Blues Junior turret board upgrades

[EL34]

See the build info below. the amp is done
The amp came out sounding greatI recorded two sound clips today. One dirty clip with humbuckers and one clean clip with single coilsThis is the clean cliphttp://el34world.com/Misc/Music/files/BluesJuniorDemo2.mp3This is the dirty cliphttp://el34world.com/Misc/Music/files/BluesJuniorDemo1.mp3




I have been working on a Blues Junior board upgrade.
Larry Rodgers at Rodgers amps sent me one with a fried tube PC board and so I CNC's a 1/8th inch think replacement board with real tube sockets
I added a bias pot, fixed some solder joints, replaced 1/2 watt screen grids and the thing worked again.

The problem is that it still has crappy pots and jacks and a pc board.
There are hundreds of thousands of Blues Juniors out there since they first came out in the late 90's, and people love them for their size and they actually do not sound that bad. Not as good as a hand wired amp, but ok

So now my next project is to gut one completely and install a turret board and tube socket board.
Someone is sending me an amp to convert and it should be here soon

I got a head start by CNCing the boards and lacing them up

[EL34]

Here's the main turret board

On the PC board, there is a +15 / -15 volt and bias circuit power supply that I am going to cut out with a dremel
The same with the solid state reverb circuit which need the power supply above

Both areas on the main boards are very small (2 x 2 inches) and I don't want to have to construct that stuff on a turret board

[EL34]

Here's the one I fixed for Larry Rodgers and sent it back to him
New CNC'd Tube board, Bias pot added
New larger screen grid resistors
Fixed some bad solder joints on the belly of the main board

[bakerlite]

Hey doug. The guitatest in my band has just given me one of these to look at with a filter cap gone along with burnt out traces where the resistor was before it smoked. Do you plan on offering these and if so How soon will you offer them?

[EL34]

Just as soon as I finish my build
It's on the  bench right now

It's a big undertaking and lots of labor, so keep that in mind

I'll be posting pics and info here as the build proceeds

[kagliostro]

Cool conversion 

Franco

[MadMax]

Good choice of amp to do this on. They do sound good, and I've seen more than one for sale "needs repair". Are the heaters powered by DC and therefore no need to twist?

[John]

Good choice of amp to do this on. They do sound good, and I've seen more than one for sale "needs repair". Are the heaters powered by DC and therefore no need to twist?

Max, only my guess, but I'd say with the layout the way it is  there's just "no need to twist". The heater wires are far away from the sensitive wires, plus with such short runs between them.


Again, just my guess.

[EL34]

The heaters are not DC on the two that I have worked on

Here's the power tranny schematic

[EL34]

The gutted chassis parts and the new parts going into the amp

That's an Allen TP24 power tranny
The choke is a Mercury Mag
Heyboer 768sp OT with 4,8,16 ohm taps (I stock this OT)

[EL34]

The Boards, trannys, pots installed
Major wires are in place and soldered

[EL34]

More pics
I added a fuse holder to the chassis

[EL34]

Tube sockets wired up

[EL34]

Components added to the board and pot leads added

[EL34]

Components added to the board and pot leads added

[phread]

Add me to the list of people that would like a turret board (unpopulated) and a tube board!

Cheers,

-Phread

[EL34]

I'll be posting back here when I am ready to go
I need to finish this build to see if all is ok with my design, and then it will be go time

[tubenit]

That is really an amazingly well done conversion !! 

Your work is just impeccable!  PLEASE give a review of how it sounds after your done ......... OR a soundclip.

With respect, Tubenit

[EL34]

Thanks Jeff,


I will be doing some sound clips when it's up and running

[moonbird]

Doug --


Wow - what a great project. I have a gutted Blues jr chassis just waiting. Sign me up for boards as well!

[EL34]

It's a monster project for sure


If you can do without the reverb, it will be way easier
I am about to saw up the main board today to see if i can remove the reverb send and receive circuit

[kagliostro]

You're the # 1 Doug

It is not in my ability, but someone of the forum that is practical could redesign a PCB for the reverb circuit + PS by copying the original

Franco

[DummyLoad]

It's a monster project for sure


If you can do without the reverb, it will be way easier
I am about to saw up the main board today to see if i can remove the reverb send and receive circuit

replicate it on a chunk of rat shack perfboard?

http://www.radioshack.com/dual-mini-board-with-213-holes/2760148.html#.VGszLzTF98E

--pete

[tubenit]

Maybe this will help.  I think most of this schematic is Revision D with the exception of the FAT switch area which I think is Revision A.

I've attached an editable version so you can edit or modify whatever one wishes.

With respect, Tubenit

[EL34]

Hi Jeff,
I have it all in Visio like my other documents

[tubenit]

I have it all in Visio like my other documents

     I'm aware of the original Fender versions.

Are you saying you have the schematic (not layout)  itself it Visio?  If so, would you be able to please post it?  If you already posted the schematic, somehow I missed it?  I saw the layout earlier in the thread and it looks great.

Thanks, Jeff 

[EL34]

I am not done yet
I'll upload a work in progress PDF file

[MFowler]

Doug like I said on facebook this is a very sweet project.


I noticed in one of your chassis photos that has chassis dimension noted that the length of the chassis is 16.375 I measured the chassis and back board to be 16 5/16 on mine?  Just thought I would mention that, small detail I know compared to all your work here.


Mark

[tubenit]

I am not done yet  I'll upload a work in progress PDF file

A Visio version of the schematic would be fantastic (and a definite visual upgrade)!  Thanks for your willingness to do that & share. 

I found the original Fender schematics rather difficult to make sense of.

With respect, Jeff

[moonbird]

Looks great Doug --


Could you provide the specs for the choke? (gotta bunch around).


Thanks again for this!!


Tubenit - Might the left over triode be incorporated into the reverb circuit somehow (recovery stage)?

[EL34]

I don't have any spec's. The customer sent me the MM choke


I have specs for the two chokes I carry
http://hoffmanamps.com/MyStore/catalog/parts11.htm

[EL34]

The Blues Junior is done with some modifications done to my original design.
I'll be updating my Documents with those changes and I'll create a build page on the web site.

That's why I build one or two, to iron out design changes

For now though the news is that the owner did not want the solid state reverb, and I was finding it hard to locate a spot to set up the solid state reverb board.
So, long story short, no reverb which is fine with me.
The solid state reverb does not sound all that great anyway and the amp owner uses external devices for his effects.

I had to make a bias board and mount it next to the main board.
The new board design will have the bias circuit on the main board
You can see the separate bias board in the pic below

The amp came out sounding great
I recorded two sound clips today. One dirty clip with humbuckers and one clean clip with single coils

This is the clean clip
http://el34world.com/Misc/Music/files/BluesJuniorDemo2.mp3

This is the dirty clip
http://el34world.com/Misc/Music/files/BluesJuniorDemo1.mp3

[EL34]

There's just was no place I could find to install these two small boards that I cut out from the original PC board.
One is the reverb circuit and one is the +15 -15 volt chip power supply. The bias circuit is also on this board

And since the amp owner did not want the solid the solid state reverb, there was no reason for the power supply board
So now I had to construct a bias supply board

The new Turret board design will have the bias supply on the board.

So now for the bad news if you were wanting the solid state reverb
I have no plans to include that in my turret board

If you want reverb you will have to use a reverb pedal or an external reverb tank

The picture below shows the reverb circuit and power supply that I cut out of the main pc board

[EL34]

Instead of the reverb control on the amp, I added a meat control (resonance)
Just like on my later 50 and 100 watt heads

The meat control gives a really nice fat bottom effect when used with humbuckers

[tubenit]

Can you have the board set up so that you have passive FX loop on the back/bottom of the chassis for either delay or reverb pedals?

With respect, Tubenit

[EL34]

Sure, but that's just someone drilling a couple holes in the chassis, nothing different on the board

You can mod the amp anyway you like


Is that what you were thinking too?

[tubenit]

Sure, but that's just someone drilling a couple holes in the chassis, nothing different on the board

You can mod the amp anyway you like   Is that what you were thinking too?

Yes,  I'd rather use a passive effects loop and either a reverb or delay pedal then try the onboard reverb with a PCB board. Just a personal preference.  If the passive effects loop is there, I wouldn't miss the PCB reverb section.

with respect, Tubenit

[EL34]

Cool
You know, there are so many of these Blues Juniors out there
They make a great carcass for projects

They have been around since the late 1990's and Fender has sold a boatload of them

[EL34]

I am getting the documentation together for the Blues junior
Layout, schematic, Lug lacing, BOM and parts list

There were several changes during the build
I attached the most recent layout - still a work in progree

[Commodore 64]

This is interesting. Another ubiquitous amp is the Hot Rod Deluxe and there's a lot more room in the chassis. I'm about to gut one and fill it with turrets, too. But I don't think I'll be trying to recreate the circuit.

[straycat]

I know this is a fairly new project. I was wondering if you could do a version of this with a pair of 6v6's? And also with a reverb circuit from a Princeton Reverb instead of the PJ reverb? I would like to build a modified PJ clone. I know why don't I just build a Princeton Reverb. Kind of like the YouTube videos of the tone and vibe of PJ over the PR. I am not crazy or tone deaf :-)

Thanks
Tim

[EL34]

I am done with the Blues Junior project and already onto the next project in my brain
I am wrapping up the documentation on the build now

You will have to build a 6V6 version.
Others have done it

All you need to do is buy the Allen TP24 power transformer replacement and you can run 6V6's in the BJ
http://www.allenamps.com/parts.php#transformers

Then for reverb, all you need to do is build a Princeton reverb because it has 4 x 9 pin tubes and the BJ only has 3

[straycat]

Thanks for the reply EL34. I am just an amateur builder who can build amps from layouts and schematics. My last build was a Marshall JTM50 Black Flag clone

 As far as converting over to the 6V6 I can wire up the octal sockets for them. I have been to BillM's and Allen's site also. Just wondering if any changes needed to be made to the bias circuit.

Adding a Princeton spring reverb to the BJ circuit is a little bit over my head. In your earlier layouts of the BJ you had a reverb in the circuit. Is that a modified version of the BJ reverb?

Thank you for time and effort on the BJ.

Tim

[EL34]

This page explains my build and why I gave up on the reverb
http://el34world.com/Hoffman/Blues_Junior_Build.htm

[EL34]

I created a Blues Jr tube board installation page today
Some folks just want to get rid of the wimpy tube board and not do a complete turret board install.

http://el34world.com/Hoffman/Blues_Junior_Tube_Board.htm

And this is the Blues Junior build page
http://el34world.com/Hoffman/Blues_Junior_Build.htm


I stock these board on this page
http://hoffmanamps.com/MyStore/catalog/parts12.htm

[Gainzilla]

I just inherited a non-working Hot Rod Deluxe? The circuit board is in pretty bad shape, and I've been wondering what to do with it. Do you think your boards would work for this amp as well? The tube board looks pretty close.

[edit] I just realized this amp uses el84 power tubes. I had no idea. Bummer, though... That would've been a nice easy solution...

Thx in advance!

[EL34]

Blues junior is a EL84 amp also

[Gainzilla]

I just re-read my post and realize I wasn't very clear. Can has words? Lol


I meant that the hot rod deluxe uses 6L6, and the blues junior uses EL84. Clearly your new board won't work for me. Still, if I could sort out the socket issue, I could drop in one of your boards. :)


Cheers,

[EL34]

Not sure what you are asking but the power tubes do not matter to my board
You can use any power tube you want as long as your transformers can handle the tubes you are using

I could have installed 6V6's in the BJ because the customer sent me an Allen PT and it can handle 6V6's

The chassis holes on the BJ are the perfect size to bolt in 8 pin sockets

[straycat]

Does the bias or phase inverter circuits need to be modified to run the 6V6's? Can I run a deluxe reverb or Blue Deluxe power supply and attach it to your preamp at the master volume?

Thanks
Tim