Nanao MC-2000-S single line going up and down - vertical collapse

john2654

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Nanao MC-2000-S single line going up and down - vertical collapse

I have a Zaxxon with a Nanao MC-2000-S that had a single line going up and down. Just did a cap kit and checked over for cold solder joints, no change. I can see the colors moving when the game is on so it looks like it has vertical collapse.

Is there an IC that needs replacement?
 

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From Key Layton's repair guide to the MC2000S:

Vertical Collapse problem: Check resistor R416 (22 ohm fusible, half watt), vertical output transistors Q401 & Q402 (both are type 2SD1138), and capacitor C523 (originally a 47 uf @ 50 volt, but should be changed to 100 uf @ 50 volt). C523 is located inside the cage around the flyback. Check tantalum capacitor C408 (10 uf) as it may be shorted.


So I guess I'll check:
- resistor R416 (22 ohm fusible, half watt)
- vertical output transistors Q401 & Q402 (type 2SD1138)
- caps should be fine, just did a capkit, but maybe didn't include C408
 
Replacing the following fixed my vertical collapse issue:

- resistor R416 (22 ohm fusible, half watt)
- vertical output transistors Q401 & Q402 (type 2SD1138)
- C408 10uf 25V tantalum capacitor


I have (1) resistor and (1) tantalum capacitor left for any that are in need.
 
The two most likely failures that cause vertical collapse on this monitor is either R416 or C408 (tantalum not in cap kits).

Then caps, then the 2SD1138.

Both of my personal monitors had bad C408s.
 
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