PLEASE HELP! My reverb doesn't work on my Twin Reverb...

[elenore19]

Reverb Fixed!

Fixed it! And closing thread. Read last post on how I fixed it, if interested.

Yeah, so I got my new used amp, and the I can't get the reverb to work...

[size=+2]What could cause the reverb not to work??[/size]


Anything I'm doing wrong that would make it not work?
I tried with the footswitch plugged in and without the footswitch plugged in. When I press the reverb button on the footswitch you could hear the click in the speakers which makes me think that the footswitch isn't broken...Reverb still didn't work at all. Vibrato works great. But no reverb...

Is there something in the back that might not be plugged in? I'm going to message the seller on ebay and see if that was a preexisting condition or not...if it was, then he didn't say and I should be able to file some sort of complaint or something...

How much would it cost to get the reverb fixed on my amp if it is in fact broken?

Anyways...sort of a bummer...Amp still sounds amazing, just no reverb...


-Elliot

 

[ocnor]

Make sure that the tube that drives the reverb is functioning. Check the rca connections on the tank to make sure they didn't come loose. Also check the connections to the circuit board. If the tank is bad you can get a replacement fairly cheap. http://www.tubedepot.com/rt-4ab3c1b.html

 

[elenore19]

Make sure that the tube that drives the reverb is functioning. Check the rca connections on the tank to make sure they didn't come loose. Also check the connections to the circuit board. If the tank is bad you can get a replacement fairly cheap. http://www.tubedepot.com/rt-4ab3c1b.html

I'll look into the tank thing. How do I know which tube drives the reverb? I checked all the tubes and the lights were all on, so that's all I know about them, they all heat up. Does that mean that they are functioning correctly? Or not necessarily...

I'll definitely check the connections to the tank though, thanks!

-Elliot

 

[ocnor]

If I remember correctly the reverb tube is V3 which is a 12AT7.

 

[dintymoore]

Doesn't it have one of those Hammond or Accutronics reverbs sitting on the bottom that has RCA ins and outs that go up top to the amp?

If so, make sure they're plugged in 'cause it's easy to imagine those coming unplugged during shipping.

I can't imagine why you couldn't use those ins and outs to check the situation also - by substituting another effects in place of it and by running the cable coming from the amp into another amp to see if it's sending signal and also by using the reverb with another amp to see if it works, and the return too.

Fingers crossed it's not plugged in...

 

[elenore19]

So I tried messing around with the reverb tank.

When I had the amp on and I hit the springs you could hear the springs through the speakers, but nothing has been effected by my guitar tone. Makes me think that the signal from the tank to the amp is fine, but from the amp to the tank doesn't work...
I only could hear the springs when I had switched the rca jacks around on the tank....So should the red jack be output or input? They aren't color coded on the tank, they are on the amp so I connect with red->red and white->white of course.

Does this mean anything to you? How do I know for sure if the tubes are working correctly or not?

Thanks for the help.

 

[elenore19]

Doesn't it have one of those Hammond or Accutronics reverbs sitting on the bottom that has RCA ins and outs that go up top to the amp?

If so, make sure they're plugged in 'cause it's easy to imagine those coming unplugged during shipping.

I can't imagine why you couldn't use those ins and outs to check the situation also - by substituting another effects in place of it and by running the cable coming from the amp into another amp to see if it's sending signal and also by using the reverb with another amp to see if it works, and the return too.

Fingers crossed it's not plugged in...

yeah I did make sure they were plugged in...no luck...
I don't have any other effects that have RCA jacks...or any other rca cables for that matter...Well, wait. I do have rca cable from my dvd player...I'll try substituting that, and hope that the cable is the issue... I don't have any other amps with rca inputs either...

 

[MajorTom]

Definitely try the other RCA cable set. And a new tube in the reverb driver position. If you don't have an extra 12AT7 to swap out to test that, you can use a 12AX7 temporarily to see if that restores functionality - it won't sound right, but if you hear reverb, that was it.

The last time I fixed a reverb problem - inside the tank, a small lead wire had broken off of one of the transducers, which are the little things on each end that have the wires going to them, all I had to do was solder it back on. That could have happened in shipping. The one on the input converts the electrical signal to physical vibrations, which rattles the springs. The one on the output end converts the physical vibrations into an electrical signal, which is then amplified along with the dry signal. Sometimes the transducers go bad and need replaced.

Since you are getting the BOINGGGGG when you smack the tank, the output transducer is working, as is the "receiving end" of the amp. At this point it is either the cable, the input side transducer in the tank, the "send" circuitry in the amp (including, but not limited to, the 12AT7 tube), or a remote possibility, the springs are off the hooks on the input end. You can test the transducer with an ohm meter, just unplug the RCA cable to take it out of circuit, and measure across the 2 terminals - if it reads open (the resistance is really high) it is bad. They come in different impedances, off the top of my head I think they should read somewhere in the neighborhood between 200 and 1K ohms DC resistance.

You could also measure the reverb output from the amp (AC volt ), to see if that's working - not sure what kind of voltage you would read on that, never measured it. I would not hook that up to an effect, using the reverb in/out as an effect loop like someone suggested - it may be fine ( I don't know what voltage & current would be there), but I suspect that it will be too hot of a signal for effects....

 

[Creamyapples1]

At this point, I'd stop everything. Load it in the car and drop it off at the nearest guitar shop and have their Tech. have a look at it. You're going to wind up doing more harm than good.

 

[elenore19]

Definitely try the other RCA cable set. And a new tube in the reverb driver position. If you don't have an extra 12AT7 to swap out to test that, you can use a 12AX7 temporarily to see if that restores functionality - it won't sound right, but if you hear reverb, that was it.

The last time I fixed a reverb problem - inside the tank, a small lead wire had broken off of one of the transducers, which are the little things on each end that have the wires going to them, all I had to do was solder it back on. That could have happened in shipping. The one on the input converts the electrical signal to physical vibrations, which rattles the springs. The one on the output end converts the physical vibrations into an electrical signal, which is then amplified along with the dry signal. Sometimes the transducers go bad and need replaced.

Since you are getting the BOINGGGGG when you smack the tank, the output transducer is working, as is the "receiving end" of the amp. At this point it is either the cable, the input side transducer in the tank, the "send" circuitry in the amp (including, but not limited to, the 12AT7 tube), or a remote possibility, the springs are off the hooks on the input end. You can test the transducer with an ohm meter, just unplug the RCA cable to take it out of circuit, and measure across the 2 terminals - if it reads open (the resistance is really high) it is bad. They come in different impedances, off the top of my head I think they should read somewhere in the neighborhood between 200 and 1K ohms DC resistance.

You could also measure the reverb output from the amp (AC volt ), to see if that's working - not sure what kind of voltage you would read on that, never measured it. I would not hook that up to an effect, using the reverb in/out as an effect loop like someone suggested - it may be fine ( I don't know what voltage & current would be there), but I suspect that it will be too hot of a signal for effects....

I'll try the new rca cable, then look into the tube. After that I don't have an ohm meter, so hopefully one of those 2 things will fix it. I'll check that all of the connections are soldered properly in the reverb tank.
Thanks so much for the help, it is greatly appreciated.

At this point, I'd stop everything. Load it in the car and drop it off at the nearest guitar shop and have their Tech. have a look at it. You're going to wind up doing more harm than good.

At this point it would be a 2 hour drive to the nearest guitar shop, and even then the guitar shop is a pretty shitty place. Also I'm not doing much to the amp at all really. So far I've unscrewed the back panel, took out the reverb tank, switched around a few rca cables, and I'll be switching a new tube in. I don't think I've done anything drastic yet. But thanks for your concern.

 

[Lt. Bob]

You're not gonna hurt anything with this stuff you're trying so keep on.

I'm gonna say it's the RCA cable. We all know those things go bad fairly often.
If you're getting the *sproing* then the tank's working so you're not getting signal to the tank. Now, that COULD be in your reverb circuit but that thing doesn't fail very often which is why I'm thinking it's the cable.
But I have seen the little wire inside the tank break off at either jack. If that's it then the tank's not getting signal 'cause of that.
You can pull that tank out and look ..... use a bright light and magnifier to be sure you can see it well 'cause the break could be tiny and hard to see. If you find one ..... just solder it back.

Lastly ...... find an amp with a reverb tank that definitely works and run your cables to that just to see if it's the circuit. You've got to know someone who has an amp with a working 'verb.
If it works thru a different tank then that's where your problem is. The top of the line Accutronics tank is only like $40 or so.

 

[Lt. Bob]

wow, I can't delete a double post?!?!?!?!

 

[elenore19]

You're not gonna hurt anything with this stuff you're trying so keep on.

I'm gonna say it's the RCA cable. We all know those things go bad fairly often.
If you're getting the *sproing* then the tank's working so you're not getting signal to the tank. Now, that COULD be in your reverb circuit but that thing doesn't fail very often which is why I'm thinking it's the cable.
But I have seen the little wire inside the tank break off at either jack. If that's it then the tank's not getting signal 'cause of that.
You can pull that tank out and look ..... use a bright light and magnifier to be sure you can see it well 'cause the break could be tiny and hard to see. If you find one ..... just solder it back.

Lastly ...... find an amp with a reverb tank that definitely works and run your cables to that just to see if it's the circuit. You've got to know someone who has an amp with a working 'verb.
If it works thru a different tank then that's where your problem is. The top of the line Accutronics tank is only like $40 or so.

I tried switching out the rca cable for another one...didn't work. I tried switching out the 12at7 for a 12ax7 that I had that I knew worked, and still no luck. I don't know which rca plug goes to the input or output of the tank. They aren't color coded like it is on the amp side of it. The weird thing is that I got the SPROIIINGG thing only when I had rca cable plugged into the INPUT of the tank, not the output. Isn't it supposed to be the output?
All my friends with amps are off to school right now, so I really don't know anybody with an amp with a reverb tank. I live in a small town...2 hours away from any sort of bigger town....

I just looked at the cables connected to the tank briefly for solder breaks, but it sounds like I have to look more closely. I"ll look into it.

Do you know which color goes to which on the tank though? as far as the rca goes...Red-> input, or red-> output?

Thanks for all the help, I really do appreciate it. I don't want to have to send this back for a refund.

Since the Vibrato seems to work, I'll assume you're plugged into one of those inputs. Looking at the schematic for that amp, the reverb appears to only work when the Vibrato inputs are used, not on the Normal channel side.

The schematic makes it look like there are RCA jacks on the chassis. If you have an RCA to 1/4" cable, you could try plugging the RCA end into the jack that has the tanks white plug and run the 1/4" plug into another amp. This signal is low level from a transformer that the 12AT7's feed. If you get signal from that jack it may indicate the tank has a problem.

I had bought a Blues Jr. off ebay and its reverb tank had a busted wire. Replaced it and worked fine.

I forget where I got it, but I've got a PDF of the service manual. I can email it to you if you want. PM me your email address.

I don't have an rca to 1/4" plug. But I'll see if i can find one. Thanks

 

[elenore19]

The schematic shows White is the Input to the tank, Red is the Output.

Thank you! Needed that information. Make sure I plug it in correctly.

Any idea on why I get the spring noise when I the input is plugged in and not the output?

 

[c7sus]

Yeah, the input lead is kaput.

That's why you hear the "sproing" of the springs themselves but no guitar.

Somewhere along that input path there is an open.

 

[elenore19]

Yeah, the input lead is kaput.

That's why you hear the "sproing" of the springs themselves but no guitar.

Somewhere along that input path there is an open.

I only hear the springs when there's vibration in the cab, or I tap the tank to make the springs heard. When I play the guitar at lower volume and make sure there isn't anything vibrating the amp but itself, I don't hear anything related to reverb...

So if it is kaput, what's my next step?

 

[elenore19]

I filed a thing with paypal asking for compensation for repair costs to get the reverb fixed. So we'll see.

 

[c7sus]

Figure out where the circuit is broken.

Take the reverb tank out of the amp.

You should be able to remove the top and take a look at the springs and the input and output jacks.

If it's not the RCA cable then it's gotta be either in the tank or the output from the amp. I would advise against opening the amp chassis, and NEVER power up the amp without speakers or a dummy load attached.

 

[elenore19]

Figure out where the circuit is broken.

Take the reverb tank out of the amp.

You should be able to remove the top and take a look at the springs and the input and output jacks.

If it's not the RCA cable then it's gotta be either in the tank or the output from the amp. I would advise against opening the amp chassis, and NEVER power up the amp without speakers or a dummy load attached.

I've checked the tank and to the best of my knowledge there are no broken solders or anything of the sort. But I mean, I really don't know what to look for. I looked with a flashlight and some strong glasses and couldn't see anything that looked wrong.
I think I'm only left with the option of bringing it to a repair shop and hoping they can fix it...

 

[c7sus]

If you have a meter you could check the continuity of the tank circuit.