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Post subject: 1975 Fender Twin Reverb
Posted: Sun Aug 07, 2011 2:34 am
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Hello,

I have just picked up a battered 75 twin reverb amp. It works but has had a hard life!
The reverb was not working but I have fixed that by turning the reverb tank upside down :lol: The springs were loose and touching the bottom of the case.

Anyway It sounds amazing, however it does seem to hum a fair old bit is this normal for an old amp or does it need a service?


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Sun Aug 07, 2011 2:53 am
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Hum ; lound or not ; change with volume control ? Yes ; probably tubes and / or 6L6 mismached or bad bias / balance

No; Filter capacitors to replace if hum is "loud"

Also those amp have bad wiring dress that can make noise


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Sun Aug 07, 2011 3:13 am
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The hum is quiet when the amp is on standby. When being used the hum comes through the speakers a bit louder. It does not get louder with volume just stays the same. Its not noticeable when playing.


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Sun Aug 07, 2011 3:53 am
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It look like your amp need a new filters capacitors to be quiet. I assume that "hum" is too loud.


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Sun Aug 07, 2011 9:58 am
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Likely, tired filter and/or biasing caps.

Replace with Sprague Atom's or F&T's. Avoid the cheap IC brand as if they were a bevy of IRS agents circling your home in anticipation of an audit!

:mrgreen:

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Sun Aug 07, 2011 1:01 pm
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It sounds like cap job time. It's a small investment for any vintage amp owner.


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Mon Aug 08, 2011 2:01 pm
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by caps do you guys mean the tubes? Sorry but not sure which components you mean?


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Mon Aug 08, 2011 2:18 pm
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Caps are capacitor , some electronic and dangerous part, inside your amp. To be done by amp tech or by some guy with good knowledge we have here in the forum.


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Mon Aug 08, 2011 2:46 pm
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The filter caps in a Twin Reverb are located beneath a metal "doghouse" on the top side of the chassis. Within it are five large electrolytic capacitors which filter out AC ripple current from the power supply's rectifier stage. DANGER! These caps often contain a lethal electric charge even with the amp switched off and unplugged. Those unfamiliar with them should refer all servicing to a qualified tech. A cap job should cost no more than $175 to $200 -- well worth the expense IMO.

HTH

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Mon Aug 08, 2011 4:08 pm
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Retroverbial ; you give always a good information with clarity ( good words ? ).


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Mon Aug 08, 2011 4:40 pm
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Mercí, mon amí.

8)

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Wed Aug 10, 2011 3:07 am
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Thanks very much guys for the help :D


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Wed Aug 10, 2011 1:05 pm
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Best of luck, Dan.

Don't hesitate to holler if you need further assistance.

8)

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1975 Fender Twin Reverb
Posted: Sun Aug 14, 2011 10:01 am
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Don't know where you live but I could help you out with thst if you're in the mid-atlantic area. I'm halfway between Philly and Baltimore. It's an easy job if you know what you're doing but absolutely positively right - it's VERY dangerous to both you and the amp poking around those voltages if you don't. I order most of my parts from MOJOTone, decent options, fair pricing, quick shipment, great customer service. Let me know, DB.


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