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BeoVision MX 6000 faulty horizontal s-correction

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jimjans
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jimjans Posted: Tue, Jul 4 2017 7:21 PM

Hello I have a problem with my mx6000 I think there is something wrong with the horizontal s-correction.

The picture is a little bit squashed toward the right and left edge does anyone know which cap that is the s-correction cap on the board?

read this on a repair site about the problem :

S-Correction Problems

  • An open S-cap will result in no horizontal deflection - a vertical line.

     

  • A shorted S-cap will likely load down the B+ possibly resulting in a blown fuse or other power supply components.

     

  • An S-cap that changed value (or in the case of a multiscan monitor, selected to be the wrong value) will result in distortion at the left and right sides of the screen:

     

    • Too low: picture will be squashed towards edges.

       

    • Too high: picture will be stretched towards edges.

    Note that this is not the same as what is commonly called linearity which would likely affect only one side or gradually change across the screen.

solderon29
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4C103 is a common failure on this chassis.It usually goe's open circuit,but may be dry jointed too.C102 next to it is worth investigating too.I'm assuming that you are familiar with the insides of TV's,if not, take great care or better still take the tv to a service agent

Nick

solderon29
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4C103 is a common failure on this chassis.It usually goe's open circuit,but may be dry jointed too.C102 next to it is worth investigating too.I'm assuming that you are familiar with the insides of TV's,if not, take great care or better still take the tv to a service agent

Nick

jimjans
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jimjans replied on Thu, Jul 6 2017 11:05 AM

They looked a little bit dry but did not help to resolder them will order new ones and replace the old ones .

But is it these caps that controlls the s-correction?

 

Will try and change the caps that is mentioned in this thread to http://archivedarchivedforum2.beoworld.org/forums/p/24571/335607.aspx#335607

 

 

jimjans
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jimjans replied on Thu, Jul 6 2017 11:05 AM

The picture looks like this sorry its only a bad paint picture..

 

solderon29
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The cap's I mentioned are indeed in the e/w modulator circuit,but your drawing does not look like an e/w correction error,it's seems more like horizontal amplitude error.

Change the two cap's C102/3 anyway as they are "usual suspects",but also check the plug/socket connection to the deflection coils on the crt.This is also a common failing particularly with the 28" version of this chassis.The horizontal coils connection can become dry jointed at the rear of the small pcb,and the connection overheats,affecting width and horiz linearity.

Regards,

Nick

jimjans
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jimjans replied on Thu, Jul 6 2017 1:58 PM

The connection to the deflection coil looked alright resoldered the connections but with the same result.

 

Here are some more pictures that I took directly from the tv.

 

 

 

solderon29
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Interesting! I've seen worse linearity on these set's though!What are you using to generate the pattern by the way?

Do you know how to access the service program?You may be able to adjust the linearity somewhat.

When you change the cap's mentioned earlier,change 4C100,220uf.this can affect the drive to the line output transistor.

Regards,

Nick

jimjans
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jimjans replied on Thu, Jul 6 2017 4:31 PM

I use a sega megadrive have a mx8000 where the picture is spotless.

The big problem is when playing a game like sonic it is looking likes like a wave in the right and left side because the picture shrinks  does not find this problem with my mx8000.

 

I have installed a button so I can reach the service menu.

But does not bad linearity only affect one side? 

I am not new to crts but it was like twenty years ago I worked with crt monitor mostly arcade ones a lot easier only one boardSmile

solderon29
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see what happens after you replace the caps?

Regards,

Nick

jimjans
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jimjans replied on Sat, Jul 8 2017 6:02 PM

I will do that but when you write 4C100 I guess you mean C100?

 

And thank you for all the help you giving me..

solderon29
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Yes indeed.It's situated close to the line output transistor and quite fiddly to get to!

Nick

jimjans
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jimjans replied on Sun, Jul 23 2017 2:59 PM

Ok I switched the caps you mentioned but with the same result are there other I should replace ?

Only have a mx8000 and a old 20" crt to campare it to they are much better.

Here is a video of the tv in action with sonic, look att palmtrees .

https://www.youtube.com/watch?v=0BkKubG9gOY&feature=youtu.be

Is it normal dont have many crt to compare it to just now, saw this on some arcade monitors sometimes to if I remember correctly.

 

 

solderon29
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4C104,105 and 106 are all associated with the final drive to the deflection coils,and could affect the scan shape,although I've never come across it.Also L3 in the same area,may be dry jointed or it's core may be loose or moved?

Nick

jimjans
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jimjans replied on Mon, Jul 24 2017 2:16 PM

Did you see the video does it look out of spec?

jimjans
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jimjans replied on Wed, Jul 26 2017 3:35 PM

Have changed all the caps on the board but not 104,105 and 106 did not have them at home. Got a much brighter picture but same problem with the linearity will order the rest of the caps to but maybe I got a tv with this kind of linearity.

Ralf
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Ralf replied on Thu, Jul 27 2017 12:18 PM

Hi,

this problem could be caused by dry capacitors in the main powersupply as well.

I always change them too, because of the age. 

Did you check all the voltages on the board and the main power supply?

Ralf

jimjans
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jimjans replied on Thu, Jul 27 2017 12:31 PM

What are the caps number that you always change in the powersupply?

jimjans
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jimjans replied on Thu, Jul 27 2017 12:31 PM

Have changed

 

C61:                                            1x 2,2uF 50

C137:                                          1x 22uF 50V

C31:                                            1x 47uF 63V

C29, C132:                                  1x 100uF 40V

 C82:                                            2x 100uF 63V

C100:                                           1x 220uF 35V

C44, C120, C121, C131, C134:     5x 470uF 25V

C46:                                              1x 470uF 63V

C48, C53:                                      2x 1000uf 35V

C52:                                              1x 2200uF 16V

C102

C103

jimjans
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jimjans replied on Thu, Jul 27 2017 12:31 PM

Remove

jimjans
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jimjans replied on Thu, Jul 27 2017 12:31 PM

Remove

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