Mark II Tube Questions 6L6 STR 420

[Woodlumn]

Hi all, I have a Mark II combo. Last night I could smell some burning smell, more than the usual pleasant odor it gives off when warm. Then there was some loud bursts of crackling from the speaker so I went to standby then powered off.

The two 6L6 tubes have black/silver around the base, a burned look to them. I'm guessing they are the culprit?

Looks like it's tough to find a matched pair of 6L6 STR 420 tubes. Are the Shuguang 6L6GC tubes as good? Should I be considering another type of tube?

Here's a picture, do these look burned out?

Thanks!

 

[b00g13mk2B]

The tubes look like they lost vacuum, which means no good. You need to know if the screen resistors are still good else new tubes will get damaged. If you are not familiar with how to check, take it to a qualified tecc.

I would contact Mesa Boogie for tubes. Be sure to tell them exactly what variant you have - MK IIA, B or C. There are several choices that work with the fixed bias.