Fender Hot Rod problem

[nevjim_3]

I know that there are similar problems on here, but not exactly the same situation. I was at a gig using my Hot Rod deluxe. About 1 minute into the very first song it started crackling and popping. 2 hours prior it was working great. I shut it down and grabbed my back up, a Blackstar 1x12. It sounded great for a bout the same amount of time, then started doing the same thing. I ended up using a friends back up twin, and used a different outlet on the stage. When I got them both home I tried each with different guitars and chords, same result. I am assuming that the power outlet at the gig had a problem. On the Hot Rod I have since swapped out all the pre-amp tubes, still does it. I also installed the supreme mod kit for the Hot Rod, which I was going to do anyway, but that should have eliminated the problem with the plate resistors and the power supply resistors. Any idea's ?

[TomCarlos]

At the gig, 2 different amps did the same thing? You were brave to use your friend's twin that night. Even if you used a different outlet, it could have been on the same circuit and you could have damaged a 3rd amp! Yes, it might have been a bad duplex with a loose wire. But I would have been extra careful before trusting another outlet. Anyway... so you now have two amps that developed problems as a result of that gig?

A friend hosted a jam at his house (in the garage). One amp blew. Minutes later, another amp smoked. That should have been a sign for everyone to STOP! Turns out, faulty wiring put 220V across the 110v outlet.

So you may have damaged the amps because of a similar problem. Check your voltages in the power supply... that is the first thing I would look at.

[nevjim_3]

I plugged into the same outlet that the bass player was using and the P.A. So I assumed that one was ok. Would the voltage levels change after about a 10 minute warm up? I do not have a schematic. Any particular component I should check in the power supply?

[TomCarlos]

Fender Hot Rod Deluxe Schematic

See page 1, Sections A4 to A5. That is the power supply.

The amp needs a couple minutes for the tubes to heat up and things to settle down. After that, if you are not playing or have an input signal, I would say that your voltages should be steady.

[nevjim_3]

Cool, Thanks, I will check it out.

[Enzo]

Modding an amp is not the way to repair it. It might take care of problems involving those exact parts, but nothing else.

First, take the back off and look CLOSELY at the solder on the pins of the power tube sockets. ANy small cracks? In fact, just resolder all the pins on the two sockets anyway.

Isolate the problem. It crackles. OK, does it do it in both channels or just one? Ball up your fist and whack the top of the amp, does that affect the crackle in ANY way? If you turn the reverb all the way down, is it still crackling? If you turn ALL of the controls to zero, is it still crackling? Pull the first preamp tube, still crackle? Now pull the second preamp tube, still crackle? Pull the third small tube, your phase inverter, still crackle? Pull one 6L6 at a time, still crackle? Crackle with no tubes?

[Steve A.]

Duplex outlets can be connected to 2 different AC circuits. In modern homes it is very common to have half of a duplex outlet connected to a wall switch.

It is a good idea to keep a DMM in your gig to check outlets and cables.

NOTE: If both amps acted up at the gig but have been running okay since then I would guess that the problem was with the AC power supply.

Steve Ahola

[nevjim_3]

I didn't install the mod to repair it. I already had the mod, but just had not installed it yet. I put that is the thread to let you guys know that these components had already been replaced, as well as re-soldering all the tube sockets and checking the rest of the pc board for bad solder joints. It only cracks while playing after it warms up. Pounding on it does not cause it. I have replaced the pre-amp tubes one at a time. I wasn't aware that you could remove the power tubes one at a time, but I will try it. Thank you

[nevjim_3]

Both amps did act up at the gig, but are since both messed up with the same problem.

[Mick Bailey]

You can easily eliminate the preamp in your Fender by plugging your guitar directly into the 'power amp in' socket. When I get problems with these amps I wait until it plays up using the regular input, then flip to the power amp in socket. If it still plays up then you're down to the output stage and power supply.

[Steve A.]

Both amps did act up at the gig, but are since both messed up with the same problem.

If you can go back and measure the voltage at the questionable outlets it might give you a better idea of what may have been damaged in your amps.

Good luck!

Steve Ahola

[Drewline]

I always recommend having an outlet tester to do a quick test. It will tell you if an outlet is wired wrong. A DVM is great to have along to check actual voltages from that outlet.

[Enzo]

YES

Those little testers cost maybe $5, and take up little room in your kit. I always carry one on the road. It takes seconds to use and answers important questions right up front.

[nevjim_3]

YES

Those little testers cost maybe $5, and take up little room in your kit. I always carry one on the road. It takes seconds to use and answers important questions right up front.

I do actually carry a dvm now, and I test before plugging in.

[nevjim_3]

I plugged directly into the power amp and the problem goes away