where to get marshall 8080 schematic

[crang85]

where can i get a schematic for a marshall 8080 amp, or can someone tell me how to fix mine. the clean chanel has a rustly sound but the dist chanel works fine

[Ripper]

HI,
I fix amps all the time usually straight tube models but I've fixed a pile of these things too.  Most of the problems with the 8080 and the valvestate models in general are bad solder joints from overheating.  You should try resoldering the joints on the pots, the ics and any others that look bad.  In most cases that fixes them right up.  In some other extreme ones, I've had to replace a couple of the ic's that cooked.  If it's your amp consider building a computer cooling fan into the back of the chassis.  It's easy to do and eliminates the problem from happening in the future.  I hope this helps.  Take care
Ripper

[crang85]

thanks ill give that a shot

[Bagge]

I did find a pdf-file at one time, but I can't seem to find it online now. However I found this link:
http://www.mif.pg.gda.pl/homepages/tom/files/Valvestate.zip

It might be helpful. :?:

[crang85]

ive tried re soldering but it hasnt helped. how do i tell if one of the parts is busted. ive had a look and they all seem ok

[Prive]

Take a look at www.drtube.com in the marshall section there is lots of PDF's.

Saludos, Marcelo.

[PaulH]

Pre & Power schematics ...

http://www.mif.pg.gda.pl/homepages/tom/files/Valvestate.zip

[Ripper]

If you feel the solder connections are okay, then check ic's 1 to 4 they are usually the ones that cause the grief.  Also double check the solder joints on the tube socket.  They tend to go bad easily.  They can appear to be alright but always a good idea to redo those ones too.  If you are resoldering the joints on the channel and gain switches be careful, they don't like alot of heat and will melt.

If you plug your guitar into the effects return (which bypasses the preamp) does the sound clean up?

[crang85]

through the effects loop it runs fine so it must be the pre amp