Noisy Marshall Super Lead

[Terje79]

Hello,

I am looking to get into doing basic work on my amps, I've always taken them to techs and kind of want to get away from that. Is there a book or dvd something like that you can recommend?

Also, My first project is going to be a Marshall Super Lead 100w reissue that I picked up a while ago on craigslist. It seems to be noisy on the Channel 1 (Treble Channel), however channel 2 sounds good. I have tried a few different preamp tubes in the different slots and none of them seem to make a difference. Also, I continue to hear guitar signal through the amp even after I power it down. It may just be more noticeable on this amp than my others. I dont really know where to begin on this one? If anyone has suggestions or can point me in the right direction I would appreciate it.

[TweeDLX]

There are a lot of good books out there that cover everything about tube amps. I hear Kevin O'Connor's books are good. I have Tom Mitchell's "How To Service Your Own Tube Amp" book. I like it because it covers the basics-speaker wiring, components, tubes, some mods, etc. You can get it here: http://www.stewmac.com/shop/Books,_plans/Amps,_electronics/How_To_Service_Your_Own_Tube_Amp.html

Mike

[WaltC]

jack Darr's book is great (a little dated as to equipment, but *great* info)

Gerald Weber's books and DVDs are good

Dave Funks stuff on Fenders is terrific

and I also like Tino Zittola's books as well.

Kevin O's books are chock full of info but that's deep water there and get over your head quickly.

All (including Tom M's book too) can be had at:

www.tubesandmore.com (click on Books, DVD's & Software)

[deke99]

If your issue is just with the treble channel, then the portion of the circuit that is problematic is very isolated. The input signal goes from the input jack, to a 68K resistor, then to the grid of V1A. From there V1A is coupled to the bright volume pot, then it gets mixed with the normal channel from there. So there isn't a lot of circuitry. You may want to check the volume pot itself which could be noisy. Otherwise, I'd look at the wire(s) connecting the input jacks to the 68K resistor, then to the grid of V1A. Any noise infused at the input will get amplified by all of the gain stages.

If everything checks out there, then the issue could be either the treble bleed cap across the input and wiper of the volume pot, or the 470K/500pf RC combo that mixes the signal with the normal channel.

Best of luck, just be careful when working on an amp due to the potential lethal voltages present.