1 ~\ J\ G J\ Z I I I r' - American Bonanza Society

are connected in series, withthe high end of the inboardtransmitter connected to + 12volts as a reference. Onegauge movement coil pulls theneedle toward the full positionand the other pu lls it towardthe empty position.The gauge-full positioncoil is attached to 12 vo ltsthrough a circuit breake r. Theempty position coil is attachedto ground. The two positioncoils are connected togetherand are attached to the transmittervariable voltage output.Refer to Figllres I and 2 fortire fol/olVing description.When the voltage outputfrom the transmitter is at zerovolts (ground ), all of the currentfl ows thru the full positioncoil and the empty positionco il doesn't have current Oowingthrough it because the voltageon both sides of the coil iszero. Therefore the gauge ind i­cates full.When the voltage outputfrom the transmitter is at 12volts, all of the current Oowsthrough the empty positioncoi l and the fu ll position coildoesn't have current flowingthrough it because the voltageDASH UNIT.....,.' 1 STUDf2 STUD IFigure 1 - Original transmitters 1962 thru 1969DASH UNITBUSS11 STUDIEXISTING INBOARD(95 -380012-1)11 STUD 13 STUD95-380012-5(INBOARD TRANSMITTER)*1 STUDEXISTING OUTBOARD(95-380012-3)'4 STUD*3 STUDJUMPER WlRE ISNOT INSTALLED ONALL AIRCRAFT.95-380012-7(OuTBOARD TRANSMITTER)FULLATTACH TOMOUNTING SCREWFIgure 4·3, Wlrlng Diagram (Inboard and Outboard Transmitter.)Figure 2 - Replocemenllronsmitters 1962 Ihru 1969on both sides of the coil is thesame, 12 volts. Therefore the gauge indicates empty.When the voltage output from the transmitter is at 6 volts,the current is the same in both the fu ll position coil and theempty position coi l because they both have 6 volts acrossthem. Therefore the needle indicates half full (or half empty ifyou are a pessimist).There are two vintages of transmitters and they can beintermixed. The original transmitters have four studs(i nboard) and two studs (outboard). The replacementtl'Onsmittel'Shave two studs (inboard) and one srud (outboard).To troubleshoot the system, remove the inspection panelabove the inboard fuel transminer. With the master switch on,verify that you have + 12 vo lts on srud #2 of the transminer.1EMPTYSrud #1 has the wire that goes to the gauge. If you removethe wire fro m stud #1 (open), the gauge should read half-scale.If you ground the wire terminal lug, the gauge should read full.If you touch the tenni nal lug to the #2 stud (+ 12 vo lts), thegauge should read empty. Turn off the master switch. If YOllrgallge doesn't read proper/y, have it overhallied.The inboard fuel transmitter case should be isolated fromground by a felt washer (Figure 3). If it is not, the gauge willread full until the acrual fuel level is close to 2/3 and then WIllmove the rest of the way faster than the change in the fuellevel , although it will read correctly when the tank is empty.Remove the wire attached to the case and that connects tothe outbound fuel transmitter. Verify that the case is not grounded.If the case is grounded, reseat or replace the felt washer.