Mesa DC-3 help needed

[kihon]

Volume keeps dropping out and the tone gets real brittle sounding. All tubes were replaced and the condition still exists. Tried different cords, guitars, and outlets.

 

Anyone deal with a problem like this before? Any advice is greatly appreciated.

 

Thanks.

[Fxrs]

Is this on both channels?Try plugging a patch cord into your effects loop, failing that, I would say try replacing preamp tubes one at a time until the offender is found. If neither of these works, see a tech. Good luck!

[tlbonehead]

Originally posted by kihon Volume keeps dropping out and the tone gets real brittle sounding. All tubes were replaced and the condition still exists. Tried different cords, guitars, and outlets. Anyone deal with a problem like this before? Any advice is greatly appreciated. Thanks.

As mentioned,check the loop contacts for dirtiness. Have you checked the new preamp tubes? Could easily be one of them.

[kihon]

Originally posted by Fxrs Is this on both channels?Try plugging a patch cord into your effects loop, failing that, I would say try replacing preamp tubes one at a time until the offender is found. If neither of these works, see a tech. Good luck!

Yeah, its on both channels. I'll try running a cord in the effects loop. What is that supposed to do?

I'd change the preamp tubes but what are the odds of having the exact same problem with a brand new set of tubes?

Thanks for the help!

[Fxrs]

The jacks on your loop can get dirty, causing the conditions you describe. Replace the preamp tubes ONE AT A TIME with a tube you know is good, until you find the culprit.

[tlbonehead]

Originally posted by kihon Yeah, its on both channels. I'll try running a cord in the effects loop. What is that supposed to do? I'd change the preamp tubes but what are the odds of having the exact same problem with a brand new set of tubes? Thanks for the help!

I didn't notice that this was your reason for changing all tubes in the first place. Not sure if they use the same types of pots as the Nomads but those could get knocked from the front and pushed back slightly and lose most of the connection,resulting in those problems. Try grabbing them and see if they have somwe play coming forward. I don't think they are the same types of pots but its worth a check.

[kihon]

Originally posted by tlbonehead I didn't notice that this was your reason for changing all tubes in the first place. Not sure if they use the same types of pots as the Nomads but those could get knocked from the front and pushed back slightly and lose most of the connection,resulting in those problems. Try grabbing them and see if they have somwe play coming forward. I don't think they are the same types of pots but its worth a check.

 

 

The preamp tube pots seem pretty firm. They also have a padded retaining cover that keeps them pretty snug. The power tubes have wire retainers for and those move around easily.

 

Do you think it could be a tube pot problem?

 

Thanks for you input!

[kihon]

Originally posted by Fxrs The jacks on your loop can get dirty, causing the conditions you describe. Replace the preamp tubes ONE AT A TIME with a tube you know is good, until you find the culprit.

 

 

I ran a signal processor through the effects return and the same thing happened. What does this mean?

 

Also, all the tubes are brand new JJ's. How do I determine with certainty which tube is good? Do I have to buy another tube?

 

Thanks for the advice!

[tlbonehead]

Originally posted by kihon The preamp tube pots seem pretty firm. They also have a padded retaining cover that keeps them pretty snug. The power tubes have wire retainers for and those move around easily. Do you think it could be a tube pot problem? Thanks for you input!

I was talking about the pots,not the tube sockets. Asin,the things that the knobs go on. Pull on the knobs and see if there is a lot of play on any of them.

[kihon]

Originally posted by tlbonehead I was talking about the pots,not the tube sockets. Asin,the things that the knobs go on. Pull on the knobs and see if there is a lot of play on any of them.

 

 

Ah, ok. They all some play in them except for a couple. None seem to be really loose. I think the Nomad knobs are flat where as these stick out somewhat.