Marshall MG30FX

[mozwell]

Dear fellow MEF people
By chance, does anyone have a schematic or service manual for Marshall MG30FX ? (not the DFX or CFX units)
A friend has one, so just in case he gets an issue with it down the track, and i get asked to fix it, thought i would ask the kind people here for the info

Yes i know its solid state with a power amp IC, and i coudl probably nut it out without a schematic, but if it ends up broken i would rather try to fix it & keep it out of landfill if i can, and a schematic will help with that.

Cheers Moz

[Jazz P Bass]

I don't know why but the whole MG FX series of schematics is not available online.

I seem to recall one of the 'CD' amps being close.

[Drewline]

Here's what I have:

MG15_30FX.pdf

[Jazz P Bass]

WooHoo.
Thankyou, Drewline.

[Drewline]

Anytime!

[mozwell]

Thanks for the schematic
My friends amp had developed a hum in the output, so i took it apart, it was the MG30CFX, and the sch appeared to match the insides of this amp.
You have to unscrew the rear panel & then the top 4 screws, and there are also 3 screws inside securing the face plate to the inside of the front panel

I checked the AC & DC voltages of the power supplies & all looked ok, but with no input connected & speaker disconnected i had about 0.2VAC ripple on the main DC supplies for the power amp. I thought for an "idling" condition, this maybe a bit high.
As something to try, and as i had them on hand, i added in parallel to the 2200u 25V caps in the power supply, a 4700u 35V to each side.

The hum has gone, and as an interesting point, my friends says the amp "seems" louder (more headroom) and the sound is more "marshall"
The power supply ripple went down to about 50mVAC after caps were added, and i know 0.2V extra on a power supply will not really give any more power output, but i just thought what my friend heard was interesting enough to report back here with

[Drewline]

This is a great forum where I received help whenever I have needed it & it is always my pleasure to share whatever I can with my fellow members.

[alvacesar]

Hello , do you have MG100FX diagram?

[Enzo]

Hi alvacesar, and welcome to the forum.

May I suggest you start a new thread for your request, you will get better response with a thread for your amp model than you will here at the end of a dead thread about a different model.

[Jazz P Bass]

As far as I know, the MG100FX schematic is not available on the net.

[Drewline]

Sorry but I do not have it.