HELP! Single Rect

[Acesofbelkan]

So I start up my single rect today to find out that the clean channel works but the distortion channel doesnt work at all. I can only hear a little tiny bit of buzzing when I max out the gain.
I turned on the amp, and I forgot to complete the effects loop circuit. I had a pedal connected to the send plug in the loop but I forgot to plug in the return.
Did I just destroy my preamp??
the clean still works but the distortion isnt

 

[Acesofbelkan]

Update: I just replaced the preamp tubes.
I was trying to figure out why the clean channel was working, I ruled out anything being wrong in the power section since sound was coming out the speakers.
I thought I fried something else i the preamp, so I kept thinking to myself, how could the clean channel work but the gain channel NOT work.
That's when I remembered that I doubt the clean channel even uses all 3 preamp tubes(excluding the effects loop and phase inverter tube which dont affect tone)
So I swapped out the v1,v2,and v3 tubes and now it sounds like I have more gain then before.

Im a complete amp noob when it comes to tube amps, but I learn as much as I can about tube amp care, I also read the entire Mesa Manual and it never mentioned that it was particularly about not completing the effects loop circuit. Can anyone shed some light on this?

 

[Acesofbelkan]

Update: I just replaced the preamp tubes.
I was trying to figure out why the clean channel was working, I ruled out anything being wrong in the power section since sound was coming out the speakers.
I thought I fried something else i the preamp, so I kept thinking to myself, how could the clean channel work but the gain channel NOT work.
That's when I remembered that I doubt the clean channel even uses all 3 preamp tubes(excluding the effects loop and phase inverter tube which dont affect tone)
So I swapped out the v1,v2,and v3 tubes and now it sounds like I have more gain then before.

Im a complete amp noob when it comes to tube amps, but I learn as much as I can about tube amp care, I also read the entire Mesa Manual and it never mentioned that it was particularly about not completing the effects loop circuit. Can anyone shed some light on this?

 

[UnderJollyRoger]

It's not a problem when you don't connect the fx-loop properly. You can't run the amp without a cabinet, however, this will fry your power section.

Probably change the preamp tubes, starting with V1-V3, as you said. It's likely that this will solve the issue.

 

[94Tremoverb]

You're correct that the two channels do not use all the same tube stages - and that the clean channel uses less. Each 12AX7 has two tubes in the same bottle.

V1 A and B halves are used by both channels
V2A is only used on the clean channel
V2B is only used on the distortion channel
V3 A and B are used only on the distortion channel
V4 A and B are the FX loop driver and return (both channels)
V5 is the Phase Inverter (both channels)

So if the clean channel is working and the distortion isn't (and if it's a tube fault, not something else), it can only be a failure in one half of V2, or either half of V3. In particular, V3 is a cathode-follower position and this is quite hard on the tube; some preamp tube types, including a lot of the Russian-made ones, have a high failure rate in this type of position, so I would immediately suspect that as being the most likely cause. Try to avoid using a Russian tube in this slot if you can.

If you didn't keep a note of which tube was which, try the old tubes back in the amp one by one to find the dead one, and keep the others as spares, you may need them! If you're not sure where the tube was made - it's often etched on, with the Russian ones, but can be hard to see - have a look at the plates, which are the grey box-like structures inside the tube. If there are two bright chrome strips across each side of the tube, outside the plates, then it's a Chinese tube. If the plate is a fairly rounded shape with a vertical 'dimple' in the side, it's a JJ (Slovakian). Anything else, it's probably Russian - at least if it's a modern-production tube.

 

[Acesofbelkan]

They were all labeled "Chinese". I read in another thread a while ago, that using anything but a chinese labeled mesa tube(or a few other different types) will cause the tube to fail.
Right now I have a (balanced)electro harmonix in the v1 and v3, and a (high gain)Mullard in the v2 position.

 

[94Tremoverb]

I would get that EH out of V3, since it's also Russian.

If there's any point in using a balanced tube at all (which IMO there isn't, but since you have them anyway...!) it's for the Phase Inverter (V5), so that's probably the best place for one of those tubes.

I would also probably put the Mullard in V1 and the other EH in V2, with two of the Chinese tubes in V3 and V4... but that's just me, you can try various combinations and see which sounds good.