Amada Miyachi Unitek STA-100A, Operation Manual, Page: 72 / 154

CHAPTER 5: MAINTENANCE
STA SERIES AC CONTROLS
5-8 990-351
1 Disconnect the blue wire from the SCR and the black wire from copper bus bar L1.
2 Loosen the clamp screw that secures the snubber and remove it.
3 Install or re-install the snubber by slipping it into the clamp and tightening the clamp screw.
4 Reconnect the black wire to copper bus bar L1 and the blue wire to the SCR.
SCR Drive Board
1 To replace the SCR Drive
Board, disconnect the
following cable connectors
from the indicated headers
on the circuit:

Six-wire cable (ten-pin
connector) from the
SCR connected to J2.

Eight-wire cable
connector from AC
Timer Main Board or
Cascade Board to J1.
SCR Drive Board Connector Locations
4 Remove the four 6-32x3/8 Phillips head screws, spring lock washers, and flat washers that
secure the circuit board to the Control and remove the board.
5 Install or re-install the circuit board with the four 6-32x3/8 socket head screws, spring lock
washers, and flat washers, being careful not to over-tighten the screws and damage the circuit
board.
6 Reconnect the following cable connectors to the indicated headers on the circuit board:

Six-wire cable (ten pin connector) from the SCR to J2.

Eight-wire cable from AC Timer Main Board to J1 or Cascade Board.
J1
TO
CASCADE
BOARD OR
AC MAIN
BOARD
J 15
To
SCR
J2