Help! Donkey Kong suddenly dead...

Racetech

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Drat. I just finished restoring this original Donkey Kong and it was working great. Then when I powered it up today--nothing. No video, game play, or audio. When on, I can hear a faint hum from the power supply-it has power. There's no glow from the back of the CRT and the 300 ma fuse on the monitor chassis was blown. When I replaced it, it blew again instantly on power up. Ideas? This is the standard Sanyo monitor (19" 20EZ I believe). Flyback? HOT? Is this a common Nintendo/Sanyo issue? Why's everything dead?

Thanks in advance for any help!
 
Blown fuse could mean your audio board is also not getting power, which could mean no sound. Good luck with your game.
 
The 300ma fuse is in the power section of the chassis. Blown fuse means a bad hot or flyback or both.
 
Do you know if the blown fuse also cause the audio amp to lose power?
 
Guys, thanks for the help! Last night the answer to my last question hit me--I knew the audio is on the monitor board because the volume pot is on the monitor chassis. The game probably was running--I just couldn't hear it or see it.

Also, I had noticed just before this failure that there was a very slight horizontal jiggle of the video. That was probaby a warning shot you think?

I'll dig up a flyback and HOT. Any suggestions for the best sources on those? Maybe capping it would be in order as long as I have it all apart. Thanks again!
 
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Bob Roberts has the hot, NTE89. Arcadecup.com has the flyback. You should get a new B+ filter cap and a B+ pot while your at it. And a cap kit wouldnt hurt either!
 
Drat. I just finished restoring this original Donkey Kong and it was working great. Then when I powered it up today--nothing. No video, game play, or audio. When on, I can hear a faint hum from the power supply-it has power. There's no glow from the back of the CRT and the 300 ma fuse on the monitor chassis was blown. When I replaced it, it blew again instantly on power up. Ideas? This is the standard Sanyo monitor (19" 20EZ I believe). Flyback? HOT? Is this a common Nintendo/Sanyo issue? Why's everything dead?

Thanks in advance for any help!

You just described my biggest nightmare. I worry about this every time I plug it in. Good luck to you. I hope you are able to fix it without too much hassle.
 
You just described my biggest nightmare. I worry about this every time I plug it in. Good luck to you. I hope you are able to fix it without too much hassle.

I had a "King of Kong" party set for this Sat night so after looking at the great responses here and checking online sources, I decided to call in the calvary in the form of a local game tech. I've used his services before when I found myself in over my head and he's never failed to fix things right away. He told me that he has all the necessary parts and for $50 more than the parts will cost me to order, he should be able to have it working by tomorrow night.

One curious thing... he says he's 99% sure it's not a HOT/flyback at fault, but rather a capacitor issue--that in his years of experience with these Sanyo monitors, only once was it a bad HOT and never a bad flyback yet. He told me that one particular cap when bad can make the HOT appear to be bad, etc, etc... He has a flyback tester and will test the HOT too. I'm having him cap it while it's out.

No matter what, he indicates that he has whatever it might need on hand including a working chassis for the 20EZ. Game on for the party Saturday night!
 
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Thats great! This was the first sanyo I have worked on and I had the same problem as you,it was blowing the 300ma fuse. I tested the hot and it was bad. Then I noticed the flyback had some brown crap leaking out the top. So after a new Flyback, hot, filter cap, b+ pot, ic601 and a full cap kit, it works! Keep us posted
 
He took the chassis out of the monitor and did a quick visual of the components and an ohmmeter test of the HOT. The HOT was shorted. The flyback appeared to have a hole burn-through. Looks like mine had what you guys posted here--both a bad HOT and bad (or on death row) flyback. I'm going to have him replace the B+ cap and re-cap the audio per the advice here. I'd like DK to keep working for a long time now.

Thanks again for all the help again! I would have given this a whirl myself but there's no way I could have gotten the parts fast enough for the party tomorrow.
 
Update

The party went great but the 20EZ monitor started acting up as the machine ran for a few hours. It developed a horizonal jitter (the monitor would think it's vertical since it's turned sideways of course). It became very touch-sensitive; even joystick movements started making it wig out and it became unplayable. It would completely lose *vertical sync*.

I had my wife watch as I tapped on various things with a plastic soda straw. When I tapped on the heat sink on the audio side of the board, it caused the symptom. I took out the monitor, removed the chassis and re-soldered some suspicious looking areas.

When I put it back in, it worked great--rock solid. Now it's doing the exact same thing again. The monitor veterans here will figure out I'm not much of a monitor tech, but I figure it has to be an intermittent connection somewhere. Before I start taking potshots (no pun intended) at it, are there some issues common to these Sanyo monitors that I should pay attention to?

Thanks in advance for your replies!

EDIT: Two things:

1. Upon further review, I figure this should be moved to the Techical-Video Games-Monitors forum
2. My answer may be in the flow chart posted there by Dokert:

http://forums.arcade-museum.com/showthread.php?t=111041

Looks like I should test and/or replace VR1 & VR2 on the Game Board; then test and/or replace VR352, VR353, & VR354 on the Monitor. However, nothing I tap on the game board causes the issue. If there's not a better guess from one of the astute folks here, I guess I'll look at the VR's on the monitor board. Any thoughts?
 
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Looks like I should test and/or replace VR1 & VR2 on the Game Board; then test and/or replace VR352, VR353, & VR354 on the Monitor. However, nothing I tap on the game board causes the issue. If there's not a better guess from one of the astute folks here, I guess I'll look at the VR's on the monitor board. Any thoughts?

replacing the pots on the monitor board should fix it. if you push on them and have your wife watch, push on them without adjusting the pot and you'll probably see the screen move. that should fix most of it.
 
replacing the pots on the monitor board should fix it. if you push on them and have your wife watch, push on them without adjusting the pot and you'll probably see the screen move. that should fix most of it.

Thanks! I'll try that test tonight. I was going to take "pot shots" at it next anyway.
 
Update

replacing the pots on the monitor board should fix it. if you push on them and have your wife watch, push on them without adjusting the pot and you'll probably see the screen move. that should fix most of it.

I tapped and pushed on the B+ pot and the screen suddenly became stable again. Now, I have to whack the machine hard to disturb the video.

Good call!

A new pot goes in tonight. While I'm at it, I'll put in a new B+ filter cap and touch up some more solder.

Thanks to you and the others here for the guidance!
 
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