1. The original ones are PA (Public Address ) speakers ... The 100 Volt Line is for rumnning Bery long lengtyh of speaker wires, using a PA amplifier (Not with a regular domestic amp).
I agree with sbg, they are probably not original.
Also agree with ajuvignesh
May I suggest the following:
Disconnect the wire going to the second speaker. It is a completely incorrect connection.
Using only 1 Speaker, Connect the wires from the speaker ONLY to the 2 terminals on the RIGHT Hand Extreme. lets Check 1 speaker first.
2. What are you using as your audio source ? Nothging is connected in the pic U have posted. Maybe you are using the FM Radio, but there is no antenna connected, so its unlikely that you will get a strong (or any significant) signal at all.
If you have a CD Player, please connect the DC Player's Left & Right Channel Outputs to the DVD Left & Right Inputs.
Do also post a pic of the Front panel with the amplifier switched on and attempting to play music.
3. When you say the sound is very weak, can you hear any music playing ?
Do revert with yr feedback
All the best.