arcade monitor problem

[Francisco]

Well, first off. I'm almost an electronics engineer so no problems with
circuits but I never dealt with TV's. Now I have some idea because I've
been touching and fixing little things.

But there is something that I can't find any solution. The horizontal size
of the screen is too big. The yoke is on the output (Colector) of a
transistor (BU206D), there are (in this order) 2 capacitors an inductor
named 'linearity' in parallel to a resistor, the yoke and another inductor
wich you can regulate by moving a cilindrical ferrite nucleus, then gnd.

At home I don't have much instruments to measure anything working, but I
looked at the schematic and I think that all the parts are ok, at least I
can't find what could be wrong.

The variable inductor does reduce a little the horizontal size, but it's
still insuficient, the image is way larger than it should be. Another thing
I discover is that moving a potenciometer near the power supply, the image
gets smaller, but looses linearity at the right, I guess that whats
happening here is that the transistor starts to cut the signal, and thats
why I see that alinearity, correct me if I'm wrong.

I can't find a sollution to this, at least not something that is broken,
could it be just a bad design?, I was thinking about a solution, maybe to
make a larger variable inductor and replace the current one, to reduce
voltage at the yoke, but I'm just guessing.

Well if you can tell me something about this I would be very pleased to here
it. If you need more info just ask.
Thank you.

Francisco

 

[eddumweer]

At first, you need to measure that the B+ voltage and other voltages are
according the specifications.

Secondly you can give the branche, model/type. Many people on the internet
are knowing more about eloectronical equipment and will share theire
kwonledge on the model.

Greetings Peter

Mailadres is corrupted because I dont need viagra.

 

[Francisco]

At first, you need to measure that the B+ voltage and other voltages are
according the specifications.

Secondly you can give the branche, model/type. Many people on the internet
are knowing more about eloectronical equipment and will share theire
kwonledge on the model.

Greetings Peter

ohh, yes, I forgot to say, this is a monitor manufactured in my country I
think (Argentina), so, I guess no one will know about it, the brand is
"Clarex".
I looked in the schematic and there is no voltage labeled B+, maybe you can
tell me where should I find it. Or any references to information on monitor
repair.
Thank you

Francisco

 

[eddumweer]

Hi Francisco,

Normaly the +B is the voltage which goes to the high voltage output
transformer.

If this voltage is to high or to low the picturesize will be variable.

Greetings Peter

 

[John DeGroof]

On Sun, 04 Apr 2004 03:03:26 -0300, Francisco

How's the arcade monitor fix going? What game is it, and what type of
monitor, raster or vector? I've worked on a few vector monitors, and
done some minor work on rasters. One reason I ask is some of the
vector monitors severely overscan intentionally.