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Post new topic Advice, please, about old 110v power transformer running hot
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Author Topic:  Advice, please, about old 110v power transformer running hot
Eric Philippsen


From:
Central Florida USA
Post  Posted 3 Jul 2017 6:28 am    
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I don't know the answer to this and was hoping someone could help.

I found an old (1954) Harmony H-20 Consolectric lap steel with a built-in amp in the case. The 3-tube amp is just a little thing - 5 watts at most. I replaced all the caps in it and checked everything else, It works fine now but its power transformer most definitely runs hot. I'm guessing that's because the wall voltage is around 122 while the amp was designed to run on 110 or so.

Short of using a Variac (which I have), is there an easy way modify the amp to see or get 110 volts? Put another way, is there any stepdown transformer, wal-wart, plug adaptor or that kind of thing that will do that?

Last, I know most older or vintage amps were built to see lower voltages. Now, most wall voltages are 120+. My experience is that it's usually not a problem but I'm guessing there is something made to help when 110 volts is desired.

Thanks in advance for your help.
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Glenn Demichele


From:
(20mi N of) Chicago Illinois, USA
Post  Posted 3 Jul 2017 7:52 am    
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You could put a light bulb in series with the power cord?
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Scott Duckworth


From:
Etowah, TN Western Foothills of the Smokies
Post  Posted 3 Jul 2017 11:13 am    
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A lot of time old transformer start to loose the coating and glue between the plates and start to vibrate, causing heat. May need to have the transformer rebuilt, or find a suitable replacement.
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Ivan Funk

 

From:
Hamburg Pennsylvania, USA
Post  Posted 3 Jul 2017 9:14 pm    
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That sounds like a cool little machine.
Can you post pictures just for fun?
I had a small 5watt amp where the power transformer was getting hot. I checked the B+ coming off the rectifier tube and it was too high. I don't know why. I replaced the rectifier tube and everything went back to working properly. Every thing else checked out good too.
I'm guessing you amp has a 5Y3 for a rectifier.
Did you try new tubes?
Does the transformer buzz or hum when powered on with no tubes in it?
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Lee Warren


From:
Nashville, Tennessee, USA
Post  Posted 4 Jul 2017 5:13 am    
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Eric, you could build/use one of these:

http://www.geofex.com/article_folders/vintvolt/vintvolt.htm
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