DC3 Takes A Massive Dive - Any ideas?

[My Guitar Weeps]

Hey guys. It's been a while since I posted. Reason being, I haven't had the slightest bit of trouble out of my DC3 head since I aquired it months ago. I've grown so fond of it, that it's my main gigging amp. Now I'm back here at the board (which was very helpful to me when I got the amp), totally sick to my stomach.....completely sick.

I play this amp every day, period. In addition, band rehearsals run 6-8 hours strait every other Saturday. I just spent the last week in the studio recording a 6 song demo with it.

While playing at home last week I noticed a funny crackle while not playing and it had a volume swell to it. It did this 3 times in just a mater of second. I know how bad tubes can act up, and I've had probs. w/ other amps before. This was one of those "What the hell was that?" sounds. About 10 mins later my volume cut in half. I was playing thru the dirty channel. I put the amp to bed, came back the next day and fired it up. No problems. Couple of days ago, I noticed a static- cackle. Not the same as the first. I never lost any volume tho. I changed out the PI for a new tube. All the tubes are less than 2 months old. No problems.

We practiced for 3 hours last night and 3 today, while suddenly half way thru a song I had ben playing a lead on.......NOTHIN. Now I know these amps get hot as hell, but I could smell some oder from the back when I went to check it out. Not the good kind of oder either, and it was coming from the send-return-effects mix area on the back panel. The transformers are right behind them.

I'm afraid I might have lost a tranny, I dunno. Any opinions?

I let it cool and tried to fire it back up. You could hear the speakers turn on when I flipped the standby off but nothing after that. I know what it's not - cables,guitar,speakers.

I'm going to throw a whole other set of EL84's in there in the morning and then go thru the preamp tubes one at a time. I guess before I change any tubes tho, I'll pull the chasis and look for any nasty signs on the board. The only thing I've done to the amp as far as mods go is the output volume mod which is just cutting a resistor lead so you get an even volume taper on the output volume.

Question: If I don't fix it with tubes and have to have it repaired, should I send it to Boogie, or try and find someone here in Atlanta? I read about folks all the time sending their Boogies back to Boogie for check ups/repairs. The amp is 14 years old afterall.

If it is a transformer, Anyone have a ballpark price range or turnaround time figure?

Thanks so much guys. I'm just sick. I love this **** amp. It replaced my Orange. Now I have to go back to the Orange. Not that the Orange is a bad amp. I like it a lot, but the versatility of the DC3 is second to none for me.

If you guys have had similar experiences or ideas and don't mind sharing them with me I would be very, very greatful.

 

[rgx612a]

I've had some volume drop issues with my .50 cal +. I think it's just some dirty effects loop jacks cause when i run a patch from the send to the return the problem goes away. I just recently used some contact cleaner on the loop jacks and it's all good now...

Try a patch cable through the effects loop, if that doesn't fix the problem then it's probably an issue with the tubes.

The smell, was it a burning smell? Could be a bad power tube that took out a resistor along with it.

I'm no expert though, so your best bet is a tech.

 

[edward]

Just for my own piece of mind, I'd pull the chassis out first, just to make sure I saw no evidence of shorts, melting, or blown components. If everything looks right, I'd go ahead and replace the 4 ELs ...and while you're at it, see if any one of them looks bad. Also, before you fire it up just double check your fuse and make sure the contacts are clean and it is of the right value. Personally, I doubt it'd be a tranny. More likely a bad power tube as I had a similar thing happen to me with sounds and weirdness (albeit no smoke or smell) when one 6L6 went poof in a very loud/scary manner. Let us know what happens...

Edward

 

[zeeman]

My only suggestion would be...

Before you fire it up with new tubes, I would post some details pics of the insides only because you may miss something that someone else may catch.

If no one else sees anything suspicious, then would fire it up with the the new tubes in and go through each preamp tube.

Good luck and keep us posted.

zeeman

 

[My Guitar Weeps]

You guys are great. I really appreciate the promptness of your replies.

I didn't see any smoke edward, just some of the burny electrical type of oder I mentioned. Not a lot, but still it was not normal for the amp.

I'm going to pull the chasis like you guys suggested and take a look (and some pics) before I start yanking tubes and put them up on the board here tomorrow. If it is a tube, they'll be covered under warranty. I only hope that it is a tube problem. I've got some shows coming up soon and I've got a lot of hours put in on this amp to get "my" sound. I have no idea without talking to Mesa what their turnaround time is. That and I'm on the other side of the states.

Thanks again guys. I'll also give the effects loop patch a try. That's one of the better qualities of the amp in my opinion having the tube driven loops. I definitely make use of them.

I let ya'll know what I come up with.

 

[Tuna141]

Before you fire it up with new tubes, I would post some details pics of the insides only because you may miss something that someone else may catch.

I agree. A power tube going bad may have taken out a resistor. I suggest you take look inside - you may be able to spot a smoked resistor or another blown component.

Be careful - dangerous voltages inside the amp. Good luck.

 

[geenads]

I had a similiar "crackle" problem with my DC3. I had it sidelined for a year, I used my MKIV as my backup (I personally like the DC3 better). I had a tech look at it, checked and replaced tubes (which were practically brand new). finally took it to a an authorized boogie repair music shop... He said it passed the bench test. but i STILL had the problem.. turns out the speaker was blown. I noticed you said it wasn't the speaker, but did you try another cabinent anyway? My speaker "looks" fine, but obviously isn't. just a thought..

 

[mule#1]

I had the same problem with a DC-5 I owned. I took it to a local repair guy and he said he knew what it was right away! It's something to do with the effects loop. He said it was shorting out and it was a common problem with that amp, but he fixed it for $50. I was surprised because I don't use the loop, so even if you don't I'd bet that is the problem. About 8 months later my other guitarist had the same exact problem with his DC-5. I would check that out as the symtoms you mentioned are the same I had.

 

[mtnb1kr]

What exactly happens in the effects loop that causes this. I ask because in addition to my DC-5 I have a Crate Vintage Club 30 that had a problem like this. While playing all the sudden the volume cut and basically all the controls went dead. Turning the volume or tone controls had no effect what so ever. If you gave the amp a slap it would work for a moment and then do the same thing. Had a tech look it over and found nothing. On a whim after reading another thread somewhere I squirted some electric cleaner in the effects loop jack and plugged in and out a few times and now it works. ?????????????

 

[My Guitar Weeps]

Good Morning!

Jus came back to check the board before I pull the chasis (what a pain in the butt). It's difficult getting this thing in and out, but it's worth the piece of mind.

I feel much better about the outcome after seeing the problems and solutions you guys came up with. Forums are awesome, especially when you've got good people on there. Thanks again to everyone.

I'll be back in a little while. Where do you guys host your pics for the site?

Also, I'm particularly interested about the effects loop shorting.



Robert

 

[My Guitar Weeps]

OK, lets see if I can get these pics to post:

 

[My Guitar Weeps]

 

[My Guitar Weeps]

 

[My Guitar Weeps]

 

[My Guitar Weeps]

All the solder connections look fine on the tubes, loop jacks. The one thing hat looks suspect to me, you can see on the main board in the 3rd pic, to the right of the blue caps. There's a row of 3 resistors and then a row of three more running in a horizontal line. Between the 2 sets of resistors it says "red" and theres a nasty looking solder connection with maybe some burning around it. There's a blue and red wire coming from the single small black tranny that's on that side of the chasis (if that's a tranny, choke, hell I don't know). Anyway, that's where the red wire solders to the main board, that nasty looking connection. It's not the side where the effects loop is located. The fuse is fine, the tubes look fine. I don't know. I've got some photos of the board from when I did the output volume mod back in September. I'm going to look and see if I can see that connection in those photos, and if it looks the same.


SORRY for the size of the photos. Next time I'll resize them before I post.

I'll wait to hear from you guys before I do anything to see if someone spots something.

Thanks

Robert

 

[My Guitar Weeps]

Just looked at the photos from Sept. 07. That connection looks the same in that photo as well.

Maybe a tube problem?

 

[stomper]

http://geofex.com/

Go to the Tube amp debugging page. The good news is you were not blowing fuses, so your transformers are likley fine. The smell you detected is likley from the resistors on the power tubes. You are playing this amp a lot, and one of the consequences is that you will need to maintain it more often. In your photo, I see the resisitors up near the big blue capacitors looking a lillte "roasty". I would surmise that a power tube shorted out and started drawing too much current through these resistors. That would cause your smell, noises and loss of power.

Pull all your power tubes out of the amp and turn it on. If the fuse does not blow you are probably safe regarding the the transformers.

If you have new or known good matched tubes you can install them and keep an eye on the amp for noises, more smells and blowing fuses. Any of those things would certainly indicate a larger issue. My guess is you will be okay. I would try this then get the amp to a tech at my earliest convenience. It is difficult to tell how much damage was done to those resistors. They look a little cooked, but might be fine. That is actually their job to a certain degree. If they didn't cook, your transformers would.

 

[My Guitar Weeps]

Here's a couple of photos from the effects loop and where it comes into the board:

 

[My Guitar Weeps]

Stomper,

Your instructions are to put all the preamp tubes back in and turn the amp on (No power tubes installed). Do I leave the amp on standby? How long should I have it turned on?

Thanks,

Robert

 

[stomper]

Start with all the power tubes out of the amp. It will make no sound (of course). If the pilot light comes on and stays on, take the amp off standby. Again, if the amp stays on your transformers are probably okay.

Turn off the amp and put your power tubes in. Turn it on and then take it off standby after a few minutes. If the fuse does not blow and there are no noises or smells, you are probably safe to use the amp.

Leave it on for a few hours, even if you are not playing it. this will let it heat up, and might reveal some other fault. I am guessing by the amount of time you had on those power tubes, they just wore out. I replace my power tubes every year, but I have 4 amps I use. If I were using an amp as much as you, I would change them every 6 months. Keep the known good tubes as spares, for when your amp craps out. It is better to ruin a used tube testing an amp than a brand new tube IMHO.