Missing Green after Sanyo EZ20 cap kit

Torin

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Hello,

I recently had a cap kit done on my DK 20EZ and now the green color is missing completely. Everything else looks great but no green. It was working before the cap kit was installed. Turning the one green pot on the neck board doesn't seem to do anything. Any ideas? I have adjusted the B+ but it doesn't seem to want to change from 91. I have checked the video connectors on the main board and have made sure the neck board is seated correctly. I am at a loss as to why the green would suddenly go away after a cap. I appreciate your help!

Torin
 
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I don't entirely know why this happens (maybe the old caps don't stress the electronics enough to expose the cold solder?), but the solution is to reflow all the drive transistors on the neckboard. the first 2 EZ's that I did I had no problems, but the last like 3-4 I did all had missing color issues. might be a good idea to reflow every major component on the neckboard.

then you should be good to go again!

also, you may have to redo all the color balances and brightness settings (there's the Brightness pot on the adjustment board, a medium brightness adjustment pot (I usually don't mess with this) and then the flyback's Screen pot) ... you may even have to adjust your B+ too, grab some alligator clips and clip one to the BJ pin (it's near the flyback) and clip another to the monitor frame for your ground to test this.
 
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Great, thanks so much for the help.

1. I tested the B+ last night and it was at a constant 91. I couldn't get it to move either way. Could this cause a color loss? I turned it up anyway and it did seem to help the screen stability.

I will adjust the brightness again to see if I can get the color up but it didn't help the first time.

2. Also, when I do the reflow, I guess I would need to discharge and then remove the neckboard? I didn't do the cap kit, so I'm new to this. Any advice here would be helpful.

3. Lastly, the only green adjustment I could find was on the neckboard and every other color has two. I don't have the invert board. Is there any other way to brighten up the green anywhere else on the EZ?

Thanks again for all your help.
 
Great, thanks so much for the help.

1. I tested the B+ last night and it was at a constant 91. I couldn't get it to move either way. Could this cause a color loss? I turned it up anyway and it did seem to help the screen stability.

I will adjust the brightness again to see if I can get the color up but it didn't help the first time.

2. Also, when I do the reflow, I guess I would need to discharge and then remove the neckboard? I didn't do the cap kit, so I'm new to this. Any advice here would be helpful.

3. Lastly, the only green adjustment I could find was on the neckboard and every other color has two. I don't have the invert board. Is there any other way to brighten up the green anywhere else on the EZ?

Thanks again for all your help.

1) cap it first. set this at 108V.

2) cap it first. :) you don't need to discharge, in fact I just did it with the neckboard attached on my DK.

3) your color adjustments won't do anything until you reflow the transistors on the neckboard. though it's highly unlikely, your tube could have a bad green gun too. there's only going to be a Green Bias control cause the green is the base color on that particular monitor. you adjust the Red and Blue drives to match the green, then fine-tune with the Bias controls.
 
Ok, thanks again. Although, when you say cap it first, I just had a complete cap kit done last week. Are you referring to capping something else? Sorry, just need clarification.

Even after my re-cap the B+ is constant at 91. Could it be a bad B+ pot?

Thanks again for answering my newbie questions.
 
I lost blue - it ended up being a bad transistor on the neck board. You can test the green by switching transistors with say the "working" red. Easy fix if that is the case - B+ on mine was 106v so not issues there. Good luck.
 
Yep, it was a bad solder on the neckboard. All colors working again! Now, fine tune the colors and test my B+ voltage tonight. Thanks for all your help!
 
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