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Re: power transformer mounting screws

24.4.254.154

Posted by Paul Joppa on November 11, 2000 at 12:37:31

In Reply to: paramour problem: power transformer mounting screws too short posted by maldar on November 11, 2000 at 07:28:39:

I suspect Doc B's internet connection is still down, so he might not see these posts until it is back up. I'll take a shot here, but remember I don't have the parts at hand.

The transformer in the pictures was from the first test batch of 26 transformers, which had 2-inch screws that were way too long. It was especially difficult to get the nuts on due to the long, varnished threads, too long for most nut drivers. For the next batch, Hammond tried to meet our original spec a little closer using 1.5-inch screws. (I think - I have not seen a sample from the production lot, just a pre-production test sample.) My sample shows about 0.25 inch of free threads. What we really need is 1.625-inch screws, but that is an uncommon size.

The fiber washers also seem a little thicker than we used on the development prototypes - they appear to be 1/16 inch thick beyond the chassis; the first ones we tried were only 1/32.

If you look closely at the transformer (assuming the production versions are identical to the sample I have at hand) you will see that the transformer is already isolated from the screws with what appear to be nylon shoulder washers. That means that extra shoulder washers are not necessary, so you can mount the transformer directly into the chassis using only a lockwasher and nut. By leaving off the fiber shoulder washers, you will gain an extra 0.125 inch which should be just enough. This should make no difference in the operation or performance of the amplifier.

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