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PostPosted: 19 Oct 2014, 00:50 
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Joined: 19 Oct 2014, 00:45
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Hello everyone,

I have a problem with a preamp. The thing is, when I try to turn on my preamp it does not, but if I let it connected to energy sometimes start. Seems like magic, so I checked the circuit and a capacitor located at the power stage (2200 uF 42 V) seems a little fluffy, so I think I would maybe the cause of the problem, but I rather ask here first instead of go right away and replace it. Any thoughts?

Thank you!


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PostPosted: 19 Oct 2014, 11:05 
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Joined: 06 Apr 2009, 10:08
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Location: US Pacific Northwest
Without a preamp model number and a schematic, it is very difficult to say. Could you give us a little more information to go on? Is this a solid state or vacuum tube unit? Is it a home built unit, a kit, or a commercial unit? Do you have a schematic you could post? And when you say that the capacitor is "fluffy", what exactly do you mean by that? A bad component could be a cause, or it could be just a symptom of a different problem.

As much information as you can provide will really help in getting an answer to your question.

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PostPosted: 19 Oct 2014, 11:29 
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My preamp is a Yamaha CX-600 and by fluffy I mean swollen, it has 2 capacitors in the power stage just after the diod bridge http://imgur.com/7DximyC I've check continuity in all parts of the circuit at it seems it has.


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PostPosted: 19 Oct 2014, 19:20 
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Joined: 12 Mar 2013, 06:07
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Location: Thunder Bay On.
If there "fluffy" replace them that may or may not solve you problem but it will defiantly solve a future problem


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PostPosted: 19 Oct 2014, 20:13 
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Location: Arizona, USA
Hi, Check for a start up delay relay or some sort of cold start up circuit. It might not be activating immediately and after a while functions. Often a capacitor is used as part of a timing circuit and if it has become defective it may not charge up properly activate the rest of the circuit. Also look for a loose fuse. I have seen them behave like you mention.

Good listening
Bruce

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PostPosted: 19 Oct 2014, 23:49 
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Location: Chilliwack, BC
Preamps of that age with one or two bad caps is a sure sign more are gone or going. Just do a recap and enjoy the awesome sound! :D

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PostPosted: 21 Oct 2014, 23:05 
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Location: South East US - Tennessee
do any of the indicators light up when you press the power on?

"fat" capacitors should be replaced in any case.

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