# NAD: Silverface Super Reverb



## cboutilier (Jan 12, 2016)

I think I've found the nicest amp I'll ever own. I've wanted a silverface fender since I started playing seriously and learned what a tube amp even was. Now I've gone an outdone myself, and got a pretty decent deal while I was at it.

The amp is a ~1973 Fender Super Reverb that was placed in a Haggerty head cabinet. Everything works flawlessly except the reverb, and the disabled master volume. I have to open her up and sort out the reverb issue, because I love reverb. I think I'm going to build a 2x10 cabinet for it, or maybe a diagonal 2x12.




On a side note, I also scored a FREE Behringer 4x12 slant cabinet, unloaded of course, on Kijiji this evening. Not sure what the hell to do with it though haha. It's sitting under the Super in the photo.


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## StevieMac (Mar 4, 2006)

Nice score. If you haven't already, use a footswitch or shorted RCA jack to check the Reverb function. Failing that, it's likely a tank replacement will bring it back to life. If you do go with a dual spkr set up, be aware that the OT is 2-ohm so you'll need to find a pair of 4-ohm spkrs...no easy task. Anyway...enjoy!


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## cboutilier (Jan 12, 2016)

StevieMac said:


> Nice score. If you haven't already, use a footswitch or shorted RCA jack to check the Reverb function. Failing that, it's likely a tank replacement will bring it back to life. If you do go with a dual spkr set up, be aware that the OT is 2-ohm so you'll need to find a pair of 4-ohm spkrs...no easy task. Anyway...enjoy!


I'm told that a tank replacement from a local tech did not fix it, but the tech was too busy to replace any components at the time. I have a good spare tank I can try though!


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## flyswatter (Apr 6, 2016)

Nice score! Congrats. You saw my post concerning mods and I've owned mine for 23 years; so fire away if you have any questions. Cheers.


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## WCGill (Mar 27, 2009)

Now that's the size Super I like, having carted one up and down stairs for years. Besides the wires inside the reverb tank, check the 12AT7, it's run awfully hard in these amps and tends to have a shortened life span. NOS works best. The shielded wires also tend to break at the RCA plugs.


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## b-nads (Apr 9, 2010)

Nice!


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## bzrkrage (Mar 20, 2011)

b-nads said:


> Nice!


What he said!
Very tidy. Hope you sort out the verb.


Sent from my Other Brain


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## cboutilier (Jan 12, 2016)

WCGill said:


> Now that's the size Super I like, having carted one up and down stairs for years. Besides the wires inside the reverb tank, check the 12AT7, it's run awfully hard in these amps and tends to have a shortened life span. NOS works best. The shielded wires also tend to break at the RCA plugs.


It's supposedly a brand new tank, but I'll check it anyways. The cables are definitely new. I've got a rca jumper plug I'll pop in the reverb foot switch jack to try that. I have a handful of 12ax7 and 12au7 tubes lying around that I can use to rule out the tube too!


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## cboutilier (Jan 12, 2016)

This amp rocks! It starts to break up with my strat around 4, and really rocks out at 5. With my 335 it is gritty at only 3, and screaming out blues rock at 5. This is with the bass at 4, mid at 7, and treble at 5 on the vibrato channel. 

I'm in love.


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## Chitmo (Sep 2, 2013)

cboutilier said:


> I think I've found the nicest amp I'll ever own. I've wanted a silverface fender since I started playing seriously and learned what a tube amp even was. Now I've gone an outdone myself, and got a pretty decent deal while I was at it.
> 
> The amp is a ~1973 Fender Super Reverb that was placed in a Haggerty head cabinet. Everything works flawlessly except the reverb, and the disabled master volume. I have to open her up and sort out the reverb issue, because I love reverb. I think I'm going to build a 2x10 cabinet for it, or maybe a diagonal 2x12.
> 
> ...


Never heard a super reverb from that era before, but if you're taste in amps is as good as your taste in rum I'm certain it's great.


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## Budda (May 29, 2007)

No master eh, it must get loud!

Congrats dude. I miss my pro sometimes


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## keithb7 (Dec 28, 2006)

Start with simple things to troubleshoot the reverb. Swap some 12a tubes around. Wiggle the reverb send and receive cords. 
Turn up the reverb and knock the amp. Does it go Kerrraaanngggg!!! ? If it does that's a good start. Means return side of reverb circuit and tank is working. If not, check back in and we'll send you more suggestions. 

Deece amp. I have a 71 SR. Still in original cab.


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## cboutilier (Jan 12, 2016)

keithb7 said:


> Start with simple things to troubleshoot the reverb. Swap some 12a tubes around. Wiggle the reverb send and receive cords.
> Turn up the reverb and knock the amp. Does it go Kerrraaanngggg!!! ? If it does that's a good start. Means return side of reverb circuit and tank is working. If not, check back in and we'll send you more suggestions.
> 
> Deece amp. I have a 71 SR. Still in original cab.


It doesn't appear that the return side is working.


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## cboutilier (Jan 12, 2016)

Budda said:


> No master eh, it must get loud!
> 
> Congrats dude. I miss my pro sometimes


It gets very loud. At 5 in my apartment, standing 10 feet away it starts to hurt my brain. I believe it's louder than my 4xEL84 Crate VC5212 50 watter 2x12. I was playing it through a 15 and a 12 in parallel.


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## Budda (May 29, 2007)

cboutilier said:


> It gets very loud. At 5 in my apartment, standing 10 feet away it starts to hurt my brain. I believe it's louder than my 4xEL84 Crate VC5212 50 watter 2x12. I was playing it through a 15 and a 12 in parallel.


Molded earplugs dude. I shouldnt have waited.


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## keithb7 (Dec 28, 2006)

OP do you have any experience with working on amps? Safety around high voltages? Soldering skills? DMM?


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## cboutilier (Jan 12, 2016)

Budda said:


> Molded earplugs dude. I shouldnt have waited.


I know what you mean. I didn't start wearing ear plugs at work until after I started noticing hearing damage.


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## cboutilier (Jan 12, 2016)

keithb7 said:


> OP do you have any experience with working on amps? Safety around high voltages? Soldering skills? DMM?


I have a bit of experience with amps, and eager to get more. Lots of experience with low voltage electronic and automotive wiring. Very good soldering skills. I teach digital electronics to electrical engineering students. I've got a good DMM with the ability to test caps too. 

I'm pretty safe with the high voltages as far as I know. Power off with the amp fired up, drain caps with a resistor, check for voltage with a meter, work with one hand in my back pocket. All that good stuff.


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## keithb7 (Dec 28, 2006)

Yup that'd be the right answers. Do you have a schematic and lay out diagram printed out?
Start by pulling the tank and inspect all the connections, wires and springs. Is a spring broken? Those tiny little input and output wires can easily break. Run a continuity check on everything you can to test.
Reverb Pan, RCA cords etc. Pull chassis and check RCA jacks for proper continuity. Are the jacks tight feeling or loosey-goosey. Inspect all wires in the reverb circuit. Connections all look good? Probe them all with a 
chop stick with amp live, with volume low. Any connections crackling? Tubes crackling when tapped? If you have another amp, it's nice to run your reverb signal through another working tank for a quick troubleshoot.
Get a long pair of RCA wires. Every TV in the 90's with a VCR needed them. We all have them stashed away somewhere. They work perfect here in this reverb circuit.

Look for wires like this with a magnifier of your choice. I found this in my 1971 SR...Not good.











Have all the cathode caps been replaced on the circuit board? Now would be a good time if they have not been done. All resistors to be measured in the reverb circuit. You cannot measure a resistor with a cap 
in parallel across it. This is a perfect time to measure the resistors along side the cathode caps, as you will be removing cathode caps to replace. If caps are good and not being replaced., you need to lift one end of each capacitor
to measure the resistor beside it. One time I found a cooked resistor in my 71 Vibrolux Reverb, replaced it and voila, my reverb was working again.

Voltages at reverb send and return tubes to be checked against voltages in schematic and layout. If a problem is found here you're onto something.

Check resistance at reverb pot. I think it should be a 100K linear pot. With a DMM on it, measure resistance across full sweep.

Unsolder all 4 wires at mini transformer between V3 and V4. That's the reverb transformer. Measure for continuity and ohms across each winding. Blue and red are connected, so are black and green.
Wires and measurements can be referenced here: http://www.classictone.net/40-18034.pdf
When I bought my 1973 Twin, it had no working reverb. I found a dead reverb transformer by checking it with my DMM. Replaced it and it works perfectly. The transformer can be had for about $14 US Funds.
I got mine here: Transformer - Fender® Replacement, Output, 3-1/2 W, 8 Ohm

Trace every connection in the schematic and lay out in the reveb circuit. Using coloured hi-lighter markers help keep track of what you have inspected and measured. It's just a process of elimination. If you are unaware
which tube does what and which pin out goes where, you can reference a 12AX7 pint out diagram here for example.










If this all seems a little complicated, I understand. I remember how it can feel that way. It's just a puzzle. Doing small bits and pieces at a time, keep at it, and you will solve it. Be safe. Discharge caps. If you are not comfortable around a live open chassis, 
take it to a tech.

Here is my completed 1971 SR after I serviced it. Replaced cathode and vibrato caps and roach. Bias caps and all RCA jacks. You can do it. Take your time. Stop for a break when your head hurts. LOL.


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## cboutilier (Jan 12, 2016)

keithb7 said:


> Yup that'd be the right answers. Do you have a schematic and lay out diagram printed out?
> Start by pulling the tank and inspect all the connections, wires and springs. Is a spring broken? Those tiny little input and output wires can easily break. Run a continuity check on everything you can to test.
> Reverb Pan, RCA cords etc. Pull chassis and check RCA jacks for proper continuity. Are the jacks tight feeling or loosey-goosey. Inspect all wires in the reverb circuit. Connections all look good? Probe them all with a
> chop stick with amp live, with volume low. Any connections crackling? Tubes crackling when tapped? If you have another amp, it's nice to run your reverb signal through another working tank for a quick troubleshoot.
> ...


That sounds pretty straight forward to me. Thank you very much. And an old fender gut shot is a lot easier to look at than my Pepco Deluxe Reverb knockoff. Its mostly real P2P.


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## cboutilier (Jan 12, 2016)

keithb7 said:


> Yup that'd be the right answers. Do you have a schematic and lay out diagram printed out?
> Start by pulling the tank and inspect all the connections, wires and springs. Is a spring broken? Those tiny little input and output wires can easily break. Run a continuity check on everything you can to test.
> Reverb Pan, RCA cords etc. Pull chassis and check RCA jacks for proper continuity. Are the jacks tight feeling or loosey-goosey. Inspect all wires in the reverb circuit. Connections all look good? Probe them all with a
> chop stick with amp live, with volume low. Any connections crackling? Tubes crackling when tapped? If you have another amp, it's nice to run your reverb signal through another working tank for a quick troubleshoot.
> ...


It's definitely on the output side. No noise from hitting the tank at all. I'm going to try running it through the tank in my Riviera head, and try new tubes tomorrow. The tubes in these are numbered starting from the right (facing from the back) with the rectifier being the last number, correct?


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## keithb7 (Dec 28, 2006)

Correct, each tube starts with V. No matter what type. V for valve.


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## greco (Jul 15, 2007)

Great thread!..Especially for electronics enthusiasts.

What is a "roach" in electronics? Thanks.


keithb7 said:


> Replaced cathode and vibrato caps and *roach*.


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## keithb7 (Dec 28, 2006)

The roach is the an LED light and varible resistor encased in black covering. It looks like a black bug. It is part of the vibrato circuit. When you adjust the vibrato intensity, I believe you are adjusting how bright the LED is inside the roach. The brighter it gets, the more resistance value from the variable resistor. The more intense the throbbing gets in your vibrato effect. 

The roach in my 71 SR photo is seen near the 3 bright orange drop caps. It has a white dot on it indicating the positive end. The orange caps are also part of the amp's vibrato circuit. These caps are often changed from stock to net a slower vibrato speed.


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## cboutilier (Jan 12, 2016)

I think I just found a line on a cheap 70s SR cabinet that needs some TLC. Now to begin my hunt for 4 decent 10'' speakers to restore the lost mojo of this beast.


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## StevieMac (Mar 4, 2006)

Feel free to contact me with any questions regarding suitable speakers in an SR. Briefly though, among those I have considerable experience with, my recommendations would include:

CTS AlNiCos (hard to find a quad in good condition);
THD greyframe 10s (even harder to find);
Emi ceramic 1058 + AlNiCo 1028 pairs (easy to find & moderately priced)
Jensen RI C10Qs (easy to find & priced fairly).

My "bang-for-your-buck" choice among these would be C10Q RIs. Once broken in, they work well in an SR.

AES is having a flash sale (25% off) on Jensens at the moment and will send USPS to Canadian addresses (orders > $89 are shipped free in US). If you consider taking this route, I'd seriously suggest the 10" Jet Falcons @ $140 USD/quad + ship, as I've heard good things about them: Speakers - Jensen, 10 inch, 8 Ohms | Antique Electronic Supply


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## PTWamps (Aug 5, 2016)

To StevieMac's excellent suggestions, I'd add the Warehouse/ WGS American Vintage series. Very affordable and available in Canada (Rosemere Musique here in QC has them). I stuck a pair of 10s in the tweed cab pictured in my avatar. With my SF SR head, they sound full and rich, that classic Fender silky warm tone -- far better than the overworn originals.


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## keithb7 (Dec 28, 2006)

Did the OP solve the reverb issue here yet? Wonder what the fix was. I like to learn from other examples. Thx.


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## cboutilier (Jan 12, 2016)

keithb7 said:


> Did the OP solve the reverb issue here yet? Wonder what the fix was. I like to learn from other examples. Thx.


Not yet. Engineering school snuck up and stole all my time. I know that it is for sure on the return side of the tank. With the reverb cranked I only get a very faint crash if I physically flick the springs. And it doesn't work running through my other tank.


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## keithb7 (Dec 28, 2006)

I'm suspecting something in the area of the circuit circled in red.
I'm curious what the problem turns out to be. Keep us in the loop once you get it figured out. No hurry. Engineering school definitely takes priority.
Where are you studying? In Nova Scotia?


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## cboutilier (Jan 12, 2016)

keithb7 said:


> I'm suspecting something in the area of the circuit circled in red.
> I'm curious what the problem turns out to be. Keep us in the loop once you get it figured out. No hurry. Engineering school definitely takes priority.
> Where are you studying? In Nova Scotia?


Civil Engineering at Dalhousie University in Halifax. It's a bit time consuming.


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## Jamdog (Mar 9, 2016)

cboutilier said:


> Civil Engineering at Dalhousie University in Halifax. It's a bit time consuming.


Nonsense. Civil engineering takes no time. 
You should do real engineering like electrical, or perhaps mechanical.


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## cboutilier (Jan 12, 2016)

Jamdog said:


> Nonsense. Civil engineering takes no time.
> You should do real engineering like electrical, or perhaps mechanical.


Mechanical was my desire. My GPA was .03 too low to get in.


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## Jamdog (Mar 9, 2016)

cboutilier said:


> Mechanical was my desire. My GPA was .03 too low to get in.


Weakling. 

    



Can you transfer mid program?


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## cboutilier (Jan 12, 2016)

Jamdog said:


> Weakling.
> 
> 
> 
> ...


I could have if I brought the GPA up, but instead I let it fall another .2. 

Oh well, Civil is a pretty good option for Nova Scotia anyways.


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## Jamdog (Mar 9, 2016)

cboutilier said:


> I could have if I brought the GPA up, but instead I let it fall another .2.
> 
> Oh well, Civil is a pretty good option for Nova Scotia anyways.


Halifax is filled with naval industry : Lockheed, L3, Thales. EE would be a great option.


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## cboutilier (Jan 12, 2016)

keithb7 said:


> I'm suspecting something in the area of the circuit circled in red.
> I'm curious what the problem turns out to be. Keep us in the loop once you get it figured out. No hurry. Engineering school definitely takes priority.
> Where are you studying? In Nova Scotia?


I've got the chassis out in front of me now. First thing I've noticed is that this amp has indeed had some work done, as I was told before. The MV pot is completely disconnected, and 9 Restistors have been replaced (PI circuit) and the bias caps appear new. 

One odd thing ive found is a little orange/brown disc capacitor going from the Reverb Output jack to ground that doesn't appear in the schematic or layout diagram for the AB763. The schematic does, however, show a cap on the input jack going to ground that isnt present on either my amp or the layout diagram. The two resistors coming from the wiper of my reverb pot are both 470k instead of one 470k and one 220k as the diagrams show. They both, however, are measuring 270k with my DMM (in circuit).

I'll take some gut shots when my phone charges up.


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## cboutilier (Jan 12, 2016)

Gut shots are taken. Reverb pot reads a pretty linear sweep from 0 to ~75k ohms. Found a nice Westinghouse MIA 5U4GB recto tube hiding in this baby!


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## keithb7 (Dec 28, 2006)

I have a late 71/early 72 Super Reverb. The same little cap is on my Reverb jack. Seen below here. This pic is before I serviced the amp. I believe my amp was 100% stock before I serviced it.

Looks like a hack may have been in your amp. I see some pretty shotty work. Someone added a bias trim pot in yours.
I'm not sure that little bias cap board is stock. You can see mine is under the jewel lamp. I can't be sure, maybe they moved it at some point. What is your chassis SN? I suspect yours is later than 73. Look for a date code on the little white Mallory caps in your circuit. For example 235-7131 or 235-7134 are on my white caps. After the dash is year (71) followed by week (31 and 34 in my case). I think I see a 75 year date on a cap near your reverb jack in one of your photos.


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## cboutilier (Jan 12, 2016)

keithb7 said:


> I have a late 71/early 72 Super Reverb. The same little cap is on my Reverb jack. Seen below here. This pic is before I serviced the amp. I believe my amp was 100% stock before I serviced it.
> 
> Looks like a hack may have been in your amp. I see some pretty shotty work. Someone added a bias trim pot in yours.
> I'm not sure that little bias cap board is stock. You can see mine is under the jewel lamp. I can't be sure, maybe they moved it at some point. What is your chassis SN? I suspect yours is later than 73. Look for a date code on the little white Mallory caps in your circuit. For example 235-7131 or 235-7134 are on my white caps. After the dash is year (71) followed by week (31 and 34 in my case). I think I see a 75 year date on a cap near your reverb jack in one of your photos.


I dated the pots to 1975 and the chassis serial to 75 as well. I'm guessing the bis board was moved when they added the MV pot to make room for that pot and wiring.


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## keithb7 (Dec 28, 2006)

This should be the proper schematic for your 1975 MV Super R:

http://schematicheaven.net/fenderamps/cbs_45w_mstrvol_pullsw_super-pro-bmstr_rev.pdf


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## cboutilier (Jan 12, 2016)

keithb7 said:


> This should be the proper schematic for your 1975 MV Super R:
> 
> http://schematicheaven.net/fenderamps/cbs_45w_mstrvol_pullsw_super-pro-bmstr_rev.pdf


Odd enough, my MV pot isn't a push pull. I wonder if this amp was a early 75 that only got the MV.


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## PTWamps (Aug 5, 2016)

cboutilier said:


> Odd enough, my MV pot isn't a push pull. I wonder if this amp was a early 75 that only got the MV.


MV was added to Super Reverb in 1972 but the push-pull for "overdrive" came only in 1977. Your single MV pot is correct for a 1975. You are better off, because the pull overdrive feature never a useable feature IMO -- sounded like crap. I cut out the MV on the most recent round of mods in my own SF and just use the channel volumes now. 

You and Keith both speculate that the bias caps are non-original. They are recent Illinois caps; definitely not original. The silver Mallory bias cap shown in Keith's is what I've normally seen in non-modified amps. Those bias caps can leak over time (in fact I found a completely dead one in a Bassman I serviced recently -- the amp was essentially non-biased), so the replacements may have made sense at the time they were done. I've used Illinois for filter cap replacements in a silverface SR (TubeStore sells them), and they are fine.


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## cboutilier (Jan 12, 2016)

PTWamps said:


> MV was added to Super Reverb in 1972 but the push-pull for "overdrive" came only in 1977. Your single MV pot is correct for a 1975. You are better off, because the pull overdrive feature never a useable feature IMO -- sounded like crap. I cut out the MV on the most recent round of mods in my own SF and just use the channel volumes now.
> 
> You and Keith both speculate that the bias caps are non-original. They are recent Illinois caps; definitely not original. The silver Mallory bias cap shown in Keith's is what I've normally seen in non-modified amps. Those bias caps can leak over time (in fact I found a completely dead one in a Bassman I serviced recently -- the amp was essentially non-biased), so the replacements may have made sense at the time they were done. I've used Illinois for filter cap replacements in a silverface SR (TubeStore sells them), and they are fine.


My MV is disabled as well. I may get crafty and add a presence control or something like that with the extra pot. Once I get this reverb sorted out of course


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## PTWamps (Aug 5, 2016)

cboutilier said:


> My MV is disabled as well. I may get crafty and add a presence control or something like that with the extra pot. Once I get this reverb sorted out of course


Good move. When I took out the MV (which had grown scratchy and intermittent over time), the whole amp came alive -- much more presence and gain on both channels, and since the overdrive was no great shakes anyway I don't mind that I've got clean headroom for miles. I just run a OD pedal in front of it. I plugged the hole where the MV pot was with a black plastic hole plug.


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## BMW-KTM (Apr 7, 2015)

Opps


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## BMW-KTM (Apr 7, 2015)

Oops


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## cboutilier (Jan 12, 2016)

PTWamps said:


> MV was added to Super Reverb in 1972 but the push-pull for "overdrive" came only in 1977. Your single MV pot is correct for a 1975. You are better off, because the pull overdrive feature never a useable feature IMO -- sounded like crap. I cut out the MV on the most recent round of mods in my own SF and just use the channel volumes now.
> 
> You and Keith both speculate that the bias caps are non-original. They are recent Illinois caps; definitely not original. The silver Mallory bias cap shown in Keith's is what I've normally seen in non-modified amps. Those bias caps can leak over time (in fact I found a completely dead one in a Bassman I serviced recently -- the amp was essentially non-biased), so the replacements may have made sense at the time they were done. I've used Illinois for filter cap replacements in a silverface SR (TubeStore sells them), and they are fine.


What component failure would you expect to cause an extremely faint recovery? With reverb on 10, there is a barely audible crash from the springs. Not even enough to hear from whacking the tank with your knuckles, on either tank. I'm thinking something must be shorting that signal to ground.


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## PTWamps (Aug 5, 2016)

cboutilier said:


> What component failure would you expect to cause an extremely faint recovery? With reverb on 10, there is a barely audible crash from the springs. Not even enough to hear from whacking the tank with your knuckles, on either tank. I'm thinking something must be shorting that signal to ground.


If there was a short, you'd expect _no_ signal, not a faint one. Check inside the tank as the springs can come detached from the contacts. Test all wires and connections beginning inside the tank, through the RCA plugs and jacks, back to the circuit components on and around the tube recovery tube. Swap the tube itself (you can just borrow V1 on the Normal channel if you don't have a spare on hand). Something has loosened or failed. 

That being said, I've gotten so sick of the noise and constant failure of spring reverbs that I've stripped them out of my own amps entirely and just rely on a Hall of Fame on my board these days. I still fix reverbs for customers -- cause you sorta have to if you're gonna be in the vintage amp business. But they always strike me as the Achilles heel of otherwise great amps, IMO.


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## cboutilier (Jan 12, 2016)

PTWamps said:


> If there was a short, you'd expect _no_ signal, not a faint one. Check inside the tank as the springs can come detached from the contacts. Test all wires and connections beginning inside the tank, through the RCA plugs and jacks, back to the circuit components on and around the tube recovery tube. Swap the tube itself (you can just borrow V1 on the Normal channel if you don't have a spare on hand). Something has loosened or failed.
> 
> That being said, I've gotten so sick of the noise and constant failure of spring reverbs that I've stripped them out of my own amps entirely and just rely on a Hall of Fame on my board these days. I still fix reverbs for customers -- cause you sorta have to if you're gonna be in the vintage amp business. But they always strike me as the Achilles heel of otherwise great amps, IMO.


It's a brand new tank and I've run it through a known working tank, with no improvement. 

Swapping tubes didn't help either. 

All resistors that I could check without lifting the caps checked fine.

Pot read a little bit low (~70k) but seemed fine across its sweep. 

All wire runs had good continuity.



I need to get my iron out and lift the caps so I can test them and their parallel resistors. My multimeter can test for capacitance. I haven't checked any live voltages yet either. My workspace was commandeered for jam and pickle making, so I'm at a temporary standstill. Is it safe to run this amp without the tank connected, provided I pull V3, or will I cook the reverb driver transformer?


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## keithb7 (Dec 28, 2006)

cboutilier: Those bypass caps are cheap. If you are in there to unsolder one end to test the resistor, you are best off just unsoldering both ends. Check resistor and reassemble with new cathode caps and resistor too if needed.
Unsolder reverb transformer wires and check for continuity across each set of wires. Won't hurt to check ohm load reading as well. If you have a DMM to check capacitance, it is most likely unreliable.
The cap may behave differently with high voltage going through it. Just my experience.


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## keithb7 (Dec 28, 2006)

On my 73 Twin with weak reverb, even with reverb pot turned up to 10. I found a bad cathode resistor right beside the cathode cap.
It was supposed to be 2.2K. It measured in at 13.82K. Replaced it and voila! Success.

The middle green circle with the blue resistor in it was my culprit:


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## jb welder (Sep 14, 2010)

Yes you can run it with reverb driver tube removed and tank disconnected.
What are your DC voltages on pins 1 and 3 of V4 ?
Is the 470K connected to the wiper of the reverb pot ok?


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## cboutilier (Jan 12, 2016)

jb welder said:


> Yes you can run it with reverb driver tube removed and tank disconnected.
> What are your DC voltages on pins 1 and 3 of V4 ?
> Is the 470K connected to the wiper of the reverb pot ok?


Now that I have my workspace back, I'll power it up this evening and take some voltage readings. I believe that 470k tested fine, but I don't completely remember.


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## cboutilier (Jan 12, 2016)

Update: reverb is now working! The cathode cap on V4 was bad, and the RCA cord on the output side of the tank was shotty. The two 470k resistors are also out of spec and need to be replaced. They are reading around 220k each. 

I now need to check out the vibrato circuit. I'm getting almost no effect from it, and as you crank the intensity it is attenuation almost all of the guitar signal.


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## keithb7 (Dec 28, 2006)

Good news. Where are the 470k resistors?


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## cboutilier (Jan 12, 2016)

keithb7 said:


> Good news. Where are the 470k resistors?


I believe, in your picture they are directly above the big blue coupling cap to the right of the three orange drops. Above V4.


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## keithb7 (Dec 28, 2006)

cboutilier said:


> I believe, in your picture they are directly above the big blue coupling cap to the right of the three orange drops. Above V4.


The Yellow/violet/yellow is 470 ohm. The one right beside it (orange/orange/green) is 3.3 M


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## cboutilier (Jan 12, 2016)

keithb7 said:


> The Yellow/violet/yellow is 470 ohm. The one right beside it (orange/orange/green) is 3.3 M


On mine there was two 470s and another resistor beside that in parallel with a little disc cap


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## keithb7 (Dec 28, 2006)

Different circuit than AA270?


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## keithb7 (Dec 28, 2006)

Sorry, yes you have the MV. Not an AA270.


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## cboutilier (Jan 12, 2016)

keithb7 said:


> Different circuit than AA270?


I believe so. On mine, and the CBS schematic I'm following for a 74-75 shows that 220k in series with the 470k coming from the Reverb pot wiper as being amother 470k.


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## keithb7 (Dec 28, 2006)

Sorry, yes you have the MV. Not an AA270.


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## cboutilier (Jan 12, 2016)

I'm just happy the verb works now. I think the pot has drifted off spec quite a bit though. The very on 10 isn't as powerful as I would expect. It measured at ~70 percent of its stamped resistance (73k iirc)


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## keithb7 (Dec 28, 2006)

I had weak reverb on a SF Fender too. Can't remember now if it was my Twin or Super. It was drifted resistor in reverb send circuit. Way outta spec. After a new one, verb was awesome, and still is!


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## cboutilier (Jan 12, 2016)

keithb7 said:


> I had weak reverb on a SF Fender too. Can't remember now if it was my Twin or Super. It was drifted resistor in reverb send circuit. Way outta spec. After a new one, verb was awesome, and still is!


This is my first SF so I don't know how powerful the verb should be, but this doesn't have as much as the SRRI I played or my Riviera. The Riveria will make a fellow sea sick if you turn the reverb up past 2. 

I'm happy with it though! It still has more than enough verb than I'll ever use


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## jb welder (Sep 14, 2010)

Have you tried changing the reverb driver tube since you've got the reverb running?
Also, whenever dealing with reverb issues in these amps, I like to verify the tank in and outs with resistance checks. The 'in' of the tank will be the lower resistance (approx. 2 ohms). One of the cables is usually marked with red at the plug, but you never know when someone may have reversed the connections inside the tank bag.
Reversed connections will weaken the reverb effect.


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## cboutilier (Jan 12, 2016)

jb welder said:


> Have you tried changing the reverb driver tube since you've got the reverb running?
> Also, whenever dealing with reverb issues in these amps, I like to verify the tank in and outs with resistance checks. The 'in' of the tank will be the lower resistance (approx. 2 ohms). One of the cables is usually marked with red at the plug, but you never know when someone may have reversed the connections inside the tank bag.
> Reversed connections will weaken the reverb effect.


I might have. Ive had all the tubes in and out a few times, and didn't keep track of which one went back to the same slot. Just that the right type of tube went where it belonged.


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## cboutilier (Jan 12, 2016)

I started a little cabinet project tonight. I'm converting one of my two Bassman 10 combo cabs into a 1x15 combo. This will make my Super Reverb into a kind of Low Power Vibrosonic/Silverface Vibroclone.

Will serve to be a sort of a "what if the Vibroverb survived into the Silverface era".


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## cboutilier (Jan 12, 2016)

Last piece of the puzzle arrived in the mail! No more impedance issues. Now to find the time to finish the combo cabinet.


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http://instagr.am/p/BL9re8Ij7zw/

I've been told 100 times to leave this as a head and build a cabinet for it, but I just don't bond with piggybacks. There's something to be said for getting in the door in one trip, no matter how uncomfortable.


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## cboutilier (Jan 12, 2016)

I tried my hand at grill cloth work this evening. Turned out perfect! Just gotta shorten the sides of the cab and glue in the new bottom and I'm geared to go on Project Vibroclone.


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http://instagr.am/p/BMHff7mjFsV/


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http://instagr.am/p/BMHzsoSDS0J/


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## keithb7 (Dec 28, 2006)

Looks great Booter. Speaking of Supers, I just had a 1965 in my shop yesterday. Local musician wanted it serviced. Man it sounded great. My first experience playig thru or servicing a BF Super. Not that different tho than my '71 Super. Maybe a little but very similar.


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## cboutilier (Jan 12, 2016)

Here she is, sitting pretty. Silverface Vibroclone.


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http://instagr.am/p/BMWvk20jgfy/

Weighed in at 53.8 lbs on the bathroom scale.


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## cboutilier (Jan 12, 2016)

It sits at 23.5 inches tall, so it's only a hair smaller than a real SFSR.

I took it out last night to test it out at stage volume. What a great sounding amp though. And no issues running for 4 hours straight. She's a loud one. I never had it up past 3 on the knob, playing with my pedals.


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