‘Delaminated’ Transformer

[Stefen7]

(Continuation of previous post: “Overheated Transformer or Failed Power Factor Capacitor, Diagnose & Repair,” in case someone else is researching info on a transformer that ‘delaminated’ not overheated.) Unit is 1954 Miller 61F.

The case has been opened! It is the transformer. Now the question, it is repairable or junk?

The capacitor seems to have leaked a little bit, but I was going to disconnect it anyway.

Thankfully, except for some dirt, the two copper transformer coils look perfect. No melted insulating varnish or other signs of overheating. No visible signs of arcing. I will clean and thoroughly inspect every part of the wiring, if the unit is repairable, but it all looks good so far.


Part of the iron core has ‘delaminated’ because the fabric tape holding it together has become brittle. Just bending a piece 180* causes it to break. One photo shows all the tape down the side just snapped. On the other side, it has completely fallen off. That has caused two pieces of the outer layer to detach on one end, and the plates on the other layers to bulge out a bit.

The top, bottom, and center area (the part surrounded by the copper core), are held in place by the frame and have not delaminated. It is the two outer ‘posts,’ that are only clamped in place at the top and bottom, relying on the tape to compress the layers, that have delaminated.

There is no evidence the pieces that detached contacted anything carrying current and caused a short.


This may be wishful thinking…. If they were only held in place with tape to begin with, would wrapping them with tape again repair the problem?

I know it is not as simple as wrapping with electrical tape and flipping the switch. But I am willing to put some effort into repair, if it’s possible. The 61F is very good quality, and an interesting piece of Miller history. It supposedly has a very smooth arc and would be worth repairing.

I am posting photos of the major parts. I do have higher resolution versions if needed, but these ones may give enough details of the problem.

I really appreciate your help.
Stefen.

[Stefen7]

1a Delaminated Side

1b Delaminated Base: Close-up of the base of photo 1.

There is a small bulge in a few of the outer plates, that may be permanent. On the left hand side, in the dark section, just below the lighter section. That shadow line. But it is only a few plates on a huge transformer carrying only 180 Amps.

[Stefen7]

2a Delaminated Side: The other side, showing the tape just became brittle and broke, causing the plates to separate.

3a Top of Iron Core Layers: Everything at the top and bottom is holding together nicely.

[Stefen7]

4a Primary Coil: No sign of overheating or arcing.

4b Secondary Coil: No sign of overheating or arcing.

[Aeronca41]

Stefen, that thing looks wonderful! That delamination is inconsequential. While the tape helps a small amount with functionality (holding the laminations tightly together increases the magnetic flux density), its primary purpose is most likely noise suppression. Those laminations will set up quite a ruckus banging into each other 120 times per second. Look for a motor winding type of Fiberglas tape made to work in a warm electrical environment. I would not use anything like electrical tape, duct tape etc. It will just turn into a sticky mess and fall off. Some old fashioned electrical friction tape (the cloth stuff-looks like what you use to wrap sporting eqpt grips) might work, but fiberglass would be better, but probably not cheap. Check with a motor rewinding shop. If there is nothing in your area, let me know and I'll check with Mr Hurlbert (80-something) who runs a shop about a half mile from my house. (Just a delightful old place with motors and power tools stacked to the roof. I will be lost when he finally calls it quits.)

I think another alternative might be just buy a bag of very large thick ty-wraps, provided there is clearance for the moving coil, but it wouldn't look very authentic.

By the looks of the coils, I'm quite optimistic you found a winner!

[Stefen7]

Thank you Aeronca41 for that information. From my limited knowledge of transformers, I thought it could be repaired, unlike a melted coil.

I will start with the ty-wraps for the initial check to make sure everything else is working. I'll look for the tape, properly restore the handle, and the other cosmetic things, if it works.

In theory, the noise would have been the reason it was taken out of service and attempted to be opened. If the coils look OK, they probably were not overheated, so I should not be overly worried about a shorted coil and all those problems when I power it up?

I will continue with the cleaning and inspection of all electrical parts, and disconnect the PFC.
Clean and lubricate the transformer jack screw and guides.
Put the cover back on, (just in case).
Set the transformer to its lowest setting and turn it on, (with my wife ready to throw the breaker in the house if necessary).
If nothing bad happens, crank the transformer to its highest setting.

At that point is there anything I really need to do, or just plug in the leads and see if it welds?


Hopefully I can find the time to get everything done and test it this weekend.

I sincerely thank you for all your help.
Stefen.

[Aeronca41]

Your planning sounds good. Those coils look pristine from the pictures. So long as all the connections are tight, I think this thing is going to weld just fine. This is a really cool project!

[Stefen7]

Thank you again for your help. I will post the results once it is powered up.

Stefen.

[Aeronca41]

Glad to help. Nice to see someone bringing back an old dinosaur. Looking forward to a very successful result!

[Aeronca41]

Stefen-any progress on the dinosaur?

[cruizer]

I use the metal binding strap for pallets to hold the steel laminations together on old machines.

[Aeronca41]

Great tip. Thanks.

[Stefen7]

Aeronca41, I saw the post asking about progress, but I’ve been swamped (almost literally). Winter will be here soon, and hurricanes are here NOW. My house is OK, but I’ve been helping others who were not so fortunate.

I did post a note awhile ago on Ryan’s ‘Helga’ thread. But I guess that’s the irony. Marvin is not as ‘se_xy’ as Helga, but not as temperamental either. A tough little soldier rescued from the scrap heap, a relatively quick and simple fix, then continue welding for another 50 years.


I named the little guy Marvin, after the very capable, but under-appreciated and therefore chronically depressed robot in Hitchhikers’ Guide to the Galaxy by Douglas Adams. Worn, scarred and dented, he looks like he is sad. But he is still very capable, if someone would just put a little effort into fixing him.


He started life doing maintenance in a large bakery, and then had at least 2 other owners before me. At some point the tape let go on the iron core laminations, and he was declared broken. Someone tried to remove the handle on top, without any regard for what damage they were doing to the welder in the process of trying to repair it. (Dumb).

I saw the ad with a photo of a grimy old welder shoved in the corner of a dirty shed with a bunch of junk. I thought if the price was cheap enough I might look at it. Then you told me it was an interesting welder from the 1950’s, and posted the link to someone else’s restoration project. I showed my wife the photos of the restored welder and she thought it looked interesting. (That is important as I need her help to move and restore it). At that point emotion began to overtake logic and I wanted to save it from the scrap pile.


It only took me a few hours with a drill to get the handle off and open him up. A shop-vac and toothbrush to clean the insides; inspect the wiring; clean the electrical contacts; Ty-wraps on the iron core; and he was ready to weld. Someone with more experience and proper tools could have had him running in an afternoon.

Unfortunately all of that work took longer on my part, because I did not have the knowledge of what was wrong or how to fix it. For example, I missed an entire sunny weekend because, despite what the person behind the counter said, a NEMA 6-50 plug will not fit in a NEMA 14-50 outlet. Back to the city on Monday morning to pick up the correct plug, etc….

I do not have a garage yet, and (unlike a similar amp Thunderbolt) at almost 300 lbs he is too heavy to carry up the stairs into my house, so he is in a storage unit. The tiny wheels he is on do not roll straight on my trailer’s loading ramps, so it takes 2 people to winch him on / off. I work nights, my wife works days, so we need a weekend that is sunny so I can set up a welder in the driveway.

Unfortunately, there are so many other thing that need to be done now, practicing my welding skills has been put off until later. I just needed to know he worked, so I could stop searching the sale ads.


I only have experience with ‘big’ DC welders in college, so I did not know what a small AC unit would weld like. Using 1/8” 6013 (80 to 130 amps recommended), I set it for 100 amps, (max in low-range), and struck an arc. The electrode basically exploded with huge globs of spatter, and nothing resembling a bead, just a few ugly globs on the base metal. I thought, “aw nuts, it’s junk, or else AC is terrible.” But I just kept dialing the amps down and trying to run a bead. Finally around 65 to 70 amps, it settled down to a nice ‘crackle’ and laid a decent bead.

I also tried high-range with 5/32” 6013, and they ran well. Started nicely, even with the low OCV.

Because of the low OCV (55 volt) in high-range, the manual recommends running Low-Hydrogen and other ‘difficult’ rods only in low-range (80 volt OCV). The LWS was out of 3/32” 7018 AC, so I was not able to try them. I hope they work well, since that will be my primary electrode.


I still need to disassemble the entire transformer jack-screw unit. The previous owner’s attempt to pound out the cross-pin on the handle, knocked the jack-screw base out of its socket. Then find a solution to replace the rusted cross-pin, and repair the mangled top handle. (Yes, I know a set of vise-grips on the jack-screw would solve both problems, but the little guy deserves better).

I also need to lift a 250 lb transformer, with no top lifting loop, to remove the wheeled cart he is sitting on. Then build a new cart, with better wheels that will roll across gravel and up the loading ramps on my trailer.

Too many other urgent projects to finish before winter, so all of this will wait until spring. Once I have the cart built, and a fresh coat of paint on him, I’ll update all (one) of you on the project.


For anyone else considering restoring a 61 or 88, it is reasonably quick and simple, and definitely worthwhile.

Thank you again Aeronca41 for your help.

[Stefen7]

I use the metal binding strap for pallets to hold the steel laminations together on old machines.

Cruizer, thank you for the tip. I used the really thick black cable ties, and they worked reasonably well. But it was impossible to get them really tight around the four 90* corners of the posts.

I looked for flexible stainless steel cable ties, but they were only available in packs of 100, for $715. (ummm, forget repairing an old 61F, I could buy a used Dialarc for that…).

[Aeronca41]

Stefen, glad you survived the storms OK. I am completely with you on winter! Much to do, and days are getting cooler and shorter-I am not ready! Keep us posted when Marvin wakes up from hibernation!