marshall jcm 800 layout/schematic

[TWANG]

both would be great.
trying to find threads with info but so far.. too many posts.. can't come up with anything.
May have blown PT.. so specs? replacements.
2203 model is later.. two filter cap model.. pcb board.. board mounted pots..
like this one.
http://i9.photobucket.com/albums/a86/bl ... C03990.jpg" onclick="window.open(this.href);return false;

[TWANGGG]

Welcome TWANG!

Though this could get confusing...lol!

[BRMSlash]

I assume those photos are actually your amp. So am I correct in that you are looking for the PT specs for a JCM800 Mk2 Master Model 100W Lead 2203?

[TWANG]

here are pics of my actual amp.. and yes that seems to be the designation.
I've done many amps, scratch builds, etc., bassman, traynor, peavey, but never 100watts
or a marshall.. so it's still very much new to me.
I get nothing on the filaments. All meter tests of the PT are totally screwy.
No tubes light up.
I did a cap job on it, because I wanted to pull the board and see what's what for how it's wired, etc.,
and I can't find any shorts or tiny wires or bad solder joints or traces, etc.
Most of what I find has four filter caps.. and some other value changes, etc. so I'd really like to see
THIS amps info in layout and schematic.
These are as is right now. New JJ and Mallory caps, one slightly large Sozo. and some resistor and cap
value changes for revoicing, etc. But nothing major there.. as I say, it was to get a look at the board, make the changes that I knew I'd want.
but then

[TWANG]

Welcome TWANG!

Though this could get confusing...lol!

You must have your compressor on all the time!


ps
here's where I got the twang idea...
http://www.youtube.com/watch?v=fLkTzcUby6Q" onclick="window.open(this.href);return false;

[BRMSlash]

I'm not particularly experienced in PT's, so can't really give advice. However you can get 2203 schematics from here: http://www.drtube.com/library/schematic ... mas#JCM800" onclick="window.open(this.href);return false;

As far as layouts go Ceriatone have one, but it's not for a circuit board type, but should be similar:
http://ceriatone.com/images/layoutPic/m ... iatone.jpg" onclick="window.open(this.href);return false;

I guess you've checked the fuses for integrity? Are they the correct type? If you just want to replace the PT, you can probably read the model number off your current PT, then try and find an after market replacement that gives the same voltages and taps. For example ClassicTone, MojoTone, Mercury Magnetics, Hammond etc have replacement PT's.

If the tube filaments aren't lighting up at all, then I guess the PT is stuffed or maybe there's a short or open circuit somewhere on the heater wiring or at the tubes. Maybe the B+ tapping is doing something funny to the PT?

[TWANG]

I will check the fuses again.. damn and I just pulled the pt, too.
It did come with a blown fuse but I replaced it. but then.. I didn't recheck it! doh!

I have the ceriatone and I got some other 2203 schematics, too.. they seem to vary but I'm getting the idea.
thanks, I'll go forth!

*they should make it a law that all schematics are printable.
esp. important for people who can't figure out how to shrink stuff.