Marshall MS-2 Micro Amp

minnow · Post by **minnow** » 18 Apr 2011, 13:54

Well, here's something for fun:

: MS_2 schematic.png (11.58 KiB) Viewed 3651 times

This is where I stumbled upon it: http://guitar-dreamer.blogspot.com/2010 ... micro.html

MS2:

: MS-MS2.jpg (16.59 KiB) Viewed 3650 times

MS4:

: MS 4.jpg (27.67 KiB) Viewed 3650 times

Hides-His-Eyes · Post by **Hides-His-Eyes** » 18 Apr 2011, 14:09

I really am impressed with the MS-4. Does the job real well.

minnow · Post by **minnow** » 18 Apr 2011, 14:54

Hides-His-Eyes wrote:I really am impressed with the MS-4. Does the job real well.

I am considering to get one! Which explains the schematic discovery.
Anyway, would you think lining up the guitar > fx pedals > MS-4 to be a good idea?

Hides-His-Eyes · Post by **Hides-His-Eyes** » 18 Apr 2011, 16:10

Don't feed it too much bass or expect fender cleans but yeah, it works fine with pedals.

BIGSMITTY · Post by **BIGSMITTY** » 21 Apr 2011, 01:42

Any mods?

himister · Post by **himister** » 21 Apr 2011, 01:52

I've just looked in my MS2 folder...

I don't know where I've found this and since I don't see any warnings on the drawing, here it is. Hope the creator of the schem want mind!
Cheers

RnFR · Post by **RnFR** » 21 Apr 2011, 04:09

i don't think those Si diodes are doing anything. the Ge's are going to clip them at a lower Vf.

pastapal · Post by **pastapal** » 22 Sep 2013, 03:00

Hey guys, long time lurker...

I recently dug my old ms-2 out to try the headphone out/speaker out mod and ran until another issue before it would work properly. In the mist of the operation I also replaced the input jack and found that when I did try to use the amp (even with out the mod) the level was exceptionally low. No where near how I remembered. Further investigation found this issue.

figuring this is probably the problem I plan on replacing it.. I just have no idea what it is( and whether this is truly the real problem, gotta start somewhere though) thoughts, ladies and gents? Thank you:)

tip142 · Post by **tip142** » 22 Sep 2013, 04:05

Well,it's probably 99% a diode like a 1n4007.
Take care how is oriented,(notice that little circular dot pointing to down?)before desoldering.

tip142 · Post by **tip142** » 02 Oct 2013, 19:30

Is there anybody out there,ther,the,th.................?

teecee4 · Post by **teecee4** » 27 Dec 2013, 19:37

The destroyed item is a 1n4001 diode -- see the schematic above, it is on the lower left.

Most like cause would be a power surge, since the only purpose of that is to absorb reverse polarity to stop taking out everything.

it should run without it. Make sure you are using the right power supply. It should be 9 Volt at around 500 to 600 ma, though it will probably work with a 12V supply. The center pin is probably positive, but check to see if it is marked.

ksandbergfl · Post by **ksandbergfl** » 01 Apr 2016, 23:42

BIGSMITTY wrote:Any mods?

This won't be news to most of you, but you can use the headphone jack as an external speaker connection. You just need to short out the shunt resistor (R11) that limits the signal going to the headphone jack. Alternatively, you can replace R11 with a 1W potentiometer, so that you can maintain that "maxed out" sound but at a lower volume.

I stuck an old 12" hifi speaker into a Radio Shack sub woofer cabinet, and I couldn't be happier.... the MS-2 "mellows" out with the bigger speaker, not so much trebly/tinny but plenty of low-end. With a drop-tuned guitar, it really snarls. With 1W of output, it is loud enough to make the wife/significant other yell "turn that down!" from across the house.

I posted a short video here: