Fixing the Reverb Tank
The reverb tank is definitely a weak spot, but its most common problem is fixable if you have the time and patience.
Check the continuity at the tank itself by measuring the resistance at each RCA jack (plug in a jumper cable for ease of access). The input side (towards the center, where the red wire goes) should measure around 60 ohms. The output side (black wire, on the right, looking at the back of the amp) should measure around 200 ohms.
It’s not uncommon for the wires that go from the input and output jacks to the reverb transducers to break right where they go into the white plastic push-on connectors. The green and black wires are pressed into the back of the push-on connector, and the connector has an insulation-piercing blade that slices through the insulation and makes contact with the wire. Unfortunately, the blade sometimes nicks the wire and it breaks right there.
Track down the broken wire by looking for continuity with a ohmmeter on each wire, from the pins to the jack. When you find the bad one, pull the wire out of the push-on connector with long-nose pliers, trim the broken portion, and push it back in again with a thin screwdriver so the blade re-pierces the insulation.
If that doesn’t do it, the problem may be with the tank itself. The very fine wires from the transducer coil to the push-on pins may have broken. You should have continuity through the pins–If you don’t have continuity on both sides of the tank, one of the fine wires is broken. These are very hard to resolder–I have to work under a magnifying lamp to do it.
At this point, you may want to just replace the tank. They’re less than $25 from suppliers such as Antique Electronics and Mojo Musical Supply. The stock replacement tank is the Accutronics 8EB2C1B. If you like long, surfy reverb and darker reverb tone, choose the Ruby 3EB2C1B, available from Mojo.
The longer tank, used in the Hot Rod Deluxe and Blues Deluxe, is electrically compatible with the Blues Junior, but it doesn’t fit inside the BJr cabinet. Some people have hacksawed the ends off the tank to make it fit, but the Ruby tank will probably give you all the reverb you’d ever want.
This is the back of the plug that connects the RCA jack to the reverb assembly. Sorry for the blurry picture, but you’ll see a pair of knives that cut the insulation when the black and green wires are pressed into the connector.
They often nick the wire, however, which breaks. Everything looks good, but there’s no connection or it only works occasionally. The fix is to pull the wire out (find out which one with an ohmmeter), trim the broken part, and reinsert it. Push it in with a jeweler’s screwdriver or other small blade.
Thanks for the fix. This is exactly what I found to be the problem with the reverb tank on my Blues Jr.
I re-inserted the wire and now it works fine! Saved me $50.00 on service plus maybe a new tank…
Thanks. My reverb tank is acting funny and my amp’s only a year old. With Master Volume at 12 and Reverb at 12 all I get is a dull, half-hearted small-time reverb, not like it was when it was new. You can’t even tell there’s reverb until the Reverb is past 6. I checked the RCA connectors; the resistance readings are correct, the way you said they’d be. I tried cleaning the RCA plugs and connectors and that didn’t do anything either. It’s not intermittent, just really weak.
I guess it’s a warranty repair so I’ll just bring it in. Boring.
Maybe the pot is broken? You can take off the cover and look at the back of the pot to see if the fiber is cracked.
Found the wires in my Blues Jr reverb tank were completely severed at the connectors. An easy fix but (like, duh) I didn’t note the polarity of the connectors before I pulled them off the pins on the tank. Can you describe which way they go back on?
The polarity of the connectors doesn’t matter. It’s dumping the signal into a bunch of floppy springs!
Bill,
I took your advice and have ordered a Ruby Tubes reverb tank (I like the long, surfy sound). Before I ordered I talked with a friend and he suggested adding a reverb bag to help preserve the sound. Once I put the new tank in the bag do I just screw the whole thing to the bottom of the cabinet? Any thoughts and insight would be great!
Thanks!
MAC
You can just attach the bag with Velcro. Simple–works well.
Hey, great tip. Broken wire in my reverb unit too. Fixed as per above, and once again, saved quite a few Pounds (UK!).
Thanks for a great website.
PS just bought a Carvin Nomad 112. Any ideas as to mods for that amp? Have to say i will probably sell my FBJ, now as the Carvin is fantastic.
Hey I was wondering, what is the biggest reverb tank that could be installed in this amp? I am assuming that the large tank like is in the vibro-king would not work electronically? does the tank that is in the hot rod and blues deluxe produce more reverb than the ruby tank?
No other tank will fit in the Blues Junior. The Ruby/Belton/MOD tank has longer, slower reverb than the stock tank.
Hi Bill, I tried the Ruby tank and some of the notes have a resonant spike that is really unmusical. All this after sending the first back, it sounded like I had a weird synth plugged in. The new one was better but still unusable. I reinstalled the original, and hate it, they sound like a toy. I had a full size Ruby tank and installed it after cutting the end off. Finally I have a reverb that sounds like a real reverb. The only thing is that it doesn’t sound as “forward” as I would like, I end up turning it almost all the way up to “feel” it. I was wondering if there was something I could do, perhaps a resistor swap? I don’t know enough about the circuit to figure it out myself. I replaced the bad electrolytic caps as you said, installed a Mercury OPT and this is on a BillM unit I am CERTAIN you did, as it has the presence control you made, the boost circuit, the switchcraft Jack and a bunch of stuff really well done and exactly as pictured on your site. Not to mention the cool little “billm” sticker. Paid about $550 on eBay, was careful like you said, there are lots of fakes. This ain’t one! Sweet amp. By the way, I wasn’t thrilled with the Texas Heat. Weber 50watt F12-150 “light dope” WAY better. Just to put my vote in! Any advice on optimizing the full size tank? Thank you!!!
What’s the tank code on the full-length tank? It may be the wrong impedance for the solid-state drive circuit. If so, there’s nothing you can do other than get a tank with the right impedance.
Went to Mojo today to buy a replacement 3EB2C1B and apparently they are no longer being sold. I haven’t called yet but am curious if this “Discontinued” means “forever” or “just until we resupply”?
Antique Electronics has the equivalent 8EB2C1B tank from both Belton and Mod. Both sound just like the Ruby, slightly longer, warmer reverb than the stock Accutronics tank.
Hi Bill,
Just a note to say I called Mojo and ordered the Ruby Tank today, so they are in stock again. I can’t wait to hear the difference. Surf’s Up!
Peace, Richard
Hi Bill,
The installation was easy on my new Ruby reverb tank. I was able to remove the original tank pretty easily and got the 2 front screws into the Ruby tank, but then found I had to pull the chassis and speaker out to be able to put in the 2 back screws in the tank. This may be because the Avatar Hellatone speaker has a bigger magnet than stock.
I love the sound of the lush Ruby reverb tank! PEACE, Richard
The secret weapon for reverb tank installation/removal is the General Ratchet Screwdriver. You can find them in most any hardware store or from Amazon.
I am thinking of replacing the tank in my BJr. I have a friend who has a 1965 Blackface Super Reverb. It has the most amazing reverb sound. I imagine it’s impossible to get that sound out of a tank that will fit in the BJr, but how close are the longer tanks you’ve recommended going to be, when you are talking about the darker surfy tone?
Try one of the tanks offered by Antique Electronics, the Belton or the MOD. Both sound warmer than the stock tank. It’ll never be a Super Reverb, but it’ll be better.
The stock reverb tank was DOA on my new Blues Jr. No big deal, I dropped in a Belton tank from Antique Electronics and now I’m back in business. The Belton sounds great in the Blues Jr. 18 bucks well spent.
Thanks. I’ll give it shot. I figured it’d be impossible to get a tank that has a sound like the Super Reverb. I haven’t done any mods yet…but I’m looking forward to trying a few things out in the future. Thanks for a being such a great, informative resource.
Bill,
thanks for the heads up about the push on connector on the reverb tank.
the green wire had broken off .
reverb now works great !!!.peace Lenny
Hi Bill!
After fixing successfully my reverb tank following your clear instructions, I am considering getting a spare tank in case of a new, but unfixable that time, breakdown.
I see that you have suggestions for the Beltron and MOD tanks (in addition to the Ruby). Would the Accutronics 8EB3C1B be an alternative in a search for a longer, lusher, surfier reverb, or would it be overkill in the Junior? Traynor for their part seem to be using the 17″ equivalent (4EB3C1B) in their YCV20.
Thanks for your help and congrats on your great work!
I’ve never actually seen an 8EB3C1B. If you find one, let me know where. Meanwhile, the Belton and MOD tanks give you the longer, surfy reverb.
Hi Bill!
I have settled for a MOD reverb tank, after all. I got it yesterday, installed it today, and it does sound much better than the Accutronics! Thanks for your advice!
Hi Bill,
I contacted mojotone.com http://www.mojotone.com/amp-parts/Reverb-Tanks
regarding which reverb tank was the Ruby replacement, this was their info:
———–
I was interested in this reverb tank for a blues jr but it is now marked as discontinued:
3EB2C1B Ruby Tubes Reverb Tank (Fender Style 3-Spring)
Is this the replacement?
M8EB2C1B Mojo Reverb Tank (Fender Style 3-Spring)
———–
Answer: You are correct, that is the Mojo replacement.
Thanks,
Steven
Don’t forget the MOD and Belton tanks available from Antique Electronics.