Heartbreaker fault (?)

[iainmackay]

I recently used my Heartbreaker for the first time after around 2 years off the road. The first gig seemed fine, but at the second I noticed the sound getting increasingly dirty as the evening progressed, to the extent that by the end I couldn't get a clean sound at all. Just as well we were into the heavier part of the set by that time. I also noticed a lot of what seemed like interference, maybe from dirty mains, including a repetitive "swishing" noise that sounded for all the world like a signal from, maybe, a chorus or trem pedal. We were on a stage with a house lighting rig, that may have been responsible for that bit.

I have, in the past, suspected that the amp displays more drive towards the end of a hot evening in summer - which this was. Do others find this?

Bearing in mind that the amp hasn't seen serious service in a while, where would Forum members suggest I start looking to diagnose the problems? My setup is:

pedalboard with home-made A/B/tuner switch, Crybaby, compression, Marshall Guv'nor, vib/trem, chorus, all connected with high-quality leads and powered by a regulated 9V supply

PRS Custom-22
Patrick Eggle Berlin Plus

All leads are pretty good quality - Gibson I think. My 6L6s were replaced in the last year I used it before storing it - it's been stored in the house so not subjected to cold or damp in the meantime.

All advice welcome.

 

[thunda1216]

Mine does not seem to get more "drive" as the night wears on, but it does seem to get louder as the tubes get hotter (much louder by the third set compared to the first).

ty

 

[halfnote]

I have noticed this with a couple of Mesas that I have owned. Once the amp is rippin hot it is almost impossible to get a clean sound, everything breaks up. I am also curious to see if anyone knows why this is. I kind of suspect it is one of the preamp tubes on it's way out.

 

[Monsta-Tone]

I would start by removing everything but the amp, cab, and guitar.
This way you're getting the cleanest possible signal to the amp.
Then try a couple of different cords.

If this doesn't work, it's in the guitar or the amp.

Try another guitar.

If no luck, look in your manual or download it if you don't have one.
Try replacing the preamp tubes that affect the channel that you are having problems with. Replace them 1 at a time with one that you know is good.

If it is both channels, try replacing the ones that are common to both channels (V5, V6, & V7) one at a time.

If that doesn't work, try replacing the power tubes.

You might also try tapping gently on each tube with a chop stick or pencil. Sometimes a bad preamp tube will make funny sounds when you do this.

 

[Tweeked]

Check all the tubes !
When I talked to Mesa about mine they mentioned 95% of the time it's a bad tube.
Read the manual,it will tell you how to figure this out.

 

[iainmackay]

Sorted! It was the tubes - two to be precise. It took a better tech than me to track this down.

One of the power tubes (6L6s) was drawing significantly more plate current than the others. He located a spare that matched the other three, installed it and that bit was fine.

Then he confirmed that there was a rogue 12AX7 pre-amp tube in the mix somewhere, as evidenced by significant microphonics on tapping anything including the chassis! It turned out to be tube 7 - the FX and Reverb send-return.

While I think that, given another such situation, I'd now be able to diagnose the pre-amp tube problem, I doubt I could have tracked down the bad power tube without more equipment and knowledge.

So, thanks to Jesse at Chandler Guitars in Kew, UK for fixing this. 1:30 drive time each way and 45 minutes in the workshop, but worth it to get a positive diagnosis and fix as well as a master class in fault diagnosis.

 

[Monsta-Tone]

Right on! Now you can enjoy the amp!