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Capacitors BAD!!! in mig welder, options for exchangin them.. HELP!

sapwood

Aluminum
Joined
Dec 7, 2013
Location
sunderland
ive got two bad caps in an Autoynx mk2 mig. their big boys the both of em' oil filled electrolytics at 250000uf. off the shelf new these will set me back over £120 each and I cant justify this. I figured my options are as follows and im looking for some response to each option from those in the know, more so than myself.
1. I have plenty old machines good for parts but I don't have any like for like caps, so can I use a combination of different caps to make up the same values. say two banks of say a 100000uf + 3x 50000uf caps
2. does anyone know of any electronics parts salvagers in the uk and Europe that are good for tested used parts like caps etc?
 
Hi
How old is that machine?? For not too much more that £240 you could buy a half reasonable new machine. Sell off the old ones for parts or scrap.
You would get a decent warranty that you would not get for used caps.

Google found this link
 
Oil filled and electrolytics are two very different types, used in very different services. You need to exactly specify the type and voltage rating.

Capacitors can be paralleled for more capacity.

Bill
 
ive got two bad caps in an Autoynx mk2 mig. their big boys the both of em' oil filled electrolytics at 250000uf.

250000uf = .25 Farad

You know how what a Farad is? and how large that is?
What is the real value of capacitance and the voltage rating? A picture if you don't know about capacitors.
 
The "competition" car stereo field makes use of large capacitors -- not at high volts or oil-filled, though. Could lead you to mfg's and sources, though.

Chip
 
The "competition" car stereo field makes use of large capacitors -- not at high volts or oil-filled, though. Could lead you to mfg's and sources, though.

Chip

Just gotta pay attention to ratings for your application. Though they look identical to the ones the car stereo guys use, I use some big canister electrolytics rated for 400V as a DC cap bank for a 30 HP VFD I rebuilt, and for the smoothing caps for my CNC retrofit
 
ive actually tested the caps tonight and with multimeter set to 2000 ohms the caps, both of them respond like I was advised they would if they were good caps. after discharging them from taking them out. out the meter probes on and they slowly ramp up and keep going, if I switch the leads it does the sme but ramps back down.
I have found out something from the sellerof this Murex mig today that he had the machine looked at before giving me it and the engineer told him its got problems controlling voltage CV and the wire feed motor is working right. But the motor sounds fine to me nd pushes wirre fine. ramps up its speed if I turn the dial and vice versa? Also didn't understqand how he stated it had problem controlling voltage. I have the rted voltages measured at the tip from my meter. I thought it amps that th wire feed side controlled and this also being where a mig gets its heat/penetration from was the machines ability to control the amps relative to the arc length it monitors and the wire feed setting.
Some to summerise my two caps are fine and im now looking within the wire feed and lso towards measuring the machines amperage delivery at the tip when welding....
CAN ANYONE ADVISE OR ADD TOT HIS WHO HAS MORE EXPERIENCE......
 
ive got two bad caps in an Autoynx mk2 mig. their big boys the both of em' oil filled electrolytics at 250000uf. off the shelf new these will set me back over £120 each and I cant justify this. I figured my options are as follows and im looking for some response to each option from those in the know, more so than myself.
1. I have plenty old machines good for parts but I don't have any like for like caps, so can I use a combination of different caps to make up the same values. say two banks of say a 100000uf + 3x 50000uf caps
2. does anyone know of any electronics parts salvagers in the uk and Europe that are good for tested used parts like caps etc?

Capacitance is added when caps are connected in parallel, two things you have to keep in mind the voltage rating of the caps and the ESR of the cap when you want to get a larger capacitance. If you connect them in parallel the ESR will drop (a good thing in this case) as you add more and more identical caps. Do not mix and match caps from different makes and and voltages if you want a stable bank. BTW 250,000uF is a rather unusual value you are more likely to find 220,000 uF or 330,000 uF caps. In a PSU type of application oversizing caps is nto a sin.

dee
;-D
 
I have been informed from the guy I got the welder from that a pro service place diagnosed this with "Problem controlling voltage CV and wire feed motor not working properly" now I know the current and the CV are linked so this is telling my limited mindset that im deff on the hunt for whatever is preventing the machine monitoring the weld t the tip which in turn controls the amperage, which the amperage is also determined by the wire feed dial setting...
I must add too that the wire feed and the voltage selector knobs are in terrible fettle. very dry and loose, not very confidence inspriing knobs at all.
 








 
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