Any pics?

This is a long shot, but I think I remember Ed from GPE saying some did that to reduce the voltage on the dc due to the voltage drop across the diodes. The thread was within the last year, but I couldn’t find it.

I haven't seen that one before. Hopefully someone can help you out. Hopefully it betters the machine some how. Interesting

Maybe to lower the DC voltage because where the game was located the line voltage was significantly above 117v? Since you can high tap it if the line voltage is too far below 117 but as far as I could see there isn't a 'low tap' if it's too high?
I saw someone mention "I added the additional bridge rectifiers as per Vid's guide' regarding a System 6 but I couldn't find it in the guide either, maybe they were actually talking about adding the extra fuses or something else.

vid1900 definitely said we were supposed to curse the previous owner when we have to desolder the spade leads on bridge rectifiers to add fuses to the AC power lines

Another system 6 in here had a third bridge rectifier added, it was surmised it *may* have been to rectify the GI to make the lamps dimmer and last longer. But can't really see the entire new circuit from the pics for that one or this one here. Might be different purposes for a third one.

Is something broken or not working? I live by the “if it ain’t broke, don’t fix it motto”

Yeah the yellow-green wire from the extra BR goes to the GI fuse.

that 3rd bridge rectifier is purely to drop a couple of volts from the supply for your general illumination.

it is not acting as a rectifier at all and staying AC.

up to you, but you could safely remove the yellow wire from the negative of the bridge and attach it back to lower terminal of the fuse holder where the yellow/green wire is that comes from the lower lug, the AC input on the bridge.

Agree. The way that is wired, you have 2 diodes pointing in alternate directions inline with the AC transformer. Each diode pair removes their Forward Voltage of about .7 volts for a typical rectifier diode on each swing of the AC cycle for a total of 1.4V removed from the 6V GI circuit.

If what MrBally said is right and it was a service bulletin, I suspect Williams had a batch of transformers that were wound incorrectly and creates too much voltage on the GI winding.

Alternative theory could be that someone wanted to hi-tap the transformer to spice up the coils and needed to reduce the GI voltage to stop bulbs from blowing. This can be confirmed by checking which terminals are connected on the transformer.

In either case, removing that rectifier will only serve to burn out your GI bulbs faster.

You could try measuring the GI voltage and confirm it is actually low with the rectifier in place.

Stock is 6.3V AC. With the rectifier in there, you should be seeing around 4.9V. If that the case, you could safely remove it.

Meter on AC. One lead on the junction terminal to the left of the row of fuses and the other lead on the left-most fuse.

I may have misread your post, and it's not a criticism, just an observation, but to check the AC voltage prior to bridge, wouldn't you remove the fast blow GI fuse and put one lead on the yellow wire where it joins the negative on the bridge and the other lead on the other yellow wire from the transformer at the far left junction tag?

and to measure the reduced voltage swap the multi meter lead from the bridge to the bottom of the fuse holder where the green/yellow wire is?

please correct me where i'm wrong as I'm always learning.

Yes, if you want to measure the voltage before the bridge (raw transformer output) you would put one lead on the far left junction and the other on the + and - terminals of the bridge (where the other transformer wire leads).

To measure after the bridge, you would have one lead on the far left junction terminal and the other on the left fuse with it in place.

Both measurements taken with the fuse in place. This way you measure the loaded voltage (the circuit is loaded by the strings of GI bulbs) which is an accurate representation of what the bulbs are seeing. If you remove the fuse, the GI bulbs are not connected and you will be measuring the open circuit voltage which will always be higher than the loaded and may not tell the true story.

4.9vac would be presuming the transformer was outputting 6.3vac and somebody wanted to bring it down. Its likely your GI circuit without the diodes would be 7.7vac and too high for the bulbs - which is why this was done in the first place.

6.1vac is perfectly fine for general illumination and I would just leave this circuit alone

Also, Schwaggs is a better tech than me so if he tells you different then ignore my advice completely

That confirms that your transformer is outputting too much voltage (7.0 when it should be 6.3). Boscokid is correct in that the 4.9 reading is what I would expect if your transformer was outputting normal voltage of 6.3. Not sure why it's reading 6.1 instead of 7.0-1.4=5.6v. It might have to do with the quality of your meter (AC is tricky to measure and is varies from meter to meter and brand to brand).

Can you check which terminals are connected on your transformer? Are there wires on terminals 3 or 4? How about 7 or 8?

4 and 8 are the typical 117V connection. 3 and 7 are the "hi tap" connection for areas with low voltage around 105V

Thanks!

That is not it. That transformer is wired for normal line conditions (not hi-tapped).