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Post subject: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Wed May 03, 2017 5:29 am
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Hi, I own a 75 Fender Twin SF and it has started to make a tapping noise similar to a helicopter when I release the standby. Although it does it with either input being used,ie normal or vibrato, it speeds up and slows down when using the speed knob of the vibrato. The tech that I have employed to fix it has found it a "tricky problem to solve" and now 5 weeks on, no solution. He says he's a licenced fender tech and works for a very reputable rehearsal space in Sydney. I know Fender have made many subtle changes to their amps through the years so each era presents its own set of problems. I guess my point is that I deperately want my amp working to full capacity again and wondered if anyone on here might be able to offer suggestions as to what it is, why its doing it and what needs to be done to fix it.. Suggestions or knowledge would be greatly appreciated. Many thanks


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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Wed May 03, 2017 4:00 pm
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It is not what we call a motorboating ? Check filter caps. I'm sure your tech check them ...

Is the amp is all original, no mods ?


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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Wed May 03, 2017 8:56 pm
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Daveyboy3 wrote:
..., it speeds up and slows down when using the speed knob of the vibrato ...


Sounds like the infamous "trem tick", common to many Fender amps with tremolo (wrongly called "vibrato"). You might do a google search for "trem tick", there are fixes.

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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Thu May 04, 2017 1:39 am
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shimmilou wrote:
Daveyboy3 wrote:
..., it speeds up and slows down when using the speed knob of the vibrato ...


Sounds like the infamous "trem tick", common to many Fender amps with tremolo (wrongly called "vibrato"). You might do a google search for "trem tick", there are fixes.


Daveyboy3 wrote ;
" The tech that I have employed to fix it has found it a "tricky problem to solve" and now 5 weeks on, no solution
" He says he's a licenced fender tech and works for a very reputable rehearsal space in Sydney"

:(

If shimilou is right. put a 0.022 mfd cap in parallel on the 100k resistor, the one is connected to the tremolo neon bulb.
I t will stop the "tick" .

To me is very far from a helicopter, more a metronome :lol:

It is a well know hint that every qualified tech must know.


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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Thu May 04, 2017 1:57 am
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One man's whop is another man's tick. :lol:

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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Thu May 04, 2017 2:17 am
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shimmilou wrote:
One man's whop is another man's tick. :lol:


A helicopter toy !


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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Mon May 08, 2017 7:53 pm
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stratele52 wrote:
shimmilou wrote:
One man's whop is another man's tick. :lol:


A helicopter toy !

Some pay good money for that. The TC Electronic Trinity pedal was basically a Hall of Fame reverb, but with two new reverb effects, one of which was a whirlybird echo.

Demo of that effect starts at 2:05:



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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Mon May 08, 2017 8:32 pm
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Just make sure you don't see the name Sikorsky or Piasecki anywhere in the amp.

But, seriously here's hoping the problem is found Daveyboy3.

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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Tue May 09, 2017 6:29 am
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Fender Strat Brat wrote:
Just make sure you don't see the name Sikorsky or Piasecki anywhere in the amp.

There's a reason why Telefunken's US office is located right next door too Kaman Aerosystems in Connecticut, just sayin.
Ride of the Valkyries always sounds better on funken valves.

That said, in my experience with electronics, oscillation problems can often be caused by bad caps that discharge themselves. Which can be a small pain to detect, because it doesn't happen until there's enough charge, so a multimeter might not pinpoint it. But is very cheap and easy to fix once you have located it.


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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Tue May 09, 2017 8:48 am
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arth1 wrote:
Fender Strat Brat wrote:
Just make sure you don't see the name Sikorsky or Piasecki anywhere in the amp.

There's a reason why Telefunken's US office is located right next door too Kaman Aerosystems in Connecticut, just sayin.
Ride of the Valkyries always sounds better on funken valves. . . .
:shock: I knew it. I knew it! Conspiracy! Conspiracy!

I bet my prankster chopper pilot cousin is behind this. His sister (also a prankster) plays a mean guitar, and his retirement from the Air Force makes him bored. :lol:
FSB

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Post subject: Re: 75 Fender Twin SF "Whop whop helicopter noise"
Posted: Sun May 28, 2017 2:59 pm
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Did the problem get resolved, Dave? If so, drop us a line to tell us how you made out.

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