JBL BP1200.I MODIFICATION POWER SUPPLY AND POWER AMP CIRCUIT
JBL BP1200.1
MODIFICATION POWER SUPPLY AND POWER AMP CIRCUIT
Muting during intense bass passages (MODIFICATION)
Under certain large
signal conditions during intense bass passages, the unit will go into
protection. These amplifiers are behaving as designed. As the unit is driven
into hard clipping, the protection circuit found in BP Series amps was
engineered to protect your loudspeakers from being destroyed by a severely
clipped output signal. This can be remedied easily by turning the volume down
somewhat on your music source.
In the event you receive a BP series amplifier with the complaint: “Under a large signal input, with music that is composed of high-level bass, the amplifier mutes for 2-3 seconds, and then returns to normal operation”, the following modification will effectively increase the amount of clipping that is allowed to occur before the protection circuit engages by increasing the threshold at which the amplifier mutes - for the benefit of customers who use the amps in SPL competition, or for customers who insist on driving the amplifiers into this potentially hazardous zone.
1) Turn the amplifier upside-down and remove the Phillips screws holding the bottom cover on.
2) Locate and change R510 from 47K to 4.7K ohms 1/5W (JBL part# RE212047200).
3) Locate and change R511 from 22K to 2.2K ohms 1/4W (JBL part# QAF0450-222).
4) If it is not already present, add new part - 4.7uf 50v electrolytic capacitor (JLB part# EC070114760) in parallel with R511. Polarity: The negative side of the capacitor must be connected to the junction of R510/R511, which can be discovered with an ohmmeter.
In the event you receive a BP series amplifier with the complaint: “Under a large signal input, with music that is composed of high-level bass, the amplifier mutes for 2-3 seconds, and then returns to normal operation”, the following modification will effectively increase the amount of clipping that is allowed to occur before the protection circuit engages by increasing the threshold at which the amplifier mutes - for the benefit of customers who use the amps in SPL competition, or for customers who insist on driving the amplifiers into this potentially hazardous zone.
1) Turn the amplifier upside-down and remove the Phillips screws holding the bottom cover on.
2) Locate and change R510 from 47K to 4.7K ohms 1/5W (JBL part# RE212047200).
3) Locate and change R511 from 22K to 2.2K ohms 1/4W (JBL part# QAF0450-222).
4) If it is not already present, add new part - 4.7uf 50v electrolytic capacitor (JLB part# EC070114760) in parallel with R511. Polarity: The negative side of the capacitor must be connected to the junction of R510/R511, which can be discovered with an ohmmeter.
NOTE: Using the
correct soldering techniques, you should be able to make these changes from the
top of the PCB without its removal.
5) Replace bottom cover; test amplifier
5) Replace bottom cover; test amplifier
Controls and Connections
1. It allows left and right input channels to
be connected to the amplifier using RCA plugs.
2. Speaker Output Connector - Connect speaker wiring to these connectors..
3. Fuse - 40Ax3 Amp ATC type Fuses.
4. Power Connection for 12V+, GND and REM connections for power wires.
2. Speaker Output Connector - Connect speaker wiring to these connectors..
3. Fuse - 40Ax3 Amp ATC type Fuses.
4. Power Connection for 12V+, GND and REM connections for power wires.
Mounting the Amplifier
The amplifiers can be mounted in virtually any location inside the vehicle. However, make sure to keep the amplifier away from heater vents or ducts.
1. At the chosen site, use the amplifier as a mounting template and mark the locations of the four mounting holes.
2. Drill a small pilot hole at each marked location.
3. Mount the amplifier and securely tighten the mounting screws.
The amplifiers can be mounted in virtually any location inside the vehicle. However, make sure to keep the amplifier away from heater vents or ducts.
1. At the chosen site, use the amplifier as a mounting template and mark the locations of the four mounting holes.
2. Drill a small pilot hole at each marked location.
3. Mount the amplifier and securely tighten the mounting screws.
5. Input-Level Control - Adjusts input
sensitivity for pre-amp level and speaker level inputs.
6. The electronic crossover is a 12dB/oct. Low pass filter which can be Set at any frequency between 32Hz and 320Hz.
7. The bass boost control will provide up to 6dB of boost at 50Hz.
8.It allows left and righ input channels such as high level speaker output signals to be the amplifier.
6. The electronic crossover is a 12dB/oct. Low pass filter which can be Set at any frequency between 32Hz and 320Hz.
7. The bass boost control will provide up to 6dB of boost at 50Hz.
8.It allows left and righ input channels such as high level speaker output signals to be the amplifier.
INVERTER POWER SUPPLY CIRCUIT
USING TL494 - IR3205
PRE AMP AND POWER AMP CIRCUIT
USING IRF9640 -IRF640
