HR deluxe preamp or input not working just changed to eurotubes

[bluesfuze]

Hello,
I am a newbie here and would appreciate any help

This is what happened:
I retubed my amp with a set of blues euro tubes. The amp was working and sounding great at low volume in my studio.
I brought it to a gig this weekend and played one tune when amp cut out but came back a few seconds later and then went out completely
luckily it was the end of tune LOL had to switch to my harp players peavey delta blues to finish gig.

I have since tried to play amp again and no sound but reverb makes noise there is amp sound from speaker and when I plug into power amp in, on the effects loop there is sound, so it seems to me it is preamp section or input jack.
How do I check any of these potential causes?
Thanks
Ric

[JJ Gross]

First thing to do is plug & unplug a jack into the effects send & return jacks. They're switching type jacks and if they get snotty, it can mess with the amp's function. If you have some electrical contact cleaner, shoot a little on the plug before you work it in & out of those jacks. NEVER spray liquid into your amp.

If that doesn't fix it you need to isolate the problem.

Plug your guitar right into the effects return.
This bypasses the entire preamp section in your amp.
If you get sound, the problem's in your preamp circuit.
If not, do a search here for Hot Rod amp before going any further.

Good luck

[Mesotech]

Since putting new tubes in is when the issue surfaced, the most likely starting point is to look at those tubes.

You've isolated it to the preamp section of the amp already (based upon your initial post). Now you're trying to determine if the problem is a tube or an input jack. I would say the easiest thing to do is to pull the new preamp tubes one by one and replace it with one of the old tubes. I would start with V1 first.

[JJ Gross]

Since putting new tubes in is when the issue surfaced, the most likely starting point is to look at those tubes.

You've isolated it to the preamp section of the amp already (based upon your initial post). Now you're trying to determine if the problem is a tube or an input jack. I would say the easiest thing to do is to pull the new preamp tubes one by one and replace it with one of the old tubes. I would start with V1 first.

... unless the PCB is cracked from pushing a tube in too hard.
Tube sockets in this amp are all hard mounted right on the main PCB.

[NTBluesGuitar]

These amps are known for failures in the tube socket PCB. Since you just changed the tubes, it's possible that you popped a joint loose, as mentioned. It would explain your symptoms.

Not necessarily your fault...just one of the reasons folks love the Hot Rod amps.

[bluesfuze]

Thanks for your reply JJ
I have done as you say and yes problem is in preamp section or input jacks but could both go at the same time?
thanks
ric

[bluesfuze]

Hi NT,
I am curious if I was to pop a solder joint in PCB would that not have made the amp work when I first put tubes in?

It worked great in my studio at low volume it is at the gig when it died.
Oh and all the tubes light up nice and bright
Ric

[bluesfuze]

Hi Meso,
That is something I havnt tried yet going back to old tubes
they were 12AX7 these are 12AT7 I love the tone of the amp using these tubes
Oh and there is one other thing I didnt mention is I did not rebias amp for new power tubes 6v6 from 6l6gc
Like I said the power section seems to working fine
Thanks
Ric

[steve25]

First rule of gig survival after you change tubes is to bring your old ones along with you to the gig as long as they still worked!

[NTBluesGuitar]

Hi NT,
I am curious if I was to pop a solder joint in PCB would that not have made the amp work when I first put tubes in?

It worked great in my studio at low volume it is at the gig when it died.
Oh and all the tubes light up nice and bright
Ric

If you stressed the joint, it may very well still be making good contact at low volumes, as the heat may not have affected those parts. At gig levels, you may have broken the camel's back with a bit of extra heat, and that stressed may have finally come open. Extra vibrations from the extra volume could work them loose, too.

This may have happened in some other components attached to the tubes on the main board as well.

The filament circuit could still be intact and the glow you see in the tubes is just the heated filaments. There are six other preamp tube pins in addition to the heater connections that could be acting up. But, if you have had a cathode bias resistor come open or fail and suddenly to have a really high resistance in it, it would send the tube into shutoff.

I would check them in this order: Pins 1 and 6 (connected to the plate load resistors), then pins 3 and 8 (they are the cathodes and connected to their bias resistors and bypass caps), finally pins 2 and 7 (the grids that signal is input to).

If your old tubes still worked, you could swap them to see if maybe one of your new tubes is bad. I just returned a brand-new JJ 12AX7 that was bad; it does happen.

Hope this information steers you in the right direction.

[bluesfuze]

Well, looks like I was one of the unlucky ones it was a bad tube in V1.
Eurotubes will be replacing it free of charge

Thanks to everyone for all their input and helpful suggestions

I will now be carrying a set of tubes for this fender and my marshall as well to all gigs.
Thanks steve25
Ric

[JJ Gross]

Easy fixes like this are cool!
Glad it worked out for you.

Cheers,
- JJ

[boobtube21]

Oh and there is one other thing I didnt mention is I did not rebias amp for new power tubes 6v6 from 6l6gc.

You may want to do that. I was not even aware that you could substitute these tube types for one another.

[steve25]

A easy cheap way to carry your spares around with you is in a travel type shave case lined with bubble rap, Plus no outsider will think of ripping off what a apears to be just a shave kit!

[bluesfuze]

Great idea..thanks steve25
Ric

[bluesfuze]

You may want to do that. I was not even aware that you could substitute these tube types for one another.

Yes, it is power tubes sub of blues option 2 for this amp from eurotubes. It cuts power to around 30 watts and seems to soften up harshness

[curt1lp]

I have at a couple of 12AT7 in mine in v1/V2 - sounds great. BTW good your trouble was fixed so easily !

[NTBluesGuitar]

Yes, it is power tubes sub of blues option 2 for this amp from eurotubes. It cuts power to around 30 watts and seems to soften up harshness

You'll have better results in using the 6V6s if you plug an open plug into the main speaker (the plug isn't connected to anything; basically breaking the tip-to-ground on that jack and isolating the 4ohm tap for use on the ext. speaker jack), and run the actual speaker plug in the ext. speaker jack. Re-bias, of course.

Now, the 6V6s will see what they want to reflected from the OT (4.25K primary on the 4ohm secondary). Anything else offers up a mismatch for the 6V6s looking at an OT setup that's designed for 6L6s.

Should be closer to 25 watts if done right.