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Author Topic: Makvision M2929D4G-TS top of screen display issue  (Read 581 times)

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PTAaron1

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Makvision M2929D4G-TS top of screen display issue
« on: April 26, 2017, 11:32:58 pm »
Monitor is a Makvision 2929D4G-TS



I picked it up last weekend, seller said it had been "gone over" by a well known monitor guy in the Chicago area.  When we got it home we found that it had some issues visible at the top of the screen.  I'm completely new to the "arcade world"  - so I don't know if this is a common problem or not as I don't really know how to describe what it is.
It appears that the very top few lines of pixels are being displayed upside down and further down the screen - here is a good example... top line "1UP HIGH SCORE 2UP" is cut off and flipped over:


Another example that shows up as lines through the top bit of the screen and "1UP" cut off the top:


When the screen isn't connected to the computer I see this when the message is near the top or bottom of the screen:




Is there a name for this condition?  It looks to me like there is something not properly lined up, but again I know nothing about monitors (yet).
I'm hoping that this is something easy to fix...

Thank you in advance for any help.


« Last Edit: April 27, 2017, 02:04:44 am by PTAaron1 »

mourix

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #1 on: April 27, 2017, 08:09:40 am »
What your monitor does is called "vertical foldover", basically part of the timing is off which causes the image to be drawn at the wrong place. The most common cause of this is bad capacitors.

PTAaron1

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #2 on: April 27, 2017, 03:10:42 pm »
What your monitor does is called "vertical foldover", basically part of the timing is off which causes the image to be drawn at the wrong place. The most common cause of this is bad capacitors.
Thank you!
I ran across that term but didn't see a good example of what it meant.
Typical to replace all capacitors or is there a specific capacitor that would cause this?

buttersoft

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #3 on: April 28, 2017, 08:06:11 am »
start with the electros in the vertical section. Some chassis are divided into sections, some just use a prefix for the different sections. Probably all C5xx or C4xx electrolytics, but you'll have to check.

PTAaron1

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #4 on: April 28, 2017, 08:55:13 am »
start with the electros in the vertical section. Some chassis are divided into sections, some just use a prefix for the different sections. Probably all C5xx or C4xx electrolytics, but you'll have to check.
Thanks for the reply!
I'll do some poking around and see what I can find.

PTAaron1

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Makvision M2929D4G-TS top of screen display issue
« Reply #5 on: May 09, 2017, 02:21:59 am »
Update:  on this monitor nothing on the board was labeled as to purpose and there doesn't appear to be a diagram - so I ordered and installed a full cap kit... all 62...
Finished a bit ago (2am) and on plugging it in I'm getting no picture at all now.

:(
« Last Edit: May 09, 2017, 07:28:47 am by PTAaron1 »

lilshawn

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #6 on: May 09, 2017, 05:59:33 pm »
gonna have to double check all the caps to make sure you didn't put one in backwards.

PTAaron1

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Makvision M2929D4G-TS top of screen display issue
« Reply #7 on: May 10, 2017, 12:27:43 am »
gonna have to double check all the caps to make sure you didn't put one in backwards.
I was extremely careful and triple checked them all before I soldered them, but yeah - that was my first thought.  Didn't have a chance to check tonight.
We also had a flap of foil come up with one of the caps and we thought we got a nice bridge along the trace to the cap - but maybe it didn't connect.  That's beyond my skill level to fix, but I have friends that should be able to help ;)

PTAaron1

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #8 on: May 13, 2017, 03:18:53 pm »
Update:
Checked caps, all were in properly.
Friend reflowed a few joints I didn't do as well as I should have... added a jumper where we had to fix the trace... and it still didn't work.
This morning we went back through and found another section of foil on the top side that had been snagged when removing the caps - used the electrical schematic to figure out that the cap was part of the 12v circuit going to an IC - my father inlaw that is great at this stuff made a jumper to complete the circuit and now we are in business!


When playing a game the foldover appears to be gone.

When it is showing the "disconnect" messages it still looks like this occasionally as it blinks across the screen:


I'm less concerned though because it looks great while playing games.

lilshawn

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #9 on: May 14, 2017, 07:28:27 pm »
still got some foldover. usually that's indicative of a failing (or starting to fail) vertical deflection IC. (IC5 TDA8172) or a resistor around there has gone out of whack (R170, R164/5/6/7/9 etc)

PTAaron1

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #10 on: May 14, 2017, 07:36:18 pm »
still got some foldover. usually that's indicative of a failing (or starting to fail) vertical deflection IC. (IC5 TDA8172) or a resistor around there has gone out of whack (R170, R164/5/6/7/9 etc)
Thank you for the information! 
I'm not sure how to test those parts, but now I have an idea where to look.

The problem is fixed (at least on the games I've tested) when displaying arcade material, only seems present when the disconnect message is bouncing around the screen, so I'll keep a close eye on it to see if things start to appear again with arcade material.

Thank you again for the reply and the info!

lilshawn

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #11 on: May 14, 2017, 08:24:18 pm »
oh, okay then, if it's just when disconnected, it's probably just the vertical size is set too high on the 15k signal then. (when disconnected the monitor runs at 15khz vertical refresh rate)

PTAaron1

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Re: Makvision M2929D4G-TS top of screen display issue
« Reply #12 on: May 14, 2017, 08:58:41 pm »
oh, okay then, if it's just when disconnected, it's probably just the vertical size is set too high on the 15k signal then. (when disconnected the monitor runs at 15khz vertical refresh rate)
That's great news!
It won't be showing that screen once it is in the cabinet, so it shouldn't be an issue.
Is there a way to adjust that, just out of curiosity.

It was very noticeable during games before the cap kit and subsequent repairs - so I think we're good to go.

  
 

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