Marconi LORAIN RHM800E50 Manual page 37

Section 4387
If the DC output leads were discon-
nected or if the BATTERY DISCON-
NECT link was removed during
repairs, refer to Test Procedure 6 for
recommended startup procedure. If
the battery was not disconnected
from rectifier output, perform the fol-
lowing step.
k)
Check the meters and indicators on the rec-
7.14 Test Procedure 5. Perform this test when check-
ing for proper gating outputs from firing circuit cards Al
through A6. The gating signal should be checked at the
gate and cathode leads of each thyrfstor used in the rec-
repfaced.
T h i s pmeedvre is Perfbd w i t h Power
applied to the rectifier. H~ZW&US AC volt-
ages capable of producing severe. perhaps
equipment cabinets while the d* is opr?r-
Place the POWER switch to the OFF posi-
tion. Do not disconnect AC or DC power
Remove the lower front pad frvm the recfi-
fier to gain access to both heatsiik assem-
blies and power transformer Tl Locate the
each heatsink assembly.
Adjust the vertfcai sensitiifty of an oxillo-
scope for 0.5 volts per centimeter (OSWcm).
Adjust horizontal time base for 2 millisec-
onds per centfmeter (2 ms/cm).
Page 34
DANGER
Do not use a grounded osciUoscope when per-
forming this pracedure: otherlhe. damage to
the nsctifir may result. At the same time. a
equipment bscmnes energized to the same volt-
age keel as the circuit under test. servlclng
personnel must eMeise cnution that simulta-
neous cmtuct is not mu&? with the test instru-
ment chassis or ease and some grmmded
object when the test equipment is annected to
the rectifiet while it is operating.
Open the meter and control panels by loos-
ening the captive fasteners.
Connect the oscilloscope probe to terminal 6
of one firing circuit card. Connect the oscif-
same circuit card.
Start the rectifier by operating the POWER
Observe the waveform displayed on the
oscilloscope. The waveform should be simi-
lar to tftat shown in Figure 73. Amplitude
peak with a varfable tfme duration depen-
dent upon AC input voltage and output volt-
age settffg. The waveform illustrated was
taken with the rectifier operating at 208 VAC
input and 52 VDC output wkft 50% load.