(Topic ID: 16772)

Gottlieb sys80b voltage nearly halved on lugs from primary xformer... Why?

By mystic

11 years ago


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  • Latest reply 11 years ago by mystic
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    #1 11 years ago

    6.3v = 3.43v
    27v = 18
    Etc

    These are readings from the primary transformer. Ideas? I've traced the problem back as far as I can.... Why would the voltages coming off the primary be nearly cut in half... Please don't say bad transformer as I won't stand for that answer. Thanks.

    #2 11 years ago

    More info. 120.5v from the wall. 120.5v at the aux plug in cabinet. Jumper are wired correctly for 110. What else is left other than the transformer?

    #4 11 years ago

    I believe that the transformer has primary taps for 100-120 or 220-240 VAC inputs. This is so it could be used in Europe as well. No need for a different transformer, just reconfigure the input to the transformer.
    You say it's set for 110 VAC. Did you double check for sure that it's not set for 220-240VAC? This would reduce the secondary , by half.
    Also are the outputs you are measuring center tapped? Are you measuring across the outs or referenced to Ground?

    What is the Pin you are working on?
    Do you have the manual or schematics?
    It should show the input Xformer configuration.

    #5 11 years ago

    It's already jumpered for 110.

    It's a system80b bonebusters. I have the full manual.

    Measuring voltage from tap to ground. Not sure what center-tapped means.

    #6 11 years ago

    Those would be the secondary windings (referring to OP's first post), not the primary. The primary is where your 120VAC connects.

    If all the secondary voltages are half, it definitely sounds like the transformer is jumpered for 220v on the primary. When set for 220V, the transformer has to half the primary voltage of 220 to 110 before reducing the voltages to the required secondary voltages (not really, it's all about winding ratios, but easiest to explain that way). If you are getting half of what you expect, then the transformer is halving your 110.

    Unfortunately all the sys80b manuals are locked down by Steve Young so I can't quickly look at the jumper diagram.

    EDIT: Pdman beat me to it

    #7 11 years ago

    Taking some picks for you guys. There is only one transformer.

    #8 11 years ago

    Because these are AC voltages, the voltages could be referenced line to line or line to ground. A Center tapped transformer, the center tap is usually tied to ground and that becomes the neutral. The voltage between a line and center tap is half the voltage from line to line. So depending on the transformer configuration and how the secondaries are wired, would dictate where you should be measuring your voltages. Can you post a pic of the manual for the transformer?

    #9 11 years ago

    Pics. You can see the jumper configuration on the schematic for 110v: Jumpers from 5-6, 9-10, and 8-12. Then you can see the picture where it's jumpered correctly. Pic of the schematic showing the one transformer. Pic of the transformer itself.

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    #10 11 years ago

    I see.. okay it's 6.3 when going across the winding. from 6.3 to 6.3 return. So apparently I'm an idiot and that transformer is good. So now I need to track down why I'm only getting 2.4 at the actual GI when I measure between the two wires attached to each socket..

    #11 11 years ago

    Have you checked all your fuses yet?

    #12 11 years ago

    Was the relay switch not making good contact. Fixed

    #13 11 years ago

    Thanks guys.

    #14 11 years ago

    Good job....That was an easy diagnostic

    Good call by pdman asking about the center tap...jogged my memory banks

    #15 11 years ago

    Love fixes like these. Good Luck with the Pin.

    #16 11 years ago

    Now on to a couple switch issues on the board and it's almost done. Stupid gi has been bugging me for a while.

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