B&K Precision 1655A - Manual - Manual (Page 38)

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No POWER ON Pilot Light
This symptom indicates either a fault in the primary power
circuit, or a tripped circuit breaker (Model 1655A) or blown fuse
(Model 1653A). The following checks should isolate the
problem.
1. Make sure the unit is plugged into a “live” outlet.
2. Reset the circuit breaker (Model 1655A) or check the rear
panel fuse and replace if burned out (Model 1653A).
3. If the circuit breaker or fuse is okay, verify whether there
is any output from the supply; select VOLTS function and
note meter reading on 0-150V scale. If output is
available, the pilot light bulb is probably defective. If no
output is noted, the trouble is probably an open in the
power transformer primary circuit. Check continuity of
the power cord, fuseholder, POWER ON switch, variable
auto-transformer, and the wiring interconnecting these
parts.
4. If circuit breaker does not trip again, or replacement fuse
does not burn out when unit is turned on, previous fault
may have been caused by an overload connected at the
ISOLATED OUTPUT.
5. If circuit breaker trips again, or replacement fuse burns
out, check for shorted variable auto-transformer or power
transformer.
No Output-Pilot Light Okay
1. If no output voltage is indicated on the front panel meter,
check voltage at ISOLATED OUTPUT with external ac
voltmeter.
2. If no voltage is measured on external meter, check rear
panel fuse (Model 1655A ) or internal fuse F2 (Model
1653A) and replace if burned out. If fuse is okay, check
brush of variable auto-transformer. Check for open
winding in isolation transformer or open current sensing
resistor.
3. If voltage is measured on external meter, but none is
indicated on front panel meter, see troubleshooting
procedure in next paragraph.
Incorrect or No VOLTS, AMPS, or LEAKAGE Meter Reading
1. Check meter reading in all three functions to further
isolate the fault.
2. For inaccuracy, perform calibration adjustments. If no
reading or inability to adjust to correct reading, a defective
component is indicated.
3. If trouble appears in more than one mode, check bridge
rectifier diodes, meter, and series resistors. If trouble is in
one mode only, check function switch and associated
metering resistors.
SOLDER TEMP Operation Abnormal (Model 1655A Only)
1. If no SOLDER TEMP pilot light, check internal fuse F1
and replace if burned out. If fuse is good, check voltage at
soldering iron outlet. If voltage at outlet is okay, pilot
lamp is defective.
2. If pilot light is okay, but no output voltage or incorrect
output voltage, check triac TR1, breakdown diode D1,
resistors R1, R2, and R3, capacitors C1, C2, and inductor
L1.
MAINTENANCE AND CALIBRATION