MA50H missing parts, still works! Yikes!

[Marshaleck]

Refurbished MA50H has missing components on the PCB.
Namely R13, R162, R163, and C8.
They are shown on the schematic, but are not on the PCB.
The amp works, but keeps blowing V2 after about 5 minutes of playing on the
"overdrive" channel. It also still makes sound on the "overdrive" channel with the volume all the way off and the gain/crunch knobs full on. Clean channel works fine.
I have the schematic, I am wanting to know if there are any revisions, I find only the one schematic available.
I am finding this to be quite funny to be missing all these parts and still work, it even sounds pretty good!
For a few minutes anyway. Your comments, remarks ,
suggestions, and experiences are welcome!

 

[Far Rider]

Welcome to the forum. Where did you get this unit from? Can you return it?

 

[Marshaleck]

I just wanted to find out if anyone knew first hand whether some and not all of the components need to be there because of revisions. I could find just one version of the schematic.

 

[iron broadsword]

Sounds like somebody started to modify it and stopped halfway, or possibly just did that thinking they knew what they were doing but really not so much...

So first - where'd you get it from? And second: You should really just restore it to stock if you're good at this stuff or take it to a tech before putting more money out on tubes. Be CAREFUL of high voltages though, find out how to stay safe in an amp if you don't know already.

 

[washburn 1]

Hi Marshaleck
I`m new to the forum and have just seen your post. I bought an MA 50h last year second- hand. I had cause to `phone Marshall and speak to a tech` and while on the phone to him I asked if he knew what mods were done to revoice the amp. Those components plus others were either removed or replaced. Sorry I cant give you a list now... too long ago. Mine works fine, sorry that yours doesn`t seem to . Just thought you might like to knoe of what I learned. All the best, Kev.

 

[Marshaleck]

Sorry, I should have posted this elsewhere! I was pressed for time. Yeah, that's it, pressed for time.
This amp is easy to work on, one PCB. Very easy to do tone mods. I'm just waiting for the 10M resistors in the mail.
Had the rest on hand. A total of six missing components, BTW. It just happened to leave a signal path so it still worked good enough to get out the door.

 

[Ken]

MA50. The PCB is for the 100 watt amp; they don't make a dedicated board for the 50's to save money. My DSL 50 is the same: lots of "missing parts"!

Ken

 

[Marshaleck]

I was able to check a MA100C PCB in hand and all of the parts are there. The only difference between them is the plug for the Crate BV120 style lights.


There's nothing missing from my DSL50!

 

[Marshaleck]

Just to put a close on this, the amp was missing C8, C110, C117, R13, R162 and R163. All installed now.
Also installed a lighted red power switch. Using Marshall white label 00055 for initial test. Ask me why.
This amp is incredibly easy to work on (and/or mod)!



"I own a few amps, can't say I favor one over another, they're like my kids, I know what they are capable of."

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