Gottlieb System 80 abnormal voltages

[Pauly540]

After some reminders from @Boots to try a stepdown transformer first and some links for cheap ones from ebay, Low and behold everything is now working correctly. 

You’re a legend, kind Sir! This problem was starting to drive me mental.

It’s a 300W version and seems to hold up well, even during multi-ball, so can’t go wrong for $35 delivered!
I will put it in the base of the machine, once I tidy up/re-cable tie the bottom panel loom that I ripped apart in desperation.



All of my weird readings have now completely vanished. Uncontrolled solenoids have exactly 38VDC, GI doesn't flicker when solenoids fire and have a perfect 12VDC to my A2 PSU.

Lesson learnt. If it has US transformers, install a stepdown.

Now I can spend some enjoyment time, playing my Volcano, the way it is supposed to play. 

[DSB]

  Glad to hear it is working and that is probably the simplest fix on a machine designed for 110 volts. Its interesting the schematic says you can wire the TX's in series for 240 volt operation yet your machine would not cope with it but other machines seem to? I would love to hear from an expert on why you were getting the strange voltages as this would also frustrate the hell out me. Why, why, why!!!!???

[Pauly540]

Glad to hear it is working and that is probably the simplest fix on a machine designed for 110 volts. Its interesting the schematic says you can wire the TX's in series for 240 volt operation yet your machine would not cope with it but other machines seem to? I would love to hear from an expert on why you were getting the strange voltages as this would also frustrate the hell out me. Why, why, why!!!!???

Interesting you bring that up.
I had been discussing this with my father (in the UK) who was an electronics engineer back in the 70’s.
When I told him about these US transformers wired in series, he almost disowned me! Started going into a rant with mathematical equations and I will admit, I tend to switch off and feel sorry for myself asking a stupid question of him. (We don’t get along to well). He was adamant that this form of set-up is a No No.

I will let him know that the stepdown did the trick, as he and Boots suggested in the first place.

It must have something to do with the only un-regulated 6.3VAC tap affecting the other regulated DC outputs? No, that still doesn't make any sense! How can voltages jump from one winding to another?
Maybe I have flaky transformers that will not tolerate the series wiring, or maybe others have not noticed (measured) outputs with an increase in solenoid power?
Would also be interested in hearing an expert opinion.

[goodolddays]

Great to hear you finally have it sorted and with a simple solution !

[Retropin]

Just be aware that those transformers are not isolated... if you look inside you'll see that the Neutral from 240V is also being used as the 110V neutral. A power surge/spike from mains will go into the machine if it occurs.

[Pauly540]

Thought I’d share my father’s email reply to the news that a stepdown fixed the issue.
All I got back was:

“You had got onto a wrong track and kept plodding on to a nothing answer.”

“What goes on in your Cowboy Country I know not, but simple Ohms Laws and expansions from them are without question the foundations of Electricity theory.”

Take it he’s not a fan of wiring transformers in series then. 

[DSB]

Take it he’s not a fan of wiring transformers in series then

I guess not. Well.... we are upside down and all but convicts.    Really though, we didn't design the series set up, its drawn as an option in the schematics........

[Boots]

Really though, we didn't design the series set up, its drawn as an option in the schematics........

Not really, if you read the full schematic the 230V wiring applies to the 230V transformers that are listed in schematics.
The picture is of one transformer with multiple wirings not two transformers.

[DSB]

Well spotted! Reading was never my strong point. 

[DSB]

And looking closely at that drawing the transformer is actually drawn as 1.