Reece 32

8. THREAD PICKUP CIRCUIT

GENERAL DESCRIPTION

The thread pickup sensor triggers a. timer on the prox. thread pickup board. Adjusting R105 (see below) on the board clockwise will increase the length of time the thread pickup fingers will stay down. Adjustment counterclockwise will decrease the amount of time. This P.C. board, through relay CRC, will send the table towards the rear during thread pickup finger extension. If a problem with the thread pickup operation is encountered, observe the sequence of operation and determine the area of probable cause using the troubles~ooting chart below.

The function of the thread pickup circuit is to operate the thread pickup fingets when·sewi~g stops but before the threa~ is trimmed. The thread pickup switch is momentarily actuated by overthrow of the clutch dog stop motion as soon as the stop solenoid is energized. When the pickup fingers operate, they pick up the ends of thre~d after each sewing cycle in readiness for the next sewing cycle. CIRCUIT DESCRIPTION The thread pickup solenoid is energized by 115 volts ac when· its circuit is completed through triac Q1. Triac ij1 conducts the 115 volts ac when 24 volts de is applied to its gate terminal. The table back solenoid is energized by 115 volts ac when its circuit is completed through relay CRC to ground. This sends the table back during thread pickup finger extension.

THREAD PICKUP TROUBLESHOOTING CHART

SYMPTOM

AREA OF PROBABLE CAUSE•

Thread pickup does not fire,

I . Main circuit board or connector.

I.

@ 2. SVI wl Interlock.· 3. Re I a t e d wI·r I ng . H. @ I • CRC relay or socket. 2. SV6. 3. Related wiring. © I. Proximity sensor.

Table goes back.

Table does not go back, Thread pickup fires OK.

2.

3.

Thread pickup does not fire, Table does not go back.

2. Prox thread pickup board. 3. Related wlrlna. • REFER TO THREAD.PICKUP OPERATION DIAGRAM - NEXT PAGE

.030

From the Library of Superior Sewing Machine & Supply LLC