Mk II

[Racing]

Hi there.
First post.

Anyways. After having fooled around with various Mesas over the yrs i just ended up with this,what i gather,early Mk II.

It is a head in black toolex that carries HG written on the side of the chassis and in turn carries 3905 for serial.

Issue(s) is that this one´s sure been tampered with. Upside from that respect is that i do a lot of work on guitar toobers as a whole..
That said it has be extensively modded with some funky RS232/D-sub 9 out back that runs back and forth to all in all three relays i believe. All good i guess,and as i see it first thing´s first and that comes down to ripping all that non stock pts out of there.

The PCB for the GE lacks two of its transistors though. From schematic i´ve concluded we´re talking MPS U95 and in turn MPS 3703.
Now,that transistors gets faded out and replaced by equivalents over the yrs is normal in my book why my first question is if anyone knows what to replace with?
Have checked online for datasheet asf and that basically comes down to..you guessed it,MPS U95.
I ask as i suppose i´m not the first nor the last one in need of new ones

I´ll shoot some pics asap. FWIW.

As such,would anyone wager a guess for age of this unit? Is it a Mk II (a) or is it a Mk IIb?
From reading up over the forum i can attest to that it carries what seems like sort of a loop at least. Up front on the preamp PCB there is what strikes me as an oversized old BC or AS series transistor,and i presume that is some kind of old opto?

 

[igfraso]

It is a Mk II-A, most probably produced in late July or early August 1979.

 

[Racing]

Thank you...

 

[igfraso]

There is no Mark IIA manual in Mesa Boogie's webpage.
FWIW, find below recommended setting:

1) Good basic setting I (manual quick start setting)
Vol1: 4
Treb: 9
Bass: 3
Mid: 3
Mast1: 2
LD: 7
LM: 1
Pres: 7
Rev: 4
EQ: out

2) Good basic setting II (manual alternative setting)
Vol1: 6
Treb: 7
Bass: 4
Mid: 0
Mast1: 2
LD: 8
LM: 1
Pres: 7
Rev: 4
EQ: out

 

[Snottyboy]

Congratulations on your Mark II!

 

[Racing]

Thanx!!

That said....
Right.

(Yep. There´s that funky D-sub)

(Yeah. A few silicon items missin)

 

[McBarry]

Jesus..

WTF is going on with those F&T caps??

Sorry to be disrespectful, but ****... I'd be tidying them and returning the filter board to standard configuration. I know F&T caps fit there easily 'cause I use 'em all the time..

That RS232 looks funky.. I'd be a bit wary of it crossing the HV and AC lines tho'... And especially as it terminates next to the mains supply stuff.. not much margin for error there....

Re IIA or IIB - i doesn't have the variable bias pot the IIA had - doesn't mean it didn't start life without one.. just none there now...
What's the serial number ?
What's the preamp board model ie - RP"xyz".
Regs, Dave

 

[Zlofengir]

Wow... Whoever did that needs to be horse whipped. Sacrilege!

 

[Racing]

Thanx.
Yeah,that´s my general idea.

Amp as a whole needs to be cleaned up in a major way. Cab is all in one piece but lacks the Boogie emblem.

Have googled for pics of stockers but have come up half empty handed,thinking that might be a good way of gettin a picture of how it´s SUPPOSED to look.
The groundlift asf are not supposed to be there around these pts. Our mains can be turned either way so..

 

[igfraso]

I apologize in advance if you don't like my comment but, if I were you, I would send it to Petaluma and ask Mike Bendinelli (great guy!) to put your II-A back to original specs.

 

[Racing]

I hear ya.
Point is that freight alone would be a killer though as i live approx 10 000km+ out and second of all,i do this on a daily basis (work on toobers that is). Hence i´m no stranger to what we´re up against here.

Just need to muster the time needed,which OTH is an issue these days.