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PostPosted: Mon Jan 09, 2017 1:45 pm 
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Bottle Rocket

Joined: Mon Jan 09, 2017 1:27 pm
Posts: 3
I just picked up a IIb combo and since this is my first MB I am a hoping someone here can help me. The tubes have been replaced with a set of JJ's just because I was not sure and the past owner told me that he was told that they needed to be replaced. The main problem I have is that I really don't have any volume on the clean channel until the Master 1 volume is 3 or better. According to the manual this should be set at 2 initially with the Lead Master also at 2. With it set like this I have volume on the lead channel and next to nothing on the clean channel. The pull boost/gain seems to work fine though. Volume is anywhere from 7 or better (as per the manual). While running the Master 1 at 3 or more, the Lead master can be around 2 to have a lead boost. Also this amp came with a Celestial V30 and seems to get rather flubby at even slightly lower volumes. I have the bass turned to 2 or less and the mids down as well to try and control some of this. Any advice would be greatly appreciated, thanks.


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PostPosted: Tue Jan 10, 2017 5:42 am 
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Mark III

Joined: Tue Sep 20, 2011 11:15 am
Posts: 167
Did you replace all the tubes,pre amp and power amp?If so did you have the amp biased for the JJ's?IIb's didn't have an adjustable bias and would either have to have a pot installed or a bias resistor or 2 exchanged to accodomate power tubes that fall within Mesa bias range.They might be ok but I think the JJ's run hotter than the Mesa tubes?
If you haven't changed the pre amp tubes I would try that first.Especially V1 since it's your clean channel that's suffering.


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PostPosted: Wed Jan 11, 2017 5:00 pm 
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Bottle Rocket

Joined: Mon Jan 09, 2017 1:27 pm
Posts: 3
The tubes were replaced and were purchased for this amp (supposedly), so no, I did not re-bias the amp after installing them. Just for the sake of argument I reinstalled the originals and the same conditions are there. I have tried a few different 12ax7's and a couple of 12at7's that I had lying around in V1, but none of them seem to change the output level. I am about to take the chassis back out and check the Master 1 pot to see what's going on there. Again, any other advice is greatly appreciated.


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PostPosted: Wed Jan 11, 2017 5:11 pm 
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Mark III

Joined: Tue Sep 20, 2011 11:15 am
Posts: 167
If you have any deoxit/contact cleaner while the chassis is out I'd spray some into the pots.(You'll see a small space where you can spray it)then turn the controls up and down a few times to work it in.Sometimes the effects send/return jacks get dirty and cause volume/gain loss but it's not usually just on one channel.Still you could run a patch cable between the loop just to see if it helps.(Just general troubleshooting stuff)
Try the spare preamp tubes in other positions too.I still think it may be the master pot though.Is it crackling at all?
ps does this amp have reverb?


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PostPosted: Wed Jan 11, 2017 5:55 pm 
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Bottle Rocket

Joined: Mon Jan 09, 2017 1:27 pm
Posts: 3
This amp does have reverb but no EQ. I did spray everything with Deoxit and that took care of a little scratchiness in a couple of the pots. But no there really isn't any crackling that I can hear. I did have to make up a new cable for the reverb with a shared ground because the original that came with the amp induced a loud hum as soon as you started to turn the reverb up. I will do a little more tube swapping with the preamp tubes just to see what they do.


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PostPosted: Wed Feb 08, 2017 7:16 pm 
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Donating Member

Joined: Thu Jul 09, 2009 1:41 am
Posts: 375
Location: Canberra, Australia
Sounds like yr losing signal in Ch1.
Question is where.

Aside from simple voltage checking (DC and AC for filaments), carefully look for cold joints or chopstick everything..
Slowly...
Carefully....

let us know how U progress(ed)..

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PostPosted: Tue Feb 21, 2017 2:50 pm 
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Mark II
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Joined: Tue Oct 11, 2011 4:36 am
Posts: 126
Location: Austria
try that (from the manual): "If your Boogie
should ever lose power or die out, always first run a cable between the two Effects Jacks before
proceeding to test tubes, etc., as such a problem could likely be caused by faulty switch contacts
in the Effects Return Jack."

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PostPosted: Wed Feb 22, 2017 10:19 am 
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Mark IV

Joined: Fri Jun 30, 2006 7:00 pm
Posts: 934
TiPiMods wrote:
try that (from the manual): "If your Boogie
should ever lose power or die out, always first run a cable between the two Effects Jacks before
proceeding to test tubes, etc., as such a problem could likely be caused by faulty switch contacts
in the Effects Return Jack."

I had exactly that same problem with a II-B and, after cleaning the jack, the problem disappeared.

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