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Sanyo TV schematics

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07engineer

New Member
Hey everyone

i have a Sanyo pro ponent mts avm286u 27" old television that the green recently has somehow gone missing from the picture. anyways am trying to swap power sources for each color to narrow down the problem. but have come to a point where i am unable to determine which wires power each color. So if anyone has any other suggestions of how to fix this problem or knows where i could get a wiring diagram/schematic for this television, this info would be greatly appreciated

Thanks
 

Nigel Goodwin

Super Moderator
Most Helpful Member
On the tube base you simply need to swap round the connections between green and one of the other colours. It's obvious which are the cathode pins on the CRT.

If it's a Philips CRT though it's most probably the CRT itself which is duff!.
 

07engineer

New Member
how do you mean swap the connections from green to another? before i got to this point i had run a parallel voltage from the red pin on the crt to the green pin on the crt and this cut out the red color and now green was in the picture. so i dont think that the problem is with the crt but more with wiring.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
With the actual pins on the CRT, if you then get green and no red, then the CRT is OK, and the drive missing. Next swap the drive wires going from the main board to the CRT board, if it swaps, then the main board is duff, if it doesn't then the fault is on the CRT board.

A common problem on various sets is the feedback resistor around the video output going high or O/C - these are usually 100K or 180K, something like that.

Mind you, first thing to do is measure the voltages on the three cathodes!.
 

07engineer

New Member
There are 2 sets of wires leaving the neck board going to the main board, one set is yellow consisting of a yellow wire with crosses on it and a yellow and red
lines on it and just a solid yellow. the other set of wires is a bundle of 6 wires, solid white, white and long red lines, white and red crosses, white with short red lines, white with horizontal red lines, and white with a red line and dot combo.
which set of wires are the drive wires?
 

07engineer

New Member
sorry the red cathode reads 10v, the blue cathode reads 10v and the green does not read any voltage. this voltages are referenced to the common ground on the neckboard.
 

07engineer

New Member
sorry my apologies i retook the voltage readings and am now getting 196v across green and 150 across red and blue you can disregard the last voltage readings :)
 

07engineer

New Member
there is a 180K resistor on the neckboard that is color coded for 180K but i cannot get a reading of larger than 100K from it and my DVM takes a long time to get the reading for some reason. like i have to hold the meter on it for about 3 min while it slowly counts up to 100k, im guessing that there is an open circuit and it is counting the resistance going through the circuit back to the other side of the resistor. the color code on the resistor is brown grey yellow gold. which is 180K if im not mistaken. would this resistor be a 1/2 Watt or 1 watt?? the one that is in there has been replaced before but looks like a half watt
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Disconnect one end of it and check it out of circuit, there should be three of them, one for each colour - I would suggest replacing all three with 1W metal film resistors.
 

07engineer

New Member
there are no sets of resistors of close to that value on the back of the picture tube. there is a set of 3 - 1 watt resistors on this circuit board and they are all fine.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
There should be feedback resistors, in the 100k's region usually, from the collector back to the base of the driver transistors. I'm presuming the transistor isn't just O/C?, have you tried swapping the green and red transistors over?.
 

ThermalRunaway

New Member
Nigel Goodwin said:
As the green driver is turned off, it's most likely either the feedback resistor, or the video output transistor.

I think he said he was getting 196V on the green, and 150V on the other two colours.

Brian
 

ThermalRunaway

New Member
By the way, I don't recognise that model number, and I've worked on a fair few Sanyo TVs. Are you sure that's the model number? How old is it?

Brian
 

Nigel Goodwin

Super Moderator
Most Helpful Member
ThermalRunaway said:
By the way, I don't recognise that model number, and I've worked on a fair few Sanyo TVs. Are you sure that's the model number? How old is it?

He hasn't filled his location in, but I presumed it's a non-UK model?.
 

ThermalRunaway

New Member
If it is a non-UK model, he'd be better off posting the chassis (should be on the label on the back of the set). I might even have a diagram for it, if it's an older model.

Brian
 
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