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Mesa TT-800. No sound on Boogie Channel?

Another Rick

Another Rick

Aug 11, 2016
17
69
Bend, OR
#1
Hello
Anyone ever had this issue? Subway channel works fine. Just plugged it in and turned it on today, and no boogie channel. Nothing is connected in the back. I can't seem to find anything in the user manual. I tried two bases, and two cables. Here's a video.
 
#2
Another Rick said:
Hello
Anyone ever had this issue? Subway channel works fine. Just plugged it in and turned it on today, and no boogie channel. Nothing is connected in the back. I can't seem to find anything in the user manual. I tried two bases, and two cables. Here's a video.
Click to expand...



Each channel has it's own effects loop. Try inserting a jumper between send and return of the Boogie channel.

The only other possibility I can think of is one of the tubes has a bad section or has vibrated loose. Per the block diagram, the Boogie channel tube is V2. Try reseating the tube...or try a fresh tube if you have one. The manual says the stock tube is 12AT7, but the circuit will also run 12AU7.

If none of these rectify the problem, maybe @agedhorse will have some other ideas.
 
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#3
Wasnex said:
Each channel has it's own effects loop. Try inserting a jumper between send and return of the Boogie channel.

The only other possibility I can think of is one of the tubes has a bad section or has vibrated loose. Per the block diagram, the Boogie channel tube is V2. Try reseating the tube...or try a fresh tube if you have one. The manual says the stock tube is 12AT7, but the circuit will also run 12AU7.

If none of these rectify the problem, maybe @agedhorse will have some other ideas.
Click to expand...

Thank you for the suggestions. Tried the jumper and reseated the tube. This has been used a max of 20 hours over the past two years and rarely comes out of the closet. Strange that it would just stop working. Thanks again.
 
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#4
Another Rick said:
Thank you for the suggestions. Tried the jumper and reseated the tube. This has been used a max of 20 hours over the past two years and rarely comes out of the closet. Strange that it would just stop working. Thanks again.
Click to expand...

Yes a failure is unusual, AFAIK the Subway line is very reliable.

If you don't have a spare tube to roll into the amp, you can try swapping V2 with V1 or V3.
 
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#5
Ok, V1 can't be the problem since it's common to both channels. Don't mess with it.

V2 is used in only the Boogie channel and V3 is used only in the Subway channel. If you swap V2 and V3, and the Boogie channel now works but the Subway channel doesn't, the original V2 is bad. If the Boogie channel continues to not work and the Subway channel still works, there is something else going on and it would be a good idea to contact our factory service department as the next step.
 
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#6
agedhorse said:
Ok, V1 can't be the problem since it's common to both channels. Don't mess with it.

V2 is used in only the Boogie channel and V3 is used only in the Subway channel. If you swap V2 and V3, and the Boogie channel now works but the Subway channel doesn't, the original V2 is bad. If the Boogie channel continues to not work and the Subway channel still works, there is something else going on and it would be a good idea to contact our factory service department as the next step.
Click to expand...

That was the issue, thank you. Swapping V2 and V3 made the Boogie function and the Subway not.
The tubes are marked 12AT7W. Is it OK to buy the 12AT7 with no W? And I don't have to buy a matched pair and replace both V2 and V3?
 
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#7
Another Rick said:
That was the issue, thank you. Swapping V2 and V3 made the Boogie function and the Subway not.
The tubes are marked 12AT7W. Is it OK to buy the 12AT7 with no W? And I don't have to buy a matched pair and replace both V2 and V3?
Click to expand...
No need for a matched pair, the factory tubes are the best for this amp, it's a TungSol 12AT7W and it's a short plate low noise tube. When you order from the factory, let them know that you need the TungSol and it's for the TT-800. These are not available at our on-line shop and generally come from our service inventory.
 
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#14
Stewie said:
Andy, the AC in my Tacoma onlyworks for about a minute, then the light flashes and it quits. Can you fix it? Thanks
Click to expand...
I used to work on larger commercial chillers when I was doing industrial controls work. Back in the day, if a light was flashing, you needed to get out of Dodge quickly.
 
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#20
dbsfgyd1 said:
Saturday On Call Dial a Tech: I wonder if agedhorse know anything about plumbing???
Click to expand...

Sorry, I avoid plumbing projects whenever I can!

lug said:
Andy, my wife doesn't want me to buy any more amps or basses. Can you fix her?
Click to expand...
I haven't fixed my wife, what makes me think I can fix yours any better? ;)
 
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