Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TubeGeek on June 07, 2013, 11:10:28 pm
-
I accepted the challenge to re-cap a Hammond B3 organ. While I am at it, the owner wants me to look at the amp in the organ and in the leslie and do any necessary component upgrades etc.
I have only worked on one other organ and it was the C3, church version of the B3. I addded a pcb that changed the sound of the bass notes to be more like a stand up bass. No problems with that mod so this should be straight forward.
Any advice or words of wisdom from any of you that have worked on b3's before?
I have the b3 in my workspace for as long as I need, I plan to study this thing and add it to my tech resume.
-
Hey TG!
Go here:
http://www.dairiki.org/HammondWiki/HammondMaintainanceAndTroubleshooting (http://www.dairiki.org/HammondWiki/HammondMaintainanceAndTroubleshooting)
Call Groundhogken with any questions!
Jim
-
Awesome! Thanks
-
Electrolytics only or all the caps in the generator too? Those may have drifted in value, be leaking, etc.
The full overhaul is quite a job...check out Stefanv.com. Have fun!
-
First task is the tone generator caps, about 60 of them or so. Also adding 12 RC filter networks.
After that I will replace the caps in the vibrato line box.
Next I will look into the organ tube amp and then leslie tube amp. A0-28 amp and another one, not sure of it's name yet.
The owner of the organ purchased several parts kits from online and once they arrived and he looked at what is involved to do the work, he called me.
I am working hard to clear my bench of amp work so I can focus on the B3. In the meantime I have been reading about and studying the B3. I have a 250 page print out of all tech details that is going to help the flow of the job.
It is quite a job. After the B3, he has a C3 for me to overhaul. Then another buddy has a B3 for me to overhaul. Maybe I should do this full time again. :laugh: :l4:
After that I'll need a vacation.
-
This how Richard Goodsell got his start. Good luck!
-
This how Richard Goodsell got his start. Good luck!
Is he a known guru on the b3?
-
This how Richard Goodsell got his start. Good luck!
Is he a known guru on the b3?
At one time before he started his amp business he was the "go to" guy for the big stars as far as Hammond organs and vintage keyboards in general were concerned. It's one of the reasons the first hundred or so Goodsell Super 17 amps were built on old Hammond amp chassis and iron. I have Clairmont Super Seventeen SN #0003 built on an AO-35. Richard is the man when it comes to the B3.
-
Good to know! Thanks
-
alerich, do you have a gutshot of that amp?
-
The only time I had the chassis out was to tighten the pilot lamp assembly and take some quick B+ measurements with a few different rectifier tubes. I didn't have my digital camera nearby and really didn't think to take any pics. It's a really simple circuit. No real mojo going on in the circuit. All of the charm of these early Super 17 amps is in the old Hammond iron, in my opinion.
-
This job is now first in line...
Couple pics to share...
A shot of of where I'll be sitting for hours and hours and second pic is of the first duty...tone generator capacitor upgrade
-
Do they need to be replaced?
-
The caps inside this are wax and tend to dry up over time. These are near 60 years old and from my understanding these particular caps are part of the formula to create the many frequency tones needed for the organ to function the way it was designed to.
Replacing or upgrading the caps will restore the original "tone" and bring the volume and restore high-end frequencies back to normal.
After the caps are replaced I have to measure each frequency level in mV, plot a graph and then adjust the output of each by moving a magnet closer or farther away from the internal tone wheel assembly. In the end all the frequency tones should be equal in their output.