So, AC power from the transformer comes in on J102, pins 1 and 2 to 3 and 4.

With heavy current draw, these pins could be tarnished/compromised, so pull the J102 plug and examine the pins. I replace pins and plugs on this connector frequently.

It goes without saying to check fuse F111.

Then it goes to BR4.

Output from BR4 goes to C11 and goes to the big power resistor next to the fuses. R224, 0.12 ohms 10W. This could be open.

This is what supplies the Red/white wires on J106 and J107... which go to the dual H motor assembly, etc.

So, I'm a little confused, you say that BR4 tested fine... but you can't test the .12 ohm resistor?

Do you have a meter?

If you have a meter, put the red probe on the wire coming out of the top of the resistor, the black wire on the wire coming out of the bottom of the resistor. Set your meter range to either beep, or the lowest range of Ohms.

At .12 ohms, this is pretty much going to test like a piece of wire. If you have a beep test, it will beep if it's good. If you are using your lowest range of Ohms, it will test as a very low number, almost the same number you'd get as if you just put your red probe on your black probe.

Instead of a fuse, for this voltage Williams has this big resistor, which in worst case will act as a fuse (open up and not conduct electricity when blown).

So when it fails, it won't register anything on the meter.

Another test... if you aren't supplying this voltage, none of your flash lamps will work, so put your pinball in test 10 (lamps and flashers), and if no flash bulbs flicker, the board probably isn't providing power. (Which is what I suspect.)

Of course, if you have a meter, just test for 23V (more or less) on pin 6 of J107.

Let us know what you find!

Oh yeah, the testing you did all looks good!

So what is going on?

Well, now we need to do a power on test, so put your board in the machine.

I know there are a lot of connectors on this board, but go ahead and plug them all in.

In particular, make sure the 4 smaller connectors in the lower left corner are all plugged in, it's easy to miss these!

Also, J107 and J106, make sure they are plugged in.

The racetrack and the engine are the problem, so when something doesn't work at all, the first thing I think about is power.

Just in case, set your meter to AC Voltage, in the range to allow you to read about 20 Volts AC (different than DC voltage!), and look on the top right corner of the Power Driver board. J102 probably has some White-Red wires coming in on pins 1 and 2, and also on 3 and 4.

AC voltage isn't measured the same as DC voltage, usually you can find a 'ground strap' or a 'ground plate' and put your black meter lead on that to measure a voltage with your red meter lead. For AC you need to pay attention to putting your meter leads on both sides of the AC circuit, in this case I put my black meter lead to pin three (3rd pin down from the top), and the red meter lead on pin 1, and try to wiggle my probes until they get a good connection on the little bits of metal in the top of the IDC (Insulation Displacement Connector).

I should read about 17.5 V AC here. If you aren't getting power IN here, you won't get power OUT of the board, so if you aren't getting AC Voltage here, we need to look at Transformer plugs, and possibly Interlock switch on the front door.

Both the Motor Driver board (for the race on the left side) and the Motor Driver Master PCB/Slave Board get power from J107 pin 6, the red/white wire on the far right of that connector.

We've been looking to see if the board is providing power here, and that's what we need to test.

So, with everything plugged in, turn the machine on, and with the meter set on a DC Volts range that would read 23V DC, I put the black meter lead to either a screw head, or just firmly to the metal backbox, or down at the bottom of the box I shove the black probe under the ground strap. I put the red meter lead on pin 6 of J107, which is the far right pin with the red/white wire.

It should read more or less 23V if the board is supplying voltage.

These boards also get 5V from one of the three connectors in the lower left corner, J116, J117, and J118. All three of these are identical, so some previous tech might have plugged any of the three plugs into any of the three jacks. I make sure I have +5v DC and +12V DC on these plugs. I really don't suspect problems with this voltage because if the Opto boards aren't getting good +12V and +5V from these plugs the game will give you all kinds of error messages, and you haven't told us about any problems with that.

Presuming that you have +23V (approximately) on J107 pin 6, and +5v and +12v on J116 (J117, J118), we know the board can supply power. The next question is to find out if the boards under the playfield are getting power.

Do they have LED indicators? Are those indicators on?

If you take your black meter lead and shove it under a ground strap, and use the red meter lead on J2 Pin 1 of the Motor Driver Master board, or the Slave board, or the Dual - H - Drive Motor Controller board, do you measure your 23V? (Interestingly, all three of these boards get the +20V power on J2 pin 1 for each board!)

Finally, after we make sure that we have power everywhere, we can start troubleshooting other things that cause this!

The replacement cap is perfect. I doubt the original was faulty and it is very unlikely to have been 'smoking'.

More than likely you have pulled out the 'vias' on the PCB when replacing this cap - it's a super common issue.

Get your meter out and confirm continuity top to bottom of the PCB tracks in question.

Read all about this and many other helpful tips at PinWiki or send the board out for professional repair.

1.5k= 1500

depending on your meter assuming it was reading Kohms you got 1.206=1206.

How is that higher?

Did you do what pins4u suggested with the capacitor mounting test?

Yes, EXACTLY as I suspected.

I think, if you are serious about pinball repairs in the future, you really should learn how to use your multimeter CORRECTLY - and - MORE THAN THAT - UNDERSTAND what it is telling you when you make measurements.

By telling us that you thought a meter reading of "1.206" was higher than 1K5 tells me you need to study up. While I'm commenting, UNDERSTANDING what the meter is telling you is important - in this case you could have 100% ignored the last two digits displayed and read the meter as "1.2".

Same as measuring voltages - in almost every case in pinball repair you can ignore the last digits. IE: A meter reading on the 5 volt supply reads 5.275 - this should be interpreted as 5.2 or 5.3 - YOU need to understand things like this AND work out if a reading of 5.2V is OK in the circumstance you are measuring.

Whoot!

Good catch!

Now that you are an expert in Pinball board repair, can I send my bad boards to you? (Hehe)

Such a good feeling when you solve a tough problem and things are back running.

Congratulations!