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This is very off topic but I figured someone here can probably answer this for me. I have a miller gas welder with a bad capacitor and it's back ordered for nearly a month and was wondering if anyone could recommend any comparable replacement or if I have to go with that exact one being as I know next to nothing about capacitors. The one it calls for is a Miller #123849 and has a rating of 1000 Uf 75 Vdc. It's a large capacitor with a diameter of about 2.5" and a hight of about 3 3/8"
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Several questions:
- It doesn't look visibly damaged...do you know for sure the capacitor is bad? (i.e. try a capacitance meter on it to check if it is 1,000uF / 1.0mF [millifarads])
-
If you did replace it, I'd recommend finding a capacitor of similar dimensions.
- For example, it's super easy to find a 1,000uF / 80v DC cap (heck, the ones on the GS mainboard are 10,000uF, 80v!) but capacitors of smaller dimensions will have a considerably higher ESR (equivalent series resistance), and as a result, will fail very quickly if subjected to large ripple current.
I did check Mouser Electronics, and found a similar-spec one (bit smaller diameter)...wow, only 4.3 amps ripple current?? https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CG102U075R3C
If I could find a datasheet on your specific capacitor, we could make a more informed substitute. Newer caps generally have better specs than old caps (especially if your cap is more than 30 years old!)
3 hours ago, Cali Carlos said:and it's back ordered for nearly a month
You're lucky--a lot of U.S.-supplied parts have lead times of over 60 weeks. Including simple capacitors!
1 hour ago, Sid Genetry Solar said:It doesn't look visibly damaged...do you know for sure the capacitor is bad? (i.e. try a capacitance meter on it to check if it is 1,000uF / 1.0mF [millifarads])
It completely fails the capacitance test on my multimeter. It also ohms out at a dead short and stays there instead of climbing in resistance.
1 hour ago, Sid Genetry Solar said:I did check Mouser Electronics, and found a similar-spec one (bit smaller diameter)...wow, only 4.3 amps ripple current??
The inline fuse is rated at 25 amps.
1 hour ago, Sid Genetry Solar said:If I could find a datasheet on your specific capacitor, we could make a more informed substitute. Newer caps generally have better specs than old caps (especially if your cap is more than 30 years old!)
I can't seem to find anything on it. It's probably right around 30 years old
22 hours ago, Cali Carlos said:It completely fails the capacitance test on my multimeter. It also ohms out at a dead short and stays there instead of climbing in resistance.
The inline fuse is rated at 25 amps.
I can't seem to find anything on it. It's probably right around 30 years old
I'd suggest trying the Mouser option. It's probably going to be a lot better than the original--especially if the old one's 30 years old!
The vendor emailed me saying that it came off of backorder early and the already shipped it out.
On 1/24/2023 at 3:59 PM, Sid Genetry Solar said:It's probably going to be a lot better than the original--especially if the old one's 30 years old!
I don't know how long a good capacitor should last but I wouldn't be surprised if this one is the original. It's at least 10 years old and only failed because the engine throttle got stuck on full throttle which is well passed its normal operating RPMs and I assume put out to much voltage to it. The machine has 14,000 hours on it
On 1/26/2023 at 10:23 PM, Cali Carlos said:The vendor emailed me saying that it came off of backorder early and the already shipped it out.
I don't know how long a good capacitor should last but I wouldn't be surprised if this one is the original. It's at least 10 years old and only failed because the engine throttle got stuck on full throttle which is well passed its normal operating RPMs and I assume put out to much voltage to it. The machine has 14,000 hours on it
14,000 hours, let me guess. It has an Onan engine on it?
14,000 hours, let me guess. It has an Onan engine on it?
You got that right! An Onan performer 16 to be exact.