Motorola HS475 tube amp into a guitar amp.

[Paulinc]

This is my first project like this ever, so I don't know anyhting about where to begin. Anyway, I got this old tube amp off craigslist and I want to convert it into a guitar amp. I posted about this in another thread but I haven't really gotten any feedback. The amp has 6 tubes, 2 are missing, the four remaining ones light up when plugged in. There are 2 6V6's and two 12AU7's. I will try post a pic and the schematic. Any help would be greatly appreciated. Thanks.

Paul

[bluesbubba]

Find out the total tube configuration and see if everything lights up. Do you have an input jack, auxiliary or mic? See if it's workable first.

I just got done converting a Teeco model 612 HiFi amp into a guitar amp head. It has 2 EL84s, 2 12AX7s and a 5y3 rectifier tube, i was lucky to have all the right stuff. I was able to convert the selector switch which supplied juice to a phono, radio, aux and mic into a single 1/4 inch input jact. That was the biggest feat. From there you can move forward and create your amp; if not you'll have problems without electronic experience.

Good Luck!

[Chuck_Farlee]

Paul,

I'd like to see the schematic. I have a Motorola chassis which looks identical to the picture you posted, but it is marked HS-606.

My amp has a 6AU6 input tube, two 12AU7s, two 6V6s and one 5Y3 rectifier. It came out of a console with a 15" Jensen speaker and a record player.

Edit, found this:

http://techpreservation.dyndns.org/schematics/56/56_Motorola_HS475_62.djvu

You'll need to download the Lizard Tech plugin to view the schematic:

http://www.lizardtech.com/download/dl_options.php?page=plugins

Regards,

chuck


This is my first project like this ever, so I don't know anyhting about where to begin. Anyway, I got this old tube amp off craigslist and I want to convert it into a guitar amp. I posted about this in another thread but I haven't really gotten any feedback. The amp has 6 tubes, 2 are missing, the four remaining ones light up when plugged in. There are 2 6V6's and two 12AU7's. I will try post a pic and the schematic. Any help would be greatly appreciated. Thanks.

Paul

[Paulinc]

I was just about to post that same link to tech preservation. It took me a little while to find that place, but it is great for info.

Here is a link to the schematic:http://techpreservation.dyndns.org/schematics/56/56_Motorola_HS475_62.djvu

After looking at the chassis and the schematic, I noticed the HS475 also has a 5Y3GT rectifier tube.
I have acouple of pics of the chassis, nothing up close though. I'll try and post them.

[Paulinc]

Here are all the pics I have for this amp.

[Paulinc]

I scanned the schematic into a jpg, so I will try and post it. I can't believe I didn't think of doing that sooner.

[Paulinc]

The amp conversion is complete!!! I ended up taking it to a local guy who does these kinds of things for fun as a side business. I was lucky I didn't shock myself through the roof. But after talking with him and learning a little more about tube electronics I am more confident for future projects.

The guy who did the work for me is Marc Meyer, he can be reached at http://members.aol.com/fyrebottle/

here are some pics of the finsihed amp.