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H.H. Scott 222C power transformer temperature test

Blast

Blast

I Wanna Rock
Subscriber
I have been interested in the operating temperature of the power transformer's in my Scott gear. Especially, since I replaced a PT in my 2nd 222C.

So I decided to run a series of tests to see how hot one actually got. And what I might be able to do to control it.

I ran 4 tests. Here is the table. Next post will be the graph:

HH Scott 222C PT temp test table.JPG
 
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One of the reasons I did this test was because my line voltage at the house was over 120vac. But in the past two weeks the electric company changed out a transformer nearby. As you can see in the test my line voltage never got over 120vac during the test.

But, by dropping the AC line voltage 5 or 6 volts the B+ voltage comes closer in line with that of the voltages shown on the schematic.

And using a fan drops the outer temperature of the transformer by 10's of degrees.

Both of which suit me fine. :yes: Now, I will do a bias adjustment.
 
Blast said:
And using a fan drops the outer temperature of the transformer by 10's of degrees.

.
Click to expand...

Using a small pancake fan is such cheap insurance against heat buildup, I think everyone should use one on their tube gear. They are cheap, readily available at such vendors as Radio Shack, and almost noiseless. You can put a plug on it and plug it into one of the accessory outlets on your amp and it will come on when you turn on your amp.
 
Nicely done. I found similar results but never charted it all out. I feel with any real vintage stuff a bucking transformer really helps, and a fan is always cheap insurance.
John
 
Moving the air with a fan works exceptionally well, especially if the air doesn't have to fight its way through a wood/metal cabinet.

My temperature readings using a fan were at least 1/3 less than without using a fan.

. . Falcon
 
Real nice thread, tests were very well done, good useful information. Interesting that the bucking transformer without the fan did not lower the temperature very much--but of course helped with the voltages. Thanks for the info.
 
Bucking transformer and fan here on my Eico HF-81:

Voltages right in spec and PT much much cooler. I can even run it with cage on...

Patrice
 
A fan should only be used with an air filter , otherwise you coat the tubes with a blanket of dust which acts like insulation and hold the heat in .
If you live in a humid climate the heat keeps the mosture out , keep it too cool and it can't do that .
 
Temperate climate here in Québec, Canada.

I then assume it's not a problem, apart maybe moving dust on tubes. A little cleaning once in a while. All my integrated except one, have a fan behind.
 
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