Mesa Boogie Mark IV

[azira]

I hope this isn't the wrong kind of thing to post here. But since I'm here anyway doing my own DIY thing I might as well ask.

My uncle just recently lent me his old Mesa Boogie Mark IV. It's probably from around 1983 and hasn't been used in like 10 years. So I cleaned up all the dust with a wash cloth and and flipped it on and woah, all the tubes lit up and it still works!!!

But it has kind of a whine to it. Real soft sort of like if your FM radio is tuned slightly off or has some interference, it's not static, just a high pitch whine that sort of wavers around a bit. It doesn't go up with the volumn. Does it need new tubes or something?
Thanks
--
Danny

 

[Netlist]

I ones had a similar problem. It's a long time ago and the Mesa Boogies don't come in every day so I’m not 100% sure but I recall the jack inserts on the back had some bad contacts.

/Hugo

 

[SHiFTY]

Sounds like you may have a microphonic tube, where the internal elements have come loose and are rattling a little. Don't worry, easily tested and fixed.

Get a wooden pencil, and with the amp on, lightly tap the small signal tubes (at a guess 12ax7 types) one at a time. If one rings like a bell through the speaker, it needs to be replaced. OK ones will just make a small "clunk" noise.

OR you could try swapping it with another one of the same type in the amp. Sometimes microphonic tubes are dead quiet in some parts of the circuit.

 

[Bricolo]

BTW, is the mesa boogie still the ultimate diy guitar amp?

 

[Netlist]

I know of three people who use MB's. They absolutely love them.
I repaired them a few times and the building quality is very nice.

/Hugo

 

[azira]

Thanks for the tips, I'll check out the jacks and try the pencil when I get home.

Ultimate? maybe yes, maybe no... I guess I'm still more of a SS guy, I like small signals... But what I do know is that this amp is -SWEET- and -LOUD-

It has 4 12AX7s in the preamp and 4-EL84s for the drivers you can switch between Class A and AB operation and you can choose on the power switch to run just 2 of the output tubes or all 4. Nice built in reverb and it also has direct outputs for recording gear to connect into.
--
Danny

 

[usekgb]

I've been playing through a MESA Dual Rectifier for several years now, and I absolutely love it! I've toured all over the US with it, and it has never given me any problems. I've had to replace the tubes once (an expensive thing to do). Other amps I own are an Ampeg JET II, and a Roland JC120. The MESA is still my favorite. My JC120 is basically just collecting dust.

Cheers,
Zach

 

[azira]

Hmm, I didn't get a good tap on the small signal tubes cause they were kind of hard to get to, nothing happened, I'll try again later when I have more time.

One more thing I just rembered about it, it totally goes away when I put it on standby.