Anything post power transformer that can cause it to hum / buzz?

loomis · 22nd March 2006, 06:20 AM

Hello.

In an old tube integrated amplifier, are there any components after the power transformer that could be bad and cause it to hum? In other words, can bad caps / tubes etc cause the tranny to hum?

You can hear the hum within 2 feet of the transformer. There is no hum out of the speakers. The amp is wired correctly.

Transformer hum occurs no matter where amp is plugged in: at home, work, friend's house, ect. Transformer bolts are tight.

Or is this a case where the windings are bad and that's all there is to it?

Thanks

lndm · 22nd March 2006, 08:12 AM

Large current swings translate to large magnetic flux and this means flexing of the xfmr laminations.

I don't know if this is your issue, but leaky electro's could be causing it. If your amp is old, replace them anyway.

loomis · 22nd March 2006, 10:33 PM

You see I am trying to determine if the transformer is bad *before* I waste money buying replacement parts. If there is no possibility of new caps etc fixing a humming tranny then I won't bother. Instead I'll look into the loose lamination issue.

Nordic · 23rd March 2006, 04:54 AM

Tried disconnecting the secondaries and just powering it up yet?

ivegotmono · 23rd March 2006, 10:39 AM

I've got an Eico HF-81 and the power transformer hums for a little while after it's turned on but then goes away as the caps charge up. I've been told that the original power transformers on those were undersized. I had a HF12 that vibrated all the time and it was the rectifier tube going bad.
Steve

ray_moth · 24th March 2006, 02:55 AM

Yes, a heavy load on the secondary can cause a buzz in the power transformer core. As the man says, check your elecrolytic smoothing caps, and anything else that could be causing excessive current drain.

loomis · 24th March 2006, 05:25 PM

Sounds like a plan. Will check out electrolytics and rectifier tube. Thanks.

22nd March 2006, 06:20 AM	#1
loomis diyAudio Member Join Date: Nov 2002 Location: Akron	Anything post power transformer that can cause it to hum / buzz? Hello. In an old tube integrated amplifier, are there any components after the power transformer that could be bad and cause it to hum? In other words, can bad caps / tubes etc cause the tranny to hum? You can hear the hum within 2 feet of the transformer. There is no hum out of the speakers. The amp is wired correctly. Transformer hum occurs no matter where amp is plugged in: at home, work, friend's house, ect. Transformer bolts are tight. Or is this a case where the windings are bad and that's all there is to it? Thanks

23rd March 2006, 10:39 AM	#5
ivegotmono diyAudio Member Join Date: Nov 2005 Location: maryland	I've got an Eico HF-81 and the power transformer hums for a little while after it's turned on but then goes away as the caps charge up. I've been told that the original power transformers on those were undersized. I had a HF12 that vibrated all the time and it was the rectifier tube going bad. Steve __________________ steve

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22nd March 2006, 08:12 AM	#2
lndm diyAudio Member Join Date: Mar 2006 Location: nsw	Large current swings translate to large magnetic flux and this means flexing of the xfmr laminations. I don't know if this is your issue, but leaky electro's could be causing it. If your amp is old, replace them anyway.

22nd March 2006, 10:33 PM	#3
loomis diyAudio Member Join Date: Nov 2002 Location: Akron	You see I am trying to determine if the transformer is bad before I waste money buying replacement parts. If there is no possibility of new caps etc fixing a humming tranny then I won't bother. Instead I'll look into the loose lamination issue.

23rd March 2006, 04:54 AM	#4
Nordic diyAudio Member Join Date: Sep 2005	Tried disconnecting the secondaries and just powering it up yet?

24th March 2006, 02:55 AM	#6
ray_moth diyAudio Moderator Emeritus Join Date: Jan 2004 Location: Jakarta	Yes, a heavy load on the secondary can cause a buzz in the power transformer core. As the man says, check your elecrolytic smoothing caps, and anything else that could be causing excessive current drain.

24th March 2006, 05:25 PM	#7
loomis diyAudio Member Join Date: Nov 2002 Location: Akron	Sounds like a plan. Will check out electrolytics and rectifier tube. Thanks.