Hello, steemians, and welcome to my page, eh!
I decided to write a several part series of articles on my current project to repurpose an old Bogan tube powered amplifier to use it as a guitar amplifier. The amp is a Bogan CHB-35A, a popular amplifier for public address use in retail stores, schools, etc. There were a lot of these kind of amps being used in the 50s and 60s, and there's still a bunch of them floating around. These amps have microphone inputs and line inputs for tape players, radio, and other inputs. There are several modifications that need to be made to these amps to be able to use them as a guitar amp.
Let's take a look at the amp. I already had started on the amp when I remembered to take a picture of the amp, so there's 2 knobs missing where I had already removed parts.
This is what the chassis looks like from the top. You can see where I already put a couple parts in the chassis, an input jack and a power switch.
I did remember to take a couple pictures before I had removed very many parts. Don't mind the messy workbench! I had already removed the microphone inputs from the back of the chassis, and some other wiring when I remembered to take this picture.
After pulling out the unnecessary circuit parts, the next thing I do is to start rebuilding the power supply. With these older amps, it's always a good idea to replace all of the power supply filter capacitors, because they will probably be going bad, which causes all kinds of problems. The big red cylinder on the lower left hand side of the picture is one of the capacitors that needs to be changed.
In this picture, the old power switch and the red capacitor have been removed from the chassis. I have found that the old power switches on these old amps tends to go bad, or at least get unreliable, so I always change them.
On this picture, you can see where I've removed the old style speaker connectors from the back of the chassis. I will put a plate on the back of the chassis to cover up all of the holes that are left from removing the old parts, and the new speaker jacks will be mounted on the cover plate through a couple of the old holes.
In this picture, you'll notice a hole in the lower left end of the chassis, this is where the other filter capacitors were mounted in a multi section can. That filter can will be replaced by individual capacitors in the rebuilding process. You can see 2 of the new individual capacitors mounted to the left of the hole. You can also see the wires for the new power switch on the inside edge of the chassis, and the new grounded power cord receptacle mounted in the back of the chassis.
This is as far as I've gotten with the amp so far. I'm waiting for several parts that I ordered to get here so that I can continue the process of rebuilding.
So, that's all I have for this post, I hope you found it interesting!
Stay tuned for the next part in this series.
Thanks for stopping by and checking out my post, eh!
As always, feel free to leave a comment or a question if you would like.
Until the next time, may the Steem Force be with you!
