AC-1200

1KVA rating Fused on new ones 40 amp common 15v 15v 6.2v Control coil Feed back voltage Ballast resistors for DZ3 Added to prevent destruction of DZ3 if 75,76,77 is gnd. Setti ng d eter mine s min. outp ut Feed back voltage set voltage from R40 control pot Output of X1A SCR firing signal Line voltage compensation (correction signal ) Control circuitry to drive OUTPUT CONTROL SCR s Pilot SCR s DRIVE SCR s Blocking diodes to keep compensation signal out of the rest of the control ckt. Provides smooth AC wave shape for wire feeder equipment AC input to board R Board SCR & DRIVE SCR supply 90vac .05mf 1000v .05mf 1000v DC control coil approx .5 ohms min =1.3vdc max =23.5 vdc output is shorted ckt or ocv conditions To test welder short ckt each tap one at a time max tap = 870 to 1800 amps middle tap = 410 to 1030 amps min tap = 210 to 590 amps must have no less than 20 ft of shorting cable 4/0 If you have max. output no control . Unplug the PC bd. . Should go to min. output. IF not , you have shorted SCR s. IF you go to min output , then you have a bad PC bd. Make sure that the control pot is ok and power is to the bd. Disconnect lead # 56 from control coils & short ckt max tap. Readings between SCR bridge. & lead 56 should not exceed ( 40 vdc) . Possible SCR problem or leakey SCR Max current thru control coils ( 55 amps) max rheo, no load ocv = 98 volts large heatsink Board SCR & DRIVE SCR supply 90vac Set s m ax . ou tpu t AC1200 is a variable voltage type power supply only used with NA4 feeders CODES: 10291C & 10292C Other CODES HELP note: Use this print for troubleshooting referances on other codes Use the wiring diagram for that code to determine differences in wiring. Resistance strip top front top front right inside metal box top front left Freewheeling diode large heatsink top center outside coils ( 5 ea side) top center inside coils Above output stud area Above output stud area Bottom half center Left top rear fan shroud top rear Center front bottom External terminal strip area left above output stud Rear top Rear bottom Bottom front left & right Top front left Right front Top of coils Below pc bd box Two terminal strip area : top front center Reconnect area (Scott connection ) right rear near input power entrance hole. (Scott connections see manual) Top front name plate NAVIGATOR USE mainmenu: