Nintendo Sanyo 20EZ Issue (June 28/10)

rockinganker

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Well, I'm having some troubles with the three 20EZ monitors I have been working on. They all have the same issue. The screen on all three of them curls in the middle like this )(. There is nothing I can do to remove this curl effect. Again, all three have this issue.

I replaced the large filter cap, IC601, Q901, full cap kit and audio board rebuild and this is what I am left with.

Also, I notice on two of them, the screen is brighter in the middle then on the top or bottom. These are installed into VS cabinets and are mounted horizontally.

B+ measures 108 and ground have been hooked up.

Any ideas?
 
With the input unplugged I still get the messed up screen. Mind you, I have to turn up the brightness to see it, but it's still con-caved.

Could any of the resistors or diodes be leaking AC current through causing this issue?

Thanks
 
I am using everything from the cabinet I am working on. This includes the original power supply putting out 100v.

All grounds have been hooked up as well.
 
That's a really odd failure. I don't think I've ever seen a Sanyo do this... and you have three of them!

I assume that the deflection yokes are correct for a Sanyo (i.e., you didn't try to hook a Sanyo chassis to some other yoke). A yoke mismatch can cause this sort of distortion.

Did you recap and rebuild all three chassis? Perhaps you made the same mistake three times? Go over them carefully, especially the vertical and horizontal circuits. Maybe you've got a cap in backwards, or the wrong value cap?

-Ian
 
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Could very easily be the IC601's, there have been some recent issues with bad ones. Do you have any of the old ones available to re-install?
 
All three IC601's are from Bob and I'll try an old one in to see if it changes things.

Some people have had issues from ones recently purchased from Bob. Since you have 3 and it is unlikely all 3 are bad, if you swap one and it works that would be a good data point. You would then be able to inform Bob of the issue as I'm sure he is unaware.
 
Could very easily be the IC601's, there have been some recent issues with bad ones. Do you have any of the old ones available to re-install?

Hmm.. What other issues have you seen with the IC601's? I repaired a Sanyo a while back for a friend. It had a bad IC601, and I replaced it with a new one from Bob. That brought the thing out of shutdown and I was able to adjust the B+ to a usable level, but I was never able to get it stable. The regulation has been horrible. I've changed the filter cap, all four rectifier diodes, etc. It's even got a new flyback and a new HOT, shunt regulator too, IIRC. It works, but it's got a distinct "shimmy" to the picture, and it's affected wildly by power fluctuations. It's right next to two other Nintendo games, plugged into the same power strip, and it's the only one where the screen jumps when someone flips the flipper on Baby Pac.

-Ian
 
I have seen post after post, where IC601 should be the answer to the fix. People order an IC601 from Bob, and things end up going south. Don't know what the problem is, bad batch of IC601's or maybe a problem with installation?

IC601's do fail, but I sure as hell don't just automatically replace them when doing a cap kit.

I would test at least 2 of the old IC601's, just to make sure that one is not bad.
 
Just thought I'd bring this to a close. Turns out the IC601 bought from Bob Roberts was indeed faulty. I put an old part back on and perfect picture.

Sadly, I still have two monitors in need of an "old" IC601 as I throw out the original parts after the first fix. I bought four parts and all three that I installed were bad...too scared to try the last one I have.

Hope this helps anyone.
 
Is this the same problem?

I have a 20EZ in a Nintendo cabinet, running SMB. It's been about ten years since I recapped it, and while adjusting the B+, slipped with a test probe and blew the LA5112N regulator chip.(So it's sat for many years, unpowered).

Recently I finally got around to working on it again, and replaced the regulator chip as well as the 2SD1090 pass transistor and B+ pot. I powered it up (with 100V) and the no-input "white screen" looked ok. B+ is 108.5 volts on my Fluke DVM.

However, when displaying the game, there is a pincushion distortion in the horizontal axis only (like the OP says, ")(" shape). It is definitely worse when playing underground scenes with mostly black background. See attachments. The center of the pic and the top/bottom do not curve towards the center, just the left and right borders.

All the controls work (brightness, width, hold, etc). but there is no adjustment for this distortion. Where should I be looking? Thanks!
 

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