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Post subject: Crackling and intermittent sound from Deluxe Reverb RI
Posted: Wed Dec 07, 2016 1:47 am
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Hi all,
yesterday I played my Deluxe Reverb RI beautifully, left it plugged in the main, switched off, didn't move it one inch.. today switched it back on and it doesn't work any more.
When guitar is plugged in (ON BOTH CHANNELS), sound comes out low volume and "chopped", stuttering, like a square wave-form random tremolo is on...
When guitar is unplugged I still hear crackling and popping sounds.
Any help for self-fixing/diagnosing, before I send it to a (hard-to-find-here) tech?
thanks a lot to everyone who'll share some insights
Andrea

ps: removed the back panel and rectifier tube glows much more than power tubes.. is this normal?


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Post subject: Re: Crackling and intermittent sound from Deluxe Reverb RI
Posted: Sat Dec 10, 2016 3:38 am
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Joined: Fri Feb 05, 2010 4:31 am
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Location: Province de Québec, Canada
Unplug and plug all tubes few time to clean contacts ; Amp switch OFF, and unplug from wall

Power supply issue ; broken solder ?
Check power tubes ?

Rectifier look normal.

Sorry amp must see a tech


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Post subject: Re: Crackling and intermittent sound from Deluxe Reverb RI
Posted: Sat Dec 10, 2016 9:38 am
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Joined: Thu Aug 07, 2014 3:25 pm
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That is an unusual symptom. It doesn't sound to me like a bad tube. The comparative glow has no significance.
Never the less, its time for you to learn the tube dance.
This is done with the back off and the amp turned on to a normal volume.
Start with the little tubes on the right.
First, thwack each tube with the back of your fingernail on its side.
You are looking for microphonic tubes here with loose parts inside. The sound from V1, V2, and V4 should be a little ringing. the other tubes should be quiet. If you hear crackling, or springy noises or see blue flashes, thats a problem that needs a replacement.
Second, pinch the tip of the preamp tubes and wirl it around in a 1/4 inch circle. This will expose bad tube contacts. A crackling tube should be rotated until it quiets down. If it won't quiet, inspect and clean the pins and sockets.
But getting back to your amp,,,,
If the amp was exposed to unusually cold weather, say in a winter basement, that is a likely time for a cold solder joint to break.
If this is the case,
Try putting the amp in a warm place and see if it improves.
If it does, it may be an indicator that the amp needs to be resoldered.
Spurious, random failures like this can oftern be attributed to lead-free solder used in modern amps.
It has caused a crisis of reliability in all amps produced with the ROHS compliant solder.
Its a similar situation when automakers were forced to use low VOC paints. Initially, it caused an epidemic of cars with peeling paint jobs.
While the solder requires more heat and more agressive fluxes, once properly done, it makes a superior bond.
Its just difficult to make it stick.
So when we techs hear about weird symptoms, we think bad solder.
I hope it works out for you. It is a great sounding amp.
The DRRI has a high frequency response of 35KHz, much higher than most except a Vox AC30. Both are nice, chimey amps.


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Post subject: Re: Crackling and intermittent sound from Deluxe Reverb RI
Posted: Sun Dec 11, 2016 2:37 pm
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Thanks a lot for helping me stratele52 & TimsAudio!
I've been out of town for a mini-tour and couldn't read nor try out your kind suggestions!
Will definitely do it asap though!
Since you took your time to share your advices, I'll update you on what happened after writing the original post.
I read somewhere that a broken PI tube could produce similar sonic "results". Since I had no spare 12aT7 at home but there are two 12aT7 in the Deluxe Reverb, I swapped them.. and the outcome was sonically completely different.
Gone was the "intermittent" chopped sound, replaced by a veeeery low volume from both channels.
Swapped them back and here comes the "intermittent" sound again.
I then started to suspect that one of the two tubes had to be "broken", possibly the PI one.
I read somewhere that it shouldn't harm the amp to replace a 12aT7 with a 12aX7 and since I had some spares at home, I did it.
The intermittent sound disappeared and I got back the Effect-less first channel in its full glory (and volume).
The "reverb" channel was still very-low gain though.
I then tried replacing the V2 (12aX7) with no result, and finally the V4 (channel two second stage) 12ax7.
This gave me back also the vibrato channel fully working!

So, when I left for the "tour", I had the amp back fully working... but I cannot shake the feeling something could still be wrong.
How could an amp perfectly working, lose two tubes in 24 hours with being moved nor used; just plugged in the mains? A power-surge from my home electric system???
I even checked the fuse (I once "fried" a Mesa Boogie because previous owner had replaced the fuse with another more "resistant" one) and found it's using a T1A instead of the fast one (F1A) suggested by Fender in the user manual. Not sure if this could somehow account for what happened... but I kinda doubt.
Sorry for making such a long story..
tomorrow I hope to start some more investigation based on your suggestions...
Thanks again!
Andrea


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Post subject: Re: Crackling and intermittent sound from Deluxe Reverb RI
Posted: Sun Dec 11, 2016 8:13 pm
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Joined: Fri Feb 06, 2015 10:21 pm
Posts: 393
Location: Oklahoma
malenky wrote:
Thanks a lot for helping me stratele52 & TimsAudio!
I've been out of town for a mini-tour and couldn't read nor try out your kind suggestions!
Will definitely do it asap though!
Since you took your time to share your advices, I'll update you on what happened after writing the original post.
I read somewhere that a broken PI tube could produce similar sonic "results". Since I had no spare 12aT7 at home but there are two 12aT7 in the Deluxe Reverb, I swapped them.. and the outcome was sonically completely different.
Gone was the "intermittent" chopped sound, replaced by a veeeery low volume from both channels.
Swapped them back and here comes the "intermittent" sound again.
I then started to suspect that one of the two tubes had to be "broken", possibly the PI one.
I read somewhere that it shouldn't harm the amp to replace a 12aT7 with a 12aX7 and since I had some spares at home, I did it.
The intermittent sound disappeared and I got back the Effect-less first channel in its full glory (and volume).
The "reverb" channel was still very-low gain though.
I then tried replacing the V2 (12aX7) with no result, and finally the V4 (channel two second stage) 12ax7.
This gave me back also the vibrato channel fully working!

So, when I left for the "tour", I had the amp back fully working... but I cannot shake the feeling something could still be wrong.
How could an amp perfectly working, lose two tubes in 24 hours with being moved nor used; just plugged in the mains? A power-surge from my home electric system???
I even checked the fuse (I once "fried" a Mesa Boogie because previous owner had replaced the fuse with another more "resistant" one) and found it's using a T1A instead of the fast one (F1A) suggested by Fender in the user manual. Not sure if this could somehow account for what happened... but I kinda doubt.
Sorry for making such a long story..
tomorrow I hope to start some more investigation based on your suggestions...
Thanks again!
Andrea
That's the exact problem I had with my new Twin Reverb a couple of years ago. The culprit was V4. All has been well after that.


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Post subject: Re: Crackling and intermittent sound from Deluxe Reverb RI
Posted: Sun Dec 11, 2016 11:14 pm
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Joined: Wed Mar 31, 2010 12:48 am
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Location: Tombstone Territory
Two dead tubes in a brand-new Fender amp while seemingly unusual thirty years ago is not uncommon today, especially given that nobody at the factory tests these products anymore before they're shipped to dealers -- they just box them up and send them to the loading dock. That so many of these defective or marginally-operating amps end up on the showroom floor at Guitar Circus is not surprising in the least. The situation is even worse among the mail-order retailers where nobody ever looks in the carton, let alone pull the product out and test it prior to sale.

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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