# Guitar Amp Techs Help



## Joe_SampleCraft (Sep 24, 2015)

Hey, I'm trying to diagnose a little problem I'm having today. My Mesa Boogie Recto Pre started to cut in and out. The cut in/out sounds like a fade not an abrupt cut. I read some articles online that suggest using electrical contact cleaner on the jacks and tube sockets. What do you think? The tubes are new,I haven't play the amp in a long time.
Thanks in advance,
Joe


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## chimuelo (Sep 24, 2015)

Either the wrong tube or capacitors leaking.
Check the caps.


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## synthpunk (Sep 24, 2015)

Hard to say, I would try the usual suspects, different cables, clean the jacks and connectors, different outlet, check your tubes, re-seat them, etc. Could very well be a bad tube as Chim mentioned, if you have a spare set to check one by one.

I would suggest using Caig Deoxit to clean.
http://store.caig.com/s.nl/sc.2/category.188/.f

Do you happen to live near the ocean ? That can cause quicker oxidization.

Other than that it really needs to be put on the bench with a scope by a good tech to diagnose if/where the problem is in the circuit.


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## Joe_SampleCraft (Sep 25, 2015)

Thanks for the tips guys. I'm going to do a full inspection of it this weekend. I live in Central Fl and the humidity can be brutal,that could have caused some oxidization?


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## bbunker (Sep 25, 2015)

Especially since you haven't played it for a while, it sounds an awful lot like it could be a leaky cap problem. You blown through any fuses? Any red-hot tubes? Or, alternatively, does it work fine in clean channels and then have problems when the other pre-amp tubes are brought in? When it fades in and out, is it really distorted sounding in the tone, or is there 'mechanical crackle,' like when you push a plug in and out of a jack?


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## Joe_SampleCraft (Sep 25, 2015)

bbunker said:


> Especially since you haven't played it for a while, it sounds an awful lot like it could be a leaky cap problem. You blown through any fuses? Any red-hot tubes? Or, alternatively, does it work fine in clean channels and then have problems when the other pre-amp tubes are brought in? When it fades in and out, is it really distorted sounding in the tone, or is there 'mechanical crackle,' like when you push a plug in and out of a jack?


Haven't blown any fuses. Tubes aren't burning red hot. This happens on both channels. Also this amp has independent outputs for live(to power amp) and for recording. The cut off happens for both sets of outputs. When it fades out it does sound a bit. No crackle or distorted sounds,just started to fade away like someone turned down the gain knob.


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## bbunker (Sep 26, 2015)

Huh. Sounds less and less like caps, or at least like they aren't misbehaving in the usual catastrophic ways. I'd guess you've already tried this, but you might try swapping the tubes as a block - moving the first 3 to the 4, 5, 6 position and vice versa. That way you could at least get an idea on where the problem is, since if you still have exactly the same problem, then the tubes are probably fine, but if the problem changes so that it only comes on in lead channels then you've found your culprit.

While you've got the amp on the bench, you might check the plate resistors as well. Less likely, but still possible...


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## sleepy hollow (Sep 27, 2015)

Pretty sure it's got to do with the channel-switching. Leave the tubes and jacks alone, check the part of the preamp that's doing the channel-switching. Bad relay/optocoupler?


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## Joe_SampleCraft (Sep 28, 2015)

I rotated the tubes then even them.Cleaned all the jacks w/the DeoxIt. Still having probs. I opened it up and took a look inside saw no broken wires ect... Guess I'll have to to take it to an authorized Mesa Boogie tech. Thanks for the tips everyone! My Mesas have been solid through there years but looks like this one is a lemon


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## synthpunk (Sep 28, 2015)

Tube amps can be temperamental.

Where are you in FL Joe ?, I know allot of the top techs in the US through the touring company I worked for.


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## Joe_SampleCraft (Sep 28, 2015)

aesthete said:


> Tube amps can be temperamental.
> 
> Where are you in FL Joe ?, I know allot of the top techs in the US through the touring company I worked for.


I'm about 30min North of Orlando
Thanks!


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## synthpunk (Sep 28, 2015)

*Let us know how you make out.*

*Amp Guys*
Altamonte Springs, FL 32714
P: 407-362-1528http://www.mesaboogie.com/support/www.ampguys.com (<br />
www.ampguys.com)

* Donald Lee Service*
Kissimmee FL 34741
P: 407-978-6690

* Gary Dahle Pro Audio*
6398 Danner Drive, Sarasota, FL, 34240, USA
P: (941) 379-2077


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## Joe_SampleCraft (Sep 28, 2015)

Awesome thanks man,Ampguys is not far from me. I get it down there next and see whats up with it. Thanks again


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