How to Fix Fender Twin Reverb Vibrato and Reverb Not Working

Neither the reverb nor the vibrato worked on this amp. The problems were not related. Follow me as I work my way through to a diagnosis and fix.

[@ferraridinoman]

Heavy swines!! Had one new in 1978 with the orange basket JBL speakers!!! (Still have the Fork lift!)

[@stuartukguitarampguy5830]

Yes crazy heavy!

[@Mark-ry3ij]

Great job sir! I've enjoyed watching the repair. Looking forward for more in the future.

[@SteverRob]

I’ve been futzing around with consumer electronics all my life. One thing I’ve learned (and your video is a shining example) in my decades of adventures is how often machines most often malfunction at the mechanical points that come in contact with humans. Switches, knobs, levers, RCA jacks 😀

[@stuartukguitarampguy5830]

So here's a plan how about... we just... ELIMINATE HUMANS! BWHAHAHAHAHA

[@charlielowe6608]

I have a fender twin reverb an I have changed tank an changed the tube with a 12ax7 an still have no reverb it clicks when I use foot switch an if you turn volume up you get a loud noise the tank cracks very loud when bumped an vibrato doesn’t work either any help would be appreciated

[@stuartukguitarampguy5830]

Very hard to diagnose over email of course. Reverb and vibrato are completely separate problems as I'm sure you know. If reverb makes sound like the crack of doom when you hit it, that means the RETURN from the reverb is working. So it's the send that is the problem. If you've swapped the tank, check the leads. Other than that, hard to say. Vibrato - common culrpit is the vibrato cell, try changing that.

[@waynewayne3709]

Full explanation of troubleshooting on amps...old school tech like us break things down in stages.. 👍👌👍

[@rheadelascy-wells6476]

I enjoyed this video; however wonder if you could help me with the normal side. Neither normal channel, 1 or 2 gives sound when I plug in the guitar. The original fault was a blown mains transformer. Replaced that, however other issues arose, I have changed out all tubes, changed the filter caps, re-tensioned the tubes seats. Still no sound, except I get 'static' on the lead alone. What have I missed?

[@stuartukguitarampguy5830]

Hi Hmm, sorry to say that could be a very large number of things which I couldn't diagnose over the internet. You'll need a tech to sort it out I'm afraid. Good luck.

[@consiquentialdiscernment]

Could you make a dedicated video explaining how to fix a non functional vibrato?

[@stuartukguitarampguy5830]

If I get one in I'll do that. It could be caused by quite a few things though.

[@cinemechanica75]

But in the normal channel does the reverb work or does it only work in the vibrato channel? in my twin work only in the vibrato channel. it's normal?

[@mikeratledgeguy]

the normal channel has no effects!

[@zombieflowers]

This is a peculiar question. I have a 76 Deluxe Reverb and the reverb will only activate if I crank it past 6. Anything between 1-5 and the reverb remains quiet. Turning the knob past 6 kicks it in at the 6 level. Any clue as to what it could be?

[@stuartukguitarampguy5830]

That's a really odd fault and I don;t have an idea of what that might be caused by, sorry. If it was in my workshop the first thing I would try would be a different reverb pan. I wonder if the pot could also be an issue?

[@zombieflowers]

@@stuartukguitarampguy5830 I was leaning towards pot issue as well. Thanks for the reply!

[@JavierrvcBodyBoulding]

I have a super ultra-linear reverb that out of nowhere the bass began to saturate at very low volumes on all channels, I set the bass to 2 so it doesn't saturate, do you know what it could be?

[@stuartukguitarampguy5830]

Hi Javier Sorry but that could be quite a few things. Do you have a tech near you?

[@JavierrvcBodyBoulding]

@@stuartukguitarampguy5830 more or less close, the Amplifier did not clip before, it started from nowhere, and the sound is not very satisfactory, also the vibrato does not work for me

[@goodun2974]

Using Right-angle RCA plugs for the connections at the back of the amp makes for improved reliability but not everyone will have good quality, well shielded right-angle RCA cables in stock. Normal RCA plugs stick out far enough that the cables and connectors get frayed and beat up if the amp gets laid on it's back in the van or tips over during transport.

[@stuartukguitarampguy5830]

Great tip, thanks. I always thought it was a bit naff the way they connect this at the back.

[@goodun2974]

@@stuartukguitarampguy5830 , if the shielded cables are in decent condition it's sometimes easiest to solder right-angle RCA plugs onto the existing cables. Otherwise, its a good idea to buy some long (3 or 4 meter) RCA cables with right-angle plugs on at least one end, and wire those up to the inside of the footswitch.

[@stuartukguitarampguy5830]

@@goodun2974 Great tip!

[@squidkid2]

I love the way tubes become valves when you transport them to the other side of the Atlantic.

[@stuartukguitarampguy5830]

No, no, no, you have that all wrong. Valves become TUBES when transported to the other side of the Atlantic!

[@birdsong2552]

Also, they become lamps once you cross the channel

[@ronnielobosmith4870]

Thank you so much!!! Going to get to looking at my twin reverb to troubleshoot!

[@JammyCrackcorn]

Stuart ukguitar…..I get a loud reverberation sound from my amp when moved….But I think I have a weak signal and I ohm-ed the returned ( I believe ) transducer which showed 191 ohms..( using 400 ohm on meter ) …The other transducer I think might be the problem….Is this the correct procedure?? If I get a loud reverberation when shaken ..is that the return signal I ohm-ed?

[@stuartukguitarampguy5830]

If you get a hideous loud clanging when you move the amp then the reverb return is working. It may be the send which is the problem. If the tank is faulty you'll almost certainly find one of the transducers is open circuit. Any other reading the tank is probably good. I would suspect the tank. 19/20 when I have a faulty reverb it's the tank.

[@victorramsey5575]

I have a Fender Princeton Chorus that the reverb isnt working. Its a solid state amp with a PCB. I took the tank out and inspected the wire connections. All look good so it must be the leads going to the board right? When I turn the reverb all the way up I hear a faint air sound in the speakers. When I unplugged the rca jacks, my touching the ends of the jacks makes noise. Any thoughts?

[@stuartukguitarampguy5830]

Sounds like the reverb tank itself? If you have a meter, measure the resistance of both of the spckets. If one is open circuit, that's your problem.

[@jorgemellooliveira9611]

ótimo vídeo congratulações

[@stuartukguitarampguy5830]

Obrigado, fico feliz que você tenha gostado

[@jorgemellooliveira9611]

@@stuartukguitarampguy5830 Eu que agradeço tenho alguns amplificadores valvulados eu faço a manutenção gostei de assistir o vídeo para aprender mais Jorge Sul do Brasil

[@felipemu7908]

Hello, I have a twing reverb and when I turn on the reverb, a noise sounds as if a cable was disconnected. When connecting the rca backwards and reconnecting them, the reverb returns but after a few days it fails again... what could it be, someone solved it? It will work by changing the rca cable for a new one...it's super strange...damn amp

[@stuartukguitarampguy5830]

Hi Felipe. I'm a bit confised. Does the reverb now work ok if you put a new RCA lead set in?

[@opiec8871]

Did a new valve correct the scratching sound? I just got very lucky and came into a ‘68 twin reverb silver face. It too has scratchy sounds along with the vibrato not working. I’ll use your tips to check it out. Thanks!

[@stuartukguitarampguy5830]

I can't remember tbh. It was a while ago.

[@Matan2222222]

Thanks for the Video! Do you have any suggestions about a weak reverb? Tried changing the reverb valve but it still very weak even on 6. I tried the same reverb tank in another fender amp and it sounds huge on 3. The amp that making problems is a 1964 Super Reverb. Do you have any suggestions on where to check inside the circuit for the weak reverb issue?

[@stuartukguitarampguy5830]

Hi Matan. Thats an odd one as you seem to have eliminated the tank and the vlave. Clutching at straws... Connecting leads? Reverb transformer? COuld also be another component (e.g. resistor etc) in the reverb circuit. Try to find out if it's the SEND signal or the return if possible.

[@stuartukguitarampguy5830]

Unplug the phono which is the RETURN from the tank. Instead plug a phono-phono lead into the amp. Touch the end of this lead with reverb turned up full. Really loud buzz? The return is probably ok. Not very loud? The return circuit may be at fault,.

[@Matan2222222]

@@stuartukguitarampguy5830 so I take the same cable that I use between the tank and the amp and plug one end to the return of the reverb on the amp and touch the other end(this end is disconnected right?) also, there anything connected to the reverb input on the amp?

[@stuartukguitarampguy5830]

@@Matan2222222 Hi The object is to see if it's the signal FROM the tank which is weak (not sure what you can do about it though!). To do this, if you can, unplug the phono lead at the tank end (signal coming FROM the tank), turn reverb up full, touch the end of this lead with your finger. You should hear a loud buzz. If it's loud, that shows the circuitry associated with receiving the recovered signal is ok. If this is ok (loud) connect everything back up then give the tank a hard thump. You should hear the 'clang of doom' coming out the speaker - e.g. really loud reverb spring noise. If this is weak, suspect the reverb tank. During all this, just leave the other cable (signal TO the tank) connected as it's not involved. If both test (touching and thumping) produce loud signals, suspect the SEND part of the ciruit or that part of the tank. But you said the tank was ok anyway?

[@Matan2222222]

@@stuartukguitarampguy5830 the tank is definitely ok. It’s working perfect and strong in my Vibroulx. What will be the next move if you were working on the amp ?

[@evankolpack]

The grumbling could also be a dirty pot. Thanks for the excellent video!

[@stuartukguitarampguy5830]

Cheers Evan.

[@tommyzhong]

This is helped me a lot. The problem with my reverb is that the reverb tank is broken/or the RCA cables were connected backwards by some idiot 🤣

[@stuartukguitarampguy5830]

Great well done Tommy

[@materiaisconstgeo]

Hi, I'm Gustavo, From Brazil! Excellent video! I have a Fender frontman 25R and the reverb doesn't work anymore. I've already checked the spring chamber and the wiring and found no defects. Is it possible that the problem is in the capacitor or even in the potentiometer?

[@stuartukguitarampguy5830]

Hi Gustavo. No almost certainly not. Are you 100% sure spring is ok? This is the most common problem. If it's connected by phono leads, unplug both at the reverb spring end. Now turn reverb up fulf and touch the centre of each of the phono plug pins. You should hear a loud hum/buzz - that's the return from the spring of course. If you don't hear that then it's not the spring. The 'send' to the spring is mnore difficult to test alas.

[@birdsong2552]

1:51 I'm afraid I disagree ;-)

[@stuartukguitarampguy5830]

What do you disagree about? All I'm doing is trying the amp at that point.

[@birdsong2552]

@@stuartukguitarampguy5830 I was just joking about it sounding "nice".

[@HoiPolloi]

Thanks for making this video. Just found it and also fixed the issue with my vibrato. It had not been working for a few weeks and it turns out it was the footswitch. Soldered up the broken wire and it's back up and running!

[@stuartukguitarampguy5830]

Well done. Nice one!

[@michaelevans3852]

Seems to be an easy fix. That's one of my favorite amps, however, I sold mine years ago because it was so loud. I now have a Pro Reverb which is loud as well, but breaks up at lower volume. My concert is similar, but much fuller in sound and without the reverb. Thanks again for an entertaining video.

[@stuartukguitarampguy5830]

Ok thanks Michael. The other thing about these amps is they are insanely heavy.

[@michaelevans3852]

@@stuartukguitarampguy5830 weight is a huge downside for me as I'm getting older.

[@j.dragon651]

My reverb works in my magnatone but as I turn it up it starts to hum. I get reverb and as I turn it up further the hum increases and it starts to get feedback from it? Since the circuitry is working I am tempted to believe it is the pot is bad. I shot it up with deoxit but no go. I am going to switch it out and see if that makes a difference.

[@stuartukguitarampguy5830]

Hi Jeroe Save yourself the trouble, it won;t be the pot. It's amazing reverbs work at all actually. You have that great big long lead snaking down to the reverb tank, picking up hum, then you massively amplifiy it! I'd look to the leads or the reverb tank itself.

[@j.dragon651]

@@stuartukguitarampguy5830 It is all original

[@sounddoctorin]

getting the stiff plastic off pedal i was hoping to find help on.....

[@sounddoctorin]

it may be new ones as i used to take old ones apart often

[@stuartukguitarampguy5830]

@@sounddoctorin Do you nean the plastic base on the foot pedal? Yes they can be tricky but usually come off with a bit of persuassion. Try heating with a hair drier.

[@sounddoctorin]

@@stuartukguitarampguy5830 yes thanks heating may do it. on scope i was only seeing max 20% signal variation. It's been so long.....that doesn''t seem enough. do you have spec. handy. it's in docs maybe

[@stuartukguitarampguy5830]

@@sounddoctorin Sorry didn;t understand your question about 20% signal variation.

[@sounddoctorin]

@@stuartukguitarampguy5830 on a scope you see eg. a 5v peak sine wave vary how much with max tremolo? The peak on this one doesn't even drop 20% which would be 4v peak on that 5v sine

[@byakuyakuchiki7464]

Great job! Very well explained, I was able to fix a problem with mine! Thanks

[@stuartukguitarampguy5830]

Excellent, that's why I do these vids!

[@stevescontriano860]

I have the remake issue of the 1965 twin reverb. My reverb cuts out. But if I hit it on the side it comes back in. Sometimes I have to lift it up An inch or two and then drop it on the ground to drop to kick it back in. Do you have any idea what could be wrong wrong

[@stuartukguitarampguy5830]

Thats almost certainly a loose connection issue. The first place to look is the actual reverb tank. The wires come unsoldered inside. See if you can narrow it down to that by just banging the tank, not the whole case. Failing that, for £1000 I can make a fooswitch controlled device which lifts the amp using a motor, then suddenly drops it back down again.....

[@stevescontriano860]

Thank you for your response. I assume you’re telling me that it’s not a very good idea to drop it. I already knew that. Lol. But I appreciate your knowledge and I will check the wires going into the tank. Thank you very much

[@stuartukguitarampguy5830]

@@stevescontriano860 United Kingdom, Reading, Berkshire.

[@stuartukguitarampguy5830]

True. True.

[@juliochingaling5824]

Great video. I have a question about the reverb tank cables. Does input go to input and output to output? God bless.

[@stuartukguitarampguy5830]

Good question that, and I can never remember myself! The 'output' on the reverb tank is the wet signal and so it goes to the input of the amp. But what I usually do is plug the phono cables into the amp, turn up the reverb and touch the ends. The one which makes a loud buzz gets plugged into the OUTPUT of the tank. Hope that makes sense.

[@juliochingaling5824]

@@stuartukguitarampguy5830 thank you sir, I will try that. God bless and stay safe.🤓👍

[@whistlebirdproductions6249]

Thanks mate!

[@ChristianFrancisco]

you are a legend for this. Thank you Stuart!

[@stuartukguitarampguy5830]

Thanks Christian!

[@zbaby82]

Good job!