Smash TV power problem, noob question

sandmanx

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I picked up a Smash TV last week and finally got around to replacing the severed AC power cord tonight. When I plug it in with everything plugged in, the monitor(K7000) comes on and I can see neck glow, but the switcher doesn't power up. If I unplug the monitor AC power, the game boots up and plays blind. I also checked the 5.9V line(from the isolation transformer to the coin door lights) and it's outputting around 6.3V with no load when I had the monitor on.

Since I'm still a noob at repairs, what should I be looking at for where the problem is? I checked the AC voltage at the switcher and it's around 134V, and it's the same at the monitor. I'm guessing it's a problem at the isolation transformer, but beyond that, I have no idea what to look for or where to troubleshoot next.
 
I did some more troubleshooting last night after I posted, and traced out the wiring, and everything looks like it's the same as the manual. I meant to say this is a dedicated Smash TV cab. The transformer is jumpered for 115V.

I didn't measure the voltage at the source, but I plan to do that when I get home later. It's output 132.6V to both the switcher and the monitor, and I did test to make sure they are isolated, but when the monitor is plugged in, the switcher doesn't power up, even though I measured the same voltage to the switching power supply when the monitor is plugged in, but the switcher doesn't start. I'm at a loss to why it doesn't start at this point.
 
The switching power supply is probably just dead. Very common on these games. I had to replace the switcher on my Smash TV as well.

Edit: I didn't realize you were able to get the game to play blind if the monitor wasn't plugged in - just saw that. Still, I'd suspect the power supply being flakey.

-Ian
 
in all likelihood, I don't understand what the AC has to do with it, but the power supply sounds like it's in shutdown.

if you're getting the same voltage on all the AC plugs/wires I wouldn't suspect AC's the cause... particularly if your K7000 isn't getting blown up. (meaning the iso works)

I'd replace the power supply, especially if it's original. this game's 21 years old now. lol
 
Check the main fuse. Sometimes there is corrosion or the clips are not tight and it will drop the voltage, but not blow. Longshot, but easy enough to test.

Also check the voltage at the power supply when both are plugged in and make sure it is putting out +5V to the board.

ken
 
Thanks for the feedback. I got home late last night and didn't get a chance to work on it, but I'll try some suggestions out as long as I can stand my hot garage tonight.

Yellowdog: When the monitor is plugged in, the power supply doesn't output on any rail, but the input was hot. I'll check it all again tonight and see if maybe it is some sort of voltage sag issue.
 
Thanks for the tip YellowDog, I turned the fuse around and now it powers ups and plays. Now I can get to cleaning the controls up!

Here is a quick video of it running now:
 
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Very cool. That's a game I've considered picking up. I've never tried it myself, but I hear those Mr. Clean magic erasers are good at cleaning control panels up.
 
holy shit, I didn't see the part where you got 134V. if it's still like that, it's definitely not going to be good for your monitor in the long term.

if it's still like that I would entertain replacing your iso, quick.
 
holy shit, I didn't see the part where you got 134V. if it's still like that, it's definitely not going to be good for your monitor in the long term.

if it's still like that I would entertain replacing your iso, quick.

I ran across another post where someone was getting the same output, so it didn't even cross my mind about how high that is. I'll check it tonight and see what it's output is at. The input from the wall is at 120V, so I wonder why the transformer is stepping the voltage up.

Edit: http://www.wellsgardner.com/pdf/Service/K7000.pdf The manual calls for 120V + 10%-15% on page 2 if I'm reading it right, which would be 132V-138V.
 
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