In a spring-loaded junction box, the two sides follow different color codes: the indicator side follows the Digi-Star code, and the weigh-bar side follows the Weigh-Tronix code. Mixing them up is the most common wiring mistake. On a five-weigh-bar unit, one port is doubled to take the extra bar.
Weigh-Tronix — weigh-bar side
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+ Excitation: Green
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− Excitation: Black
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+ Signal: White
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− Signal: Red
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Ground: Bare / Orange
Digi-Star — indicator side
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+ Excitation: Red
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− Excitation: Black
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+ Signal: White
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− Signal: Green
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Ground: Bare / Orange
The catch: Weigh-Tronix uses green for +Excitation and red for −Signal, while Digi-Star uses red for +Excitation and green for −Signal. Black, white, and bare/orange are the same on both — that green/red flip is what catches people.
Process-of-elimination testing
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If you can, unbolt the junction box and lay it flat for easier access to the leads.
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Disconnect all but one of the weigh-bar / load-cell cables at the box.
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Zero the indicator and watch what happens after pressing zero.
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Work through the bars one at a time to find the faulty one.
Need parts or a hand? We build and repair junction boxes, summing boards, and bars for any brand — call 800-582-3175.
