DC 5 with problem

[neilp]

Hi

First post here! I have owned my DC5 combo for over 10 years and have never had any problems at all - yep even the tubes are original. Great amp I can not find anything else that gets close!

However I have now got an intermittent problem on the rythym channel. The volume fluctuates - the amp gets much quieter and then louder, for no reason. The gain seems to be part of the issue as it sounds much dirtier at times.

I know I should replace all the tubes but that isnt in the budget right now.

I am suspecting a preamp tube but which are the for clean channel?

The problem is sufficently intermittent that it is very difficult to diagnose. I have a Fender Hotrod Deluxe that I will use to borrow tubes from to swap in to the DC5 and find the problem.

I have been working with a new project recently and really need to get the DC5 back in reliable shape. That Fender just doesnt have the nuts fot this job!

Thanks for any help

Neil

 

[cvansickle]

My DC-5 used to do this. It's power tube failure. Bite the bullet and replace them.

 

[neilp]

cvan~

If it's power tubes I had assumed that it would be noticeable on both channels?

Am I AFU in my thinking here?

IIRC preamp tubes can be pretty much mixed as far as brands etc but power amp tubes have to be matched?

Thanks

N

 

[Boogiebabies]

After ten years you could not have put a dime a week away for new tubes?

I would be lucky to get 10 years out of a NOS 6L6GC.

Try the preamp tubes first, but that baby is way overdue for some power tubes.

If you really cant afford them, please PM me and I will see what I can dig up and send you.

 

[Ken j]

V1a first rhythm
V1b first lead
V2a second lead
V2b third lead
V3a fourthlead
V3b FX return
V4a second rhythm
V4b third rhythm
V5a reverb send
V5b reverb return
V6a&b phaser spliter/driver

 

[neilp]

Thanks for the replies.

I'm off armed with Kenj's info to do some tube swapping ...

Wish me luck!!

N

 

[neilp]

Ok looking at the tube list from Ken I guessed that the offender is V4 as this is the only tube that only supports the rythm channel.

Is this logic good?

Anyway I have swapped a good tube from the Fender (Sovtex 12ax7) into that slot and put the tube from the DC5 into the Fender.

So far the both work just fine - at least I didnt screw up a tube been awhile since I messed with one! But I'm not much further forward regarding diagnosis.

Guess I'll go play some and see if it starts misbehaving. I hate intemittent problems ....

Neil

 

[Ken j]

Remember half of the tube can fail. Example V1a can fail while V1b is still operational. Since your Fender also has 6L6s you can also try those.