Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Mason on January 11, 2022, 02:43:11 pm
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Hey yall, I've got a power transformer that got a little banged up in shipping. It's a Dagnall transformer that instead of having leads for the windings, has posts that quick connects attach to. Some of these posts have broken off, the quick-connect blade is still securely soldered to the winding, but the plastic post has broken. I'm looking to basically glue the posts back in place and want to know what to use. Will epoxy work? Or maybe silicone? Will just any non-conductive adhesive that can withstand a bit of heat work? Attached are a few pictures to give you a better idea, you can see some of the posts are broken/out of position.
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I would check first with a ohms meter if the windings are still good.
Looks like a delicate job to fix those terminals.
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It's definitely still good. I tested with a multimeter and then gave it a bit of power from a variac and the voltages check out.
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Dude, same thing happened to me. See here:
https://music-electronics-forum.com/forum/amplification/guitar-amps/maintenance-troubleshooting-repair/51012-marshall-what-were-you-thinking-shiipping-a-transformer-like-this
At first, I thought it was Marshall doing a terrible job packing. But after looking at it, I believe that it was a customs agent destroying the original packing, and just throwing a loose transformer back in the box with no packing material. It looks like they originally enclose it in a plastic bubble with a cardboard frame, which would have been totally fine had it not been destroyed.
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To the best of my knowledge, epoxy alone is non conductive provided it's not mixed with anything else. I would think you can safely use epoxy to re-secure the terminals in place. 30 minute epoxy is stronger than 5 minute epoxy. Maybe start with a little dot to secure, then a light build up of the surrounding area to build strength. I would suggest a little research with regards to using epoxy for this purpose. Then again you could reach out to the vendor and let them know your product arrived damaged and see if they will ship you a replacement.
G. Rees
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Picture is too poor to help .
I would use epoxy to hold the contact in place safely.
I would not use this terminal with a snap-on connector at all.
I would solder a wire to this terminal and take the other end of the wire to another terminal and use that one
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Gorilla All Purpose Epoxy Putty Stick (https://www.amazon.com/Gorilla-4242501-Epoxy-Putty/dp/B07PGKYF5X/)
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https://www.homedepot.com/b/Paint-Paint-Supplies-Epoxy-Epoxy-Resin/N-5yc1vZ2fkoqdb
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https://www.homedepot.com/b/Paint-Paint-Supplies-Epoxy-Epoxy-Resin/N-5yc1vZ2fkoqdb
This epoxy as well as JB Weld works fine too. BUT... it's runny and will flow all over the place before it cures. Best to use painter's tape to create a "dam" around the terminals to contain the epoxy while it cures. That's why I suggested the putty. It stays where you put it while it cures.
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https://www.homedepot.com/b/Paint-Paint-Supplies-Epoxy-Epoxy-Resin/N-5yc1vZ2fkoqdb
This epoxy as well as JB Weld works fine too. BUT... it's runny and will flow all over the place before it cures. Best to use painter's tape to create a "dam" around the terminals to contain the epoxy while it cures. That's why I suggested the putty. It stays where you put it while it cures.
You are right.
I work so many time with these "liquid " putty. Making a dam with painter tape is so easy for me. A 5 minutes epoxy with warm hair dryer will dry very fast
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Thanks for the suggestions y’all! I think I’ll give the putty a shot. Normally I would reach back out to the vendor, but this transformer had to come from Marshall and took over 2 months to arrive. I feel like it’d just be wasting time to try again and risk another botched delivery. I know the transformer works so I might as well live with it.
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I'm quite sure epoxy does not adhere well to all plastics (not sure, but it is either PVC or PE). Any chance you could identify/ask someone to identify the plastic? If epoxy doesn't bond well, you might have more luck with a solvent glue, "plastic glue" in some parts of the world, smells like acetone.
(Plastic welding?)
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I'm quite sure epoxy does not adhere well to all plastics (not sure, but it is either PVC or PE). Any chance you could identify/ask someone to identify the plastic? If epoxy doesn't bond well, you might have more luck with a solvent glue, "plastic glue" in some parts of the world, smells like acetone.
(Plastic welding?)
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Epoxy work on plastic. I use epoxy every where.
The secret is in the preparation of the surface to be glued
For any glue, the surface must be clean and not shiny; sandpaper must be used and it will stick
I don't know about the Gorilla epoxy, I always use liquid epoxy
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Dude, same thing happened to me. See here:
https://music-electronics-forum.com/forum/amplification/guitar-amps/maintenance-troubleshooting-repair/51012-marshall-what-were-you-thinking-shiipping-a-transformer-like-this
At first, I thought it was Marshall doing a terrible job packing. But after looking at it, I believe that it was a customs agent destroying the original packing, and just throwing a loose transformer back in the box with no packing material. It looks like they originally enclose it in a plastic bubble with a cardboard frame, which would have been totally fine had it not been destroyed.
Wow !