Service manual

Outputs:

NODE MEASUREMENT

A2U6-6

≈2 to 4Vdc sawtooth, 45KHz

A2U6-12,13

≈ 19V pk, 15µs pulses, 45KHz

A2Q3 (emit)

≈ 20V pk, 5µs pulses, 45KHz

A2U5 (OUT) 2.5 Vdc

A2R50, A2CR11 (anode)

≈ 0 >V > 0.007Vdc

A2R46, A2R47 2.5 Vdc

To check if load on + 5V is shorted, remove jumper A2W3

+15V On A2 Control Board. Voltage regulator A2U12 regulates the voltage across resistor A2R29 to be 1.25Vdc. That

sets the current through zener diode A2VR1 at 7.5mAdc. The output voltage is 1.25Vdc plus 11.7Vdc across A2VR1 plus

the voltage across A2R34.

Circuit Included. +15Vdc bias supply circuitry from connector pin A2P1-27 through test point A2J3-2 on A2 control

board.

Setup. The Main Troubleshooting Setup, Page 48. Apply the ac mains voltage to the isolation transformer, and set the

external supply to 0Vdc.

Input:

NODE MEASUREMENT SOURCE

A2U12(IN)

A2C17 (+)

≈ 24Vdc

A1U1, A1C1 (+)

Outputs:

NODE ( + ) NODE (-) MEASUREMENT

A2U12 (OUT) A2U12 (ADJ) l.25Vdc

A2U12 (cath.) A2U12 (anode) 11.7Vdc

A2VR1 (anode) A2R34, A2R33 2.05Vdc

A2LR3 (cath.) A2VR3 (anode) 6.2Vdc

To check if load on +15V is shorted, remove jumper A2W1.