Tuner IC MXL661 Schematic Diagram PDF
MXL661 Circuit Diagram PDF High-Performance Digital TV Receiver Circuit Diagram Frequently Used Samsung and TCL LED TV High-Definition Circuit Diagram View This schematic diagram is part of our IC series in which we will publish helpful circuit diagrams of Sony, Samsung, TCL, and LG in pictorial form and PDF format. In this, we will also explain the relevant circuit.
MXL661 Power supply details
This tuner IC has 24 pins. We will describe its input and output signals, voltage, and AGC here so that the concept becomes clear. Let’s talk about this circuit first. Its VDD is 3.3 volts. This voltage is applied to the pin numbers of the IC: pin 1, pin 15, pin 11, and pin 23. It generates these voltages. A regulator is installed on the 5-volt power supply line. This step-down IC, AZ1117, provides a fixed 3.3V to the circuit.
MXL661 VDD 1.8V
Another power supply goes to this IC; this is VDD 1.8V. I have observed that most technicians ignore it. If this supply is not present, the IC will be a plane raster, i.e., no image. This supply goes to pin number 12.4. This is also supplied to this pin by a step-down buck converter circuit. Remember that this voltage should be fixed and have an accurate value in the entire circuit.
MXL661 12C interface with system IC
This IC works with the 12C interface, i.e., clock data through the system IC. Its pin numbers 16 and 17 are connected to the system IC. They have 100-ohm resistors in series, which are connected to 3.3V to 1.5K resistors to keep them in the high state. My personal experience is that these resistors need a lot of attention. Often, one of these resistors increases its value.
MXL661 if output signal
IF output signal is output from pin numbers 9 and 10. Its destination is the system IC. This signal is connected to the system IC by installing two ceramic capacitors and two inductor coils and then two indicators. These parts filter the signal so that there is no noise in the image and a perfect result is obtained.
MXL661 RF signal in put
RF signal input This section of any tuner is very sensitive. This signal is applied to pin numbers 2 and 3 of this specific IC. Two ceramic capacitors are connected in series, and this connection goes from various inductor coils to the cable pin. All the parts here are very important. All of them together block unnecessary signals for the best visual result.
AGC auto gain control section
Auto gain control is an important section of every tuner. In this circuit, pin number 6 is for AGC. This pin is connected to the system IC by applying 100 ohms. Here, it is important to understand how this section works. You should understand it like this: the tuner is receiving 100 channels. The signal of each channel can be low or high. This section levels this signal.
Circuit Diagram PDF full preview
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Pin description
Pin 1 VDD_3P3A
Pin 2 LNA_INP
Pin 3 LNA_INN
Pin 4 VDD_1P8A
Pin 5 AGC_2
Pin 6 AGC_1
Pin 7 F_OUTP_2/GP
Pin 8 IF_OUTN_2/GPO_2Â
Pin 9 IF_OUTP_1
Pin 10 IF_OUTN_1
Pin 11 VDD_3P3B
Pin 12 VDD_1P8B
Pin 13 VDD_1P2
Pin 14 GND_DIG
Pin 15 VDD_IOÂ
Pin 16 SCLÂ
Pin 17 SDA
Pin 18 CLK_OUT
Pin 19 XTAL_N
Pin 20 XTAL_P
Pin 21 GND_XTAL
Pin 22 VDD_1P8C
Pin 23 RESET_N
Pin 24 AS
Conclusion
MXL661 Circuit Diagram PDF We have described this IC in detail in this article and have also published the circuit diagram. According to my knowledge, this tuner IC is used in TCL and Samsung main boards. It may be used in other models as well, but the circuit diagram will be the same. Sony LED TV Repair Center Lahore will continue to publish many more circuit diagrams, block diagrams, and schematic diagrams in a wide range for you.
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Shaukat Ali has over 30 years of experience in LED TV repair, specializing in chip-level repair work. He is an expert in Sony LED TVs, and also repairs other major brands like Samsung, TCL, Orient, and Haier. His expertise includes display panel faults, motherboard issues, power supply circuits, T-Con, and HDMI faults. Based in Lahore, he shares real-time fault finding cases from daily repair work to help technicians and learners with practical experience.
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