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Discussion Starter #1
Hi everyone, i have a issue with my Mitsu, i want to know if i am on the right track!

I have a WS-73903
CHASSIS: VZ6-V15
This is the Convergence chip for it: STK392-040

OK, now the problem.... One day i turned it on and i have sound but no image, I can see the "input 1" in the top corner..and its convergence is off. So being a arcade tech, and having worked on monitors, i was not afraid to jump in and poke around.

I removed the "Conv-Gene" board form the chassis. Without the Conv-Gene, i turned on the TV and i now get a picture and sound. The picture is way out of convergence! I can not adjust the convergence without the the generator. So i put the Conv-Gene board back in and turn the TV back on....now i am back to the original problem...no picture except for the "input 1" in the top corner.

So my question is... is it a bad Con-Gene board or bad Convergence ICs..or both...or what???

Thank You!!!!
 

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Can you change inputs? Do you get OSD?
 
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Discussion Starter #3
Yes i can...i can change inputs, goto menu...goto all sub menus.

Now WITHOUT the Conv-Gene i can get a image on the screen of the input, and the convergence is WAY out of wack! I am also unable to adjust the convergence.

When i put the Conv-Gene back in and turn it back on. I get menus and OSD, and audio...but NO IMAGE.
 

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Look very carefully for coolant that has leaked onto the signal board.
 
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Discussion Starter #5
Yeah it did have some coolant leakage on the board in the middle and the board on the left (not the HV board) I doesn't look to bad at all. It might even be old, nothing seems damp.

What do you recommend? Is my problem fixable? Is that what has caused the problem? But then why do i get a image if i take out the Conv-Gene board?
 

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Map the area carefully so that you know where it has been after you clean it. Pull the board, rinse it with denatured or isopropyl alcohol, repair any damaged components and traces, then check the continuity of EVERY feed through between the two sides of the board in the affected area.
 
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Discussion Starter #7
Thanx lcaillo for your help so far.

I got the chassis out and before i dive in i thought i would take some pix of the area in question, just so that we are on the same page :)

The bottom of the chassis seems to be fine, i would say no rework needed. But what worries me are those 2 jumper wires. Is that crud conductive?

The board to the left (double sided board) seems even better, but i will do some continuity checks on some vias.... all the traces look ok.



 

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If it did not get on the double sided board the job is easy. Just clean off all of the corrosion and crud very well with alcohol, repair any broken connections and it should be OK.
 
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Discussion Starter #9
It didnt work :(

I cleaned the scrubbed the infected area, re-flowed the inter board connections and still the same results.....no picture, but i do get OSD.

SOOO...back to my first question.... Why is it that when i take out the Conv-gene board and turn on the TV i get a picture??? And when the Conv-Gene board is in the TV all i get is OSD and no picture???

:explode:
 

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I'd be looking more carefully for coolant on the signal board or the connectors between the two boards. My bet is on a drop or two of coolant on the signal board.
 
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