MatsuSHITa picture collapse?

qbass187

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Hey guys,
I know these things suck but does anyone have any idea what would cause a picture collapse on a 19" Matsushita?
It was fine one minute and then POOF! MatsuSHITa...
 

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Classic vertical field collapse....

....or maybe an poor conenction to the relevant yoke coil. Persoanllay I'd download the manual and guess which parts of the circuit do what (while obviously observing safety precautions). If it's a TM202G the Atari branded manual seems to be pretty good.

At least you know the HV is good.
 
It's a long shot but...
I was working on my 202G last night and there is a slider switch on the back of the chassis near the B+ adjustment pot (the one that is probably locked in place with silicone). I was curious to what it did so I swapped the position and it came up with a single line across the middle of the screen (albeit green). You might want to check what that switch does, check which position it's in and check the contacts are working.
 
I replaced both the Vert transistors and still nothing.

What should I look at next? Any ideas?

I really appreciate it.

ERIC

Is there voltage getting to the vert output transistors? Often when they short they take out a fusable resistor that feeds voltage to them from the power supply or sometimes a voltage derived from the FBT.
 
Had a MatsuSHITa in my Pole Position when I got it, had vert. collapse. Was a cold solder joint, but I can't remember where off the top of my head. ... Worked for a little bit, then something else fried and I just set the thing aside and haven't looked at it since.
 
Had a MatsuSHITa in my Pole Position when I got it, had vert. collapse. Was a cold solder joint, but I can't remember where off the top of my head. ... Worked for a little bit, then something else fried and I just set the thing aside and haven't looked at it since.

Yeah, it started smoking after a little while...if the tube wasn't so clear and flawless I'd just trash it.
 
Yeah, it started smoking after a little while...if the tube wasn't so clear and flawless I'd just trash it.

For those... I subscribe to the idea that the tube has no burn-in because the monitor broke so fast it didn't get a chance to burn anything in. :D

If you want to keep the tube... might be easier to get an aftermarket chassis and slap it on. Save yourself the headache of fixing it and future house fire from running it.
 
For those... I subscribe to the idea that the tube has no burn-in because the monitor broke so fast it didn't get a chance to burn anything in. :D

If you want to keep the tube... might be easier to get an aftermarket chassis and slap it on. Save yourself the headache of fixing it and future house fire from running it.

Yeah, that though had crossed my mind.

I believe the pin out on the neck is an odd one...and idea what aftermarket chassis would work?
 
Yeah, the tubes used in these monitors are odd - you won't find an aftermarket chassis that will work.

Check the solder joints around the deflection yoke connector, and check the vertical transistors.

-Ian
 
Yeah, the tubes used in these monitors are odd - you won't find an aftermarket chassis that will work.

Check the solder joints around the deflection yoke connector, and check the vertical transistors.

-Ian

Yeah, I replaced both vert transistors.
I moved teh little toggle switch on teh back of the chassis and the pic came back but only filled 3/4 of the screen. Then it started to smoke and now I only get about a 4 inch band in the center of the screen.

I'm a little out of my league at this point.
 
Oh dear. Mine didn't do that (although I powered it down before moving the switch). So when you say the picture came back did it breifly actually fix the problem? Have you downloaded the schematics yet? They show the vertical section of the circuitry in Figure 9 on page 15 of the schematics (page 21 of the pdf). It looks like the switch (SW301) is a service switch and it probably connects via a couple of resistors to pin 6 of the IC, marked as 'V osc'.
 
Oh dear. Mine didn't do that (although I powered it down before moving the switch). So when you say the picture came back did it breifly actually fix the problem? Have you downloaded the schematics yet? They show the vertical section of the circuitry in Figure 9 on page 15 of the schematics (page 21 of the pdf). It looks like the switch (SW301) is a service switch and it probably connects via a couple of resistors to pin 6 of the IC, marked as 'V osc'.

No, flicking the switch didn't fix the probelm. It went from total vertical deflection to partial.
I could see the game only in the middle of the screen with about 2" on the top and bottom still collapsed.

I flicked it back and then fro again and I got smoke and now the partial deflection takes up 2/3 of the screen with a 1/3 in the middle visable...
 
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