9110 swap for Polo

[marshall]

The insulation tape is on the wires as I cut RED and BLUE then swapped them over.

[grantspain]

is it  only the blue and red that you rewired or have you cut and joined other wires?

[marshall]

Only RED/BLUE, everything else is as it was.

[grantspain]

that plug looks like its not on correctly

[marshall]

Just had a look and I agree, its not.

But the monitor is in my living room to prevent it getting cold/damp whilst Im not using it, an I nipped out to get the plug off the machine which was then just quickly assembled to take the picture. It was all good when connected up and running.

[grantspain]

ok well i am at a loss to whats causing the problem,you can get more width via the width coil but it does not explain the lack of height

[marshall]

Its been in and out of the cabinet several times so Im sure its not the plug.

I take it that if the plug wasnt on correctly, that would produce the symptoms I have?

If you think of anything let me know please.

[grantspain]

a photo of the best screen you  got so far will help

[marshall]

That would be this one, its like the resoloution is set wrong, my pc does that if I set incorrectly.

I wired this direct to the incoming mains wire, in the cabinet I removed it from it came through a EMI transformer, could that have anything to do with it?

[grantspain]

you can run polo direct from wall socket,have you tried adjusting anymore of the controls to see if they work

[marshall]

Its been cold and Ive been busy so not done much the last few days, but have wired the monitor up to its own plug in the living room and switched it on having taken the mainboard out to check for bad joints, then adjusted the H AMP to find it fills the screen with picture like you said it should. When it was on the machine that was not the effect it had! Obviously there is no video input at the moment.
The V AMP didnt need adjusting because the screen was full in that direction anyway. Now got to reconnect it to the machine to see what happens so that will be tomorrow now.

[grantspain]

you do realise that the polo is a 230vac chassis and not 110vac like the mtc9110

[marshall]

Yes I know that, it was wired to 240volts but to a transformer input inside the machine.

I measured the voltage before connecting it up. When I plugged it directly to a wall socket the screen was the same as when it was inside the machine, but the adjustments seemed to be working properly which they wasnt doing before, will see what happens when its back inside the cabinet.

[marshall]

I dont know why, but its working!!!

Did what you said and wired it direct to wall, played around with H & V AMP which filled the screen, reconnected it to the machine and its working. The colors look a little washed out but Im sure some fine tuning will sort that.

Thanks grantspain for all your help. 

Cant tell you how good it feels to have sorted it!!!

[grantspain]

the adjustments for colours are on the neck card

[marshall]

Yes, Ive been fiddling with them since 1pm today and the picture above is the best I can get it, so going to leave it on all night and have another fiddle tomorrow. It looks quite GREEN, and have had to turn all the colors down to get that picture.

[grantspain]

hmm could be a leaking drive transistor on the green
you should find 5 adjustments on the neck,3 cut offs and 2 drives(red and blue)
turn the cut offs down to minimum and then adjust the drives-if you still see a green washout then change t4(i think from the top of my head),its the middle of the 3 drive transistors

[marshall]

Do they go clockwise or anticlockwise to turn them down and do you know the value of the transistor as I don't have the schematics for this unit.

[grantspain]

bf859 is the drive transistor-i am pretty sure pots anti clockwise to minimum
if you have any solder skills a quick way to fault find the problem is to simply remove the green drive transistor

[marshall]

I 'inherited' a new chassis for this today, but when it was all connected it doesnt work, so it looks like ill have to change the transistor.

[grantspain]

another thing that can cause the colour issue is the lm1203n ic on the neck card

[marshall]

I can't seem to find that transistor in either maplin, farnell or rs, do you know who supplies them or an equliverlant?

[lilshawn]

try and swap around those transistors first... if your colors move to another, its your problem...and yes those lm1203 chips do go bad...and can cause dim colors/dead colors...swapping the transistors will eliminate the lm1203 as the colors will stay the same.

an nte171 will work in place for the BF859

[marshall]

Ive changed the transistor with no effect, the colors are not dim/dark and Im thinking its more of a set up problem now as its not showing black, more like red.

[lilshawn]

supposedly you are able to set the monitor black level as follows...

1: leave monitor turned on for 10 mins.
2: remove video signal
3: set the cut off pots for the red green and blue to obtain a voltage of 180v on the COLLECTOR of associated colors transistor..
4: adjust contrast to  minimum and brightness to maximum
5: adjust the screen on the flyback to get a just barely visible raster scan
6: eliminate the predominant color by turning down that cutoff color until the raster is gray

should the brightness increase following the adjustment, turn down the screen on the flyback a little until the raster is barely visible again. repeat 6

[marshall]

Thats great, thanks.

Which pin on the transistor is the collector?

[lilshawn]

for a to-220 case  BCE... Base Collector Emitter... viewed left to right with the printing facing you

but some packages are different, sometime you will have an oddball, best to check the datasheet for you transistor here...it's free and they have nearly everything:

www.alldatasheet.net