Cutting, drilling, mounting etc. for the absolute beginner

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#462
Bondo it is...

The complete package seems to run at the same temp as the exposed trans did (judging by feel).

I cannot claim that this will work with a hot running setup (yet), but the stuff seems to be a pretty good conduit of heat.

I'm now wondering if mixing AL shavings ( I make 'em myself!!)with it will provide EMF sheilding. I'm a big fan of separate PSUs, it makes a big difference with my other gear (class A), but my GCs seem impervious. Might try it someday, all in one case...

Still working fine...

E
 
#467
Just occured to me...

I test for EMF by using a compass (strength, by distance before effect) and a small neo magnet (held lightly between forefinger and thumb, it vibrates. You can move it around the trans, and "see" the shape of the field).

Here's the thinking... Wrap the trans in plastic wrap (electric insulator), then AL foil, then imbed.

I'll mess around with this, and report back.

E

Edit: M, just caught your post (slow typist here). Sounds reasonable to me.
 
#470
The household wrap is not going to change the fact that you get a shorted turn. Its the same reason why torriodals are allways mounted with a bolt through the center. If you connect the head of that bolt to the chassis....youll get a shorted turn as well. I have never tried that myself, but rumors says that its quite a beautifull show of fireworks 🙂

Magura🙂
 
#473
Question! I builded a chassis almost exactly like Peter's amp 2 and I get a short turn. In Peter's design there is a ac inlet seperate the transformer form the chassis wall, but my design have nothing between the chassis wall and the transformer and the chassis wall is tightly against pushing the transformer toward the heatsink. So there is not room like the pic suggested in here post #4 . Then how can I elimate the short turn without changing the chassis? (It had been 5 weeks hardwork and $80 value on materials)

Second questions, I had a bolt mounted from one chassis to the big Avel transformer's iron washer, and then connecting another bolt to the other side of the chassis wall. Will I elimate the short turn if I don't connect that extra bolt? If so what do you think I shoud add to fill in that hole?

Third questions, I recently had a short with the chassis and the transformer. After I saw the spike I turned the amp off immidiately. Do you think my transformer will survire? and what kind of materials should I use to add and extra warp around the transformer? - black electronical tape...etc? Plz help !!!
 
#474
If you won't be using that bolt (through center of transformer and chassis), you will not get a short. A bolt and a chassis creates a closed loop that goes around the transformer's core and this generates heat.

You could use some sord of rubber to isolate transformer form chassis. That's what Plitron is using.

Your transformer might be still fine. Just plug it in and see, don't come too close though😉
 
#476
Magura said:
The household wrap is not going to change the fact that you get a shorted turn. Its the same reason why torriodals are allways mounted with a bolt through the center. If you connect the head of that bolt to the chassis....youll get a shorted turn as well. I have never tried that myself, but rumors says that its quite a beautifull show of fireworks 🙂

Magura🙂
Click to expand...

I presume we are talking here about potting transformers using aluminum shaving as filler. As long as your potting material won't go through the center of toroid, or it will go, but you won't cover with potting compund the top part of transformer (in order not to close the loop), you will be OK.
 
#478
need help too...

Is it sonically better to place the diodes in the separate PSU? Many I have seen are built this way, but all my PS gear has the diodes mounted in the amp cases, and AC going in.

The only case where I have no choice is the stereo mini.

Is this just another "six of one, half dozen of the other" situation?

Thanks,

E

Edit, again... Gotta learn to type faster...

Thanks, Peter. As usual. Again. For the millionth time...

😀
 
#480
Peter Daniel said:
As long as your potting material won't go through the center of toroid, or it will go, but you won't cover with potting compund the top part of transformer (in order not to close the loop), you will be OK.
Click to expand...

Yes! We're talking magnetic path here, it has nothing to do with electrical path/contact with the transformer. Besides, I would not think that the very loosely coupled bits of metal would provide much shielding--but they might improve the thermal conductivity.

Anyone have thermal data for Bondo? Their website has about squat beyond the MSDS. It is cheap and readily available, I might have to try this. I have been wanting to try out DIY potting but hadn't wanted to spring for mail-order chemicals.
 
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