Sanyo 20EZ - Vertical collapse [FIXED]

TheYeti

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So I bought this 20EZ from a guy on craigslist who had it in a VS machine. He didn't know anything about monitors so he said that he had another guy cap the monitor for him. Well he says it worked fine for 2 months and they went into vertical collapse.



So when I got the monitor, I noticed right away that TR402 was not right. So I swapped in another and now I get this picture.





And.... after tweaking some pots, this is the best I could make it look:



I'm pretty confused right now because I seemed to have gotten rid of the vertical collapse. (sort of) but I'm not seeing any image from my Test Pattern Generator. And my B+ is at 110VDC.

I have already ordered a new cap kit, filter cap, B+ pot and new transistors (TR402 and TR403) but I was just curious of anyone has seen this kind of picture on a Sanyo before? I really have no idea if the previous person's cap job was done correct until I put my caps in but I just wanted to know if anyone has seen this behavior before. I don't really like those lines down the left side of the screen. That looks like it could be related to the yoke. And the jittery waves on the edges of the screen are also weird. (Not to mention that the chassis doesn't want to show an actual image)

I also didn't notice any obvious cold solder joints or broken traces (yet). And there are no cracks in the board. I'm also fairly certain the tube is ok and the yoke ohms out ok as well.
 
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So I bought this 20EZ from a guy on craigslist who had it in a VS machine. He didn't know anything about monitors so he said that he had another guy cap the monitor for him. Well he says it worked fine for 2 months and they went into vertical collapse.



So when I got the monitor, I noticed right away that TR402 was not right. So I swapped in another and now I get this picture.





And.... after tweaking some pots, this is the best I could make it look:



I'm pretty confused right now because I seemed to have gotten rid of the vertical collapse. (sort of) but I'm not seeing any image from my Test Pattern Generator. And my B+ is at 110VDC.

I have already ordered a new cap kit, filter cap, B+ pot and new transistors (TR402 and TR403) but I was just curious of anyone has seen this kind of picture on a Sanyo before? I really have no idea if the previous person's cap job was done correct until I put my caps in but I just wanted to know if anyone has seen this behavior before. I don't really like those lines down the left side of the screen. That looks like it could be related to the yoke. And the jittery waves on the edges of the screen are also weird. (Not to mention that the chassis doesn't want to show an actual image)

I also didn't notice any obvious cold solder joints or broken traces (yet). And there are no cracks in the board. I'm also fairly certain the tube is ok and the yoke ohms out ok as well.
I'm curious too since this monitor is also in my DK machine. Hopefully someone chimes in and helps.
 
I'm curious too since this monitor is also in my DK machine. Hopefully someone chimes in and helps.

Actually, I just had some more developments last night...

I pulled another working 20EZ from my DK Jr last night and hooked up my Test Patter Generator to it.

To my surprise, it had the same gray screen. Turns out, the 9v battery in my TPG was dying...or was dead! LOL.

I know that I'm not out of the wood yet on that chassis because it still might have partial collapse and it has the wiggles/shakes...but the gray screen mystery has been solved.

I'll update this thread after i have done a completely new cap kit on this chassis to see if that nips the problems listed above.
 
Actually, I just had some more developments last night...

I pulled another working 20EZ from my DK Jr last night and hooked up my Test Patter Generator to it.

To my surprise, it had the same gray screen. Turns out, the 9v battery in my TPG was dying...or was dead! LOL.

I know that I'm not out of the wood yet on that chassis because it still might have partial collapse and it has the wiggles/shakes...but the gray screen mystery has been solved.

I'll update this thread after i have done a completely new cap kit on this chassis to see if that nips the problems listed above.
Nice! Excited to see how it looks after the new cap kit!
 
Hi Yeti,

Yes, I have had this phenomenon happen on Sanyo EZ's. This is very typical for this model chassis.

I rebuilt one out of a Red Donkey Kong cabinet I acquired, and had this happen.

First thing you need to check:

Cold solder joints. Reflow everything! and I mean every single solder joint on the chassis. Watch for any solder splashes or solder that may have leaked over to another pad and caused a short if someone perhaps worked on it before. I have found that cold solder joints are the primary issue.

Secondly:

HOT if it is defective or not. Make sure you get an exact replacement if you replace it. test it thoroughly before you install it.

After I did the two above, my chassis was great. Collapse went away.

I hope this helps.
 
Hi Yeti,

Yes, I have had this phenomenon happen on Sanyo EZ's. This is very typical for this model chassis.

I rebuilt one out of a Red Donkey Kong cabinet I acquired, and had this happen.

First thing you need to check:

Cold solder joints. Reflow everything! and I mean every single solder joint on the chassis. Watch for any solder splashes or solder that may have leaked over to another pad and caused a short if someone perhaps worked on it before. I have found that cold solder joints are the primary issue.

Secondly:

HOT if it is defective or not. Make sure you get an exact replacement if you replace it. test it thoroughly before you install it.

After I did the two above, my chassis was great. Collapse went away.

I hope this helps.

Thanks Oldworldman!

I worked on this chassis over the weekend and made some baby steps. (The screen doesn't wiggle anymore) Maybe your assessment of my situation will change after seeing my latest image below.

So I got rid of (some) of the vertical collapse by replacing TR402. The one in there previously wasn't even the correct model number! LOL.

I also completely re-capped the chassis...including the large filter cap. It's worth noting the last person did a really terrible job capping this monitor. Not even all the caps were replaced and I think some were even out of spec.

I also replaced the B+ POT...and the voltage is currently 108.5VDC.

But...I still have the same image I did before. So the bad news is that the cap kit and new B+ pot didn't fix it. But the good news is that I didn't make it any worse. :)

Here is what the picture currently looks like. This is pretty interesting because it looks like it's still in partial collapse. The image will not fill the screen completely from left to right (vertically when the monitor is oriented horizontally) AND I'm getting these narrow white lines down the left side of the screen. (I already know the picture is way out of focus and needs to be converged too)

I've tested another known-working chassis on this monitor and confirmed both the tube and the yoke are good. So this issue is isolated to the chassis.

Adjusting the horizontal hold and the vertical size pot does move the picture around...but does not make it any better.

My next guess is going to be re-flowing the entire chassis, or better yet...replace TR403 next.

 
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There you go! Keep plugging away at it!

You are quite welcome!

I know you will get it resolved sooner or later. Sounds also like you have great tech skills.

Sanyos can be frustrating, but the reward is worth while.

Keep us all posted with your progress as you are doing. We always like to put a new solution to a problem in our book of knowledge if there is one other than we know.
 
I have fixed the problem with this monitor. It turned out to be far more easy than expected....but I was just shooting myself in the foot.

I decided to take another look at TR402. But this time I pulled another known-working chassis to compare with.


Here is the reading of TR402 on the working chassis. Looks good to me!


But here is my reading on the broken chassis. Yea...that's not right at all.


So I had another 2SC2073 transistor and took a reading from that one before installing it. Looks good!


My original hunch that TR402 was the bad part was actually correct. BUT...the original transistor I put in there was only HALF working so it literally only fixed HALF of the vertical collapse.

As soon as I used a working transistor, it obviously eliminated the collapse.

What's the moral of the story? Test your parts before you install them or you will wind up chasing your tail. :) Also...make sure you have a good 9v battery in your TPG.

The picture looks much better now, but I'm not out of the woods yet. It's still a bit out of focus and needs some color correcting...and the tube might even need to be rejuvinated.

But more importantly, I still have some moderate (to severe) convergence issues. I really hope I can work that out with the rings. I HATE adjusting yokes. Scares the snot out of me.

But hey!....I'm in a much better spot now. :)

 
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Wow pretty interesting stuff! I wouldn't even know to begin where to look to fix the problem. Learning a lot from you guys. :)

The more time you spend in this hobby, the more games you will acquire. And the more games you acquire the more monitors you will have to maintain. And more monitors means more problems to chase down.

It may seem tricky but this issues was actually the easiest issue I have ever had to fix. Arcade monitors can have MUCH more odd-ball issues. And the older these monitors get, the more odd the issues are getting because uncommon parts are starting to fail.

Ultimately, vertical collapse can be one of the hardest issues to resolve on a 20EZ. So I actually got lucky.

And my solution was actually right there in plain sight in the 20EZ flowchart.

Speaking of, flow-charts are always a good place to start when working on monitors. They definitely help you diagnose the area the issue may be coming from. (At the very least) Flowcharts don't always hand you the solution on a silver platter, but they can get you pointed in the right direction.
 
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Glad you got it fixed Yeti!


I knew you would figure it out.


Yeah always check those parts before you install them so whatever you have to do to get a good reading such as you did check and known one with a bad one.


Have a great day!
 
Just a final follow up...

I got the pictured all calibrated and cleaned up. Luckily I didn't have to adjust the yoke. I just needed to adjust the purity ring and got the colors looking nice and vibrant. Also good news because it doesn't look like this tube needs to be rejuvenated. :) I just really love how good the picture looks on a Sanyo.

Oh and those green lines I was seeing earlier on the checkerboard pattern was just because the brightness pot was turned up too high.

Now I have my 2nd spare Sanyo I can stash away for a rainy day. :)

(The lines in the picture are just a reflection in the mirror I was using to adjust the monitor)

 
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