marshall 6100 100 watt anniversary amp head

[Enzo]

Hi Edward.  I don't think you were a troll.  The reason an experienced tech like myself or others might question if you knew the pin numbers is that we always look first for the simplest explanation for something.  (That is known as "Occam's Razor")  So if someone counts pins the wrong direction, then what they think it pin 5 is really pin 4.  And all of a sudden, it makes sense to see 500v there.   Add to that that despite that it happened to you, finding +500 on the grid pins is EXTREMELY unusual, and hard to imagine a cause for.   SO we go out of our way to make sure it indeed is really what was going on.

Move forward to your explanation that you do know pin count, and then we have to start looking for ways it could happen.

We know from experience that an open trace from the bias to the grid will cause the tube to red plate and draw current, but we also know that will not likely cause +500 to be there.  A lack of -50, yes, but no way to expect +500 there.   I believe you that moving a resistor or replacing it or whatever made the problem go away, but also from experience, it SEEMS at least more likely that the resistor itself wasn;t the problem, but in the process of working with it, you also managed to move whatever was causing a short circuit and thus remove the problem.

SO hopefully that helps understand our reactions.   I am glad you got your amp working.

[EDWARDEFFECT1]

thanks Enzo! i always respect your comments on this site.sometime when i go to my sisters house in michigan to visit i would love to stop in to your shop and shoot the bull if it was possible it would be an honnor to meet you. i am sort of self taught and have been lucky to have a good friend that has 50 + years of television repair.he is pretty knowledgable with testing and troubleshooting ect.he went to alot of classes on tv repair thru the years.thanks for being such a good friend Big Jim!!..had to give him a plug also as he deserves it.

Enzo thanks for all the help you always give.you have a very good outlook on troubleshooting with a very methodical approach.love your humor also.also my many thanks to all of the people who have helped take their time to answer my questions. there are to many of you to be able to list.....thanks  to everyone that has helped!!...ed!!