User's Manual

Circuits Included.

Constant Current (CC) Circuit on A2 control board.

Setup. The Main Troubleshooting Setup, page 33, except connect the external supply with polarity reversed to the unit's +

OUT ( - ) and - OUT ( + ) terminals. Apply the ac mains voltage to the isolation transformer. Set the external supply to

3.0Adc constant current with a voltage limit in the range 5 to 20Vdc. Set mode switches B1, B2 and B3 to 0. Set IP to 0Vdc

by connecting to

P or set IP to + 5Vdc by connecting to A2J7-24 according to SETUP below.

Outputs:

NODE ( + ) NODE ( - ) SETUP MEASUREMENT

IM A2J7-4 IP = 5 (6015A) 0.125Vdc (0.88Vdc, 6015A)

A2U4-8 A2J7-4 IP = 0 -14Vdc

A2U4-8 A2J7-4 IP = 5 +14Vdc

If the failure symptoms include output current oscillation, check if the differentiator circuit is at fault by removing resistor

A2R35 ( 1M ohm) (3.3M ohm, 6011A). If oscillations stop, the differentiator is probably at fault.

Troubleshooting OVP Circuit

Flip-flop A2U8A-A2U8D is set by comparator A2U8C and reset by PCLR . TTL low at A2U18-12 inhibits the PWM.

OVP Program Voltage on A2J7-7 is equal to Eout/10.

Circuit included. OVP Circuit and 2.5V bias supply on A2 control board.

Setup. The Main Troubleshooting Setup, page 33, except connect the external supply to the unit's + OUT ( + ) and - OUT

( - ) terminals. Apply the ac mains voltage to the isolation transformer. Adjust the unit's OVP limit to 10Vdc. Set the

external supply (EXTERNAL) as instructed below.

Outputs:

NODE ( - ) = A2J7-4

NODE ( + ) SET VOLTAGE

EXTERNAL (Vdc)

SETUP MEASUREMENT

A2U7-2 - 2.5Vdc

A2J7-7 - 1.0Vdc

≈2.2Vdc (6015A)*

A2J7-13 5 hi

A2J7-13 15 lo

A2J7-13 5 lo

A2J7-13 5 cycle power hi

* Front panel OVP control turned fully cw.

Note Connecting a test probe to either input of either comparator in the OV Flip flop (pins A2U8-1, 6, 7, 10, 11

or 13) may cause the flip flop to change states and cause the probed input to be low.