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

Next 20 Messages  
89AmStd

Studio City, CA

Apr 3rd, 2017 05:12 PM   Edit   Profile   Print Topic   Search Topic

Does anyone have the installation instructions for Billm's Blues Jr. bias pot mod? I recently had the Billm mods done on my amp, but I didn't have the printed instructions, so the tech was unsure how to install the bias trim pot. Multiple email requests to his son have gone unanswered. Any help is appreciated!

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

So. Cal. USA

Apr 3rd, 2017 05:19 PM   Edit   Profile   Print Topic   Search Topic

This is somewhat my bad so let me say this is a very early green board amp. IMO it needs to be done "exactly" the Billm way. Drill the hole etc.

Just wondering? How to you like the changes in the tone stack?

89AmStd

Studio City, CA

Apr 4th, 2017 01:36 PM   Edit   Profile   Print Topic   Search Topic

Hi Hammond-

The tone stack changes have opened up the amp and there's more bottom end.

Does anyone have the printed bias trim pot instructions that Billm included in the mod kit? I'd greatly appreciate a copy.



Pinetree
Moderator Emeritus
(with many stars)

NW Pennsylvania

Apr 4th, 2017 06:25 PM   Edit   Profile   Print Topic   Search Topic

I looked all over his site and couldn't even find a mention of the Bias pot mod.


Sorry.

External link

(This message was last edited by Pinetree at 08:28 PM, Apr 4th, 2017)

twangdoodles

michigan usa

Apr 5th, 2017 03:59 AM   Edit   Profile   Print Topic   Search Topic

I may still have them around. Anyone know if it's the same for green and cream board BJs? I also have ethical concerns since it looks like you didn't buy the kits from BillM.

amphead4

Cincinnati, USA

Apr 5th, 2017 06:49 AM   Edit   Profile   Print Topic   Search Topic

twangdoodles, I'm thinking through your concerns and am not quite sure yet that I'm in the same place.

I do know that billm was very free with sharing his knowledge, published it on his site and regularly shared it on this board, time permitting. I'm not sure he had any intellectual property that he wanted to protect, from a legal perspective, and he freely shared large amounts of information about products designed and sold by another company which, to my knowledge, was not concerned about him or his business. And if his son doesn't answer emails, it leads me to believe that the business passed with Bill.

I did buy his kit because I respected the work he did for musicians and wanted to support him. But with all due respect to billm, and I do have tremendous respect for him and his work, I don't think he owned a proprietary method and I suspect he would want us to continue to enhance our Blues Jrs in his absence.

The great thing about the kit is it included the bit for drilling the hole for the trim pot lead. I still have the printed instructions (with color pictures) somewhere, I'll look for them this weekend.

(This message was last edited by amphead4 at 08:56 AM, Apr 5th, 2017)

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

So. Cal. USA

Apr 5th, 2017 11:23 AM   Edit   Profile   Print Topic   Search Topic

Sorry twangs, not trying to do anything nefarious here. I am certain the OP purchased the kit(s) from Billm. It was years ago. He however lost the documents that came with them. I have a copy of the invoice for the kits/parts emailed to me by the OP. I was presented with the trim pot and a drill bit in the parts bag,(as well as all of the other kit parts I installed) just no documents. I've done work for and sent parts to many members of this board. No smoke and mirrors here. Just looking for a bit of help ourselves for a change.

The process is a bit different for the green and cream board amps. Parts locations and values change. Where does the hole go???

I personally own a cream board BJr (NOS Tweed)that I installed a trim pot in but did it with my own design/build scheme, no drilling. Since I was brought this amp to install the kits "the Billm way" that is what will be done. Could I do a work around, yes, but that is not what I was asked to do.

BTW, the tone stack mods, input jack upgrade, volume pot mod, HV preamp, TO20 OT, filter cap stiffening/replacement, parallel output jack and coupling cap mods have already been completed and the amp returned to the OP. With the documentation for the trim pot the balance of the work could be completed by me or another tech.

I actually have more time in researching the mods than the 2 hours or so of pulling the board out and making the above mentioned mods. It's not a $$ thing, I'd just like the OP to have his amp modded the way he wants it.

Thanks to all for your assistance!


twangdoodles

michigan usa

Apr 5th, 2017 11:51 AM   Edit   Profile   Print Topic   Search Topic

No worries. The thought of an unscrupulous tech hadn't entered my mind (and I think I know enough of you to know that you aren't one of those), I just don't wanna ruffle any feathers at BillM Inc.

I've located my instructions but they are for the cream board. I can scan and email if those will work for ya. Lemme know if so and whom to mail 'em to.



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

So. Cal. USA

Apr 5th, 2017 01:31 PM   Edit   Profile   Print Topic   Search Topic

Many thanks and for the kind words as well. My email address is in my profile. I will forward to the OP. I have a feeling the cream board instruction would be easy to apply to the green board circuit. I'll know after a look at them.

Once the OP has the docs he can bring the amp back to me or choose another tech if he wishes.

Still looking for the green board stuff if possible.

Thanks again!

twangdoodles

michigan usa

Apr 5th, 2017 08:05 PM   Edit   Profile   Print Topic   Search Topic

Sent.

009
Contributing Member
****

USA

Apr 5th, 2017 08:06 PM   Edit   Profile   Print Topic   Search Topic

(...)

(This message was last edited by 009 at 10:08 PM, Apr 5th, 2017)

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!

Next 20 Messages  

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




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