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FDP Forum / Amp Mods, Repairs, and Projects / Blues Jr Billm bias pot install instructions

Previous 20 Messages  
Hammond101
Contributing Member
**********

So. Cal. USA

Apr 6th, 2017 01:29 PM   Edit   Profile   Print Topic   Search Topic

Got the cream board instructions, yay! Many thanks!

I'll have a look at the green layout and schem tonight and see what can be done.

009
Contributing Member
****

USA

Apr 6th, 2017 05:33 PM   Edit   Profile   Print Topic   Search Topic

For some reason I thought you got ahold of the green board photo instructions, and so I deleted the links I posted yesterday. So, I post them here again; perhaps you may find some use in them. (I realize that you may already have seen these.)

Pg. 2, para. 29 by Mstr.Bones verbally describes the installation here. My naïve supposition is that if someone is familiar with the schematic and the physical board layout, the correct hole drilling/installation could be/would be known:

https://www.thegearpage.net/board/index.php?threads/billm-mods.781204/page-2


Here's some "old green board" voltage info, para. 105, mpaq, Nov. 4, 2011, first paragraph - "Update." No installation hints, per se, but perhaps some relevant information:

http://bluesguitarunleashed.com/forum/index.php?threads/blues-junior-modifications.8138/page-6


...and this PDF academic paper that seems to be in every search result, but here's the link anyway. The schematics are too small and too low res to readily read; some was barely readable by enlarging the image on my computer screen. (But I guess you have the schematic...? I don't know if this one is green or cream.)

https://courses.physics.illinois.edu/phys406/Student_Projects/Spring11/Darby_Hewitt/Darby_Hewitt_P498POM_Final_Report_Sp11.pdf


I like looking for stuff on the internet, esp. on days like yesterday, when I was too sore and worn out from working on Phase II of my fencing project to do anything else.

89AmStd

Studio City, CA

Apr 6th, 2017 07:00 PM   Edit   Profile   Print Topic   Search Topic

Yea--the FDP come through! Thanks twang!

Hammond, do you know if the green and cream board bias pot install is the same?

Not sure what I wrote that suggested that it looked like I didn't buy from BillM, but I definitely sent him $137 for mod parts. I had deferred installing for years, but remembered I had the parts when I read that he passed recently. By then I couldn't find the written instructions, so I appreciate the info that Hammond wanted to correctly complete the project.


Hammond101
Contributing Member
**********

So. Cal. USA

Apr 7th, 2017 09:42 AM   Edit   Profile   Print Topic   Search Topic

I haven't had a chance to look at the above links, sorry. I'm a bit screwed right now with sciatica. This has been going on for nearly a month. It's taken all my energy away and I refuse to mask it with pain killers as I'm sure I will reinjure myself when comfortably numb. No excuses, just the facts.

I'll try to look at this above on lunch break today.

Hammond101
Contributing Member
**********

So. Cal. USA

Apr 7th, 2017 09:56 AM   Edit   Profile   Print Topic   Search Topic

Ok, thanks 009. Actually the printed cream board instructions are better when used with green schem and layout. Confirmation of Bill replacing R51 in the green board is helpful.

Many thanks to all!

Malcolm
Contributing Member
******

Edmond, OK

Apr 8th, 2017 11:41 AM   Edit   Profile   Print Topic   Search Topic

Weren't there versions A, B, C and maybe D? I remember there several versions.

89AmStd

Studio City, CA

Apr 8th, 2017 11:55 AM   Edit   Profile   Print Topic   Search Topic

Hammond or twangdoodles or ???-

Would you please send me a copy of the bias pot install instructions that I requested in my original post? If anyone has the printed instructions specific to the original green board that would be great, too.

My email is cjmurphy at mindspring.com

Thanks for the help.

Hammond101
Contributing Member
**********

So. Cal. USA

Apr 10th, 2017 04:22 PM   Edit   Profile   Print Topic   Search Topic

I will forward the instructions to you this evening. I spent the weekend ignoring the world and resting my sciatica.

Hammond101
Contributing Member
**********

So. Cal. USA

Apr 10th, 2017 08:31 PM   Edit   Profile   Print Topic   Search Topic

Email sent sir!

guitarcapo

U.S.A.

Apr 11th, 2017 11:57 AM   Edit   Profile   Print Topic   Search Topic

I had a tweed Blues Junior that Bill modded for me and it sounded great. He added the tiny pots but after that I never really adjusted them much. I didn't have a bias probe for EL84 size tubes. It seemed to sound great with whatever tubes I put in there with no problems after that.

I guess what I'm saying is that you might want to just change the resistor values to the values he recommended instead of adding those tiny pots. Either way it was a great improvement. More headroom, clarity and bottom end.

89AmStd

Studio City, CA

Apr 18th, 2017 12:21 PM   Edit   Profile   Print Topic   Search Topic

Thanks to Twang and Hammond for sending along the printed cream board instructions. Very sorry to hear about your sciatica.

Hammond, do you have the info now to do Billm's green board bias pot install? According to an ancient Billm post, "the stock bias resistors in a green board BJr are R31 and R37, 22K and 33K respectively. In the cream board, they're designated R52 and R51, also 22K and 33K respectively." I'd like to get the some new tubes and get the bias control to finish the project.

Also, the reverb doesn't seem to work since the basic mods. Any ideas?

See Bill's comments in post #5

89AmStd

Studio City, CA

Apr 18th, 2017 12:24 PM   Edit   Profile   Print Topic   Search Topic

Thanks for your input, guitarcapo!

I think I might as well get the bias pot installed since I already have the part.

I agree that the mods add headroom, clarity and bottom end.


blackandblue
Contributing Member
**********
****

MT, USA and Jura, FR

Apr 19th, 2017 09:03 PM   Edit   Profile   Print Topic   Search Topic

89AmStd,

If you go to the "waybackmachine" and search on:

http://home.comcast.net/~machrone/bjr/bjbias.htm

you will find the directions for the bias pot install on a green board Blues Junior. These are the directions I used years ago, and they work great.

A major nod to Billm; the Bell Tolls for Us All.

waybackmachine

(This message was last edited by blackandblue at 11:11 PM, Apr 19th, 2017)

twangdoodles

michigan usa

Apr 20th, 2017 05:00 AM   Edit   Profile   Print Topic   Search Topic

Nice work!

Here's the direct link:

click

89AmStd

Studio City, CA

Apr 24th, 2017 05:54 PM   Edit   Profile   Print Topic   Search Topic

Thanks blackandblue for the "wayback" info and to twangs for posting the link! Very cool. I agree that Billm deserves a major nod--he was a good 'un!

Hammond101, do you have all the info you need to do Billm's green board bias pot install? Please let me know.

Malcolm
Contributing Member
******

Edmond, OK

Apr 25th, 2017 11:41 AM   Edit   Profile   Print Topic   Search Topic

"I've got a 'Clean Boost' mod for a green board. I bought one, then I got Bill to install one. It's in classifieds.

(This message was last edited by Malcolm at 01:42 PM, Apr 25th, 2017)

89AmStd

Studio City, CA

May 3rd, 2017 09:04 AM   Edit   Profile   Print Topic   Search Topic

Hammond101, do you have all the details needed to do Billm's green board bias pot install for me as well as the bandwidth to complete the project?

Please let me know if we need to request more info and/or if I need to find another tech to make it happen. Thanks@

GuitarKaos

USA

May 4th, 2017 10:52 AM   Edit   Profile   Print Topic   Search Topic

This is a bit of topic but still in the spirit of the post at least... I was also trying to get ahold of Bill's son about an order with no replies to email, but I found him on Facebook under "BillM Audio" I believe, and he answered in about 30 seconds to a message (your mileage may vary)...

Just an FYI to anyone needing to get ahold of him.

Happy Modding!!

BillM Audio Facebook Page

(This message was last edited by GuitarKaos at 12:59 PM, May 4th, 2017)

Hammond101
Contributing Member
**********

So. Cal. USA

May 9th, 2017 10:00 AM   Edit   Profile   Print Topic   Search Topic

Thanks for that info! I messaged Bill's son yesterday through Facebook and got an auto reply however in 30-45 minutes he sent the green board instructions file no questions asked.

Good to have this method of contact.

Thanks GK, great suggestion.

Matt_Krush

usa

Sep 26th, 2017 04:41 PM   Edit   Profile   Print Topic   Search Topic

I removed the 33k resistor (R36) and placed a 50k mini pot with a 10k resistor in series in it's place.
The 10k resistor prevents you from going to Zero ohms.

You only use 1 leg of the pot and the center/wiper.

Set bias as shown in Bills videos.

Previous 20 Messages  

FDP Forum / Amp Mods, Repairs, and Projects / Blues Jr Billm bias pot install instructions




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