Fender Hot Rod Deluxe Problem

JoshwaBurke · #1 04-17-2014, 06:02 PM

Hey guys,

I have a 2005 Fender Hot Rod Deluxe Tube Amp. When I press the channel select button or foot pedal for my drive channel, I'm not getting much sound in return. I can hear itfaintly if I turn the master volume all the way up. Not sure what the problem may be. Could it be one of my pre-amp tubes? I've never replaced the tubes but my clean channel still works great. I only use this amp on occasion and at low volumes since I'm in an apartment building. Let me know if you guys any wisdom or suggestions before I bring it to a professional.

Thanks,
Josh

jonfields45 · #2 04-18-2014, 06:24 AM

Try swapping the two preamp tubes farthest from the power amp tubes and see if the problem changes. Highest likelihood is you need a new tube. Jon

JoshwaBurke · #3 04-18-2014, 06:31 AM

Thanks Jon for the suggestion. I'll try that tonight after work.

Bob Womack · #4 04-18-2014, 07:24 AM

Hey, Jon. There is s resource you need: the Unofficial Fender Hot Rod Deluxe site. This was a site filled with fixes that increased reliability and mods to improve the amp. It is pretty comprehensive - I couldn't imagine owning a HRD without a copy of it lying around. It used to be an online interactive site but the author/owner, Justin Holton, moved on to other things. It has since been archived as PDFs and re-posted to the Internet and you can find it HERE. Browse through it and see if you can find a reference to your problem.

Bob

JoshwaBurke · #5 04-18-2014, 08:26 AM

Looks like a great resource. According to the FAQ section. The second pre-amp tube (V2) is dedicated to distortion. When I looked last night the bulb seemed to be illuminating just fine but I'll swap them tonight. Hoping it's a quick fix!

clintj · #6 04-18-2014, 09:19 AM

I had one of those amps for a few years. The unofficial user guide linked above is a must-have for those amps.

My recommendation is swap V1 and V2. V2 is the "drive/more drive" tube, V1 is used in the clean channel. They are the two furthest from the power tubes. If you swap those and get little to no sound on any channel, you've had one or both of the dual triodes die in V2. If you get exactly the same result as you have currently, you've probably lost a grid resistor for V2 - time for an amp tech to troubleshoot and repair.

The V2/V3 swap above will also work. If you swap and suddenly have low volume in all channels and the sound is really rough and distorted, or you get almost no volume, that tube is dead.

JoshwaBurke · #7 04-18-2014, 11:54 AM

Quote:

Originally Posted by clintj

I had one of those amps for a few years. The unofficial user guide linked above is a must-have for those amps.

My recommendation is swap V1 and V2. V2 is the "drive/more drive" tube, V1 is used in the clean channel. They are the two furthest from the power tubes. If you swap those and get little to no sound on any channel, you've had one or both of the dual triodes die in V2. If you get exactly the same result as you have currently, you've probably lost a grid resistor for V2 - time for an amp tech to troubleshoot and repair.

The V2/V3 swap above will also work. If you swap and suddenly have low volume in all channels and the sound is really rough and distorted, or you get almost no volume, that tube is dead.

I swapped V1 with V2 and yeilded the same result as before. Guess it's time to bring it to a professional. Thanks for taking the time to help. Much appreciated.

clintj · #8 04-18-2014, 12:27 PM

You're welcome, glad to help. Those resistors are a weak link, sometimes when a tube goes it will take one with it. It should be an easy job for a competent tech to find the bad part and swap it for a new one.

BTF · #9 04-18-2014, 03:33 PM

Another area to check would be the two 330/470 ohm dropping resistors which lower voltage and provide the power rails to the switching.

Good Luck getting her running again!

Xtremca · #10 04-18-2014, 04:58 PM

Solder joints are another weak spot for the hotrod that can cause unexplainable issues. I had one that would pop on an open a string and we finally tacked it down to a cracked solder. Sad part is my amp never left the same spot in the house. Found a few other problematic spots while digging around inside.

clintj · #11 04-18-2014, 11:56 PM

Quote:

Originally Posted by BTF

Another area to check would be the two 330/470 ohm dropping resistors which lower voltage and provide the power rails to the switching.

Good Luck getting her running again!

Ohhhh, yeah. Those guys. I had a flickering power light that oddly enough seemed to trace back to those cement resistors.

I separated them a little bit to help cooling and it seemed to help. Either way, not something to try checking at home unless you're familiar with how to drain caps and check circuits dead. Tube amps can be lethal if not respected.

donh · #12 04-19-2014, 08:15 AM

Quote:

Originally Posted by clintj

not something to try checking at home unless you're familiar with how to drain caps and check circuits dead. Tube amps can be lethal if not respected.

What? You don't like being tossed across the room?
.

Bob Womack · #13 04-19-2014, 08:41 AM

Quote:

Originally Posted by donh

What? You don't like being tossed across the room?

Been there. I was against the wall of the studio disconnecting a Neuman U-47 tube mic from its power supply and the next thing I knew I discovered myself sitting on the floor across the room, panting, with an impression of the back of my head punched into the sound treatment on the wall behind me. Apparently my finger draped over the edge of the power supply connector as I withdrew it and made contact with the blades before they disengaged from the supply.

Bob