Magnavox 32md359b/f7 White Screen and with sound only

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

13.87, 84, 92, 99............ Those are the readings of all 4

[tom66]

Re: Magnavox 32md359b/f7 White Screen and with sound only

On the 20k ohm range? Any decimal points to report? Most of those transformers look off (all are more than 3% out from each other) but the real bad one is probably the "13.87" one.

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

Ok readings went as follows 13.87 , 84 , 92 , 99 readings seem really close

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

Ok I understand what your saying now,

[tom66]

Re: Magnavox 32md359b/f7 White Screen and with sound only

Can you show a picture of the meter in the setting you are using just so we can be sure it is OK. When probes are not touching do you see a "1"?

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

On 20k ohm 13.87 13.84 13.92 13.99

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

yes when probes aren't touching I do see a one, sending picture now

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

This is amazing help your giving me, I just would like to extend my thanks regardless of fixing or not,,,Wow I'm very greatful

[tom66]

Re: Magnavox 32md359b/f7 White Screen and with sound only

I am happy to help. Any TV saved from landfill is a victory.

All your transformers are fine they are well within spec. Next check, see picture. Use 200V DC range. I have no idea what it should be, other than around 50V, from what I heard of this chassis, but it is really unconventional.

I am suspecting you may have a broken CCFL tube inside the screen, but to find out you will need to take it apart - literally pull the LCD off - and it's not an easy operation and one that is easy to mess up.

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

186 volts tom66,

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

I don't understand why it would be broken unless it fell right? So in taking this off, is this a repairable job at a low cost?

[tom66]

Re: Magnavox 32md359b/f7 White Screen and with sound only

We have seen bulbs on this forum which have cracked without obviously being dropped - at least according to the owners. I don't know how or why it happens, but it seems to be happening. Perhaps some internal pressure of small crack introduced at the factory damages them.

What is the voltage rating on that nearby big capacitor? 186V is very high. Far higher than I expected. Again this chassis is alien to me though so I am not sure what it should be.

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

470uf/100V that is the rating on the Cap itself

[tom66]

Re: Magnavox 32md359b/f7 White Screen and with sound only

It shoudn't be 186V then if the cap is only 100V rated. Maybe that test point is incorrect. I am checking the SM now.

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

Ok on one side the left side it reads 186 on the right side it reads 56, from description points from above picture...

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

It's definitely 186 volts though...

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

Point closest to Cap reads 186V....furthest side reads 56

[tom66]

Re: Magnavox 32md359b/f7 White Screen and with sound only

It may be that I told you to test the wrong side. 56V seems much more reasonable I recall someone else here had around 50V.

I have looked at the schematic and they use a very dodgy feedback scheme which looks like it doesn't have a specified voltage.

There should be a pin marked BACKLIGHT-SW on the connector "CN201". Can you see it?

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

I see pin CN201 not marked backlight sw, but it is next to the flat ribbon plug

[YEROC37]

Re: Magnavox 32md359b/f7 White Screen and with sound only

On my printed paper schematic it does list it as that, I'm with you now