Roadblasters voltage problem

Shavenyak

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My RB won't boot up. The board appears to be getting 4.5 volts on both the mother and daughter boards. The switcher in the machine is putting out 5.1 volts. The problem is the same when I switch out the regulator III with a known working one.

The regulator III board is showing 14 volts on the tab that is supposed to run around 10 volts. The known working one is running about 11 volts on the 10 volt tab in my working Indiana Jones. It jumps to 14 in the RB.

Is is time to switch out the two big blues in the bottom of the cab? They're both 27,000mfd which is too big to test with my meter. If it's not one of the big blues, what else could it be??? Thanks!
 
I didn't think system 1 used 10v, I thought it was 15v. I'm pretty sure it is used for audio, so the tolerance is pretty big. I've used 12v from a switching PS.


The +5v being 4.5 is a problem.

Possible solutions:
1. adjust the power supply up so you get 5.1 on the PCB
2. troubleshoot the connectors / harness (bad connections at the pins cause voltage drops)
3. Try powering up the game with the RB cart removed and check the voltages. This won't fix anything, but if the voltage is higher, it would suggest a problem on the RB cart.
4. Try swapping in a difference mother board or cart. It's possible that something is messed up on one of the boards and causing the voltage drop
 
So how does one know when it's time to replace big blue? I don't think most multimeters will test a cap that large. I know mine won't.
 
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