How to Mount Power Transformer on Chassis?

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RJ Guitars
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Re: How to Mount Power Transformer on Chassis?

Post by RJ Guitars »

I am following to some extent part but I really need a picture... rj
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overtone
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Re: How to Mount Power Transformer on Chassis?

Post by overtone »

Yes, a photo or two will really help to see what your situation is, length of bolts, etc.

Your question touches on some of the points in your last thread about how to ground Bassman transformers. Usually I would expect to see four isolating shoulder washers at each end on this type of PT. It is a simple way for the manufacturer to ensure that the long bolts that tighten the laminations together do not touch or damage the lamination cores. Below is a picture of this type, the thin shaft goes inside to center the bolt. Is this what you have?

You should use them, if they are there.
Either a) just drop in and add four extra bolts and toothed washers inside the chassis, or b) drop in the PT with the laminations flat to the chassis and remount the isolating washer and original nuts on the inside. You may need larger holes for the shoulder washers.

Two further notes that may apply:
I use as large a washer as possible inside to spread the load at each fixing point.
I would really prefer to ground the PT to the chassis if it was electrically "floating".

Hope this helps some, it was a good question.
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The New Steve H
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Re: How to Mount Power Transformer on Chassis?

Post by The New Steve H »

I guess I should fire it up the way it is and see if there are any problems.
Relax. It's SUPPOSED to smoke a little.
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overtone
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Re: How to Mount Power Transformer on Chassis?

Post by overtone »

The New Steve H wrote:I guess I should fire it up the way it is and see if there are any problems.
Have you rigged up a light bulb current limiter?
You can probably build it out of parts you have lying around or for next to nothing. Most of us use them when firing up.
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The New Steve H
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Re: How to Mount Power Transformer on Chassis?

Post by The New Steve H »

No. Sounds like a great idea. But in this instance I just meant checking for noise, so I would have to connect a cabinet.
Relax. It's SUPPOSED to smoke a little.
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The New Steve H
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Re: How to Mount Power Transformer on Chassis?

Post by The New Steve H »

Someone asked if I have 4 insulating doodads on my screws. I only have three. The fourth screw is uninsulated, and it's pretty clear that they did it that way on purpose. I guess I could rig my chassis up so the fourth screw and nut don't touch any metal, but I think the smart thing is to see how noisy the amp is before going to all that trouble.
Relax. It's SUPPOSED to smoke a little.
diagrammatiks
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Re: How to Mount Power Transformer on Chassis?

Post by diagrammatiks »

they used to hang a lug off of one of the screws and attach the center tap there.
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The New Steve H
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Re: How to Mount Power Transformer on Chassis?

Post by The New Steve H »

I am seriously starting to think someone should take this away from me.

I was putting the components on the eyelet board, and I could not find my 47nF capacitors. I actually went and bought one. Then I got home and found I had .047 uF jobs, which were the same as 47nF. Then I realized I had read the schematic wrong when I was making the parts list, and I actually needed a 47pF. Then my head started to hurt because I forgot whether pico was bigger than nano, and I had to look it up.

Now I just want to have a beer.

Anyway, the board is ready to solder, except for one capacitor. But I have this nagging question in the back of my mind: did I put 100 ohm resistors in my other amp, where it was supposed to have 100K?
Relax. It's SUPPOSED to smoke a little.
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M Fowler
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Re: How to Mount Power Transformer on Chassis?

Post by M Fowler »

Slow down and make this enjoyable build :lol:
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The New Steve H
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Re: How to Mount Power Transformer on Chassis?

Post by The New Steve H »

If I went any slower, I would actually be taking the amp apart!
Relax. It's SUPPOSED to smoke a little.
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RJ Guitars
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Re: How to Mount Power Transformer on Chassis?

Post by RJ Guitars »

The New Steve H wrote:If I went any slower, I would actually be taking the amp apart!
I laughed hard at that... because I can relate so well! :lol: :lol: :lol: :lol:
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The New Steve H
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Re: How to Mount Power Transformer on Chassis?

Post by The New Steve H »

It's my own fault. The soldering and screwing takes an hour, but because I'm too cheap to buy prefab cabinets and chassis, the other stuff takes 10 years.
Relax. It's SUPPOSED to smoke a little.
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