skarkowtsky
Member
- Joined
- Oct 29, 2017
- Messages
- 10
- Reaction score
- 0
Hi everyone,
I joined the board this morning. I received a Mark IV combo yesterday. I believe it's from 1995. Cosmetically, the amp is pristine. However, there are a few things to note, and I need your expertise to determine how bad things are about to get for me.
The amp produces a constant hum when switching from Standby to On. The hum is very subtle in Pentode mode, but very loud in Triode mode. Also, the Pen/Tri switch on the rear creates a static crackle when switching.
Two of the power tubes glow blue when switching from Standby to On. I pulled each power tube (4 Mesa 6l6), checked contacts, and reinstalled in a different order, taking note of where the "blue tubes" were installed. Sure enough, those tubes glowed blue, even in different sockets. Is blue normal or indicative of a faulty tube?
I also checked the pre-amp tubes (Ruby 12ax7) to ensure a snug connection. All was fine. Maybe I should swap for Mesa?
After the power tube swap, the hum still persisted in both Pentode and Triode. Also, even with all volumes set to 0, there is a loud pop when switching from Standby to On.
I'll call Mesa on Monday to hear what they think. I truly hope this is a minor issue I can work out or simply a tube replacement.
Any thoughts?
Thanks!
John
I joined the board this morning. I received a Mark IV combo yesterday. I believe it's from 1995. Cosmetically, the amp is pristine. However, there are a few things to note, and I need your expertise to determine how bad things are about to get for me.
The amp produces a constant hum when switching from Standby to On. The hum is very subtle in Pentode mode, but very loud in Triode mode. Also, the Pen/Tri switch on the rear creates a static crackle when switching.
Two of the power tubes glow blue when switching from Standby to On. I pulled each power tube (4 Mesa 6l6), checked contacts, and reinstalled in a different order, taking note of where the "blue tubes" were installed. Sure enough, those tubes glowed blue, even in different sockets. Is blue normal or indicative of a faulty tube?
I also checked the pre-amp tubes (Ruby 12ax7) to ensure a snug connection. All was fine. Maybe I should swap for Mesa?
After the power tube swap, the hum still persisted in both Pentode and Triode. Also, even with all volumes set to 0, there is a loud pop when switching from Standby to On.
I'll call Mesa on Monday to hear what they think. I truly hope this is a minor issue I can work out or simply a tube replacement.
Any thoughts?
Thanks!
John