Biasing Hot Rod Deluxe

GloryJones

Member
Messages
857
I searched for some answers but was not able to find exactly what I was looking for. If there is a thread that answers my questions, please redirect. Thank you.

I have an older Fender Hot Rod Deluxe (Made in USA). I am the third owner of this amp and to my knowledge it has never been through any sort of upgrades / modifications. I have a brand new set of tubes waiting at my house and a bias that needs to be adjusted.

I am capable and comfortable changing tubes. I know how to clean the sockets and install the tubes correctly.

I have never biased an amp before. I've watched the video on EuroTubes (https://www.eurotubes.com/eurotubes-Hotrod-Deluxe-How-To-Bias-Video-6L6-6V6-millivolts-mA.htm). I have a multimeter.

I understand there are risks in working on amplifiers. I'm comfortable with doing little projects, but I am nervous about biasing this amp. For those of you with experience, is this as easy as it looks? What are some tips you can offer so I can avoid catastrophe? I don't have an amp tech nearby where I can go for a quick biasing. I'd much rather do it all on my own. Is this something I should attempt on my own? I'm looking for all opinions and any advice you can give!

Thank you!
 

pine

Gold Supporting Member
Messages
835
There are lethal voltages stored in the capacitors of a tube amp that are present even when it is unplugged. You are probably lucky you didn't get zapped cleaning the tube sockets. Find yourself a good tuba amp book, and learn how to discharge the capacitors before working on a tube amp, and work with one hand in your pocket at all times.
 

thegoochie

Member
Messages
171
It is easy to bias this amp PROVIDED YOU TAKE NECESSARY PRECAUTIONS. I have the same amp, though it is only a backup/backup amp I keep it in shape.

After you unplug and remove the back panel, you need to discharge the caps. You can find out how to do that relatively easily with manuals or even youtube videos. If you do get zapped...well, good luck. So I would really do my homework first.

As far as biasing goes, the amp has a bias check point on the bottom left corner of the mounting board. you can ground your multi meter on the chassis and then there is a biasing pot with a screwdriver slot in it. It is also has a label. 75-80 works well for that amp, but its personal flavor. If you run it too hot you will shorten tube life of course.

Please keep in mind that the amp needs to be on during this process which takes place after you have replaced the tubes. It is DEADLY if you touch something that you should not. Please please be super careful.

If you are not 100% comfortable in this scenario then reconsider an outside tech. If you can't find a spacious and safe quiet place where you can focus, please consider an outside tech.
 

Geosh

Member
Messages
2,395
Thank you for the input. I will find a professional to take care of this.
Yeah, the USA made models aren't as easy to adjust bias on. They don't have the adjustable pot like the MIM models do, so you actually have to change out a resistor if you need to adjust bias.

Definitely a job for a tech if you aren't comfortable working on amps.
 






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