Lamp socket shorted?

G.I. wires connected to the correct socket terminals?

Staple shorting a wire somewhere?

You are correct, the lamp socket orientation doesn’t matter.

But often times the AC power wires are connected at both ends of a string of lamps. Let’s say they are a red and a white wire. You have two separate wire braids running from socket to socket, correct?

If you connect the red wire to one end of one braid and the white wire to the other end of the same braid it will be a short.

With all of the bulbs removed, test continuity across the lamp sockets. You will easily identify the shorted string.

Measure continuity across the sockets from braid to braid. One of those strings has to be shorted.

What about the lamp sockets in the bumpers ? Any of those touching the coil mounting bracket?

Do you still measure a short when you disconnect the playfield from the rectifier board?

Note: one G.I. wire is connected to ground at the rectifier board, the other G.I. wire connects to the transformer on a very very low resistance winding. The "short" you are now measuring might just be through the transformer G.I. winding which is normal.

So disconnect the playfield J1 connector off the rectifier board and remeasure for short circuits across the playfield lamp socket quadrants (presuming you've separated the quadrants from each other).

To add to what Quench said:

Looking at your pics above, with the playfield disconnected, put one ohmmeter lead on the orange wire and the other on the blue wire and see if you have a short.

Then put one lead on the red wire and the other on the white wire and check for a short.

Repeat for the other two quadrants.

Follow these instructions and you will be able to narrow it down. I had the same problem with my Fireball II swap and this helped me figure it out.

I had 2 of the braided ground wires stapled together that were supposed to be separate from each other, so maybe look for that. Hope this helps

Copied from fliperwinkle

Fuse F5 - General Illumination (G.I.) Fuse Woes.
There isn't much to this circuit, so if fuse F5 blows, this usually means there is a shorted general illumination bulb or socket. This is never a quick or easy fix - you'll have to do quite a bit of looking and eliminating to find the problem.

First, a good idea is to purchase a clip-on circuit breaker. Instead of replacing the F5 fuse for each test "power on", the circuit breaker can be reset and reused. This is great for G.I. problems and saves lots of money on fuses. Just clip the breaker onto the rectifier board's fuse clips with alligator test leads. A mini circuit breaker can be purchased from any lighting store.

To issolate the G.I. problems:

Remove connector J1 (playfield) and J3 (backbox) from the rectifier board, leaving J2 (cabinet wiring) connected. Power up. If fuse blows, there is a short in the main cabinet G.I. wiring (probably the coin door lamps).
If fuse doesn't blow, remove connector J1 (playfield) from rectifier board, leaving J2 (cabinet) and J3 (backbox) connected. Power up. If fuse blows, there is a short in the backbox GI wiring.
If fuse doesn't blow, remove connector J3 (backbox) from rectifier board, leaving J2 (cabinet) and J1 (playfield) connected. Power up. If fuse blows, there is a short in the playfield GI wiring.
Each time plug J1/J2/J3 is removed, that part of the G.I. circuit is removed. What ever plugs are left connected are the wiring sections being tested. If the short is in the cabinet wiring, this is easy to fix. Just examine the coin door lamps. If the backbox wiring is the problem, this too is fairly easy to examine. A very common problem here is the ground braid that connects the head to the backbox. This can bunch up and touch one of the lamp sockets on the back side of the insert (display) panel (when the insert panel is closed). Unfortunately the playfield G.I. is the most troublesome section.

Now that the offending section (playfield!) has been isolated, it is time to further isolate which strand of lamps has the problem. There are two G.I. lines in the game- red/white wires, and orange/green wires. Now find a strand (either one), and de-solder one of the lead wires to the strand (thus taking the strand out of circuit). If there is a double wire (double green, orange, red, white) on the strand, be sure to keep the double wire connected together once it's removed from the strand. This lets other strands "downstream" continue to have power. The basic idea is to disconnect a strand, power up, watch the fuse (or breaker), and repeat until you find the offending strand.

It's never easy or quick to find a problem like this, but this is about the only way to systematically find the short without pulling out every bulb or looking at every socket/wire.

I had the identical issue when I did a playfield swap on a Playboy machine. If I plugged in J1 or J3 the fuse would blow. The resistance between TP4 and ground was 0 ohms even with the blown fuse (only when J1 or J3 were connected). What I found was that I had incorrectly connected (crossed) the GI Bus and GI Return lines on both the backbox and the playfield. Once I modified the connections so the Green wire was on the same line as the White wire, and the Red wire was on the same line as the Orange wire, everything worked fine. The reading was about 3 ohms between the lines with no bulbs installed, and the fuse didn't blow.

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off topic, but where did you get those staples for the braid?

what brand gun is it if you don't mind me asking?

i like the narrow head as opposed to the original ones.

It's a DeWalt DWFP1838 pneumatic stapler using 1/2" 18 gauge narrow crown staples.

Thanks

You Sir are a lifesaver! Thats exactly what was killing my F5. I had the red and white wires reversed. Switched them and all is well