Marshall Lead 12 schematic needed.

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Well that is a surprise, T0-3 transistors. Looking at the schematic I first thought a simple brute force way of insuring the outputs live (no protection circuit) and then I thought maybe they went with as smaller case style. Today someone posted the gut shot of their amp, now we know.
 

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"Awful" ????????
It´s a KILLER amplifier, very well regarded and used by some of the best Guitar Players in the World, including ZZ Top.

I guess way back then Marshall had a truckload of transistors, bought all Factory surplus, got a HEAVY discount, whatever, because they used that particular pair (MJ2501/MJ3001) and which usually is somewhat expensive, *everywhere* , from 50/100W amplifiers (where they are justified) to 12W ones such as this one where they are way overkill.

Very expensive or hard to find today, I suggest you use plastic TIP142/147 instead, mounted on a conventional heatsink instead of that "spider" type one and, yes, mount T4 in contact with heatsink or plain epoxy it there.

Sound is killer and it deserves good speakers:

YouTube
 
Hey guys, I know it has been a while, 'cause i had a lot of tube stuff to fix and build and I decided to revive this topic because I got 3 small boxes full of various components from the 70's (leftovers form yugoslavian factory near my town) boxes have a lot of small transistors, but there are bigger ones like RCA7905, and because of my poor transistor/regulator/solid state knowledge I wanted to ask could they be used as power transistors in Lead 12 and what are they actually?
 

PRR

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...I got 3 small boxes full ... a lot of small transistors, but there are bigger ones like RCA7905, ... what are they actually?

We can't say. We can't see your boxes from here. "Like" something else says nothing (they could put anything in a transistor case).

What are the part numbers? Run them past Google, maybe you can find some data. (Yes, Russian letters can be hard to search.)
 
I had one of these for a while. They are neither terrible or awesome. They do have the ‘marshall’ sound in spades but lack bass and the treble is almost impossible to dial out.

Better with external speakers but as with many solid state amps, sounds ace to begin with but after a little while tends to be a bit tedious on the ears and the tweaking begins... found this too with a Yamaha g100 2x10 great reverb though. Compared to a more recent amp like the peavy envoy 110 which does a nice tubey thing or even a Marshall Valvestate 8040 (with a tube) it’s mane be “better” but probably no better than your favourite pedal of that flavour. Still historically for the time it may well have been the beez-neez.

Guess we may think that of a Kemper down the track too.

The best solid state (practice) amp that I have found so far is a Yamaha thr5. Probably not the best equivalent to the lead 12 but sets a standard none the less.

Recon that a 10” stereo version between 15-30 Watts would be a killer grab and go amp especially if it comes with a foot pedal / presets or app for a phone to load or save them.
 
We can't say. We can't see your boxes from here. "Like" something else says nothing (they could put anything in a transistor case).

What are the part numbers? Run them past Google, maybe you can find some data. (Yes, Russian letters can be hard to search.)


RIZ BC-239, RCA H8110, BC 108B Ei, Motorola SM-6509, AF124 ?, Motorola MRF607, BC 136 MRF, Ei BC287, RCA 8114, 2N 3819, BSJ 67, BSJ 63 ....
There are really many of them. And there is also 2x AD469, RCA 7905, RCA ER20 or 2D i am not sure because letters are pale...
 
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