Mesa Reverb Ground Fix - Look Here
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Boogiebabies
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Boogiebabies
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Boogiebabies
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Pardon my ignorance, but reverb fix for what and why? Did I miss something? The outside (grounds) of both the RCA jacks on the reverb tank are grounded to the tank, making the connection in your drawing redundant, I don't understand the need. As long as one of the leads from the chassis to the tank has a ground from tank to chassis a second one is not necessary.
Boogiebabies
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guy_incognito
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sorry, the original link is broken and I can't find any more info on this online; could someone inform me please?
hey guys,
if anyone has saved the info re: this reverb grounding it would be awesome if you could post/PM it to me. I'm having massive dramas with my IIC because of the noisy reverb, and I cant find the info anywhere else.
Cheers,
Alistair
if anyone has saved the info re: this reverb grounding it would be awesome if you could post/PM it to me. I'm having massive dramas with my IIC because of the noisy reverb, and I cant find the info anywhere else.
Cheers,
Alistair
guy_incognito
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yeah, I can't quite wrap my head around it either; I got BB to PM me an image of the basic gist of the repair, but I'm nowhere near confident enough that I understand it to try to taking a soldering iron to my amp. I've basically been picking up the message that this is all common knowledge and has been discussed to death, but I can't find it anywhere on the internet. (and my reverb is still making horrible noises). So, yeah, any detailed, comprehensive explanations that a guy like me with a little bit of electronic knowledge, but not a lot, can wrap his head around would be nice.alistair said:
Boogiebabies
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Years ago, Boogie made this an official repair. I have an 84 IIC+ that was service by Mesa in 1992 and Mike B. did the repair. The only thing I did was use photo shop to show how simple it is. Your not messing with the amp, your soldering a single wire to the sleeves of $ 3.00 reverb cables. Don't worry. Basically, the white wire is the ground for the reverb circuit. As we all know if a circut does not have a path to ground it does not work. If it gets lifted above ground by resistance or corrosion the reverb has commonly known quirks, static, pops etc. In this case we use the chassis ground from the sleeve of the gray cable input to provide a ground. It's not even remotley intrusive and can be done in 30 seconds.
If you want to fix the ground properly then you will have to take out the preamp board and scrub the chassis and replace the washers. That will take about a week.
Just do it. ( Copyright 1997 Nike Inc. Beaverton, OR)
If you want to fix the ground properly then you will have to take out the preamp board and scrub the chassis and replace the washers. That will take about a week.
Just do it. ( Copyright 1997 Nike Inc. Beaverton, OR)
Boogiebabies
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Posted another copy at the top.
guy_incognito
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hey, I finally got around to doing this and it did the trick, thanks so much.
Boogiebabies
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Finally, a testimonial of the official Mesa one wire repair !!!
Amen brother.
Amen brother.
guy_incognito
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blargh! perhaps I spoke too soon...
For starters, it did vastly improve the situation. However, after playing my Strat at a reasonably high volume (this happens when the tone is clean, but it's more vulnerable on distorted settings, which I don't use as much) for maybe 10 minutes or so, it starts to get little distorted cracks and volume spikes. Like I said, it basically did do the trick, so is it possible that I just need to go back and make sure my soldering job is completely solid?
(I've also been playing a Rickenbacker 12-string through it, which produces more of an even sound than the percussive Strat, and that hasn't been having this kind of problem, except at extremely high volume (channel 2, volume 2 at 5 and master at 5), so it does seem to take some kind of provocation with an especially harsh attack)
For starters, it did vastly improve the situation. However, after playing my Strat at a reasonably high volume (this happens when the tone is clean, but it's more vulnerable on distorted settings, which I don't use as much) for maybe 10 minutes or so, it starts to get little distorted cracks and volume spikes. Like I said, it basically did do the trick, so is it possible that I just need to go back and make sure my soldering job is completely solid?
(I've also been playing a Rickenbacker 12-string through it, which produces more of an even sound than the percussive Strat, and that hasn't been having this kind of problem, except at extremely high volume (channel 2, volume 2 at 5 and master at 5), so it does seem to take some kind of provocation with an especially harsh attack)
Boogiebabies
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Clean the reverb tank contacts and the cable ends.
A volume drop out sounds like a tube or pot.
A volume drop out sounds like a tube or pot.
guy_incognito
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It's not a volume drop out, it's that for a fraction of a second it gets much LOUDER than I have it set to (with distorted, ear-splitting results)
Boogiebabies
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When your reverb circuits output gets lifted slightly above ground it basically turns your reverb circuit into a highly distorted 1 watt amplifier.
From there, if you have the reverb knob on 5 it adds a ton of gain and volume when the circuit is held above ground reference. It's basically giving the circuit just enough ground to function, but not a full ground to allow the reverb circuit to work properly. The 1 watt boost is huge and causes a massive increase in distortion and output.
How do I know?
I have been working on a IIC+ that does the same thing.
You need to pull the chassis and remove the RCA connector from the chassis and replace the rusted washer. Also, soak the area with contact cleaner and scrub it and all of your reverb connectors with scotch brite.
The other RCA jack is unreachable unless you pull the preamp board so unless you want to spend a ton of time, this is the best repair I can offer.
Clean everything, even the reverb tank connectors until they shine or you are positive that you have all funk free contacts.
From there, if you have the reverb knob on 5 it adds a ton of gain and volume when the circuit is held above ground reference. It's basically giving the circuit just enough ground to function, but not a full ground to allow the reverb circuit to work properly. The 1 watt boost is huge and causes a massive increase in distortion and output.
How do I know?
I have been working on a IIC+ that does the same thing.
You need to pull the chassis and remove the RCA connector from the chassis and replace the rusted washer. Also, soak the area with contact cleaner and scrub it and all of your reverb connectors with scotch brite.
The other RCA jack is unreachable unless you pull the preamp board so unless you want to spend a ton of time, this is the best repair I can offer.
Clean everything, even the reverb tank connectors until they shine or you are positive that you have all funk free contacts.
