Help - fender HRD volume drop.

benvall

So at a gig last night, I took my fender hotrod deluxe. Before the gig I picked up a jmp1 pre amp. First set no problems, at the break I plugged the jmp1 into the power amp in on the HRD just to try it out. I plugged everything back in as before for the second set but I had lost a lot of volume on the clean channel.

I did the rest of the gig using the OD channel which seemed unaffected.

Does anyone know what caused this volume loss? I've moved around the pre amp valves but the volume loss is still there.

Any ideas greatly appreciated.
Thanks

ICBM

Jumper the Preamp Out to the Power Amp In with a cable and see if the volume loss is still there. If not, it's the switch in the Power Amp jack probably.

It may be affecting the dirty channel as well - it can't not be, unless it's something very specific to one tiny part of the clean channel, if you've swapped the valves round, and which is not very likely to fail - but you may not notice because the dirty channel master volume taper is so non-existent, so the smallest extra nudge on the knob and it will seem like it's back to normal compared to the clean channel.

benvall

Thanks @ICBM I was hoping you would show up, I really don't use the OD channel so it probably is affect that channel too. I use the amp clean with pedals.

I've tried jumping the preamp and power amp, there is no difference. Still quieter than normal.

The tone of the amp sounds the same, but I can have it on 2 indoors which normally keeps up with a drummer.

Thanks

bertie

benvall said:

 but I can have it on 2 indoors which normally keeps up with a drummer.

the clean channel ?

bertie

benvall said:

 but I can have it on 2 indoors which normally keeps up with a drummer.

the clean channel ?

benvall

Yeah, the clean channel. I normally gig with it on 3 to 3.5

ICBM

Have a close look at the valves and see if both the power valves are glowing properly - orange filament glow and blue glow (which you might have to look very carefully to see, most obvious when you switch from standby to on) - and that the phase inverter (preamp valve next to them) has both filaments lit (two orange spots at the top of the valve). You might have to take the back panel off to see them clearly - take out the six screws in the back panel and loosen the four in the ends of the amp about a couple of turns, but not right out. It's safe to do this as long as you don't poke about inside when it's on!

If all the valves look OK, it's a trip to a tech unfortunately. These amps do have a couple of well-known problems which cut out the drive to one half of the power amp and reduce the volume - although usually produce an odd distortion as well, but you might not notice that at lower volume.

By a not particularly amazing coincidence I have one here right now which had the same fault - this one was caused by a cracked solder joint on one of the valve sockets...

benvall

Thanks, I've gotta get my son fed, bathed and to bed so it'll probably be tomorrow before I take the back off. Cheers

benvall

I've managed to have a look at the valves. They all look good, as described. It doesn't sound any different just quieter, looks like I need to find a tech is NW Kent SE London.

@ICBM Thanks for all your help.

BenSirAmos

East Grinstead too far?

benvall

@BenSirAmos, it's not too far, I'm between Sevenoaks and dartford.

BenSirAmos

@benvall

You could take it to Fender.

http://www.fender.com/en-GB/contact/

They were pretty reasonable when I took my HRD to them. They diagnosed a hummy valve - and only charged me for the cost of the valve they'd replaced.

benvall

So following on from this, I tried the amp last night (having not taken it to a tech yet) and the volume issue was still there. However, while playing, slowly the volume increased almost like using a volume pedal. Seemed ok for a while, then at one point the volume went down again and then came back up. Again, like using a volume pedal.

So, any further thoughts? I'm gonna ask a silly question..... Dusty pots?

ICBM

Unlikely. Sounds more like a bad valve or a failing filter cap.