Magnavox 37MF231D/37 Ficker/ power off

[kawmagnum]

First -new ton excellent forum and thanks in advance for any help. Free tv and after researching a bit it seems likely a PS problem . Power-on and tv flashes about 1 sec. Replaced 2200uf cap . None are bulging or leaking . Voltages on 12 pin 1-5 are 24v - nothing on pins 6 & 7 should be 2.6 and 6.1. I am going to replace the 2 1000uf and the 1200uf, should I be looking for something else? Concerned that no visible damage.

[ben7]

Re: Magnavox 37MF231D/37 Ficker/ power off

Does it truly turn off or does it stay on? If it stays on, look at the screen closely with a bright flashlight, you should be able to see an image. Oh, does the sound come on.

[kawmagnum]

Re: Magnavox 37MF231D/37 Ficker/ power off

Ok Power green is ON, Sound does work. Menu bar at top stays on about 1/2 sec sometimes and indicates AV3 is input. Every push of power button causes light ficker seen from back. No apparent picture.
I don't have the remote so I am stuck with buttons.

[johnboy1313]

Re: Magnavox 37MF231D/37 Ficker/ power off

There are two small LED's on the main board. Do they both come on when the TV is on? Do they stay on, or flicker as well?

[budm]

Re: Magnavox 37MF231D/37 Ficker/ power off

It sounds like the inverter turns off. Any pictures of the inverter board. BTW, the new cap looks like general purpose cap?

[kawmagnum]

Re: Magnavox 37MF231D/37 Ficker/ power off

It is polarized 2200uf 50v, thought I would take a shot at what failed most. The original one was probably ok. Attached are photos. Main board is board with outputs? next to PS. If so , I cannot see any LEDS with board connected, but the room is bright.

[johnboy1313]

Re: Magnavox 37MF231D/37 Ficker/ power off

Main board is board with outputs? next to PS. If so , I cannot see any LEDS with board connected, but the room is bright.

You're right, this main board, or a substitute of it, is used in the 26" through 42" versions of these tvs. In the 37" that I just fixed this week, the main board is mounted so that you can't see the LEDs. After reading it again, it sounds like bud is right too and that the back light is cutting out on you. In my case, the lights would stay lit, but the picture itself was flickering.

[tom66]

Re: Magnavox 37MF231D/37 Ficker/ power off

Darfon inverter... Bad transformer is more than possible. Test the secondary of each transformer (6008xxxxxxx large eight-legged grey/black devices.)

[kawmagnum]

Re: Magnavox 37MF231D/37 Ficker/ power off

Thanks for the help here. What are the correct voltages or can you point me to the data.
Can't seem to find a service manual for this model

[tom66]

Re: Magnavox 37MF231D/37 Ficker/ power off

Resistance, not voltage. There is no correct reading per se, but all must read within 3% of each other (general rule.)

[kawmagnum]

Re: Magnavox 37MF231D/37 Ficker/ power off

Well I measured at the connector to the display on each transformer.

1-6 & 8 measure 5.58 kohm, #7 measures 13.65,
That's the one with the puke on it. Actually it is something hard.

[kawmagnum]

Re: Magnavox 37MF231D/37 Ficker/ power off

Correction- measured at the 2 end pins on the connector side of each device.

[tom66]

Re: Magnavox 37MF231D/37 Ficker/ power off

#7 is bad, then. Just to be sure, you measured between the top left and bottom left of each transformer?

[kawmagnum]

Re: Magnavox 37MF231D/37 Ficker/ power off

Yes- these are replaced by desolder the 8 tangs on the surface? where to buy?
also should i replace all the 4 ps capacitors? That big one is a little funky but should work.

[tom66]

Re: Magnavox 37MF231D/37 Ficker/ power off

Yes, they are easily replaced. Just heat up the legs, pull them up slightly, and the transformer will come off.

Will need the full 6008xxxxxx number to find a replacement.

[budm]

Re: Magnavox 37MF231D/37 Ficker/ power off

Yep, those darn DARFON!
Order spare since more likely the other will go as well. I sometime order the whole board since the whole set of transformer costs more than the replacement board.

[kawmagnum]

Re: Magnavox 37MF231D/37 Ficker/ power off

Thanks for all the help. I bought a used board which I hate to do, because could not get the exact component. We shall see in a few days.

[tom66]

Re: Magnavox 37MF231D/37 Ficker/ power off

Definitely keep the old board for spare transformers in case the new board fails again.

[retiredcaps]

Re: Magnavox 37MF231D/37 Ficker/ power off

Thanks for all the help. I bought a used board which I hate to do, because could not get the exact component. We shall see in a few days.

6008B available from ebay.

http://www.ebay.com/itm/161032443969