What happened to my boogie??

[rickou812]

Hello all,

I am the proud new owner of a boogie .50 cal +. Just got it yesterday and have a question.
It looks practically brand new, so it was well cared for by the previous owner. He also sent a copy of the service record. The last inspection/overhaul was performed 12/2006.
The amp sounds great and everything seems to work as it should and has plenty of volume :shock:
Now to the question, today while I was playing at a fairly low master volume of 2, gain at 10 and lead at 2/3 with EQ on set V shape..
Just out of the blue the volume started to fade away, I looked behind the amp and the power tubes where completely red and slight amount of smoke started coming out from inside the case.... I switched it to standby to let the tubes cool for about 5 minutes are so...
I then switched back on to see if it would play, and it was back to normal. I played for another 30min to hour and it never repeated this event...
Can someone explain to me what happened and does it need to be looked at?

Thanks,
Richard

 

[stokes]

The tubes being "completely red" says the current draw increased to dangerous levels.Could be that you lost bias voltage to the power tubes.Maybe a bad solder connection,or something.Smoke indicates something burning,like they say "where theres smoke...",best to have it checked out before things get worse.

 

[Elpelotero]

+1. I wouldn't play it again until you get a tech to look at it. See mesa's site for authorized repair centers

 

[Sixstringpsycho]

Agree I would have a tech look at the amp, just explain exactly what you saw and what it did.

 

[rickou812]

Thanks guys for the replies.

I live in North Florida and there doesn't seem to be any Mesa techs any where close to me... Is there anything in particular that I could check out?

Thanks,
Richard

 

[rickou812]

whenever you smell burning (like I did once on my ex-RK1) or see flames/smoke, something is burning or was burning.

could be a screen grid resistor or like in my case a pent/triode switch.

I'm not familiar with your model, but it looks like it has two 6L6. you can't pull any tubes in this case. you can try replacing both tubes with two known good ones.

contact mesa or find a tech. it needs to be looked at "under the hood".

did a fuse blow?

Your right that it has (2) 6L6's... No it did not blow fuse, when it started fading out, I switched to standby, let it sit for about 5 minutes and then switched back on, and everything was back to norm...

I am going to order a tube set, what is the recommended replacements?

 

[kiff]

I live in North Florida and there doesn't seem to be any Mesa techs any where close to me... Is there anything in particular that I could check out?

I would ask around and find the best amp tech in your area. Most likely he'll be able to fix it or point you to someone that can

I am going to order a tube set, what is the recommended replacements?

I would still have a tech look at it before doing that

 

[rickou812]

Thanks again for the advice, I will see if I can find a local tech... Just a little nervous letting just any one finger my boogie..lol

 

[stokes]

If it is no longer under warranty,it doesnt have to be a "Mesa tech".I'll say it again,there is nothing magical about Mesa,they are just tube amps,any good tech will be okay.Since you say the problem didnt appear again after you shut it down and powered up again,it is probably what we call an intermitent problem,it didnt fix itself,and could occur again without warning.Next time could be its last.Get it checked,before you turn it on again.Tubes redplating like that and losing power should have blown the fuse,that is what it is there for,it is a saftey device.The fact that it didnt blow could indicate it isnt the proper value,and could cause more serious problems if the condition occurs again.

 

[Fxrs]

I would recommend SED's from Doug's tubes, or KCAnos.

 

[stokes]

Get it fixed before you try new tubes,you dont want to fry a new set of power tubes.

 

[rickou812]

Just an update.
I removed the amp from the enclosure so I could get a better look at the board and such.

I could not find any obvious signs of any over heating on the board.

The fuse was intact and was the correct SloBlo 2.5amp fuse.

The smoke I saw was coming from the area of the reverb springs..However, they looked in order.

One of the power tubes seems to be excessively loose in its base, not in the holder, the tube itself..is this normal?

All the tubes are original and numbered when the amp was built except for the number 4 pre-amp tube (reverb). It had been changed to a sylvania 12AU... supposed to be a 12AT7A.. could this have caused something to go wacky with the reverb?

It is cool to see all the handwritten initials and numbering on the components. The build date is even handwritten on the chassis.. It is a 1991 built amp BTW.

 

[rickou812]

BTT for the update..
Any thoughts.