HF MIG170A capacitor mod/upgrade - REDUX
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  1. #1
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    HF MIG170A capacitor mod/upgrade - REDUX

    I know this has been pretty much done to death at this point, but given the mods I'd seen so far, I figured that my particular implementation of the mod might be on interest to others.

    I'd seen a lot of the previous installations using 12 and 10 gauge wiring, which many admitted was probably too light for this role. I decided to use the largest size I could comfortably handle inside the 170's case, so I settled on 6AWG stranded wire as used in the 6/2 wire sold at Lowes and Home Depot. I stripped off the outer sheath and used the two main conductors, using the black wire to the Positive capacitor terminals, and the white to the negative terminals. I would expect this should handle most any likely amperage, within reason. Certainly if others are getting away with using lighter guage wiring in their setups.

    I was have a lot of trouble finding relatively inexpensive capacitors in the 100,000uf range and appropriate voltage. Prices seemed to vary from 60 to over 80 dollars!. Instead, I came across some 33,000uf 63V units on eBay costing under 10 bucks each, so I got 4, for a total of 132,000uf capacitance. This did however give me the headache of needing to figure out how to connect all these together. 4 caps gives a total of 8 terminals that need connecting to the rectifier plates, not to mention the bleed capacitor has to be added somewhere.

    I initially planned to daisy chain them, but I wanted ring terminals that were beefier that the typical automotive style ones often used. I found some with a #6 opening that would fit the capacitor terminals and accept the 6GA wire. But I still had to connect them together, which would be tough with wire that big. So I decided to separate the caps into 2 pairs, and try and wire them all to a central point which would then be connected to the plates. I originally had planned to put ring terminals onto a bolt that would be mounted to the partition wall that separates the spool side from the transformer side, but I was concerned about isolating the bolt from the metal casing, and whether a bolt would handle the current.

    As I was digging through my wires and connectors to see what I had, I came across a 16-hole ground bar for use in electrical panels, so I cut it into two 8-hole electrical bus bars, one for the positive leads, the other for the negative leads. With 8 holes each, I would use two for mounting each bar, and 5 more for each of the 4 terminals, plus one more for the line to the rectifier. I realized I could use the 6th hole to bridge the bars with the bleed resistor, which saved me having to try crimp or solder its terminals to wires and ring terminals. Looks quite neat and unobtrusive.

    I also wanted it to be switchable, and many of the switch solutions I'd seen didn't seem all that satisfactory, given the low current rating of most of them. So I searched on eBay again and found a battery disconnector for boats and cars that was rated for a maximum of 300A, with a max voltage of 60VDC. The positive line from the bus bar goes to this switch, mounted above the power selection switches on the front panel, and from there over to the rectifier.

    Concerns I have about this setup are the fact that I needed to isolate the bars from the metal of the case. I did this by using nylon spacers that hold the bus bars about 1/2 an inch from the metal surface, with nylon inserts into the holes in the case through which the bolts pass. I also added bolt head covers so that the (energized) bolts would be covered if I was changing out the spool in the compartment. I was concerned that they might physically interfere with the use of 10LB spools, and I didn't have one to test it with, but using some pictures I found online and paused youtube videos, it looks as though they're far enough away to avoid interference.

    My other main concern is how close the ring terminals are to each other on the capacitors. I'd like to have something non-conductive between them, in case a screw loosens and the terminal shorts to the other one. I also need to figure a way to prevent the capacitor terminals from contacting the inside of the case, perhaps by covering the ends somehow.

    I've not yet had a chance to test it, so perhaps those with more experience might have a look before I plug in. Neither the positive nor negative sides are shorted to ground, and read 50ohms to each other by way of the bleed resistor installed between them.

    Pictures to follow...

  2. #2
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    First, an overview image;

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    Next, a close up of the bus bars, including the bleed resistor;

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    Capacitor and terminals;

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    Next is the Spool side, showing the 4 covered bolt heads;

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  3. #3
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    For some reason, all of the previous images posted sideways. Probably because they were taken with my phone, sorry.

    Finally, here is the switch front;

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    And the back of it;

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  4. #4
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    You do nice work! That's a lot neater than the original.
    HF MIG-180 with all the mods.
    Grizzly H8153 Stick/Tig Pulse 130/160.
    Wards PowrKraft AC-230. Stick & carbon arc.

  5. #5
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Quote Originally Posted by California View Post
    You do nice work! That's a lot neater than the original.
    Thanks! I'm hoping to get a quick test in tomorrow, more an explosion test than a welding test, probably. Need to make sure nothing's going to fail catastrophically before securing the caps and putting the cover back on.

  6. #6
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Odd's are the rectifiers will need a upgrade. The rectifiers and main relay are week spots.
    The transformer is good size. You may need a larger cooling fan too.

    I upgraded the main relay and changed the ground wire to #4 10 foot long.

    See thread at
    https://weldingweb.com/showthread.ph...or-Freight-170

    Works great

    Dave

    Quote Originally Posted by JC_Phoenix View Post
    I know this has been pretty much done to death at this point, but given the mods I'd seen so far, I figured that my particular implementation of the mod might be on interest to others.

    I'd seen a lot of the previous installations using 12 and 10 gauge wiring, which many admitted was probably too light for this role. I decided to use the largest size I could comfortably handle inside the 170's case, so I settled on 6AWG stranded wire as used in the 6/2 wire sold at Lowes and Home Depot. I stripped off the outer sheath and used the two main conductors, using the black wire to the Positive capacitor terminals, and the white to the negative terminals. I would expect this should handle most any likely amperage, within reason. Certainly if others are getting away with using lighter guage wiring in their setups.

    I was have a lot of trouble finding relatively inexpensive capacitors in the 100,000uf range and appropriate voltage. Prices seemed to vary from 60 to over 80 dollars!. Instead, I came across some 33,000uf 63V units on eBay costing under 10 bucks each, so I got 4, for a total of 132,000uf capacitance. This did however give me the headache of needing to figure out how to connect all these together. 4 caps gives a total of 8 terminals that need connecting to the rectifier plates, not to mention the bleed capacitor has to be added somewhere.

    I initially planned to daisy chain them, but I wanted ring terminals that were beefier that the typical automotive style ones often used. I found some with a #6 opening that would fit the capacitor terminals and accept the 6GA wire. But I still had to connect them together, which would be tough with wire that big. So I decided to separate the caps into 2 pairs, and try and wire them all to a central point which would then be connected to the plates. I originally had planned to put ring terminals onto a bolt that would be mounted to the partition wall that separates the spool side from the transformer side, but I was concerned about isolating the bolt from the metal casing, and whether a bolt would handle the current.

    As I was digging through my wires and connectors to see what I had, I came across a 16-hole ground bar for use in electrical panels, so I cut it into two 8-hole electrical bus bars, one for the positive leads, the other for the negative leads. With 8 holes each, I would use two for mounting each bar, and 5 more for each of the 4 terminals, plus one more for the line to the rectifier. I realized I could use the 6th hole to bridge the bars with the bleed resistor, which saved me having to try crimp or solder its terminals to wires and ring terminals. Looks quite neat and unobtrusive.

    I also wanted it to be switchable, and many of the switch solutions I'd seen didn't seem all that satisfactory, given the low current rating of most of them. So I searched on eBay again and found a battery disconnector for boats and cars that was rated for a maximum of 300A, with a max voltage of 60VDC. The positive line from the bus bar goes to this switch, mounted above the power selection switches on the front panel, and from there over to the rectifier.

    Concerns I have about this setup are the fact that I needed to isolate the bars from the metal of the case. I did this by using nylon spacers that hold the bus bars about 1/2 an inch from the metal surface, with nylon inserts into the holes in the case through which the bolts pass. I also added bolt head covers so that the (energized) bolts would be covered if I was changing out the spool in the compartment. I was concerned that they might physically interfere with the use of 10LB spools, and I didn't have one to test it with, but using some pictures I found online and paused youtube videos, it looks as though they're far enough away to avoid interference.

    My other main concern is how close the ring terminals are to each other on the capacitors. I'd like to have something non-conductive between them, in case a screw loosens and the terminal shorts to the other one. I also need to figure a way to prevent the capacitor terminals from contacting the inside of the case, perhaps by covering the ends somehow.

    I've not yet had a chance to test it, so perhaps those with more experience might have a look before I plug in. Neither the positive nor negative sides are shorted to ground, and read 50ohms to each other by way of the bleed resistor installed between them.

    Pictures to follow...
    Last edited by smithdoor; 12-31-2019 at 02:39 AM.

  7. #7
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    I actually installed a 10-25 DINSE for the ground cable and used a 6-foot length of 4AWG welding cable I bought from an eBay vendor. They're the same company from whom I bought the 10-foot lengths for my stick/tig welders electrode and ground leads. The 400A HF ground clamps work really well. The DINSE allows me to repair and/or upgrade the cable much more easily. In fact, I could use the 10-foot one I made for the stick welder if necessary.

    Can you provide an example for a replacement rectifier, perhaps a part number? I'm assuming I could get it on eBay. The relay is the one on the wire feed speed board, correct? I can't see it in your photos.
    Last edited by JC_Phoenix; 12-31-2019 at 11:53 PM.

  8. #8
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    I got a brief chance to test it out today. First off was the "explosion test" - as in, if I plug it in and switch it on, will it explode and burst into flames. Switched it on wearing safety glasses and a full-face splash guard, but nothing exploded. Switched on and off the capacitor function using the installed switch, still no problems.

    Did a small welding comparison on a piece of 2 by 2 angle, definitely had a much smoother sound with the mod switched on than the harsher crackle when it's switched off. I went up through the settings to ensure the mod wasn't going to fail on MAX 2, unfortunately I held the nozzle too close to the piece, and the flux wire fused to the tip, rendering it unusable. I was able to take the tip off easily, although the flux core shield I was using was distorted by the heat. I'm not very experienced with welding in general, so mistakes are going to be made.

    I'll drop by HF tomorrow and pick up some replacement tips.
    Last edited by JC_Phoenix; 12-31-2019 at 11:54 PM.

  9. #9
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Got the replacement tip today, used the 25% New Year's Day coupon to get it. Decent value on the Chicago Electric 20-pack of tips, even if I can't use the .045 ones. I also cut off the melted end of the flux core nozzle that had distorted, it is now much shorter, but still long enough to cover the gas holes on the gun. So the welder's now back in operation, just need to find a way to cover the ends of the capacitors, then figure out some beginner level project to build.

  10. #10
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Got the caps strapped into their final positions on Saturday. The strap's not as tight as I might like, but they don't move at all, so they should be good. I'll likely glue some plastic to the inside of the cover to ensure if they hit the cover they won't short across their terminals.

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    Name:  Front_Strapped_Caps.jpg
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  11. #11
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Looks good 👌
    I would add a heavy main relay.
    The only reason I say this is really is on board and under size for work.
    The rectifiers can be replaced any time even after they fail.

    Dave


    Quote Originally Posted by JC_Phoenix View Post
    Got the caps strapped into their final positions on Saturday. The strap's not as tight as I might like, but they don't move at all, so they should be good. I'll likely glue some plastic to the inside of the cover to ensure if they hit the cover they won't short across their terminals.

    Name:  Overall_View.jpg
Views: 107
Size:  100.6 KB


    Name:  Front_Strapped_Caps.jpg
Views: 104
Size:  95.8 KB
    HF 170 welder
    HF 4x6 band saw
    South Bend 9N
    Mill
    B&D mag drill
    Victor torch

  12. #12
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Quote Originally Posted by smithdoor View Post
    Looks good 👌
    I would add a heavy main relay.
    The only reason I say this is really is on board and under size for work.
    The rectifiers can be replaced any time even after they fail.

    Dave
    Question: Will the wire speed knob still affect the wire speed if there's a relay in front of it? I thought a relay would make the wire speed to just off/on.

    Maybe the onboard relay could control a beefier one mounted elsewhere? it's not clear to me what that undersize relay does.
    HF MIG-180 with all the mods.
    Grizzly H8153 Stick/Tig Pulse 130/160.
    Wards PowrKraft AC-230. Stick & carbon arc.

  13. #13
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Error
    Last edited by smithdoor; 01-07-2020 at 11:17 PM.

  14. #14
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Quote Originally Posted by California View Post
    Question: Will the wire speed knob still affect the wire speed if there's a relay in front of it? I thought a relay would make the wire speed to just off/on.

    Maybe the onboard relay could control a beefier one mounted elsewhere? it's not clear to me what that undersize relay does.
    The relay turn the main transformer on and off.

    I use the relay on the board as pilot for new heavy duty relay.

    I have drawing https://weldingweb.com/attachment.ph...1&d=1523495850

    Dave
    Last edited by smithdoor; 01-07-2020 at 11:20 PM.

  15. #15
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Quote Originally Posted by smithdoor View Post
    The relay turn the main transformer on and off.

    I use the relay on the board as pilot for new heavy duty relay.

    I have drawing https://weldingweb.com/attachment.ph...1&d=1523495850

    Dave
    Thank you!

    First owner of my MIG-180 was clearly an experimenter. It has the longer stinger with better gun, heavier and longer ground cable with oversize dinse connector, a big capacitor mounted external with switch and resistor, and a relay below the wire spool. I asked him what the relay does, he only replied don't worry about it.

    The original and replacement gun looked flawless when I got it, likewise the cabinet. I suspect this was a toy to experiment with, not a tool for productive work. The thing welds properly so I never bothered to figure out what he had done to it. I simply bought it as an inexpensive tool to use, a literal 'black box' that provides the expected output.

    I now suspect that relay is wired per your diagram. I need to trace the circuit to confirm this.

    Thanks!
    HF MIG-180 with all the mods.
    Grizzly H8153 Stick/Tig Pulse 130/160.
    Wards PowrKraft AC-230. Stick & carbon arc.

  16. #16
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Smithdoor,

    Not sure you've provided it before, but would you have the part number for that relay?

  17. #17
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Quote Originally Posted by JC_Phoenix View Post
    Smithdoor,

    Not sure you've provided it before, but would you have the part number for that relay?
    Or see this post ...

    https://weldingweb.com/showthread.ph...42#post8666642
    HF MIG-180 with all the mods.
    Grizzly H8153 Stick/Tig Pulse 130/160.
    Wards PowrKraft AC-230. Stick & carbon arc.

  18. #18
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    This one used it 240 volt 30 amp
    Rated motor starting which is a very high amperage compared to welding. None motor rating is 40 amp.


    https://www.grainger.com/product/5X8...200110005006:s
    Or
    https://www.amazon.com/Dayton-5X851-...+240VAC+30+amp
    Or
    https://www.zoro.com/dayton-open-power-relay-4-pin-240vac-spst-no-5x851/i/G1577852/#specifications


    Quote Originally Posted by JC_Phoenix View Post
    Smithdoor,

    Not sure you've provided it before, but would you have the part number for that relay?
    Last edited by smithdoor; 01-09-2020 at 09:15 PM.

  19. #19
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Thanks!

  20. #20
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Take a look at a copy of the HF170
    https://www.sears.com/seg-170-amp-dc...d/p-A032180412

    Dave

    SEG 170 Amp-DC, 240 Volt, MIG/Flux Cored Welder CL2147
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    Description Item # SPM8947281326 Model # SEGPLUM2147
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    This 170 amp MIG flux wire welder is ideal for the beginner. The hassle-free welder comes set up for flux core arc welding and only requires adding shielding gas with other necessary components for full MIG welding applications. The MIG flux wire welder features constant voltage, thermal overload protection and a welding cable with gun.
    Added on December 24, 2018
    HF 170 welder
    HF 4x6 band saw
    South Bend 9N
    Mill
    B&D mag drill
    Victor torch

  21. #21
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Quote Originally Posted by smithdoor View Post
    Wow! Sears lets that guy charge $540 for a HF170 that doesn't come with the HF warranty? What a deal!

    I see he has the canvas bag to catch sawdust under a table saw - for $130!!! That bag is $6 at HF and he even uses their photo.

    Sears must be in even more desperate shape than we realized if they are letting scammers like this advertise on their site.
    HF MIG-180 with all the mods.
    Grizzly H8153 Stick/Tig Pulse 130/160.
    Wards PowrKraft AC-230. Stick & carbon arc.

  22. #22
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    Quote Originally Posted by California View Post
    Wow! Sears lets that guy charge $540 for a HF170 that doesn't come with the HF warranty? What a deal!

    I see he has the canvas bag to catch sawdust under a table saw - for $130!!! That bag is $6 at HF and he even uses their photo.

    Sears must be in even more desperate shape than we realized if they are letting scammers like this advertise on their site.
    Yeah, probably no surprise that they're dying... :O

  23. #23
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    Re: HF MIG170A capacitor mod/upgrade - REDUX

    I did find a great deal
    https://m.ebay.com/itm/Chicago-Elect...id=26030558642

    Dave

    Quote Originally Posted by California View Post
    Wow! Sears lets that guy charge $540 for a HF170 that doesn't come with the HF warranty? What a deal!

    I see he has the canvas bag to catch sawdust under a table saw - for $130!!! That bag is $6 at HF and he even uses their photo.

    Sears must be in even more desperate shape than we realized if they are letting scammers like this advertise on their site.
    HF 170 welder
    HF 4x6 band saw
    South Bend 9N
    Mill
    B&D mag drill
    Victor torch

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