Suddenly no juice

Finally, i go my 1973 Scamp 318 all stock running with minor change such as:
2176 edelbrock intake
1406 carburetor
Procomp HEI distributor with PC-91 Coil
Mini starter

Engine started at every turn
Then i decide to connect the tachometer. After installation, i cranked the ignition switch, then i hear something inside engine compartment. Then nothing work. It fail to turn. I lost all power to the car including headlight, horn, doom light, signal.etc everything is dead
Things i checked:
Battery at 12.6V
All fuses under steering column seem OK

Help,,,,,
scamp