#1
asdf
Mesa/Boogie Road King v1
Marshall JMP 2203 '78
Vox AC30 H2 Heritage HW
Fender Deluxe Reverb '65 RI
Gibson Les Paul Custom '57 Historic RI '05
Fender American Vintage '52 RI Telecaster '02
Fender American Vintage '62 RI Stratocaster '07
Last edited by RMB at Jun 26, 2017,
#2
Do you get anything if you plug in your guitar into FX return?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#3
You can try looking / posting in the Boogie Board as well - http://forum.grailtone.com

There is a ton of deep tech info regarding Mesas over there.

Good luck! I hope it's something simple!
Guitars:
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
Jackson DKMGT Dinky (EMG 81/85)
ESP E-II Eclipse Custom (JB/'59)
ESP LTD EC-1001FR (EMG 81/60)
Fender MIM Strat

Amps:
Mesa/Boogie Dual Rectifier Roadster 212
Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
#4
Thank you Cathbard, I've tried this because of your suggestion but unfortunately no sound at all, not even on a gain channel. Ofcourse I tried both loops, not bypassed and loops activated.
I guess this suggests that it's a power section problem?

Metalmingee, thank you for the forum reference, I'll post there when UG can't help to fix this!
Mesa/Boogie Road King v1
Marshall JMP 2203 '78
Vox AC30 H2 Heritage HW
Fender Deluxe Reverb '65 RI
Gibson Les Paul Custom '57 Historic RI '05
Fender American Vintage '52 RI Telecaster '02
Fender American Vintage '62 RI Stratocaster '07
#5
That would point towards the power amp, yes. Try replacing the phase inverter first.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#6
Thank you, but I already switched out all preamp tubes one by one twice, with a known working other preamp tube. No luck there, also not in V5
Mesa/Boogie Road King v1
Marshall JMP 2203 '78
Vox AC30 H2 Heritage HW
Fender Deluxe Reverb '65 RI
Gibson Les Paul Custom '57 Historic RI '05
Fender American Vintage '52 RI Telecaster '02
Fender American Vintage '62 RI Stratocaster '07
#7
Power tubes next.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#8
Yes, I've swapped all 6 of them out like I said on the first post, also no luck
Mesa/Boogie Road King v1
Marshall JMP 2203 '78
Vox AC30 H2 Heritage HW
Fender Deluxe Reverb '65 RI
Gibson Les Paul Custom '57 Historic RI '05
Fender American Vintage '52 RI Telecaster '02
Fender American Vintage '62 RI Stratocaster '07
#9
Just because one 12ax7 was switched out, it doesn't mean anything, you could have two or maybe even three bad ones (if it ain't a circuit problem). As far as you know, all five could be bad and then you'd need to switch them all out (having a couple of full spare sets of tubes/fuses at all times is optimal). However, the chances are that it ain't the case, just try every tube in every position mixed with the good working one. Mark them by number and use NPR (basic probability theory) to find out your combinations. If not, then I don't know. The actual reason I looked into the thread was due to the title
The above post is in terms of 'YMMV' and 'IMO', etc...

Quote by Offworld92
This debate is exhausting to read.
The guitar world is drowned in fairy dust.
We need to start at the very beginning. What is tone.
#10
I will try to replace more 12AX7s at the same time, but I think it's not really to be expected that 2+ tubes went bad at the same time.
Mesa/Boogie Road King v1
Marshall JMP 2203 '78
Vox AC30 H2 Heritage HW
Fender Deluxe Reverb '65 RI
Gibson Les Paul Custom '57 Historic RI '05
Fender American Vintage '52 RI Telecaster '02
Fender American Vintage '62 RI Stratocaster '07
#11
Quote by RMB
volume dropped to whispering volume, then it fluctuated louder and quieter while I played. After a few seconds it just died out totally and now I can only hear some (talk volume) sound on the high gain channels with volume almost on max.

...

Then I switched all power tubes with brand new ones I had laying around, all 4x6l6 and 2xEL34 were switched out, no luck...

Definitely sounds like power tubes. The 'new' tubes you put in were brand new and matched? I would get a octal tube probe and a multimeter and check your plate voltage and bias.

Sorry you said or if I should know but do you have another amp you can try your tubes in? Can you slave out or external speaker cab out?
#12
Thanks 311,

Unfortunately I don't have any other 6L6 amps so I will only be able to test the EL34s in another amp (which I did).
Theoretically the Roadking should run with broken 6L6 tubes when I put the channel on EL34, but also at that point: no volume, just the whispering of the preamp tubes.

I must admit I am unsure if the new tubes are matched, they are new Grooves I got a while ago when I bougt a Mark IV.
This amp has a fixed bias, does it still make sense to check it?
Mesa/Boogie Road King v1
Marshall JMP 2203 '78
Vox AC30 H2 Heritage HW
Fender Deluxe Reverb '65 RI
Gibson Les Paul Custom '57 Historic RI '05
Fender American Vintage '52 RI Telecaster '02
Fender American Vintage '62 RI Stratocaster '07
Last edited by RMB at Jun 17, 2015,
#13
It is possible to lose two tubes at once but it's quite rare. From this point on it gets a bit hard to diagnose, those amps have more switches than a space shuttle. Try jiggling those and see what happens but really, I think you're in "take it to a tech" stage.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#14
Quote by Cathbard
It is possible to lose two tubes at once but it's quite rare. From this point on it gets a bit hard to diagnose, those amps have more switches than a space shuttle. Try jiggling those and see what happens but really, I think you're in "take it to a tech" stage.


Oh how the mighty have fallen, 'tis a sad day indeed...
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#15
Well, a Road King isn't a plexi. Pretty hard to diagnose remotely beyond the obvious things. That's the problem with such complex amps.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#16
Quote by Cathbard
Well, a Road King isn't a plexi. Pretty hard to diagnose remotely beyond the obvious things. That's the problem with such complex amps.


Agreed, was just giving you crap.

The other concern I sometimes have is if the other party can't read a schematic they probably don't have the skills necessary to safely troubleshoot or fix anything of significance anyway and if they can read one they don't need me...
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#17
Okay thanks for the help everyone!
I understand the Roadking is too complex to troubleshoot through a forum, unfortunately I need to bring it to the tech.
It's my first time bringing an amp to a tech, usually I fix everything myself when it is something small and easy .

Thanks Cathbard!
Mesa/Boogie Road King v1
Marshall JMP 2203 '78
Vox AC30 H2 Heritage HW
Fender Deluxe Reverb '65 RI
Gibson Les Paul Custom '57 Historic RI '05
Fender American Vintage '52 RI Telecaster '02
Fender American Vintage '62 RI Stratocaster '07