Problem with my AFD!

[Mats A]

Earlier this week when playing on my AFD i decided to try to set the Power Volume on 10 and use the master as on a normal master volume Marshall. When i turned up the Power Volume to 10 i heard kind of a low hum that went away when i turned down the PV past 3 o`clock. Suddenly there was a little pop and the hum was gone. Then i discovered that the led closest to the bias trim pot was lit. I did the bias adjust procedure on the amp and the led was not lit anymore. Next time same thing and i had to do the bias adjust two times to make it not light up. Tonight it was lit even after two bias adjusts. The amp have worked fine all the time and i hear nothing strange in the sound. Can it be just a faulty valve or should i have the amp sent to a tech for a check?

[surfnorthwest]

It could just be a valve, easy enough to change them in that amp with a spare to find the bad one. Do that first and if it doesn't fix it, then yes time to take advantage of that warranty.

[Mats A]

Problem is i don´t have any spare 6550´s. I talked to one of the guys in my music store and he thought best to send it to the Nordic agent for a check so i took it to the store to be sent. Feels a bit hard but i´m sure it´s worth to have it thoroughly checked

[kissfanps]

i would order some tubes before sending it out. in all likelihood its a bad tube.

[gtrman]

I just fired up the AFD ... hadn't played it in a few months ... I got some volume drops every 10 seconds.
First time I experienced that... did an Bias adjust and it fixed he problem.
Maybe one of the tubes is starting to go bad ...

[Mats A]

Maybe the EPA is causing problems with time.

[big dooley]

no, that is definatly a tube acting up...

[Mats A]

Mine has been away for two weeks now so i guess it must have been something more than a valve.

[Slashwannabe1]

Mine has been away for two weeks now so i guess it must have been something more than a valve.

Yeah probably unneeded shop time or it HASN'T EVEN BEEN LOOKED AT!...


A little off topic from the AFD itself but a useful cautionary tale to amps in general....

This situation is exactly why I started fixing my amps myself, after a month of waiting for the bad news on my 1966 Blackfaced Fender Bandmaster amp I went down to the shop to ask them wtf was up with my amp and it was still sitting in their doorway with other amps stacked on it. I took one look at my amp being mistreated like that ripped it out from the pile and said "thats not the way you treat a classic" and from that day forward I fixed my own amps, I figured at the very least if I can't fix it, it will be treated better than having its tolex indented by other peoples shit.

Whenever you bring something to someone to fix weather its a car or amplifier for example, YOU ARE totally at the mercy of their honesty and sadly when you're paying for someone elses living directly in a fashion like that, they WILL take their time, which is why when I must have somebody else do something that I can't (due to lack of proper equipment,bad situation or time) I pay for results, not time when I have projects done.

This was one of the many reason that I'm so glad that Steve D is such a stand up guy who loves his work and his profession to such an extent to take the time to help a guy like me out in finding a solution to fixing the Vintage Modern litterally hours after it had things go wrong. I can't think of another manufacturer that would support their customers like Steve and Marshall have. I still chuckle to myself when a tech in my area said he doesn't work on Marshalls because the support "sucks" and "parts are tough to get", its been a breeze.