chicago electric mig Diodes

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Hi girls & boys, I joined this forum a couple of weeks ago, so i'm new as to --how you do things. I have a question about chicago electrc  or harbor freight mig welders, I have a 170 & 180 amp. they both weld very good, the beads look as good as my Hobart 175 amp. Here's my question, the 180 has a rectifier with 16 total  diodes in 2 plates and the 170 amp has a rectifier with 8 total diodes in 2 plates. Why does one have 16 and the other only 8, they are both this years model and only about 3 weeks old, I don't see any markings on the diodes, but they appear to be about the same size in diameter, the 180 amp has a 6 position heat switch and the 170 amp. has a min max 1 and 2 push buttons so why does the 180 have 16 and the other only 8 ?   Thanks in advance  Buddy1
Reply:I think you're going to have to learn Chinese and call the manufacturer for that information. Only they know why they do some of the things that they do.CharleyMiller MM252Miller Bobcat 225NTMiller DialArc HF / DIY Cooler2 Victor O/A TorchsetsMilwaukee 8" Metal SawMilwaukee Dry Cut "Chop" Saw 5 Ton Wallace Gantry Various Grinders, Benders, etc.
Reply:Hi Charley, you're probally right about calling China, I was just hoping one of the electronic whizz's might respond with an answer. Another reason I wanted to know was because the welder with 16 diodes has a 20% duty cycle @ 140 Amps and the othert has 20% @ 110 Amps, just wonding wheyher the diodes has anything to do with duty cycle. Anyway thanks for the response, however, don't think I will be learning Chinese anytime soon.
Reply:Having more discrete components will allow a higher duty cycle because it distributes the current (and thus the heat) over more parts; that is, each diode bears less of a load.
Reply:Thanks Dave, I was thinking it may have a little to do with duty cycle, but I also understand diodes are very cheap, so why don't they use more in all machines, I did read somewhere that Lincoln has 16 diodes in there machine, not sure which one or maybe all of them. anyway thanks for the reply, I may take the 170 back and get another 180, but I sure like the way the 170 welds on thinner metal, I added a 10 ft. gun on the 180 and will do the same to the 170 if I keep it, the more I think about it, the more i'm in favor of keeping it, if something happens to it, I'll just throw it in the car and head for HF to get another one. Buddy1
Reply:Hey Buddy1, where did you get the 10 ft. gun for the HF welder?
Reply:Originally Posted by Buddy1Thanks Dave, I was thinking it may have a little to do with duty cycle, but I also understand diodes are very cheap, so why don't they use more in all machines
Reply:Paralleling small diodes can be done if they are closely matched, but it is not a good engineering practice."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:I have a Chicago Electric 170 amp mig/flux wire welder that blew a diode in the rectifier last week. Looked around on eBay and found some 50amp diodes that are press fit. About $4 plus shipping each. I am guessing these will work to replace the blown one. My reasoning is  170amps divided by 4 ( 4 positive and 4 negative diodes )  would be 42.5 amps each. I figured overkill would not hurt. Is there any way to keep from blowing a Diode again. It happened when carbon filled the welding tip area and shorted the gun to ground. I think I need to get some tip dip to keep this from happening again. Also Buddy1 said he put a 10 foot gun on his Harbor Freight welder. Where do you get one of those.ScottR