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variac and selector switch for easier access. Remove the A/D, I/O and the Controller
boards from the card cage.
1. Remove the AC Hot (black) wires from the PTT button and the footswitch. Connect
the black wire to K1:B common, K2:B common, and K2C common.
2. Connect a 20 gauge red wire to TB2 pin 1 on the Power Supply board and terminate
the other end to the footswitch pin 1,one end of the PTT button and one end of K1:A
coil.
3. Remove wiring from footswitch pin 2 (red) to the PT button to J1 pin 1 on the Zero
Start Interlock board to T2 pin 2.
4. Replace the wiring on the other end of the PTT button with a wht/grn wire and
connect to the footswitch pin 2 and also K2:A coil and an added 1N4936 cathode.
5. Connect the other end of K2:A coil to the 1N4936 anode and also to the ground
terminal block.
6. Connect a red 20 gauge wire from J1 pin 1 on the Zero Start Interlock board to K2:C
NO contact.
7. Connect a red 20-gauge wire from T2 pin 2 to K1:B NO and K1:A NO.
8. Connect a 26-gauge jumper on the rear of the I/O board from U6 to P1 pin 1A.
9. Remove top cover of card cage held by eight (8) M4 x 7mm black hex head screws
and two (2) M4 kep nuts.
10. Remove four (4) kep nuts securing the Motherboard to the back of the card cage and
solder a 26 gauge wire to the rear of the Motherboard J3 connector pin 1A. Run this
wire out of the card to a small breadboard containing a 4.7K ohm ¼ watt resistor and
a 2N2222 transistor. See schematic for electrical connection of this circuit. This
breadboard needs to be mounted on the side of the card cage by drilling one hole and
mounting with a nylon spacer and M4 hardware adjacent to the K2 relay.
11. Run a 20 gauge green wire from the 2N2222-transistor emitter and connect to the
ground terminal block.
12. Reassemble unit.
Z
S
ERO
TART
1. Check that the output control knob is completely adjusted counter-clockwise.
I
NTERLOCK DOES NOT ENGAGE
Baker Instrument Company
The Measure of Quality
18
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