Mesa Boogie Mark 2

[ikemhla]

Hi All,

I am new to this forum.

I recently picked up a Bargain Boogie 2 at an auction.
I believe the serial number is as follows:

XPHRG TR1009 08/03/79

This is written on the chassis with Black Marker pen.

The pre amp is missing the relay for the overdrive.

1) Does anyone have details of what type and voltage the relay works on.
2) Does anyone have a Pre Amp layout of this Amp as I need to get it back to good working order.

The Amp seems to have gone through many inexperienced hands and the overdrive and Reverb sections do not work.
There are some components missing.

The Boogie 2 schematic I downloaded has many differences to what is on the amp.

There is no value for the input capacitor to V1A.

V3 A and V3 B seem to be reversed functionally.
The schematic shows V3A getting input from V1B via pin 2.
On the amp it is V3b pin7 which is the input from V1B.
Pin 2 V3A is connected to the reveb circuit.

Surprisingly enough, the Amp still works and is a very powerful Beast played through my Strat.

Any help will be very much appreciated.


Regards

Ike

PS corrected error

 

[mark2boogie]

Ike,

--- recently picked up a Bargain Boogie 2 at an auction.

Lucky Man you are... :wink:

Have a look to my MKIIA thread, as it may help you, maybe :

http://forum.grailtone.com/viewtopic.php?f=27&t=54614&start=45

--- 1) Does anyone have details of what type and voltage the relay works on.

The relay is a standard size and a 5VDC coil is convenient. Choose it from the best quality you can (low resistance golden or platinium contacts if available) and do not be surprised if you experiences remaining (sometimes big) "Kloks" when switching from lead to clean and vice-versa while playing : that's normal. A DPDT (2RT) relay is required.

--- 2) Does anyone have a Pre Amp layout of this Amp as I need to get it back to good working order.

Sorry I don't have that (maybe someone else ?), but it is quite easy to trace it (with patience, a DMM and a magnifier) and compare with the original schem. With the exception of some simple GND and heater circuits located near the PWR Xfo, there is no traces under the PCB.

--- The Amp seems to have gone through many inexperienced hands and the overdrive and Reverb sections do not work.
There are some components missing.

Post a picture as detailed as possible so we will be able to see l'étendue des dégâts.

--- The Boogie 2 schematic I downloaded has many differences to what is on the amp.

This is possible and maybe normal : the IIA went on several changes during production, probably as far as each amp slightly different from the previous and following one...

--- There is no value for the input capacitor to V1A.

On my MKIIA it was a 0µ39 / 50V, probably tantal. My suggestion : remove all the components tied to V1A grid and only leave a 1M grid to GND resistor and a 10K input to grid serial resistor. You will have a crisper, cleaner tone.

--- V3 A and V3 B seem to be reversed functionally.
The schematic shows V3A getting input from V1B via pin 2.
On the amp it is V3b pin7 which is the input from V1B.
Pin 2 V3A is connected to the reveb circuit.

That's the same on my MKIIA, and original. When it comes to differences...

--- Surprisingly enough, the Amp still works and is a very powerful Beast played through my Strat.

The IIA is underrated, clearly. When properly reworked, it's a premium amplifier. You (We) are lucky, I said it !

I hope that my MKIIA thread will give you some hints for your amp.

A+!