AnsaldoSTS F-42, Установка, эксплуатация и обслуживание

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PARTS LIST
SM 5924, Rev. 1, June 2009 4-5
3. For D4, use pins 1(+) and 2(-). The Zener voltage at 0.020 amperes should fall between
40.8V and 45.2V (across D4 only).
4. If board CBC does not meet the specified requirements, replace with a board in operating
condition.
4.5.2 Optional Surge Protection Modification
F-42 units manufactured prior to 1975 (serial numbers lower than XX75XX) may experience
unusual fuse blowing problems when exposed to surge conditions. The optional modification
described below can sometimes alleviate or reduce the number of fuses blown in this situation.
Refer to Figure 4–2 for orientation with these wiring changes.
1. The lead from P3 to pin 2 (CB3) to TP6-2 should be moved so that it goes directly from P3,
pin 2 to SCR1 cathode. This lead should be a black wire and should be twisted together with
a green wire that runs from P3, pin 3 (CB3) to SCR1 Gate.
2. The wire that goes from TP6-2 to SCR1 cathode should be moved so that it goes from TP6-2
to Dl anode.
3. Change resistor R2 from 82 ohms to 180 ohms, 1/2 watt.
4. Change resistor R3 from 200 ohms to 430 ohms, 1/2 watt.
4.6 CB2 STARTING CONTROL BOARD (N451120-3002)
Check the Zener diode voltage. Operational tests can be performed by observing the ON and
OFF operation of Q2 which, during the starting cycle, connects the 130 ohm and 62 ohm starting
resistors to DC (output pin 1).
If board CB2 does not meet test specifications, replace with a board in operating condition.