Athena 3020 Series Manuale di istruzioni - Pagina 15

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Troubleshooting

Symptom

Controller dead. No output

light, no meter deflection

Probable Cause

- No line voltage input

- Open PC board to back-

plate connector (defec-

tive connector)

- Open power transformer

Symptom

No output, step 1 ok, meter

nulls at ambient

Probable Cause

- External backplate

jumper missing (all mod-

els except "S" and "F")

- Defective relay

- Open heater or heater cir-

cuit wiring

Symptom

No output, meter reads full

scale positive, no heat

Probable Cause

- Open thermocouple or

T/C wiring

Symptom

Full output, no control.

Ouput light stays on.

Probable Cause

- Thermocouple connec-

tions reversed

- T/C lead wires shorted

between T/C

and control

Symptom

Full output, no control.

Output light goes off. Meter

goes upscale.

Probable Cause

- Relay contacts welded

closed

Check

Verify 120/240 Vac, 50/60 Hz input voltage. Check

heater for shorts. Look for open breakers or open

external fuse. Remove input power. Check continuity

through power transformer primary. With ohmmeter,

read between pins: 8 and 9 for 225 or 450 ohms

+/-10% and 8 and 10 for 680 or 1000 ohms +/-10%

Corrective Action

- Replace heater, if shorted

- Restore power

- Replace either power transformer or backplate

connector

Check

If no readings in either step above, remove controller

from housing and repeat resistance measurements as

above, but directly on PC board lands corresponding

to pins 8, 9, and 10. Correct readings indicate open

PC board to backplate connector problem. Incorrect

readings indicate power transformer problems.

Visually inspect relay contacts.

Heater continuity and wiring.

Corrective Action

- Install jumper

- Replace relay if contacts are worn or dirty

- Replace open heater, correct defective wiring

Check

T/C continuity. Disconnect T/C connections from

instrument. Measure T/C circuit resistance. Ohmmeter

should read 100 ohms or less.

Corrective Action

- Replace T/C. Correct defective wiring

Check

Connection polarity. T/C wires are color-coded. Red is

the negative (-) lead. (for U.S.A.) T/C lead wiring.

Corrective Action

- Connect correctly

- Repair or replace

Check

Disconnect power and load. Measure resistance

between pins 12 and 13. Should read infinity.

Corrective Action

- If resistance reading is near 0 ohms, replace relay