# Super Reverb question.



## PaulS (Feb 27, 2006)

I have a 73 Fender Super Reverb I am working on and I am looking to replace the power supply filter caps. I can find the 20MFD caps but the 70MFD caps are the ones I can't find exact values for. Close as I can get is 80MFD. My question is ... will the difference of 10 MFD make any difference as it is in the power filtering. Thanks for any advice given.


----------



## Ripper (Jul 1, 2006)

The 80's will work fine, it's always better to go higher than lower and considering the tolerance specs on caps 10MF is really nothing. Just make sure your voltage ratings are as high or higher than the old ones.
Have fun


----------



## PaulS (Feb 27, 2006)

Thanks ripper, I did some googling and came up with pretty much the same answer. The supply caps and tubes need a changing in this thing, after that it should sing... :food-smiley-004:


----------



## Ripper (Jul 1, 2006)

Those are great amps! There are some great mods for those silverfaces too.


----------



## Wild Bill (May 3, 2006)

PaulS said:


> Thanks ripper, I did some googling and came up with pretty much the same answer. The supply caps and tubes need a changing in this thing, after that it should sing... :food-smiley-004:


Don't forget the cathode bypass caps on the preamp tubes! You know, those 25 mfd ones across the 1K5 cathode resistors.

These are electrolytic inside, the same as the filter caps in the power supply. They too will dry up and fail over the years. The sneaky thing is that everything will seem normal! You will read the right voltage on the 12AX7 cathode. You will not get any more hum 'cuz that's not what these bypass caps do.

What they do is increase the gain of the stage by a BUNCH! When they no longer work every thing seems fine except the amp has no balls!

These caps are cheap. Change them too!

:food-smiley-004:


----------



## PaulS (Feb 27, 2006)

Thanks for the heads up Bill, I'll include them in my project.


----------



## nonreverb (Sep 19, 2006)

PaulS said:


> I have a 73 Fender Super Reverb I am working on and I am looking to replace the power supply filter caps. I can find the 20MFD caps but the 70MFD caps are the ones I can't find exact values for. Close as I can get is 80MFD. My question is ... will the difference of 10 MFD make any difference as it is in the power filtering. Thanks for any advice given.


While you're at it, you might consider doing the BF mod to the phase inverter and also the coupling cap at it as well. This will tighten up the bass and get the PI workin' better...:smile:


----------



## Ripper (Jul 1, 2006)

Do the cap changes first then play it to see if you like the way it sounds. Then if you still aren't 100% then start with some of the BF mods. Lots of people like the sound of the silverfaces just the way they are.


----------



## PaulS (Feb 27, 2006)

*Grounding*

I wish this was mine but I am just fixing it for a friend, he liked the way it sounded so I will just change out the caps, tubes and see what he thinks.
The filter supply caps are the main item, a couple are done in and one shorted, I believe this is what fried the tubes and blew the fuse. Not to mention these tubes are 35 years old, he has had no work done on it till now.
Inside the chassis looks good, still clean and no heat issues. There was one thing I noticed and it struck me as odd, it has a three wire AC cable on it and inside the chassis the ground wire was cut, not broken, looks like cut with side cutters. I am wondering if this was an add and the grounding actually caused problems, it also has a polarity switch (ground) which swaps the AC polarity going to the tranny, this could have been an issue with the 3 wire hookup.


----------



## nonreverb (Sep 19, 2006)

PaulS said:


> I wish this was mine but I am just fixing it for a friend, he liked the way it sounded so I will just change out the caps, tubes and see what he thinks.
> The filter supply caps are the main item, a couple are done in and one shorted, I believe this is what fried the tubes and blew the fuse. Not to mention these tubes are 35 years old, he has had no work done on it till now.
> Inside the chassis looks good, still clean and no heat issues. There was one thing I noticed and it struck me as odd, it has a three wire AC cable on it and inside the chassis the ground wire was cut, not broken, looks like cut with side cutters. I am wondering if this was an add and the grounding actually caused problems, it also has a polarity switch (ground) which swaps the AC polarity going to the tranny, this could have been an issue with the 3 wire hookup.


One thing that should be mentioned is... if this isn't your amp, the more things you change the more the amps tone will change. Now I know someone's on here's gonna say that it'll be better BUT sometimes people get used to the way their amp sounds...such as your friend. When you change tubes and things like the cathode caps, it's going to sound different and I feel you need to make him aware of that. Also, since it's not your amp, I wouldn't do the BF mod unless he gives you permission to do it.


----------



## PaulS (Feb 27, 2006)

That's good advice nonreverb but I don't think he'll mind as the amp was not working when he brought it in. Both 6L6's failed the tube tester and the reading on the 5U4 rectifier tube was poor. Also 2 - 12ax7's and 1 - 12at7 failed the test. Filter caps are pooched and the fuse was blown. One 6L6 was in the bottom of the cabinet and 2 speaker leads were unhooked. Checked the speakers all seem ok 4 - 8ohm 10" Jensen's wired in parallel, load at jack 2 ohms.


----------



## nonreverb (Sep 19, 2006)

PaulS said:


> That's good advice nonreverb but I don't think he'll mind as the amp was not working when he brought it in. Both 6L6's failed the tube tester and the reading on the 5U4 rectifier tube was poor. Also 2 - 12ax7's and 1 - 12at7 failed the test. Filter caps are pooched and the fuse was blown. One 6L6 was in the bottom of the cabinet and 2 speaker leads were unhooked. Checked the speakers all seem ok 4 - 8ohm 10" Jensen's wired in parallel, load at jack 2 ohms.


Wow! Well...anything would be better than that! :smile:


----------



## shoretyus (Jan 6, 2007)

you should say it's a unserviceable and park it a my place.... for a couple of months any way :smile:


----------



## nonreverb (Sep 19, 2006)

shoretyus said:


> you should say it's a unserviceable and park it a my place.... for a couple of months any way :smile:


I suppose yer lookin fer a couple of "unserviceable" B3's too?:smile:


----------



## shoretyus (Jan 6, 2007)

nonreverb said:


> I suppose yer lookin fer a couple of "unserviceable" B3's too?:smile:


Yeah sure you got a couple that need to be patio' fied? I be at yours with the Hammond Hauler Deeluxe


----------



## PaulS (Feb 27, 2006)

Well changed out the caps, put in all new tubes , give her the once over and plugged it in. Sweet... no humm, no hiss, just pure sweet tone. But there was one problem.. No reverb or Vibrato...  I don't like the looks of one of the leads going into the tranny, shows signs of heat. I think this may be the problem. Any suggestions on where a good spot to get one of these ? When the amp was dropped off there was one of these lying in the bottom of the cabinet, but it doesn't look like it is any good, one of the windings is open circuit. Just looking at the schematic and it says it is a 125A20B


----------



## nonreverb (Sep 19, 2006)

PaulS said:


> Well changed out the caps, put in all new tubes , give her the once over and plugged it in. Sweet... no humm, no hiss, just pure sweet tone. But there was one problem.. No reverb or Vibrato...  I don't like the looks of one of the leads going into the tranny, shows signs of heat. I think this may be the problem. Any suggestions on where a good spot to get one of these ? When the amp was dropped off there was one of these lying in the bottom of the cabinet, but it doesn't look like it is any good, one of the windings is open circuit. Just looking at the schematic and it says it is a 125A20B


Before you start ordering the tranny, check the wires on the reverb tank itself. 90% of the time one of the wires is broken inside the tank. Also check the leads from the tank to the amp and the 12AT7 tube. If both check out then check for continuity on the transformer. ALso shake the tank with the reverb up...do you hear it rattle?
Have you got the vibrato/reverb switch? If you do, you must use it to turn on the vibrato as it won't work without it. You can always short out the vibrato switch input too to check it. If it still doesn't work, check V5 from the right (looking from the back of the amp) it's the 12AX7 beside the phase inverter. If that doesn't work there's a chance the LDR may have crapped out. Let me know what you find and we'll go from there:smile:


----------



## PaulS (Feb 27, 2006)

Thanks for the advice nonreverb, I'll check that out over the weekend and get back with a report. :food-smiley-004:


----------



## PaulS (Feb 27, 2006)

Couldn't wait for the weekend, I haven't checked the leads on the reverb tank but a quick test on the rattling. No response, the amps just humms a bit when you turn on the reverb. I haven't checked the tube on the vibrato, but they were all new tubes, 9 in total. When you click on the vibrato pedal you hear a clicking noise and it will vary with the speed pot but there is really no vibrato effect on the guitar. I'll run the 12ax7 and the 12at7's through the tester and see how they check out.


----------



## nonreverb (Sep 19, 2006)

PaulS said:


> Couldn't wait for the weekend, I haven't checked the leads on the reverb tank but a quick test on the rattling. No response, the amps just humms a bit when you turn on the reverb. I haven't checked the tube on the vibrato, but they were all new tubes, 9 in total. When you click on the vibrato pedal you hear a clicking noise and it will vary with the speed pot but there is really no vibrato effect on the guitar. I'll run the 12ax7 and the 12at7's through the tester and see how they check out.


Hey Paul,

Which input are you using on the amp...the middle ones or the ones on the far left?


----------



## shoretyus (Jan 6, 2007)

Try another reverb tank.


----------



## PaulS (Feb 27, 2006)

nonreverb said:


> Hey Paul,
> 
> Which input are you using on the amp...the middle ones or the ones on the far left?


As for the guitar, using the channel 2 input or the vibrato channel as it is called. On the back the tank and footswitch were labelled.


----------



## Ripper (Jul 1, 2006)

First thing I would check is for cold/bad solder joints (I've seen this with vibratos before) and check the small capacitors that are around the vibrato "bug". One other thing that can effect the vibrato is bad lead dress. Also check the vibrato footswitch jack and make sure the center pin is shorted to ground. As for the reverb, once again I'd check solder joints on the tube sockets and the fiber board. Do you have a scope to check the signal through the path? You can trace the problem that way as well.


----------



## nonreverb (Sep 19, 2006)

Ripper said:


> First thing I would check is for cold/bad solder joints (I've seen this with vibratos before) and check the small capacitors that are around the vibrato "bug". One other thing that can effect the vibrato is bad lead dress. Also check the vibrato footswitch jack and make sure the center pin is shorted to ground. As for the reverb, once again I'd check solder joints on the tube sockets and the fiber board. Do you have a scope to check the signal through the path? You can trace the problem that way as well.


With all due respect ripper, solder joints are not the first place to check with these amps regarding reverb problems. I work on Fenders almost daily and granted on rare occasions ground wire will come free from the ground strip but it's not something I'd be looking for first. Checking caps is not necessary either until the obvious is eliminated.The obvoius problems are where to go first. Then when they are eliminated, proceed to the solder and caps and resistors.
Reverb problem...check the tank first, check the leads, check the tube. They are the easiest places to start and almost always the problem.
Vibrato problem...check the footswitch switch, cable , connector and tube.
You'll make your life easier and save a whole lot of time by doing these steps first Paul....sorry to press the issue and I fully expect to get flamed for this but I feel it's important enough:smile:


----------



## shoretyus (Jan 6, 2007)

nonreverb said:


> You'll make your life easier and save a whole lot of time by doing these steps first Paul...


If they fail .... I will pick it up tonight...:smilie_flagge17: I have storage !! 

Worst case scenario is we can run it up to nonreverb's work bench next week:wave:. I have to go pick up my free B3


----------



## nonreverb (Sep 19, 2006)

shoretyus said:


> If they fail .... I will pick it up tonight...:smilie_flagge17: I have storage !!
> 
> Worst case scenario is we can run it up to nonreverb's work bench next week:wave:. I have to go pick up my free B3


LOL!!....along with the free Leslie and '59 Les Paul I have for you!!!


----------



## Ripper (Jul 1, 2006)

nonreverb said:


> With all due respect ripper, solder joints are not the first place to check with these amps regarding reverb problems. I work on Fenders almost daily and granted on rare occasions ground wire will come free from the ground strip but it's not something I'd be looking for first. Checking caps is not necessary either until the obvious is eliminated.The obvoius problems are where to go first. Then when they are eliminated, proceed to the solder and caps and resistors.
> Reverb problem...check the tank first, check the leads, check the tube. They are the easiest places to start and almost always the problem.
> Vibrato problem...check the footswitch switch, cable , connector and tube.
> You'll make your life easier and save a whole lot of time by doing these steps first Paul....sorry to press the issue and I fully expect to get flamed for this but I feel it's important enough:smile:



The majority of my post was in regards to Pauls vibrato problem, which is a fairly common problem. Also I have fixed a fair amount of reverb related issues that have turned out to be bad solder joints on the driver tube socket or related components on the fiberboard, it most certainly isn't always the tank or cables. You had already given Paul suggestions on checking the tank and wires so I didn't feel it needed to be mentioned again.

Obviously you feel you have had far more experience with these amps and problems than anyone else here could possibly have had, so I leave it in your capable hands.

Good Luck with the fix Paul


----------



## nonreverb (Sep 19, 2006)

"Obviously you feel you have had far more experience with these amps and problems than anyone else here could possibly have had, so I leave it in your capable hands."

Hey Ripper,

Please don't take my post the wrong way. There is always the possibility that there could be problems with solder joints or caps etc. and you're right in pointing them out. My point was that, in my opinion, there are logical steps to proceed with when faced with these problems. Doing the obvious first eliminates them and can save a lot of time.
I'm not trying to compare my experience with anyone else here as I'm the first to admit that there are new problems that present themselves all the time that I learn from. I'm just trying to help a fellow poster the best way I know how.:smile:


----------



## Ripper (Jul 1, 2006)

nonreverb said:


> Please don't take my post the wrong way. There is always the possibility that there could be problems with solder joints or caps etc. and you're right in pointing them out. My point was that, in my opinion, there are logical steps to proceed with when faced with these problems. Doing the obvious first eliminates them and can save a lot of time.
> I'm not trying to compare my experience with anyone else here as I'm the first to admit that there are new problems that present themselves all the time that I learn from. I'm just trying to help a fellow poster the best way I know how.:smile:


As I stated before the 1st steps for the reverb had already been mentioned and I didn't feel I needed to repeat it again, as Paul was already working on testing those. 

I find it demeaning to someones intelligence when people on a forum restate things over and over to someone after they have already acknowledged they have tried or are trying those points, so I didn't mention it, I merely offered a suggestion of areas to check if the reverb pan and wiring did prove to be good, areas that I had had be the cause of problems many times over the years. 

The same goes for the vibrato, I didn't figure Paul would need one of us to tell him to check the cable on the footswitch, and once again I mentioned problems that I have come across fairly commonly over the years that cause the problem Paul is mentioning.


----------



## nonreverb (Sep 19, 2006)

Ripper said:


> As I stated before the 1st steps for the reverb had already been mentioned and I didn't feel I needed to repeat it again, as Paul was already working on testing those.
> 
> I find it demeaning to someones intelligence when people on a forum restate things over and over to someone after they have already acknowledged they have tried or are trying those points, so I didn't mention it, I merely offered a suggestion of areas to check if the reverb pan and wiring did prove to be good, areas that I had had be the cause of problems many times over the years.
> 
> The same goes for the vibrato, I didn't figure Paul would need one of us to tell him to check the cable on the footswitch, and once again I mentioned problems that I have come across fairly commonly over the years that cause the problem Paul is mentioning.


Fair enough Ripper...point taken...I didn't get the impression that you had acknowledged my initial post so I reponded as such...but I understand your position now. I'm sure between the both of us he'll have it fixed in no time:food-smiley-004:


----------



## shoretyus (Jan 6, 2007)

nonreverb said:


> I'm sure between the both of us he'll have it fixed in no time:food-smiley-004:


Tap Tap Tap..... he promised that I could play it before it leaves.:rockon2:


----------



## PaulS (Feb 27, 2006)

Pat - It's still here.... nonreverb and ripper, I respect both of your opinions and will check out all the suggestions given to me, by trade I am an electrician, not the residential type but more with process controls, you know computers and things. My knowledge of electricity is wide as I do know the regular stuff associated with electricians. I also dabble in electronics, but I haven't done too much with tube amps other than change tubes, power supply caps, bias tubes and some mods picked up on the web which I mainly did to my valve jr. I looked over the board when I took the amp apart because of the blown fuse. I didn't see any signs of heat or anything really abnormal about the components. The tubes were all new but I have been sent a bad one before so I'll run all the 12A's through my tube tester. The only thing I did notice was a previous hot spot on the TR4 tranny. I will test the windings and see what readings I get. I'm going to pull the tank, I had the amp on and turned the reverb up full then tapped the tank.. nothing. The other thing was when I used the footswitch on the vibrato it clicked in but all I got was a ticking noise which responded to the speed pot. I checked the footswitch and it is working properly, next I'll look at the tank. But on this amp the vibrato is important, cause there's nothing like the tube style vibrato.
I'll have to ask Joe if the vibrato was toasted before he had his meltdown. Again thanks for the info guy's ... it's all good and appreciated. I'll check into some of the ideas and you all have a good Thanksgiving weekend.... :food-smiley-004:


----------



## Wild Bill (May 3, 2006)

PaulS said:


> Pat - It's still here.... nonreverb and ripper, I respect both of your opinions and will check out all the suggestions given to me, by trade I am an electrician, not the residential type but more with process controls, you know computers and things. My knowledge of electricity is wide as I do know the regular stuff associated with electricians. I also dabble in electronics, but I haven't done too much with tube amps other than change tubes, power supply caps, bias tubes and some mods picked up on the web which I mainly did to my valve jr. I looked over the board when I took the amp apart because of the blown fuse. I didn't see any signs of heat or anything really abnormal about the components. The tubes were all new but I have been sent a bad one before so I'll run all the 12A's through my tube tester. The only thing I did notice was a previous hot spot on the TR4 tranny. I will test the windings and see what readings I get. I'm going to pull the tank, I had the amp on and turned the reverb up full then tapped the tank.. nothing. The other thing was when I used the footswitch on the vibrato it clicked in but all I got was a ticking noise which responded to the speed pot. I checked the footswitch and it is working properly, next I'll look at the tank. But on this amp the vibrato is important, cause there's nothing like the tube style vibrato.
> I'll have to ask Joe if the vibrato was toasted before he had his meltdown. Again thanks for the info guy's ... it's all good and appreciated. I'll check into some of the ideas and you all have a good Thanksgiving weekend.... :food-smiley-004:


Just one quick check you might try with the reverb, Paul. The reverb circuit is essentially just a SE amp with its own little output transformer that feeds the input of the reverb tank. The signal travels down the springs and then is converted back into signal to be fed to a recovery amplifier and mixed in with the regular "dry" signal".

That tank input is about 10 ohms, very close to an 8 ohm speaker load. You could plug that line into a speaker instead of the tank input and you should hear up to a watt or two of power! This will tell you if the driver side of things is working right.

To lose both trem and reverb is more complicated. I'd look at that recovery triode stage. A 'scope can make things go SO much faster!

Good luck!

:food-smiley-004:


----------



## PaulS (Feb 27, 2006)

Well I tested the 12AT7's and they were good, then the 12AX7's, all 4 failed the tube tester...  I had some others sitting around so I tested them and they were good. I put them in but still the same problems. I really find it hard to believe that all 4 failed but I tested them twice, They light up when they are in the amp, they are EH brand. Strange that the 12AX7's didn't affect the amps sound when I had the EH tubes in there or when I put the good ones in. The first set of replacements were the originals and it was very microphonic. The second set were some I had on the shelf that tested good. They were not microphonic but there was a little bit of scratchy noise. Still no reverb and no vibrato, just the clicking noise for vibrato. Going to send these 12AX7's back to the tube Store for replacements...


----------



## Ripper (Jul 1, 2006)

PaulS said:


> Well I tested the 12AT7's and they were good, then the 12AX7's, all 4 failed the tube tester...  I had some others sitting around so I tested them and they were good. I put them in but still the same problems. I really find it hard to believe that all 4 failed but I tested them twice, They light up when they are in the amp, they are EH brand. Strange that the 12AX7's didn't affect the amps sound when I had the EH tubes in there or when I put the good ones in. The first set of replacements were the originals and it was very microphonic. The second set were some I had on the shelf that tested good. They were not microphonic but there was a little bit of scratchy noise. Still no reverb and no vibrato, just the clicking noise for vibrato. Going to send these 12AX7's back to the tube Store for replacements...


What type of tube tester are you using Paul? I know that on one of mine you have to read the small print in the setting manual for the 12ax7, as it won't flash the tube over to good, you have to go by the actual numeric reading.


----------



## PaulS (Feb 27, 2006)

Ripper, it's an Olson -TE148 tester, I used the manual settings and it works on the other 12AX7's just these 4 EH tubes have read bad. Is there something with the EH tubes? The same settings work for a 7025 or JJ 83S. Basically the same settings as the 12AT7's just less shunt setting, and they tested fine.


----------



## Ripper (Jul 1, 2006)

PaulS said:


> Ripper, it's an Olson -TE148 tester, I used the manual settings and it works on the other 12AX7's just these 4 EH tubes have read bad. Is there something with the EH tubes? The same settings work for a 7025 or JJ 83S. Basically the same settings as the 12AT7's just less shunt setting, and they tested fine.


I haven't used any EH 12ax7s for a little bit but I have had good luck with them. Have you tried the ax7s in another amp to see what they do in there?

The reason I asked about the tester is my one shows 12ax7s as a "fail", whereas 12at7s and the like will show "pass" but if you read the tube setting book, it tells you that the 12ax7 will do that and you need to see what range they read in to determine good or bad, and I was wondering if your tester was the same.


----------



## PaulS (Feb 27, 2006)

Ok I have tested the 12AX7's in another amp and they appear to be ok, they fooled my tester ??? I checked the reverb tank and it is open circuit so that explains the reverb but I am still trying to figure out the vibrato. Checked all the solder joints and they look good, same as resistors checked them, all within tolerance. Most of the circuit looks good just got to check the caps.

I think I lucked out on the reverb tank, springs are fine but the wire to the jacks have broken off over time, will solder these back on and give it a test.


----------



## PaulS (Feb 27, 2006)

Soldered the wires, put it back together and we have reverb, and I will say a sweet reverb. Damm this is one fine sounding amp, I'll post a couple pics tomorrow. Now just got to figure out the vibrato problem and that would put the icing on the cake...


----------



## PaulS (Feb 27, 2006)

Talking to the owner and it appears neither the reverb or vibrato was working before he brought it in. Doesn't care about the vibrato and is estatic about the reverb. So it's going home tomorrow, I'm going to miss it, did a lot of playing on it the last few days.


----------



## shoretyus (Jan 6, 2007)

PaulS said:


> So it's going home tomorrow, I'm going to miss it


Sounds like me too


----------



## nonreverb (Sep 19, 2006)

PaulS said:


> Soldered the wires, put it back together and we have reverb, and I will say a sweet reverb. Damm this is one fine sounding amp, I'll post a couple pics tomorrow. Now just got to figure out the vibrato problem and that would put the icing on the cake...


Hey Paul...good work!:smile:


----------



## PaulS (Feb 27, 2006)

Well it's gone but I still have memories....








[/IMG]








[/IMG]


----------



## Ripper (Jul 1, 2006)

Glad to hear you got it working Paul!


----------

