Mesa DC 5 Problems

[wolfgang6505]

My DC 5 is having problems. First I'll say my guitar cables,speaker connections,speaker, tubes have all been checked as wll as my guitars.

All the tube are brand new 2 Sovtek 6l6's 6 12ax7wa's
My amp tech has done a cathode bias mod to amp. These problems are not related to the cathode bias mod.

1. The amp sounds like there's a wind storm inside it. Best described. Plug mic into you amp and blow in it lightly and that's what it sounds like. It doesn't do this all the time it fades in and out slowly and gets louder and quiter. This problem is always happening no matter what.

2. The amps graphic eq directional switch(rotary type not toggle) on the back is going bad sometimes it works fine sometimes it causes the sound to completely cut. It requires a jiggle to cut back in. I can't find a replacement for it anywhere. Anybody ever had this problem. Where can I buy this switch??? Searched and Searched no luck. I've tried the internet and everything.

3. The channels(both channels) LED lights will be normal brightness and then they go dim and then it goes back to normal. This happens over and over the entire time the amp is on. Someone I talked to said it might be the output transformer but I can't just go by that. The tone of the amp is great.

The amps features aside from the switch on the back work fine except when I pull the gain boost on ryth. channel, when I pull the gain boost on the rythm channel and the knob is on 8.5 and up it gets muddy and sounds like bad distortion that sounds damaging in a bad way. The pot has been cleaned and isn't bad in anyway. My tech did the cathode bias mod installed the tubes and tried the amp out and said it works fine, but he doesn't use as much gain as I do so, he just thinks it's mesa preamp design having alot of gain but I've tried other mesa's and this problem didn't happen. No matter how you have gain set it shouldn't do this. As a matter of fact, I thought the other mesa's sounded great on there ryhtm. channel with the gain all the way up.

Please help with any info Thanks -Jim

 

[Monsta-Tone]

Since you checked the obvious, I'll leave that alone.

1. You could try cleaning and re-tensioning the Preamp Tube sockets.
This should only be done after the amp is unplugged and the capacitors are discharged. Otherwise, you will get a 200 volt surprise.

2. If that doesn't help, try changing Preamp Tubes 1 at a time. Start with the tubes that are common to both channels.

3. You can also try inserting a good patch cord between the FX Loop Send & Return jacks. Sometimes the Send jack goes bad and causes problems to happen.

4. If none of these work, you should find another tech or send the amp back to Mesa. It could be a failing component or a cold solder connection.




As for the EQ Switch, you will find the model # in the back of your manual.

Call Mesa and they should be able to get you one or tell you where to find one.

You could also try Mouser Electronics, www.mouser.com

If you call them, they are very helpful.

 

[Ken j]

Hi Wolfgang and welcome to the Boogie Board.

As far as the pull for gain you are correct it should not be muddy. Keep in mind though that different tubes (brands) may not react the same in various circuits. Considering your problem it may very well still be a tube. Do you have any others to swap? Maybe from another amp you own. I still use Mesa tubes in my DC-5 but I have tried various NOS power tubes and they sounded darker.

With the LEDs changing brightness I would think something in the power supply, possibly a cap.

The switch should be available from Mesa if all else fails.

 

[wolfgang6505]

Thanks I'll try to download the manual online because my dc didn't come with a manual(gotta love that) when i got it used.

 

[Monsta-Tone]

If you can't download it, I can email it to you.

Some months ago, I downloaded all of the Mesa Manuals so that I could reference them more easily.

 

[fatboy135]

3. You can also try inserting a good patch cord between the FX Loop Send & Return jacks. Sometimes the Send jack goes bad and causes problems to happen.

That happens in a lot of boogies amps, because the jack becomes degrade and it makes sometimes false contact

 

[wolfgang6505]

I have the manual now(download worked) but I could try a patch cord because I've never used the fx loop so it might help also.... Thanks

 

[jukesgtr]

3. The channels(both channels) LED lights will be normal brightness and then they go dim and then it goes back to normal. This happens over and over the entire time the amp is on. Someone I talked to said it might be the output transformer but I can't just go by that. The tone of the amp is great.
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Just a quick note here...the fx loop led in my MK4 combo (not in the foot switch) behaved the same way and it simply was a bad connection of the LED itself, moved it slightly and it is OK now...probably caused by vibration that occurs in many combo amps....