The protect mode setup provided to protect the speakers against burning due to the amp output short circuit. protecter activated means one or more channels of the O/Pamp is short circuited(defective) in your amplifire . First of all Remove the Power cable from the Amplifier and make sure no power connected to the Amp.
1.First step identify the faulty O/P Amp Channel---------
Inside the Amp you will see Five O/P Amp Sections (all are looking similar this is the common idea to locate the O/P Amps) there will be ten power transistors fitted on heatsink (2 transitors for each channel).some cases damaged transister are visible physicaly then easily you can identify the faulty channel(maybe cracked or blowned). There is no visible signs then you must do some tests with multimeter.You will find Five relays on the pcb( mostly square or rectangular ice cube relays) each relay have coil and N/O contacts built in and the terminals soldered to the pcb first you should identify the contact terminals (mostly it will be marked at the top side of the relay) otherwise a simple idea is , look on the pcb solder side trace the printed copper track going from the terminals of the relays you will see one is going to the speaker out socket this terminal called Sp O/P, other one going to the Amp O/P Transisters legs (some cases it pass through a coil of few turns) this terminal called Hot O/P . Do the same follow up and find the both terminals for the all the 5 channels.
Next step make sure you or not touching any live power (220v or 110v A.C) tracks or wires inside the Amplifire and you should keep this in your mind althrough the following tests
Take your multimeter select the D.C Voltage Range connect the Negative probe(Black) to the Metal Body of the Amp and put the positive probe (Red) apart safely. plug back the power cable to the Amp and power it from your wall socket then switch on the Amp. Turn the volume control knob to zero and select the input selector switch to Linein or Aux and remove the RCA Cable connected to that input socket. Now carefully touch the Hot O/P terminal of the relays with the positive probe and note down the voltage readings on a paer (Do this for all 5 relays one by one, values result may be + volt or -- volt or zero volt). After see the reading values we can find the faulty Amp section
1. The channels showing zero voltage are in good condition.
2. The channels showing + volt or -- volt ( may vary from 1 volt to 30 volt ) are faulty damaged Amp sections.
Now we located the faulty Amps then how to fix the faulty ones.
before going to do the next step switch off the Amp and remove the power cable from the wall socket. Check all active components one by one (transistors,diodes,zener diodes) and resisters capacitors in the faulty Amp section replace the faulty components by the same value new ones. carefully test the components twise. if you miss a small defect component or replace it in wrong way this single mistake will blow up your Amp again. After replaced the defective components do the relays Hot O/P terminals volt reading test process again. if all the readings are zero volt you have successfully repaired your amp still the reading showing some voltage means you must do the components checkup process again. If you do it slowly with full concentration surly you will fix your problem and your Amp will work back to enjoy the music .GOOD LUCK.
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