Bubbles Ground Prong

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Surprise surprise, the ground prong is missing from the Bubbles that I bought a while ago. I replaced the plug with one that has the ground prong (as I did for all my other games that had no ground prong), and now Bubbles doesn't work at all. The LEDs don't light up, the marquee light doesn't come on, etc. Do I have to rewire something at the power brick, or should I go back to the plug that has no ground prong?

Shawn
 
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Check the continuity between the AC prongs and the ground pin at the plug. You may have accidentally shorted the wires when you replaced the plug or there may be a short to ground inside your cabinet.

ken
 
No continuity between the ground prong and either of the AC prongs.

There is power getting somewhere, I accidentally touched one of the wires on the switch at the back door and got a bit of a shock.

Any things I could check next?

I checked the voltages at the power brick. Not sure if it means anything, but the voltages were all very low, and all fluctuating a lot.
 
That may mean that the interlock switch (the white switch on the back door) is bad.

Backtrace the AC power lines coming in and verify that you are getting 120VAC on those two lugs of the interlock. If those are good, check the other lugs with the interlock pulled out to the on position, in the off position and pressed in to the on position and verify that the voltages are 120VAC, 0V and 120VAC.

If those are good, then unplug the machine and test the continuity between the interlock switch and where it plugs into the transformer to make sure there isn't a broken wire of intermittent connection.

ken
 
Well, if there wasn't something wrong with my interlock switch, there is now. I was testing the power at the lugs, and one of the lugs must have touched the metal housing (one of the clips that keeps it in place was broken, it has always been really loose). I saw a huge spark (frightened the be-Jesus out of me), and now there seems to be no power to any of the lugs.

Can I replace the interlock switch (if I can find one)? If I need to get an entire power transformer block (wiring and all) I might be able to find some used parts in the area from other Williams games, but which ones are compatible? Bubbles is not very common here but I always see a few Robotrons, Sinistars and Jousts around.

Any other suggestions?

Thanks in advance
Shawn
 
Now you need to check the fuses at the bottom of the cab.

The best thing for you to do at this point is to download the schematic for the game and follow the wiring from the AC plug through the fuses and interlocks to the power supply itself. You'll find something either bad or incorrectly wired.

Also, if you are trying this with the back door (and coin door if there are interlocks there too) open then you either need to hold the interlocks closed or set them in bypass mode (some will allow you to pull out on them to click them into place for that) to allow them to pass power through them.

RJ
 
I checked the voltages at the power brick. Not sure if it means anything, but the voltages were all very low, and all fluctuating a lot.

If you have an autoranging meter, it probably scaled down to the millivolt range. You will see those kinds of fluctuations based on random magnetic fields inducing current into the system.

As Channelmanic said, make sure the interlocks are pulled out. It sounds like you found the main one (the one that 'bit' you). That is a good place to start. Next check the continuity of the fuse (with the power plug pulled). Just because it looks good doesn't mean it is. Always meter fuses.

Because of the line filter, you can't just check for continuity from the plug to the transformer, but you can check from the plug to the line filter (the little silver box in the upper left hand corner of the power brick.

Also when you are checking things make sure to flip the power switch both ways. Operators sometimes flip the switches over when they reinstall them so up is not always on and down is not always off.

ken
 
Because of the line filter, you can't just check for continuity from the plug to the transformer, but you can check from the plug to the line filter (the little silver box in the upper left hand corner of the power brick.

You should be able to!

Line filters are just a filter coil with some caps that connect from there to ground. If you can't read continuity through a line filter then the coil has opened and the filter has gone bad.

RJ
 
I'll have to try it again. I've run into trouble in the past so I don't usually bother anymore. I usually measure from the plug to the input and from the output to the transformer (with the switches all on, of course ;) ).

ken
 
Fuse is definitely toast. What is the correct fuse to replace it with? I have the schematics (Drawing set and Instruction manual were included with the game), but I can't find that fuse on the diagram. I can see the 5 fuses that are on the power supply board, but can't find the one down on the transformer on the diagram.

In the notes it says "For 115 VAC 3A fuse and 130 V varsistor(??) are used." Is that the rating for the fuse I am looking for?

The last time I saw one of these diagrams was high school Physics, but those were a little simpler :)
 
It is a 3 A Slow Blow fuse. The transformer pulls a lot of startup current so don't use a standard 3 A fuse. You should be able to get replacement fuses at Radio Shack.

ken
 
OK, the power is much better. I now get the monitor, board etc to power up, but I still get the repeating rug pattern.

I tested the voltages at the power supply and get:

Pin 1 -5.02
Pin 3 11.87
Pin 4 -13.63
Pin 5 11.10
Pin 6 11.10
Pins 12-15 are all within the 5.00 to 5.02 range

When I test the voltages at one of the RAM chips I get -5.00, 12.71 and 4.71. I assume the 4.71 is the problem. Can I trace the 5.0V back until I find where it's losing voltage? There are lots of points in between where it could be lost, but how do I find out where?
 
So what can I check next? As I said, repeating rug pattern (restarts every 7 seconds or so), no sounds, all 3 LED lights are lit. Someone in another thread suggested reflowing the solder to the pins on the MPU or buying another MPU.

Thanks again,
Shawn
 
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Yeah I read somewhere in the schematics about how to increase/decrease the voltage.

I'll try that when I get home.
 
There is a 51K resistor on the power supply that can be used to bump the voltage. It is R10. I have found that if you rebuild the power supply, starting with the capacitors, it usually makes it unnecessary to remove R10.

ken
 
If you have a logic probe, place it on pin 37 of the CPU chip. It should stay HI. If it pulses at the end of the RAM test that means that something is interfering with the normal watchdog reset and the watchdog is resetting the CPU.

ken
 
This is strange.

I measure the voltages at the power supply board itself (with the connector off) and everything is fine.

I put the connector on, and the voltage at Pin 3 drops to 4.75 (from 14.12) and one of the 5V readings drops to 4.75 (Pin 14 I think)

Could that be a connector problem? I didn't replace the connector at the PS board because I don't have a molex connector that big. I guess I could use two smaller ones together.

Also, I don't have a logic probe, but if I thought it would help getting this thing back up and running, where would I get one?

Thanks again
Shawn
 
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