wells garner wgm 2792 monitor inoperable

[berlincam86]

Ok so I got this monitor that will only show this line as shown in the pic. Where should I start looking?

[grantspain]

check the deflection yoke connections and the yoke itself,it looks like you have a vertical collapse and a horizontal size problem
either you have a load of faults or the deflection yoke is the cause of the lot

[berlincam86]

I did notice resistor 312 was red hot. Do you happen to know what that's for?

[grantspain]

yeah right on the vertical deflection ic that resistor is
desolder one side and read it with a multimeter,i expect the ic is shot for a start
any electrolytic caps around that ic will need checking/replacing plus check D301


the above will explain vertical collapse but won't explain why the line is so far down the screen and why the picture is so narrow

[berlincam86]

Ok I'll check that out. Could the horizontal output transistor be bad?

[grantspain]

Ok I'll check that out. Could the horizontal output transistor be bad?

no because you would get no picture at all,a couple of chassis run with a short hot but produce a vertical line(sanwa es31 is one)

normal vertical collapse will show line across dead centre of screen and not towards the bottom like yours,this is why i am leaning towards deflection yoke being bad-and these monitors are well known for it

does your deflection yoke look intact and in the home position?
do each of windings read correct impedance?

[berlincam86]

Probably going to need more explanation on checking that. I know how to check a transistor and all that just not familiar with checking the yoke.

[grantspain]

multimeter to ohms and read the red/blue pair then the yellow/green pair
pretty sure it should be around 0.8 ohms and 5 ohms

[berlincam86]

I got .7 on the red and blue and 2.7 on the yellow and green.

[berlincam86]

Crap I didn't look to see how they were plugged in. I got it set green,yellow,blue,red is that right?

[grantspain]

photos please,but the deflection coil connector is offset so its virtually impossible to connect it incorrectly

[berlincam86]

It's 2 separate connectors. Red and blue on one and yellow and green on the other. Are those readings ok?

[grantspain]

just dug out my d9200 yoke and it reads 0.350 ohms on horizontal(red/blue) and 3 ohms on vertical(white/green)-this is for a pure flat type crt,is yours curved or pure flat?

[berlincam86]

Curved

[grantspain]

so the yoke is possibly ok

[berlincam86]

Ok great. Thanks. I have a chassis on the way. I have 2 of these monitors. So I'll use that chassis to get one going to use as a guide for the other.

[lilshawn]

It's 2 separate connectors. Red and blue on one and yellow and green on the other. Are those readings ok?

i'm pretty sure the 2792 has a single yoke connector. not 2 as you describe. (unless someone broke it.) are you sure this is a 9200 series?

a few old WG monitors (7400/7500/u2000 etc) had seperate horizontal/vertical yoke connections.

in any case, the vertical yoke connections (yellow/green or white green) are slightly narrower spaced than the horizontal connection (red/blue)

the horizontal is only wider spaced by 0.06 inches (1.7mm) so it would go if forced, but would be kind of obvious.

[lilshawn]

i'm unsure of the readings. I have a LCR meter I use to measure yoke windings, therefore any reading I were to give you would be meaningless since it measures in "henrys".

the vertical IC also supplies pulses to the horizontal subsystem.

if the resistor feeding the vertical deflection IC is hot (IC301), it's likely toast and will need to be replaced. replace the resistor too for good measure.

be forewarned, this particular chassis has a real bad habit of blowing one tiny system....and the more it runs, the more and more blows up. It has multiple power supplys that will keep going regardless if a system stops working or not. (an engineering snafu) you need to replace this IC asap before you run it any more or you chance it getting to a point where it's irreparable.

I had a HOT go on one and it was left running in this state for who knows how long. the horizontal power supply goes down into overload which isn't a big deal, but it has 5 other power supplies that keep going... breaking down and down and down. I must have replaced over 2 dozen parts. It never did get running again.

[berlincam86]

Thanks for the info. I'll take a pic of the connector when I get a chance. I'm pretty sure it was 2 connectors. Didn't look like they were broke but I'll look harder next time.