Standby Switch for Blues Junior
By popular demand! People have been asking me for years for a standby switch on the Blues Junior, and here it is. I’ve seen a couple of implementations over the years, but they typically used an on-off-on switch with standby on one side and play on the other–kind of a kludge. Also, they involved cutting into the high-voltage wiring. I don’t like creating possible points of failure.
There isn’t room inside the chassis for another switch next to the power switch, even if you relocate the pilot light. Yes, you could cram a cheesy little switch in there, but we’re talking high voltage here, and only a heavy-duty switch will do. Fortunately, Carling, the same company that makes the power switch that’s in your Blues Junior, makes a clever progressive switch. It has three positions: off, standby, on–very logical. In standby, the high voltage supply is cut off. The filament and bias supplies receive power.
The kit is super-easy to install. There’s no soldering and–if you’re sensible enough to unplug the amp before you start–no danger. I supply everything you need: the switch, high-voltage wire, and a special connector, plus photo instructions. You can be back up and running in minutes.
Even though standby switches aren’t really necessary on low-powered amps, I’ve gotta say… it’s pretty cool! It’s a handy way to mute the amp when taking a break or when changing guitars. And even with the Billm cooler bias, the output tubes do run even cooler on standby.
The kits are available now. Order from the Mod Kits and Services page.
The kit does not work for the Pro Junior. The switch can be adapted, but requires removing the circuit board and doing some soldering.
Will this Standby Switch for Blues Junior work on a peavey classic 20 amp?
I’m sure you could wire up the switch to work, but the kit is specifically for Blues Juniors.
I’ve come across a bit of information that might be of interest to your international readers. I’ve been repairing a cream-board Blues Junior sold in the UK that had been cooking it’s output tubes. Not only was the Bias set WAY too hot (as was expected) but the plate voltage was around 380V! The combination of the two was leading to the tubes dissipating about 16W at idle… toasty! In poking about, I noticed that Fender had the export transformer wired for 230V mains, but there was also a 240V option on the schematic. Thought I’d give it a try — it’s as simple as swapping the white/black wire connected to S2B (on the mains switch) with the black wire connected to P6 (on the main board next to the fuse F1). Now it’s running cool with a B+ of
346V with the bias set correctly. If Fender are shipping all Blues Juniors to the UK (and Europe?) set for 230V, I’m guessing a lot of people might be running in to problems depending on their local
voltage. So might be worth advising people to check their B+ and adjusting the transformer if necessary.
Tom, I just checked my UK Blues Junior, and it was wired for 230v. Not any more! Thanks for the tip!
Would installing this Standby switch void the warranty on a Blues Jr … or are the changes easilly reversible ?
I’m sure that it would void the warranty, but it is easily reversible.
Hello,I’m living in France and i will buy your standby switch. Do you give the schemat with it?
Thank you
The instructions cover the international version of the amp, too. Photographs show how to connect it.
Will your standby switch for the BJ, work on my PRRI?
Yes it works. I’ve installed one, and it’s pretty cool. Unfortunately, I neglected to write down the lengths of the connecting wires, so I can’t offer it as a kit until I get another PRRI in hand and install another.
Would this by some chance also work Peavey Delta Blues?
Thank you!
In theory, yes. In practice, you’d have to route the B+ supply to the switch and back to the board. Someone knowledgeable about the Delta Blues would have to do it. The connector I supply in the kit is specific to the Blues Junior.
This kit was super easy to install! You just have to take your time and be very careful when pushing/pulling the connectors onto the PCB. I braced the PCB with a finger while I did this. Works great, excellent work Bill!
Hi, will this standby switch work for Princeton Reverbs ? Thanks
The fit is very tight on a Princeton Reverb (Reissue). I’m not currently offering it as a kit, but I may do so in the future.
Hello again,
Will this switch fit / work in a blackface or silverface Princeton Reverb ? If so, how much is it and how can I order one ? Thanks again
It’s a very tight fit in a Princeton Reverb, at least in a reissue. I’m not offering it as a kit right now. The switches I stock have push-on connectors, so you’d have to install female connectors on the appropriate leads in the PR.
Hi!
I installed the switch while drinking a cup of coffee nursing a hangover on a Saturday morning! Easy to install and works great!
Thanks Bill!
Hi All
To save any confusion thought would confirm officially voltage for UK changed from 240volt to 230volts(-6%,+10%) as of January 1st 2004
Hi, The change of UK mains voltage from 240v to 230v is purely cosmetic. Nothing has actually changed, they’ve just shifted the error bands as shown in Steve’s post. It’s still effectively 240v, folks.
(This is to harmonise with the rest of Europe btw.)
Love this switch…are the installation instructions on this site? We bought a few of them for the Lynda Kay band and I think someone else got my copy. Thanks can’t wait to have it in. -AM
The switch kit comes with instructions, 600V-rated jumper wire with insulated push-ons installed, and wire ties for putting it back together neatly.
is the middle position just not connected to anything?
I’m interested in adding a switch like this to my Blackheart Handsome Devil, and i’m wondering if this would work on it. Thanks!
In the middle position, there’s power to the heaters and to the bias, no high voltage to the plates. Since the HD is cathode biased, you don’t have to worry about the bias. But you can wire it so that it interrupts the high voltage supply and leaves the filaments on.
I have the relic’d version of the Blues Jr and I’m wondering if my ‘aged’ nut and washer will work on the threads of this switch?
Yes, the nut will fit. On Relics, I also rough up the switch with sandpaper and/or a file and rub some black and brown permanent marker into the scratches to complete the rusty look. I do the same with the replacement input jack, which uses a different-sized nut than the original.
Good luck getting the back and case screws out.
ha, thanks Bill. I’ve already done your basic mods so getting in a second time won’t be a problem, it sounds amazing so far, I can’t wait to try the TO20 tranny I also ordered…