Magnavox tv problem,

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Janitor Tzap
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Post by Janitor Tzap » Fri May 11, 2007 12:28 pm

dacflyer wrote:well i am still working on this gagbox tv..
but i have narrowed it down to this,, i have my 5 and 8 volts source,,but as soon as i push power..the voltages goto almost zero...
i am sure its a short,, Edd sent me a schematic,,but the circuit is kinda complicated for the 5 and 8 volt sources..i have checked all i can think of,,
but no luck yet..

if i shared the schematic with anyone,,,think you can help me ?
getting desperate here...

i already checked tons of stuff in the area.but nothing checks bad yet..
Well, you could start lifting loads on the 5Vdc & 8Vdc lines.
Then with no load on those lines.
Start reconnecting the items one at a time.
Till you find the one that is drawing down those two lines.

Then you can concentrate in that area for the short.


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Post by dacflyer » Fri May 11, 2007 2:55 pm

janitor >> i tried that already and gave up as the crazy circuitry is too complicated,, it runs in circles.. Edd just sent me a e-mail on a few other things to try,, if i don't get it by this weekend,,then i give up..
but it pisses me off when i fail to fix something that i know could be a simple fix..

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Post by Janitor Tzap » Fri May 11, 2007 5:00 pm

dacflyer wrote:janitor >> i tried that already and gave up as the crazy circuitry is too complicated,, it runs in circles.. Edd just sent me a e-mail on a few other things to try,, if i don't get it by this weekend,,then i give up..
but it pisses me off when i fail to fix something that i know could be a simple fix..
Well don't feel too bad about it.:wink:

I've been running into the problem of trying to find parts for these older TV's, for some time now.

If a Television Set has "In House IC's" or a specialized High Voltage FlyBack.
And is Older that 3 Years.
Good Luck in finding those parts.

Your "Magabox" is 11 years old now.
So, I'm not surprised that it is hard to find parts for it.

This is also true for monitors as well.
I had to junk a 18" GateWay LCD monitor just because the Back Light Inverter Board was bad.
I could get a Replacement Board, but after cost of the board, shipping & my labor.
It was about $200.00 Total.
{About the cost of a new LCD monitor.}
I could of gone and got a schematic, and repaired the inverter board.
If one was available from Gateway.
But I would run into the same problem of getting parts for it.:sad:



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dacflyer
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Post by dacflyer » Sat May 12, 2007 12:13 pm

well i decided to dig out my variable power supply out and inject power where it was missing,, i belive the set is brain dead..
so no use of beating a dead horse any longer.. i gave up {:>(
thanks to all who gave their tips.. the set going to the scrap pile..well the board is anyway...rest goes to the dump..



janitor >> " This is also true for monitors as well.
I had to junk a 18" GateWay LCD monitor just because the Back Light Inverter Board was bad.
I could get a Replacement Board, but after cost of the board, shipping & my labor.
It was about $200.00 Total.
{About the cost of a new LCD monitor.}
I could of gone and got a schematic, and repaired the inverter board.
If one was available from Gateway.
But I would run into the same problem of getting parts for it. "


ever thought to try just a generic CCFT inverter to run the backlight ?
they can be gotten for little or nothing,, i have salvaged so many from old scanners and even have bought them for as little as $10.00

just a thought...

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Post by Janitor Tzap » Sun May 13, 2007 11:22 am

dacflyer wrote:well i decided to dig out my variable power supply out and inject power where it was missing,, i belive the set is brain dead..
so no use of beating a dead horse any longer.. i gave up {:>(
thanks to all who gave their tips.. the set going to the scrap pile..well the board is anyway...rest goes to the dump..
Oh, Well....
Eleven years out of a Television is pretty good, considering that most TV's
are expected to only last Five years at the most.:wink:
dacflyer wrote: janitor >> " This is also true for monitors as well.
I had to junk a 18" GateWay LCD monitor just because the Back Light Inverter Board was bad.
I could get a Replacement Board, but after cost of the board, shipping & my labor.
It was about $200.00 Total.
{About the cost of a new LCD monitor.}
I could of gone and got a schematic, and repaired the inverter board.
If one was available from Gateway.
But I would run into the same problem of getting parts for it. "


ever thought to try just a generic CCFT inverter to run the backlight ?
they can be gotten for little or nothing,, i have salvaged so many from old scanners and even have bought them for as little as $10.00

just a thought...
Yeah, I looked into getting some generic CCFT inverters.
But saw that the monitor had three CCFT's, thus three inverters.
Plus, these are run by a controller IC on the inverter board.

Thou, I was talking to a friend in the surplus recycling business.
He had several of the gateway monitors come in that had this same problem.

I asked him why he didn't try to repair them.
His reply was simple.
To much time and money.
He explained that for it to be worth his while to repair them.
He would need at least 20 that were all the same make and Model.
But even then, the re-sale of the used monitors wouldn't make up much of a profit.


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Post by dacflyer » Sun May 13, 2007 6:47 pm

i have to replace an inverter for a apple monitor..a cinima screen its called.

i already got the board in, just have to swap it out..
the inverter has 2 inverters on it,,this screen has 2 CCFT tubes. the top 1/2 is out.. cost 50.00 for the replacement board..not too bad. considering the monitor was 600.00 new,

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Chris Smith
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Post by Chris Smith » Sun May 13, 2007 7:11 pm

I remember from the 70s the professor said we will all become “part jockysâ€

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Janitor Tzap
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Post by Janitor Tzap » Sun May 13, 2007 8:15 pm

[quote="Chris Smith"]I remember from the 70s the professor said we will all become “part jockysâ€

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Chris Smith
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Post by Chris Smith » Sun May 13, 2007 8:47 pm

I used to work on,.... and diagnose things, .....then we became "parts changers" like the professor said.

In the old day we actually fixed a broken or worn out thing, by hand very often, and that’s where all the good training came in.

Decades later, all we did was diagnose the problem, open a box, and replace the item.

It was time to exit this way of life, but things never got any better.

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Joseph
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Post by Joseph » Mon May 14, 2007 6:42 am

Janitor Tzap wrote:
dacflyer wrote:janitor >> i tried that already and gave up as the crazy circuitry is too complicated,, it runs in circles.. Edd just sent me a e-mail on a few other things to try,, if i don't get it by this weekend,,then i give up..
but it pisses me off when i fail to fix something that i know could be a simple fix..
I have found shorted components by substituting in my own power supply for the one being shorted. I cranked up the current, checking for the shorted component by either heat generation on the bad component or supply voltage drop in the millivolt range at various components using that supply.

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