G07 input voltage - How much is too much?

TheYeti

Well-known member
Joined
Sep 3, 2015
Messages
5,698
Reaction score
5,326
Location
Centennial, Colorado
I've been reading a few threads about isolation transformers outputting "higher than expected" voltages and the opinions on this topic seem to be mixed. Hoping the monitor experts here can help.

I just finished wiring up a power supply that will be power for a jamma cabinet. (Formerly an empty super-pac cocktail). Before connecting my G07 monitor, I obviously wanted to check what voltages the isolation transformer was outputting.

To my surprise, the isolation transformer it outputting 129VAC. (Without load, of course. Not sure if that makes any difference)

I checked my wall outlet and it's outputting 122.4VAC.

Now, I understand that a G07's input voltage is rated between 108VAC and 132VAC. So technically speaking it falls within the tolerance. However, 129VAC seems a bit high. Not sure why my transformer would be stepping up the voltage that much.

So is this transformer safe to use on a G07? From what I have been reading, it sounds like it would be fine in the sort-term, but in the long-run it could put stress on the G07 and components could fail faster?

What would you do?

Isolation transformer output voltage
1760372218299.jpeg

Wall outlet voltage
1760372242187.jpeg

Power supply
1760372265795.jpeg

Isolation Transformer
1760372292055.jpeg
 
Part of the reason it might be higher is because there is no load on the transformer.
I was wondering the same thing so I tested a different isolation transformer that I use on my on my test bench rig (a very similar model) and that one tested about 122VAC without load.

So obviously not all isolation transformers are the same and one should expected all sorts of variances.

Would it be stupid if I used the 105V input lug on the transformer to bump the output voltage down? Is this just a waste of my time and I'm overthinking this?
 
Would it be stupid if I used the 105V input lug on the transformer to bump the output voltage down? Is this just a waste of my time and I'm overthinking this?
You have that backwards. If you want to lower the voltage, you would want to use the 125V lug. Those lugs are intended for what your input voltage is. If you use the 105V lug, the output voltage would likely be higher.
 
You have that backwards. If you want to lower the voltage, you would want to use the 125V lug. Those lugs are intended for what your input voltage is. If you use the 105V lug, the output voltage would likely be higher.
Oh wow....thank you for clarifying that for me. Those other input lugs have always been a little confusing to me.

Ok, cool...thanks guys. Sounds like this is normal and probably shouldn't be an issue.
 
the old Williams games run everything at 130V on the secondary side. alas, this is what voltage regulators are for. but I wonder if that's the reason those things kind of go through marquee lights like popcorn. I tried changing the jumpers to lower the output voltage years ago and that just made the transformers run very hot for some reason.

so there's a lot of games out there in the world running monitors with 130V.
 
Back
Top Bottom