Weigh-Tronix 660 Indicator — Service Guide (Install, Operation, Calibration & Troubleshooting)

The Weigh-Tronix 660 is a rugged, battery-capable digital weight indicator for animal weighing, single-platform scales, and portable load-bar setups. It reads directly from analog weigh bars and is the heart of many chute, alley, and platform systems. Its motion-averaging logic locks a stable reading once an animal settles, and Bluetooth-equipped units can read, log, and calibrate from a phone or tablet.

Keypad

• ON/OFF (↵) — power; also Enter inside menus (left side).

• HOLD / MENU — hold a reading; press and hold to enter the menu; acts as ESC (right side).

• TARE (▲) — capture a tare to subtract; scroll up in menus.

• G/N (▼) — toggle Gross/Net; scroll down.

• ZERO — re-zero the empty platform.

• PRINT (◀) — send a print/output record; move left.

• M+/RM (▶) — add to / recall the accumulator total; move right.

Installation & wiring

Most field problems trace to wiring and grounding, not the indicator. In order:

1. Mount where the operator can read it and the cable is protected from gates and hooves; keep it out of washdown spray.

2. Route the weigh-bar signal cable away from AC power, VFDs, and gate motors — parallel runs cause unstable readings.

3. Land the bridge: +EXC, −EXC, +SIG, −SIG, and shield per the terminal labels. Through a J-box, confirm each bar lands on the matching color/leg.

4. Ground the shield at one point only (the indicator end) — never both ends, or you'll create a ground loop.

5. Power up, warm a few minutes, and confirm a stable, non-drifting zero with the platform empty.

Four bars through a J-box with an open or reversed signal leg reads as wandering weight or a wildly wrong span — ohm each bar leg at the box (see the weigh-bar troubleshooting values) before chasing the indicator.

Daily operation

• Zero before each session: clear mud/manure/snow off the platform, then press ZERO. Buildup is the most common reason a herd seems to "gain weight."

• Animal weighing: the 660 locks a weight once motion settles; HOLD/MENU freezes it so you can record it. If it never locks, the averaging window may be too tight — loosen it slightly in configuration.

• Gross / Tare / Net: G/N toggles the basis; TARE captures a container/empty weight; Net = Gross − Tare.

• Totals & print: M+/RM adds to the accumulator and recalls the TOTAL; PRINT outputs a record.

Calibration

Calibrate after any install, bar replacement, or when readings drift from check weights. Use certified test weights.

1. Confirm a clean, stable zero. If zero won't hold, fix that first — calibrating on an unstable zero bakes in the error.

2. Enter calibration mode (keypad sequence or the Bluetooth app) and capture the zero / dead-load reference.

3. Apply a known span weight — ideally near your working capacity — and enter that exact value.

4. Save and exit; power-cycle to confirm it stuck.

5. Verify at a low, middle, and high weight (linearity shows up as good-at-one, off-at-another).

Tip: span near the weight you actually use — a chute weighing 1,200 lb animals should be calibrated up near that range, not at 50 lb.

Bluetooth

Bluetooth-equipped 660s pair to a phone/tablet to mirror the live weight, log weights, and drive calibration without standing at the keypad. Make sure the app is updated and the unit is powered; re-pair if it doesn't appear.

Troubleshooting quick hits

• Unstable / wandering weight: cable routed near power, moisture in a connector, or a bad bar leg — check wiring/grounding and ohm the bars first.

• Won't hold zero: platform buildup or an unstable bar — clean and re-zero before anything else.

• Won't lock on an animal: loosen the motion-averaging window.

Need a hand or a repair? Call Central City Scale at 800-582-3175.