Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Blooze on July 01, 2024, 03:02:39 pm
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So I'm looking at the way I've done the safety earth ground in the few amps I've made and questioning whether I need to go back an change them.
I typically use a solder tab with a star washer under the bolt head and under the solder tab and double nut it or use a nyloc nut. The other end is soldered to an IEC terminal. My Vibrochamp was soldered to a ring terminal (not crimped and the whole neck of the tab was also soldered to the chassis) that was connected to one of the power transformer bolts. When I replaced the power cord I just reused the ring and used my star washer/bolt/nut combo and soldered the wire into the ring terminal (uncrimped).
I don't really have crimpers I'd trust for a ground connection (I have some ratcheting ones and a pair of Klein 1005's). Or maybe I don't trust my ability to crimp properly. I wish I could get premade pigtails with ring terminals in something other than 12 awg so it could be soldered to an IEC terminal.
What's you're preferred way to connect safety ground.
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I've found that crimp connectors can be soldered to.
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I use a ring terminal bolted to the chassis. I use either crimp or solder terminals, both seem fine.
I think soldering to the chassis is less secure than a bolt and a locknut. You can easily over engineer this basic safety item!
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I have always found it odd that some of the same folk who say "solder is not glue" also use a pool of solder on the chassis to secure the earth ground with no mechanical connection.
I drill a hole, remove the burrs, clean the area, and bolt down a solder terminal with a keps nut. I add no other grounds on that bolt. It's a good place for overkill.
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I have always found it odd that some of the same folk who say "solder is not glue" also use a pool of solder on the chassis to secure the earth ground with no mechanical connection.
I drill a hole, remove the burrs, clean the area, and bolt down a solder terminal with a keps nut. I add no other grounds on that bolt. It's a good place for overkill.
Thanks for describing how you do it. This is essentially what I have been doing, although I’m planning on using keps nuts in the future. I can’t get them locally unfortunately. I’ve never understood the crimping a ring on a wire and then soldering it to the IEC. I’m not sure I’d trust a crimp that wasn’t make with a calibrated high dollar crimper for this particular usage.
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Soldering to chassis is just horrible
I typically use a solder tab with a star washer under the bolt head and under the solder tab and double nut it or use a nyloc nut. The other end is soldered to an IEC terminal.
You're doing it exactly right.
Soldering to chassis is just horrible. You need a scrupulously clean surface, a huge iron, and the right kind of solder. It is not safety compliant (UL-60065) unless the wire is also clamped down in place, in which case you need screws anyway, so why bother with a soldered connection. Yuk. In fact, the standards are not clear about whether soldering to chassis is permissable at all, and when it comes to safety standards, if it's not definitely compliant you can bet it's not compliant. :laugh:
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I use a ring terminal bolted to the chassis. I use either crimp or solder terminals, both seem fine.
I think soldering to the chassis is less secure than a bolt and a locknut. You can easily over engineer this basic safety item!
A good solder is as solid or better than a bolt with locknut.
With a solder you can't forget to tightened the bolt or forget the lockwasher when working or servicing the amp
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With a solder you can't forget to tightened the bolt or forget the lockwasher when working or servicing the amp
Why would anyone ever unscrew the earth bond for servicing :w2:
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With a solder you can't forget to tightened the bolt or forget the lockwasher when working or servicing the amp
The best reason for making sure it is a dedicated connection. Regardless of the type of connection, the connection should be labeled as a safety electrical connection that should not be removed, IMO.
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Only solder to steel chassis. Solder will not work on aluminum.
The only reasons to ever remove the safety ground screw would be to replace a defective power cord or if the screw interferes with the removal of some other component (This should never be an issue).
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way to connect safety ground.
Step 1: tightly crimp the bare multi strand earth wire to a Crimping ring terminal (before applying any solder to the wire). It is important to establish a tight mechanical connection so if crimping with hand pliers, use big pliers to apply mega force, or use a crimping tool or a vice.
Step 2: once the crimp is mechanically tight, flow solder through - this will help maintain the electrical connection
Step 3: tightly bolt the ring terminal to the chassis with a dedicated screw bolt and locking nut or nut and spring washer.
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I've become a big fan of IEC power inlets, where the cord is completely removable for storage inside the amp. Bad cord? Replace it; three-prong cords are everywhere. Also, wired-in cords fastened to the cabinet have that 'tail' of cord that loops outward before it gets stuffed back inside the amp. Murphy has decreed that those tails will banged against walls and doorways at the rate of 7.43 times per gig.
I know, it ain't vintage, but ...
I use the ones with a 5mm fuse holder built in, and a holder for a spare. The plug itself covers the fuse area so the fuse cannot be removed without unplugging the power cord from the amp.
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Only solder to steel chassis. Solder will not work on aluminum.
The only reasons to ever remove the safety ground screw would be to replace a defective power cord or if the screw interferes with the removal of some other component (This should never be an issue).
I typically work with aluminum, so I’ve never even tried. I figured it would oxidize so quickly the the solder blob would pop off at some point.
What is your preferred method? I’m just curious as there are a handful of y’all that I know I’ll be getting correct advice on this and many other things. The help here is excellent.
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Solder lug (https://www.tubesandmore.com/products/solder-lug-6-or-8-hole-locking) and dedicated bolt with kep nut (https://www.tubesandmore.com/search/node/kep%20nut).
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From brazing, soldering and oxy/fuel welding I know that with a well made solder joint - the tensile strength of the joint is often stronger than the material. Keeping surfaces absolute clean before soldering is key.
Having said that, I usually drill and tap/thread the chassis (2mm aluminum) for ground bolts. I apply a tiny bit of Loctite and screw the bolt in from the underside of the chassis. Than I use a crimp ring connector (also soldering the cable), toothed washer, flat washer and a locking nut to secure the connection.
/Max
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Step 2: once the crimp is mechanically tight, flow solder through - this will help maintain the electrical connection
Note: solder should only be added if you doubt the quality of your crimping, e.g. you're doing it with pliars. With a proper crimp tool (of the correct size for the crimp terminal!) it should not be soldered, as this creates a point of fatigue in the wire.