or compressed air?

I have encountered many caps which are temperature sensitive. Heating them up, or cooling them down makes them work better.

[smigglet]

Re: Sceptre 32" Flashing (Video)

I have a hair dryer and a compressor, i will try that out. Thank You i greatly appreciate your help, we havent fixed my tv, but thank you for your dedication. I will try the hair dryer and compressor method.

[tom66]

Re: Sceptre 32" Flashing (Video)

In this case, compressed air cans are needed because they can be used to make freeze spray. Actual compressed air is not good enough unfortunately.

[smigglet]

Re: Sceptre 32" Flashing (Video)

Just came back from the store, tried it, and no go.

[tom66]

Re: Sceptre 32" Flashing (Video)

Hot air or cold (freeze) air?

[smigglet]

Re: Sceptre 32" Flashing (Video)

Cold compressed air. I warmed it up with the dryer, and then i quickly used the cold air, it even turned white when i was spraying it.

I wish it was just a blown capacitor, that would be easy to fix. Its kind of strange because it was able to turn on once, and stay with out flashing.

[tom66]

Re: Sceptre 32" Flashing (Video)

Poly capacitors are generally cold temperature sensitive. If you sprayed it and it continued flickering, that component is likely OK.

However the main bulk capacitor is high temperature sensitive -- it works better when hot. Have you tried heating this one up?

[smigglet]

Re: Sceptre 32" Flashing (Video)

Yeah i did the bulk one too, i put the hot hair dryer on it for a while and nothing. I got it to stay on with out flashing just now, i dont know what i did. i was just measuring all the caps with my multimeter, and it stayed on. First it started flashing, but then it stopped.

i connected to my pc just to video something.

[tom66]

Re: Sceptre 32" Flashing (Video)

That's a clue. The heating did work, but it took time before it worked. Measure the voltage across the bulk cap. If it's increased, there's your fault. If not, it could still be faulty, but passing more ripple to the rest of the power supply causing the flickering backlights.

Try to get it to start again using freeze spray then repeat the hot air test.

[smigglet]

Re: Sceptre 32" Flashing (Video)

Nope, it didnt go away. Here is a video of what had happened to me.
http://s962.beta.photobucket.com/use...70803.mp4.html

[tom66]

Re: Sceptre 32" Flashing (Video)

OK, but it is clearly cooling down and going wrong. Maybe the freeze spray doesn't cool it down enough.

Now it is faulty, heat that cap big black capacitor (bulk cap) up.

If it restores operation maybe 5 minutes later, then you have a cause-effect relationship... and the problem is most likely with that capacitor.

Please check the voltage across it when it is working too.

Rule #1 of any repair: A problem which goes away by itself will come back by itself.