Here's a schematic I traced of the Marshall handwired 20 watt, 2061X

[plexibreath]

Hey,

I've searched the internet far and wide for a schematic of the Marshall reissue Handwired 20 Watt Head, the 2061X. The 2022 is close but has quite a few things different, especially in the phase inverter and some values in the preamp.

So I just went ahead and traced my 2061X and entered it into my OrCAD schematic capture software and created a .pdf file. It documents much more detail than most schematics with voltage readings everywhere and wire color in places to make working on one of these easier. I'm not affiliated with Mercury Magnetics but I did list on the schematic which replacement transformer models they offer so anyone who wants to home brew this amp will find it useful.

I don't know if the forum still has a schematic repository, but if so maybe this should be archived there.

See attached.

John Kelley Brown
Kaliphoria Music

Attachment removed due to errors, further down the thread is fixed schematic.

[Enzo]

Wow, nice work.


I wrestled with posting this, I am not trying to upstage you, but here is the factory drawing for comparison.

I note your cathode resistor on the PI is 8.2. I assume that is a typo, as it is 8.2k. And the upper tone cap on the two channels is shown as 4n7 and 470p, while you have them the same. Maybe they are the same on your unit.

We still have the ampix - Home picture site associated with this board. I use it to post oversized files. the most recent forum upgrade increased the upload file size on thsi board, so I don't use ampix as often anymore. But you can start a gallery over there or add it to the general collection.

[plexibreath]

Thanks Enzo! I always appreciate having my work checked, it's easy to miss something. Too bad I couldn't find that schematic through any internet search I tried, would have saved me a lot of work.
As I get older my eyes aren't what they used to be, my amp does match the Marshall's schematic of 8.2K on the PI phase inverter. I have tweaked the amp in a couple places and thought I made the schematic the way it originally was, I remembered to take out the screen resistors I put in but forgot other things.
But I'm glad I did the schematic anyway, I like having the voltages on the schematic as well as some wire color codes to make it easier to find my way around the amp. I'll post a fixed version rev A1 when I get around to it.

Thanks again,
Kelley

[plexibreath]

Okay, attached is the fixed schematic. It's rev A1.

Kelley