wires are present, capacitor is missing.

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Hello , from Texas. Fort Worth not Dallas. I bought a AEAD-200LE, it's birth certificate is HE763793. It' an ac/dc unit driven by a Onan ccka ms/2677g with a serial # 0374772614. 1st question how to tell if it is a 50 Hz or a 60Hz? 2nd ?   It is missing a capacitor paper-oil .5 uf 200 volt dc part #031 683 item no. 146 on dia.mkgs. c2. What I'm trying to avoid is stupid. as in what logical or fact of reasoning would it be missing.THe Resistor is present. Could this be what gives out before it hits the diode? The onan had been rebuilt completely by a engine builder at his machine shop, Fired right up on 2nd turn of the key.Previous owner said he thought it might be a diode because it would generate elect to the plugs but no arc at the stinger. any and all information offered will be appreciated in this evaluation of  this problem. thank you much.peace
Reply:http://www.millerwelds.com/om/o411a_mil.pdfEngine speed determines frequency and the specific Stock Number would indicate which.  Stock No. 900 468 is 60Hz (1800rpm) or Stock No. 901 363 is 50Hz (1500rpm).  Weld speed is 3000rpm.C2 is a buffer/filter and the resistor allows it to "bleed-off" residual voltage.  The original C2 may have failed shorted and blew or it may have failed open leaving it to be of no effect either of which could be why it was removed.  If/when replacing C2, resistor R2 should be checked for proper value (1000ohms +/- 10%) and replaced as needed as well.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Hello,duane55 and thanks for a timely reply. so just the facts. digi key sent the closet match available:cap film 0.47uf  1kvdc axial and the resistor is res 1k ohm 6.5w 5% ww axial. both items are considered non directional. have made repair, but no arc. checked rpm at idle 1243; to work1789;and to weld 2944. I have cleaned the brushes and slip rings. up and down with restat or called fine current adjust. how again do i wake up the exiciter? 12 volt dc to both sides momentarily. Is it possible to attain a trouble tree with values in order to eliminate other possible problems like diodes that look a bit frayed. I do like my chances of getting this problem resolved so that said I'm  waiting for a direction and instruction. I should try band locate tech. manuel. I have complete faith in the talent of those that can help with this process as garrett the coach would say
Reply:The only thing that I see could be wrong with the replacement parts is that the capacitor that you used is a DC unit.Oil and paper capacitors are AC or DC.I doubt the the resistor/capacitor combo would be the problem.Need to dig a little deeper.Sorry , just read your post again, your parts should be good.Last edited by Bluewelders; 11-04-2014 at 07:45 PM.
Reply:update on the aead 200le ... with the new cap & res in place. no arc on dc connections. as for the ac side when i scratch the welding rod I get a faint arc, nothing that would even cause the rod to stick.as to the cap being a dc flavor, why or what is that telling me? That the machine was mostly ran in dc mode, compared to the ac mode as it is still trying to weld. question  can the diodes be tested in place, without removing from the machine. 2nd question is what is the value given at the brushes  when in the welding mode. and i should also have a value in the working mode. I have found the replacement diodes for 58.00 apiece. is it fair to assume that a diode is not fixing to go out , it is either functional and working  or there gone. nothing gradual. and thank you bluewelders for the input.
Reply:C2 and R2 are not critical components, can you strike an arc on AC? do you measure any output voltage on the AC receptacles?  The wiring diagram provided by Duaneb55 shows that the 12v battery excites the exciter field through the slip rings 27, 22 that creates  a voltage (115VDC)that is rectified and then powers the main revolving field thru R1. 1. test for 12v at the slip rings 22,272. test for 115v at the exciter stator 22, 27
Reply:when testing for 12v,  I have nothing at slip rings and batt. is putting out 12.77. I used a jumper from - batt - meter +direct to center and far or back ring. nothing. i'll fire up the machine in the morning it's too late for the dayshift is sleeping
Reply:without the engine running and the start switch in the run position,  you should have ~12v at the slip rings 22 being ground and 27 being positive. determine if you have  no ground or no positive.  If no positive, check for positive on both sides of D8.Last edited by sparkness; 11-06-2014 at 08:37 AM.
Reply:Ohms between the middle and back ring is 23 of 37 value given in schematics. Thank you sparkness, for the descriptive information. no 12v at the rings 22 - and 21+ in the start position. on to d8
Reply:with 1 meter probe on a good ground you should have +12V approximately on either side of D8. One side of D8 goes to the + side of the ignition coil and the other side goes to a slip ring. If no +12V at all then check wire going to ign. coil. if +12v on only 1 side of D8 then a bad diode. if +12v on both sides of D8 then check wire going to slip ring. Also you should measure 12V at the DC Receptacle on the front of the welder. All these measurements done with the the engine not started and the start switch in the run position.Last edited by sparkness; 11-08-2014 at 04:16 PM.
Reply:No 12v on either side of d8, proceeded to the ignition coil, found a weathered coil wire to + post, 1 of 3. contacting exhaust stack.applied liquid tape and bunched a few together and let me admit what i thought was ac/dc internal switch is actually weld / power. so nothing has changed but my experience,so I plug in dc leads to see what might happen, it will almost stick 1/8 6013 to ground clamp.when i get a chance I need to recheck all contacts. just want to verify the information that offering is correct. right now I got a motorhome in need of a some wizardry of some sort, A potion of big hammer maybe. thanks for the help and i will re check all to this point in my next post. I appreciate my blessings and the help afforded thanks
Reply:I did forget to mention that almost everything contacted with probe found ground, as gave tone for continuity