Mod-Your-151 How-To Guide

[foresaken001]

Could someone please post pictures of the cap mod? The pics from the instuctional on this page has expired or been removed. I am wanting to add this cap mod to my Chicago Electric 180.

[foresaken001]

ty for link

[foresaken001]

I didn't mean this page. I meant the 1rst few pages. I think the pics were posted long ago and have been removed since. Please Please repost these pics.

[foresaken001]

I have a 200,000 mf cap and a 60,000 mf cap. Both are rated at 75 volts. Each one is bigger than a tallboy beer can. If I run both of these in parallel, would it work well for the mod? I am building a heavy duty tray to house them under the welder.

[xmmancharl]

put a dinse connector for the ground...



assembly



added better contactor for wire feed



installed



Charl

[California]

added better contactor for wire feed



Charl

Can you explain how that contactor works? Thanks!

[xmmancharl]

it replaces the relay on the board, for the wire feed.


2 wires connect the button on the torch..other 2 wires go to board, where relay is located

Charl

[California]

Ok, that makes sense how it works. Does this provide a more steady, or powerful current to the wire feed?

[smithdoor]

I did same to my 170

Dave

put a dinse connector for the ground...



assembly



added better contactor for wire feed



installed



Charl

[Cacatunda]

Bringing this awesome thread back from the grave!
Hey guys,
So long story short after some searching i found that the welder my dad almost threw out 3 years ago(that i grabbed) and has been sitting in the corner of my shop is this Mig 151 made in italy. I assumed it was a POS HF welder but after spending a day reading all the mods and what not seems to be a gem of a welder. I have some questions.
1.Just for comparison its the 230v model 120a so im guessing equivalent to a Red 125? with the mod will bring to a Red 140,Red 180, or beyond? I read somewhere guy claimed welding 3/8" full penetration and 80% on 1/2" seems like a stretch but
2.I see alot of flux comments. with these mods is the machine still capable of running normal wire and AL with gas?
3.Does anyone have any updated list of parts and where to get them some posts/links are near 10yrs old.
4.Does this mod increase the duty cycle?
5.What would this modded welder top out at? 3/16,1/4,5/16?
6.Here is a guy on youtube that did some of the mods might be worth a watch since some of the pics are no longer on the site hope this helps.

I just finished bringing 220v out to my shop and was in the market for a welder of my own and was looking at the Hobart 190. My thoughts were possibly mod this and it would purpose as my 1/32"-1/4" material welder and i could purchase a cheap stick machine for material thicker than 1/4"? I have like $800 tops and would save a ton of money going this route if possible and after purchasing the mods and a cheap stick i would have plenty of money left for gloves,helmet,cart, and possible some tanks.
Seems too good to be true but thought id ask.
Thanks!

[lornbeckwith]

Moved, I cannot seem to get the pics to come up of how you wired in the small rectifier. Could you please send me some, this is my last hurdle to overcome on my super modded 151 t/2... thank you

[smithdoor]

Are using a phone to view the site.
I have to go to desktop view some photos.

Dave

Moved, I cannot seem to get the pics to come up of how you wired in the small rectifier. Could you please send me some, this is my last hurdle to overcome on my super modded 151 t/2... thank you

[California]

The photos going back a couple of years are visible in Firefox. But the old ones by Mobe in 2009 on the first page of the thread, now show only a broken image symbol.
WW moved to Amazon web storage a couple of years ago. So the url's for old photos have the wrong location prefix ahead of the specific image name.

Here's a workaround. Mobes posted it in Post #818, above. Thanks Mobes! In his words:
"try replacing "http://www.1jz.com" with "https://s3-us-west-2.amazonaws.com/mobes-photos/1jz.com" in the image URL."

It's PIA to update the url for each image but this works. Going for all of the broken ones would be a task but maybe someone is up to it.

Here's the long-form version of Mobe's advice:

Using Firefox look at Mobe's Post #1 in this thread.

With the cursor on the broken image: Right click / View Image Info / look at Media tab.
Copy the second half of the image Location - everything AFTER http://www.1jz.com. Paste that second half into Notepad.

Then, still in Notepad, paste in
https://s3-us-west-2.amazonaws.com/mobes-photos/1jz.com
as the new prefix ahead of that specific image's location.

Label (new line) that new combined url as 'Photo in post #1' to start making a re-usable index.

Copy your new edited combo url from Notepad.

Open a new Firefox tab, paste the new combo url into the destination box. Enter, to view the photo.

And if you can, please return here to share your index.

[smithdoor]

This may help
Method 1 is easy to do.
Method 2 works well.
Method 3 works well.

Note: since the wire feed uses a scr do not try a pure DC or power feed will run at full speed.

Diagram shows add a heavy duty power relay to last for ever.

Dave

[jjnitzh]

"Method 2" above is the best configuration.
You want the Cap to smooth the supplied voltage to the inductor so that the inductor can do it's job better.
Think of the inductor as a flywheel. It keeps the current flowing despite changes in the voltage, and varying distance between the end of the wire and the workpiece.
Without the capacitor the power supplied to the inductor goes to zero 120 times a second. The capacitor fills those gaps meaning the inductor has much less work to do and consequently does a better job of steadying the welding current.

Putting the Cap at 1, will result in the cap REDUCING the effectiveness of the inductor at keeping weld current constant and potentially subject the cap to dangerously high flyback voltages if the gun is pulled away from the work while power is on resulting in capacitor failure.

Putting the Cap at 3 results in an LC "Tank Circuit" which can introduce HF components into your welding and can again subject the cap to dangerously high voltages. It could also result in the cap being subjected to reverse polarity if the circuit starts resonating on arc start or stop which will destroy the cap fairly quickly.

1 and 3 both keep the capacitor in a circuit with the inductor when the arc between the outputs is removed. Not saying they won't work, but they are not optimal.
With configuration 2, the capacitor does not see flyback voltages created by the inductor, they are shunted through the rectifier.

Also, you will get better capacitor life from more smaller capacitors in parallel, than a single giant capacitor.
For instance 6 or 7 x 10,000 uf caps instead of a single 65000.
The smaller caps will have a higher ripple current capacity and heat up less resulting in longer life. They may also be easier to fit in your case.

[smithdoor]

Straight DC with SCR will lock on feeder full speed.
This can fix by putting the feeder wire be for all the capacitors

Dave

"Method 2" above is the best configuration.
You want the Cap to smooth the supplied voltage to the inductor so that the inductor can do it's job better.
Think of the inductor as a flywheel. It keeps the current flowing despite changes in the voltage, and varying distance between the end of the wire and the workpiece.
Without the capacitor the power supplied to the inductor goes to zero 120 times a second. The capacitor fills those gaps meaning the inductor has much less work to do and consequently does a better job of steadying the welding current.

Putting the Cap at 1, will result in the cap REDUCING the effectiveness of the inductor at keeping weld current constant and potentially subject the cap to dangerously high flyback voltages if the gun is pulled away from the work while power is on resulting in capacitor failure.

Putting the Cap at 3 results in an LC "Tank Circuit" which can introduce HF components into your welding and can again subject the cap to dangerously high voltages. It could also result in the cap being subjected to reverse polarity if the circuit starts resonating on arc start or stop which will destroy the cap fairly quickly.

1 and 3 both keep the capacitor in a circuit with the inductor when the arc between the outputs is removed. Not saying they won't work, but they are not optimal.
With configuration 2, the capacitor does not see flyback voltages created by the inductor, they are shunted through the rectifier.

Also, you will get better capacitor life from more smaller capacitors in parallel, than a single giant capacitor.
For instance 6 or 7 x 10,000 uf caps instead of a single 65000.
The smaller caps will have a higher ripple current capacity and heat up less resulting in longer life. They may also be easier to fit in your case.

[California]

In contrast to the sophisticated mods in this thread - My simplest improvement to my MIG-180 was simply a new wire feed roller wheel from Ebay/China.

I had thought that uneven feed speed was caused by the electronics. No, it was just poor traction on the wire, causing burnbacks into the tip. Or if the flux wire was crushed from too much tension it wouldn't feed through the tip at all.

I bough this welder used, and I suspect this feed problem was a frustration for its first owner. Replacing the original (?) feed roller was all it needed to make the welder work properly.

Like most anything from HF, 'Some Assembly Required' by the owner was what it needed to bring it up to spec.

[smithdoor]

The Harbor freight 170 uses the voltage from MIG transformer for feed rate.

Then feed rate goes up and down with welder voltage.

If you use straight DC the SCR would lock at full speed.

In contrast to the sophisticated mods in this thread - My simplest improvement to my MIG-180 was simply a new wire feed roller wheel from Ebay/China.

I had thought that uneven feed speed was caused by the electronics. No, it was just poor traction on the wire, causing burnbacks into the tip. Or if the flux wire was crushed from too much tension it wouldn't feed through the tip at all.

I bough this welder used, and I suspect this feed problem was a frustration for its first owner. Replacing the original (?) feed roller was all it needed to make the welder work properly.

Like most anything from HF, 'Some Assembly Required' by the owner was what it needed to bring it up to spec.

[Artimust13]

Hey I have a 131 and my lil toddler ripped many cords out I got the schematics and think I got it but I can't understand the transformer wiring as the schematics don't make a whole lot of sense. // Can you take a few detailed pics of the switch wiring and send them to me . I have a 1996 version if that's what you have . It' says on the bottom of the bridge rec. artimust0ne@gmail.com .. (the 0 is a zero)

Since then I've done a 131 and helped do a Hobart 125.

I used a spare liner from my Miller Cricket, cut to length.
I made the new spindle so that a Lincoln M15445 reel adapter would fit it.
Some 2amp diodes will drop the speed with plenty of safety margin

If I was to guess, I would say I gained about 25% more amps on the high range,but I never measured it before the changes .
The capacitor totally changes the way it sounds and welds.[/QUOTE]

[Foxhole]

I know this thread is as old as dirt. Is there anyway to open the pictures that were originally attached?
Thanks

[smithdoor]

I do not know but I have a 170 witch very close to the 151.
What are you looking for ?

Dave

I know this thread is as old as dirt. Is there anyway to open the pictures that were originally attached?
Thanks

[California]

I know this thread is as old as dirt. Is there anyway to open the pictures that were originally attached?
Thanks

Keep digging around in the thread, and similar threads. As I recall the original photos were hosted on a free site that went to pay and deleted them. Then years later somebody re-posted some of them from his own copies. Maybe not in the same thread.

I bought a heavily upgraded HF MIG-180 and found that the prior owner had documented his efforts as comments in one of these 151 upgrade threads, as he applied mods he found there.

Just ask, what you need to know. Some of those original posters still respond occasionally in this and the other 'HF modify' threads.

HF's more recent models work as expected and don't need mods so this HF sub-forum isn't as active as it once was. I'm not sure its worthwhile upgrading a 151 today with so many cheap welders on Amazon. One from there plus the $30 Amazon 3 year warranty might be cheaper overall compared to upgrading a 20 year old HF that was built cheap to start with.

[California]

I know this thread is as old as dirt. Is there anyway to open the pictures that were originally attached?

Mobius found the solution and I summarized it in post #838, above:

=====

"WeldingWeb moved to Amazon web storage a couple of years ago. So the url's for old photos have the wrong location prefix ahead of the specific image name.
Here's a workaround. Mobes posted it in Post #818, above. Thanks Mobes! In his words:

"try replacing "http://www.1jz.com" with "https://s3-us-west-2.amazonaws.com/mobes-photos/1jz.com" in the image URL."

It's PIA to update the url for each image but this works.

=====

(See #838 for more details).

[California]

Mobius found the solution and I summarized it in post #838, above:

Bah. That worked last time I tried it. Now, no.

[smithdoor]

I think the biggest problem with Chicago welder is with light duty switches and rectified Chicago used.
Adding capacitors improves the weld.
The transformer is very good from calculations I did.
The wire feed is OK and be upgraded.

Dave

Bah. That worked last time I tried it. Now, no.