Fuse Holder Polarity?

The Ballzz

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In my frame of reference, I've always felt that anything bad that CAN happen and can easily be guarded against, probably should be! Always better to be safe than sorry!
Just My Take On It,
Gene
 

cometazzi

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And assuming a locking nut or two is involved, why wouldn't it be OK?

Using an existing screw saves a few cents on drilling a hole and installing a new one. As long as there's good electrical contact to the chassis, there's nothing wrong with it that has anything to do with engineering or safety.

Because the physical stresses on the chassis caused by weight and vibration of the transformer can cause the nut to come loose or otherwise compromise the integrity of the electrical connection.

I have seen vintage Fender amps (steel chassis mind you) where they used a PT bolt for power amp grounding point -- the blob of solder cracked and the keps nut loose.

Not worth saving a few cents IMO.

A *lot* of the amp safety stuff we discuss comes in different shades of better-osity. This is an example; our smart friend @dsutton24 mentions a couple more, but there are dozens. Bleed resistors, extra-long ground wire on power entry, loctite, star washers... dozens.

As King Fan says, maybe it's shades of better-osity. Maybe also I'm overthinking it, too. My thoughts:

1) The chassis will be subject to vibration, either while on stage bathed in band noise, or in a van being transported somewhere. The transformer is a big heavy lump of metal bolted to a (comparatively) less-heavy sheet of metal. They're hunkered down tight together, but all it takes is one nut to slip even a microscopic amount (see #2). The different masses will cause them to react differently to vibration (i.e., one moves more than the other) and that could loosen all nuts over time.

2) Heat Cycling: Transformers get hot. The pan will act like a heat sink to draw the heat out but it will usually be cooler than the transformer. When you turn the amp off they will cool at different rates, and if they are dissimilar metals they will also expand/contract at different rates. Again, mechanical forces that can loosen fasteners.

Another consideration with Heat Cycling is corrosion. Yes, the whole chassis gets warm during use, but the transformer usually gets much much warmer. Heat is a catalyst, especially with dissimilar metals. Corrosion can weaken the electrical connection, and eventually the metal parts and such.

3) It's more stuff you have to take apart if you need to work on one or the other. Obviously if you're replacing a power transformer you've got bigger problems. But you know... what if your cord gets run over by a forklift and you need to replace it, etc.

Some of my thoughts. Again, I'm probably off in the weeds on this one.
 




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