Heathkit IO-4205 - Initial Tests

Page 80
INITIAL TESTS
....--- PICTORIAL 5-1
0
RESISTANCE MEASUREMENTS
an ohmmeter is available, measure the resis-
tance between each flat plug prong and the
round prong on the line cord . In both measure-
ments you should obtain an infinite indication .
Be
sure the test probe is not touching the chassis
or any connection.
If you do not obtain infinite indications, recheck all
primary wiring and make sure no fine wire strands at
any connection are touching another connection .
Use
an ohmmeter to make the following resistance
measurements before you apply power to the Oscil-
loscope.
This will insure that the power supply will
not be damaged due to a wiring error or some incor-
rectly
installed or faulty part. If you do not get the
proper indication in a step, check the wiring and
installation ofthe parts listed in the "Possible Cause"
column for that step. You may also refer to the "In
Case of Difficulty" section ofthe Manual (Page 97). He
sure you obtain the correct resistance reading before
proceeding.
Refer
to Pictorial 5-1 for the following steps.
' ( )
Position the Oscilloscope bottom side up.
J Connect the negative ohmmeter lead to the
chassis of the Oscilloscope. Then touch the
positive meter lead to the points indicated in
the following chart.
NOTE: Not all
ohmmeters are polarized the same.
Therefore, if
you do not get the correct meter reading
the first time, connect the positive meter learl to the
chassis and touch the negative meter lead to the point
indicated in the chart . If this produces the correct
indication , cross out the word "positive" in the head-
ing of
the first column and write in " negative."
NOTE: The ohmmeter that was used to make the fol-
lowing measurements was powered by a 1.5 volt bat-
tery
and set on the RX1000 range.
Make all of
the following measurements on the power
supply circuit board.