GE VALUTROL MAIN CONTROL MODULE Instructions Manual page 27

In general, setting below 10
0'
clock will show signs of
increasing sluggishness. Settings greater than 2
o'clock may show signs of hard or even continuous
bumping. Full
RESPONSE
setting (5 o'clock) will
usually trip the IOC.
7.
Reset
liN TIME
to required setting.
TROUBLE SHOOTING
Although many of the problems which may arise can be
effectively located with a multi-meter, an oscilloscope is a
very powerful trouble shooting tool. The only
requirements are that the selected scope have a DC input
capability and a line synchronization mode. Caution
should be exercised in measuring any point with a pOSSIble
high potential with any instrument; however, particular
care should be taken WIth an oscilloscope since the common
clip is normally connected directly to the instrument case.
If the grounded plug has not been defeated, it will cause a
short circuit between the high potential point under test
and ground.
RECOMMENDED INSTRUMENTATION
Simpson Multi-meter (or equivalent) 10,000 ohms/volt (or
higher).
Hewlett-Packard or Tektronix (or equivalent). Dual Trace
oscilloscope rated for operation from DC to 10 MHZ at
0.01
V
/CM with deflectIOn factors to provide 0.01
V
/CM to
1300 peak to peak deflection when used with appropriate
attentuator probes.
PROCEDURES
In trouble shooting this drive system the most appropriate
place to start isto follow the SEQUENCE OF OPERATION
(previously described) until a discrepancy or fault is noted.
This step by step procedure will determine which part, sub-
assembly or printed circuit card is causing the problem.
Included in this procedure is the use of the built-in
Diagnostic Card (DGC) (or Test CircUlt Fig. 23). This is
another powerful tool for quickly locating drive system
faults.
If the malfunction is a performance problem, then the
quickest way to discover the problem is to follow the
CALIBRATION PROCEDURE (previously descnbed).
There are two calibration procedures: (1) With Motor
Field Control (MFC) and (2) With Motor Field Exciter
(MFE).
GEK-24994
Detailed adjustments for these two cards are found in GEK-
24971 for the MFC card and GEK-24972 for the MFE card.
REMOVAL/REPAIR
PRINTED CIRCUIT CARDS
There should be no need to retune the drive after
removal/repair of a conversion module, an SCR or any
other removable sub-assembly unless, of course, an
adjustment was inadvertently moved or disturbed. If a
printed circuit card is replaced (other than the power
supply card·PSC):
1. Add stab-on jumpers to the replacement card just like the
jumpers on the card that was replaced or as listed on the
System Elementary Diagram "Programming" Table.
2. Add stab-on resistors and capacitors to the replacement
card just like the components on the card that was
replaced or as shown with values on the system
elementary main control card (MCC) at stab-on
terminals on terminals TR, RJ, SFB, NDE, CLl, CU,
and LT2 or on the DM1, DM2, etc. Terminals on any
other printed circuit card.
3. Set the potentiometers on the replacement printed
circuit card to the position as was set on the card that
was replaced or the position shown on the test data
sheet. Recheck the recalibration procedures described.
4. Use caution when connecting or disconnecting stab-on
connectors on the printed circuit cards to avoid
breaking of the connector posts. Support the card if
possible and use a pair of long nosed pliers to hold on to
the connector crimp. Avoid pulling on wires when
removmg connectors.
27