夏延飞机维护手册 Cheyenne IIIA PA-42-720 AMM 2(34)

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The annunciator systemincorporatestwo annunciating light strings, enginefire indicating lights, a controller(computer), a horn, and actuating components in the affected systems of the aircraft.
Componentsare also incorporated for testing the operation of the annunciator lights as well as the
lights in the lighted switches used on the instrument panel and in the overhead switch panels.
Equipmentto operate this part of the system consists of an ANNUN TEST (annunciator press-to-
test) switch in the left side of the annunciator panel; and, a number of diode array connectors
installed behind the overhead switch panels. When the test switch is held depressed, a ground is
applied to the annunciator controller and the diode array connectors via a ground apply relay. At
the same time, 28 Vdc is also applied to the controller test circuit. With the ground and power
applied to the controller, a circuit is made which should illuminate all the annunciator lights. With
the ground applied to the diode connectors, a circuit is completed to all of the lighted switches
whichshould cause them to be illuminated.
NOTE: The Fixed Dimming circuit provides a continuous voltage (5 Vdc in BRIGHT; 3 Vdc in DIM) to the lights inside the lighted switches. When the "ANNUN TEST' switch is activated, the appliedground completes the circuits to all the affected lights, illuminatingthem as selected by the Fixed Dimming Circuit.
EFFECTIVITY:

040-999 PAGE
31-50-00Jan
10/90

PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCEMANUAL

B. Annunciator Panel
The annunciator panelmonitorsvarious functions of the electrical system. The annunciator panel
contains indicator light bulbs that are grouped together and extend across upper center portion of
instrumentpanel below glareshield(Figures 1 and 401). The annunciatorcontroller is secured to
instrumentpanel support bracket directly behind center panel of instrument panel.For identification of
annunciatorlights, refer to Chart 1.
/
AnnunciatorPanel 
Figure 1 
EFFECTIVITY: 
040-999 
JanJan10/9031-50-0010/90 

PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL

B. AnnunciatorPanel (continued)
1. Removalof AnnunciatorPanel(Figure401)
NOTE: Replacementof a bulb does not requireremovalof annunciator panel. To replacea
defectivebulb,push in on appropriatelightcoverassemblyuntil it clicks. Remove the light cover assembly.Removeold bulb and replacewith new bulb. Placelightcover assemblyin proper cut out andpushin until it clicks, locking the lightcoverassemblyin
place.

(a)
Removescrewssecuring cover to glareshield assembly;removecover.

(b)
Removescrewssecuringcenterpanelof instrumentpanel and pullback on panelto gain accessto annunciator controlbox. Disconnect annunciatorpanel connectors.

(c)
Removescrews securing annunciatorpanel to glareshield. Removeannunciatorpanel.

2. Installationof Annunciator Panel(Figure401)
(a)
Placeannunciatorpanel into positionon glareshield.Securewith screws.

(b)
Attachannunciatorpanelconnectorsto annunciatorcontroller.Installcenterpanelof instrumentpanel. Securewith screws.

(c)
Position cover on glareshield assembly.Secure with screws.

Skin
AnnunciatorPanel
Figure401

3. Removalof Annunciator Controller
(a)
Ensurebatterymasterswitchis off.

(b)
Removescrewssecuringcenter panelof instrument panelassembly. Pullpanelout to gain accessto annunciator controller.

(c)
Removeelectricalconnectorsfrom annunciator controller.

(d)
Removescrewssecuringannunciatorcontrollerto instrument panelsupportassembly. Removecontrollerfrom supportassembly.

EFFECTIVITY:
040-999
31-50-00Jan10/90

PIPER AIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL

B. AnnunciatorPanel (continued)
4. Installationof Annunciator Controller
(a)
Holdannunciatorcontrollerin position on instrument panel support assembly.Securewith screws.

(b)
Attach electrical connectorsto annunciator controller.

(c)
Place center panelinto position. Secure with screws.

Remove Four Screws For Access To

A B C D E F G H J K L M GrimesPart Number For AnnunciatorBox 80-0372-7
CircuitCard Installations (Top View Of Box)
AnnunciatorControllerInformation
Figure2 (Sheet 1 of 2)

EFFECTIVITY: 
040-999 
Jan 109031-50-00 Jan 10/90 

PIPER AIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL

B. AnnunciatorPanel (continued)
PA-42-720ANNUNCIATOR (GRIMESP/N80-0372-7)

CIRCUITCARD  ANNUNCIATOR  CIRCUITCARD 
　
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