SERVICE - NEWS BULLETIN No. 94BE002
MODIFYING OF M48 AND M48EQ STEREO MODULES
INTO M48-2 AND M48EQ-2 MODULES.
The old stereo modules, M4, has 2 unbalanced stereo inputs (one stereo pair on each XLR-connector). The new electronic balanced stereo modules M48/M48EQ can be modified to work like the old M4 modules regarding to inputs using the SEL-button. The inputs on the modified M48/M48EQ modules will be unbalanced as the M4 inputs.
In order to get an unified modification of modules we recommend to use the following schematic and description. It will be in the interest of both users and serviceperson.
You desolder the orange/brown and blue/white cables from their original places on the PCB, and solder them around the S1 switch as shown. Then you make two new cables (grey and red) from the S1 to the positive part of the inputs on the PCB (Z1).
Remember only to use special spray to clean faders!