(Topic ID: 175785)

testing a transformer

By mark532011

7 years ago



Topic Stats

  • 4 posts
  • 2 Pinsiders participating
  • Latest reply 7 years ago by Billc479
  • No one calls this topic a favorite

You

Linked Games

Topic Gallery

View topic image gallery

IMG_2039 (resized).JPG

#1 7 years ago

I have an old United Brazil and I have started trying to debug what is wrong. The GI lights come on but nothing else.

I am trying to test the transformer power to see if it is working correctly and I am not getting what I expect but I don't know enough to know if its just me doing it wrong.

According to the schematic, From common to one side should be 50v and common to the other side should be 6v. https://bingo.cdyn.com/machines/united/brazil/resources/schem-brazil.png

When I put the tester on the 50v side I am getting nothing.
A couple of basic questions:
1) is that the right way to test it? there are 8 places where wires plug into the transformer (5 on the front, 3 on the back).
2) do I need to disconnect everything to check for output or can it be done all wired up like that?
IMG_2039 (resized).JPGIMG_2039 (resized).JPG

#2 7 years ago

With the machine unplugged, check the resistance of the transformer secondary (50 Volt) at the lugs on the transformer. I did not see tap numbers on the transformer, so you will have to follow the schematic to make sure you get on the right lugs. Just to be comfortable, read the resistance of the 6 volt winding, and the primary winding. (115volt)

I would expect low resistance on each of the windings, but not zero.

#3 7 years ago

I have retested and things looks better. I am getting 50 volts on the one side and 6 volts on the other.

However,

When checking the voltages at the fuses. There is a handy little paper sheet under the fuses which says what voltage it is at. Every one (110v, 50v, 6v, etc.) is correct - except one, it says it should be 17.5v and I am measuring 73v. Seems weird that the fuse doesn't blow, but it seems to be OK.

Is that something that would happen because of a short? I wouldn't think so, I am guessing I still may have a transformer problem.

#4 7 years ago

I am guessing this is a bingo machine, something I have never dealt with. Regardless, check the voltage (AC) across the open switch of either 1,2,10, 13,14,17,19,20,21, or 22. You should be seeing the 17VAC. I don't see how you could get 73 VAC unless you're reading across the entire secondary, which means you have the wrong ground reference for that test point. (50 + 6 + 17 = 73) If you're seeing that, then I am guessing your transformer is OK and you are having difficulties with your test points. Good Luck

Reply

Wanna join the discussion? Please sign in to reply to this topic.

Hey there! Welcome to Pinside!

Donate to Pinside

Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!


This page was printed from https://pinside.com/pinball/forum/topic/testing-a-transformer and we tried optimising it for printing. Some page elements may have been deliberately hidden.

Scan the QR code on the left to jump to the URL this document was printed from.