Armstrong 6100 - Page 24

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4. If fuses are OK, check voltage to contactor coil.
 (a) Ifvoltageis24-28VACatcontactorcoil,checkcoilresistance.Itshouldbe8W with wires
disconnected. If resistance is OK, check voltage drops across the contactor.
 (b) Ifnovoltagetocontactorcoil,checkcontinuityofwiresfromPCboardtocontactor.If  
continuity is OK, PC board is likely defective.
5. Checkvoltagesignaltopowermodule.ThevoltageacrossTAB8-1andTAB8-2(lowvoltagesignal
  topowermodule)shouldbe12Vdc.
 (a) Ifnoorlowvoltage,thePCboardislikelydefective.
 (b) IfvoltageisOK,butgreen“SIGNAL”LEDonthepowermoduleisnoton,powermoduleis 
defective.
6. If green “LOAD” LED on power module is on, check voltage drops across power module.
Humidifier overfills with water on initial fill.
1. Checkelectrodecanister(floatcanisterforDIunits)andlevelelectrodesfordebrisorscalebuild 
up. Clean as needed. See Page 21 for cleaning procedure for electrodes. On DI Units, the high
water float switch may be defective or “hung up”. Check continuity across wires to the switch.
Make sure switch movement is vertical so float lever arm swings freely.
2. The fill valve may be stuck open. Turn off power to the humidifier. If fill valve does not close,
clean or replace valve.
3. If the high water circuit is closed and the fill valve shuts off when the power is turned off, the PC
board is defective.
Humidifier runs continuously, %RH is well over set-point.
1. Verifyhumidistatsignalisn’tsendingfalse100%demand.
2. VerifyhumidistatorRHsensoriswiredcorrectlyandstat/sensordipswitches(S2&S3,See 
 Fig.10-1and11-1)onthePCboardaresetcorrectlyforthehumidistatsignal.
3. If humidifier generates steam with the humidistat disconnected.
 (a)Checkforpoweratthecontactorcoil.If24-28VAC,PCboardisdefective.
 (b)Checkvoltagedropacrosscontactor.Ifvoltagedropislow(itshouldbelinevoltage),  
remove, disassemble and inspect contactor.
 (c)Checkgreen“SIGNAL”LEDonpowermodule.IfitisONorblinking,PCboardislikely 
defective.
 (d) Checkvoltagedropacrosspowermodule.Ifvoltagedropislow(itshouldbelinevoltage), 
power module triacs may be failed closed. Shut off main power and perform continuity check
across high voltage input and output terminals. Continuity indicates a shorted triac. Note:
Some power modules have two triacs rather than three. Check schematic on power module
to verify.
 (e) Checktoseeiftheaquastatisreadingavalvelowerthantheaquastattempsetting.