Heathkit IB-5281 - Troubleshooting

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Precautions for Bench Testing
e Test transistors carefully. Although they
have aimost unlimited life when used prop-
erly, they are much more vulnerable to dam-
age from excessive voltage and current than
other circuit components.
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o
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p
@
@ jon] a
ground when you make voltage mea-
amente Tf th i am
surements. if tne probe slips, for example,
Donot remove any components from the circuit board
while the RLC Bridge is turned on.
When you make repairs tothe RLC Bridge, make sure
you eliminate the cause as well as the effect of the
trouble. If, for example, you find a damaged resistor,
make sure you find out what (wiring
caused the resistor to become damaged. If the cause is
error, etc.)
eliminated the
not eliminated, te © replacement r resistor mey become
damaged when the Bridge is put back into operation.
Refer to the “X-Ray V Views, ” “Identification Charts,’
and the “Schematic Diagram” to locate the various
Ese 8 | OL iia tO HOldte Lie call
components.
Use a high impedance voltmeterte make the specified
measurements in this section’
In an extreme case where you are unable to resolve a
difficulty, refer to the “Customer Service” informa-
tion inside the rear cover of the Manual. Your war-
ranty is located inside the front cover.
TROUBLESHOOTING CHART
This chart lists the “Condition” and ‘‘Possible Cause”
eavaral malfiin ana If a salar rrart ornarte aro mario
parlululal part Ul partoaiy
of several m malfuncti Ons. 11
mentioned (Qi for example) a
a possible cause,
check that part to see if it wa
correctly. It is also possible, on
r
No DC voltage change at point A when R@ is adjusted.
C3 is shorted. '
Range switch miswired or loose connection.
Rg defective. —
No AC voltage at point A. 1.
2
3
No DC bias voltage change at the collector of Q8 when R33 is
adjusted.
Ci through Cé6 interchanged.
C1 open.
Open range switch.
Q6 through Q10 installed incorrectly or shorted.
C13, C17, shorted.
No meter indication.
Q6 through Q10 installed incorrectly or shorted.
Range switch miswired or has loose connection.
Open meter.
Weak batteries.
Meter gives reverse indication.
Balance control is ineffective. Null occurs off scale. 1.
2
3
Level control is inoperative.
D4, D5 installed backwards.
| |
2.
Wires
to
meter
reversed.
|
Balance control miswired.
amnanant A nf ennmn nt
1
Compor eit out Ul ratige
T1 open. |
Level control miswired.
T1 open.