HandTop HTA2500UV_K Stop Circuit Repair
A HandTop HTA2500UV_K flatbed printer would not run once the unloader was switched on. The screen was holding an UnloadError, and the machine had been down since the previous Saturday. The emergency-stop wiring was the suspected area. The buttons themselves were not the fault.
Inovance screen — UnloadError, with the unloader on, from the morning of the callout.
Stop circuit from X30
On this machine the stop loop leaves an Inovance H3U-3232MT at input X30. It goes to a terminal strip beside the PLC, out to the STOP2 button, back to that strip, out to the STOP1 button beside the electrical cabinet, and returns to the 0 V junction.
Both stop buttons tested correctly. Continuity from the PLC input to the adjacent terminal strip was intact. The run from that strip out to STOP2 was open.
Control cabinet — Inovance H3U-3232MT on the left, terminal strip beside it, servo drives along the bottom.
Wire TB7-26&U0-X30 on the PLC input terminals. This end of the stop circuit was continuous.
Broken conductor in the DB15
The stop conductors leave the cabinet through a DB15 mounted between the linear rail and the table. That plug carries other cables as well. At the plug, only one of the two connections expected from STOP2 was present.
The shell had been worked on before. The two stop-circuit wires showed an earlier repair, and some of the insulation around them was already damaged. One conductor was broken inside the connector.
Broken conductor in the DB15. The joint was resoldered and the plug put back.
After the joint was soldered
The stop loop was continuous again. Pressing either emergency stop still took the machine down.
The print gantry was off its towers when we arrived, so the printer was not run on this visit. Putting the gantry back was arranged for the next day, separately from the wiring repair.
The unload error was not a failed stop button, and it was not an open wire at the PLC. The break was in a connector out on the rail, on a circuit that had already been reworked once.
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