Due to the harsh environment, such as car vibration and serious dust, car audio is prone to failure. The car audio internal power amplifier integrated circuit block works in a higher voltage, high current state, and the failure rate is higher. In fact, a large part of the power amplifier integrated circuit block can be replaced by the easy-to-buy TA7240AP or domestic D7240P power amplifier integrated circuit block. The following describes three service replacement examples for reference.
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Example 1 A Tianbao CTR-2020TC car audio is silent when it is received and played.
During the overhaul, using the interference method and testing the voltage of each pin of the integrated circuit block, it is easy to judge that the faulty part is the fault of the power amplifier block UPC1185H, and the domestic D7240P power amplifier integrated circuit block is replaced. Both UPC1185H and D7240P are 12-pin single-in-line plastic package structures. The circuit functions of the two are basically similar, but the pin ordering of the same function is different. Therefore, the replacement should be properly changed. The corresponding pins of the same function are shown in the table. 1.
Table 1 UPC1185H and D7240P pin correspondence table
UPC1185H pin | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
Working voltage / V | 0 | 7 | 13 | 2 | 12 | 0 | 0 | 12 | 14 | 13 | 7 | 0 |
D7240P corresponding pin | 4 | 8 | 9 | 3 | 5 | 6 | 1 | 2 | 10 | 11 | 12 | 7 |
In addition, such as Kaige 4B20 car audio HA1377 power amplifier integrated circuit block damage, can also be replaced by D7240P according to Table 2; such as Lida JM-700 automatic rewind car audio LA4445 power amplifier integrated circuit block damage, according to Table 3, Replace with D7240P.
AN7178 pin | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
HA1377 pin | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
D7240P corresponding pin | 2 | 1 | 3 | 4 | 6 | 5 | 8 | 9 | 7 | 10 | 11 | 12 |
LA4445 pin | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
D7240P corresponding pin | 1 | 2 | 4 | 3 | 5 | 6 | 9 | 8 | 10 | 12 | 11 | 7 |
M51102L pin | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
Working voltage / V | 13.6 | 6.9 | 4.2 | 1.2 | 0 | 0 | 0 | 0 | 1.2 | 7 | 13.6 | 13.9 |
D720P corresponding pin | 11 | 12 | 3 | 2 | 1 | 7 | 4 | 6 | 5 | 8 | 9 | 10 |
Table 2 AN7178, HA1377 and D7240P pin correspondence table
Table 3 LA4445 and D7240P pin correspondence table
Example 3 A Sanyo FT220M-2 car audio is silent when it is received and played.
After inspection, it was found that the M51102L power amplifier integrated circuit block was damaged and replaced with D7240P. The corresponding relationship between the two pins is shown in Table 4.
The specific substitution method is: first cut the M51102L pins and the printed circuit board, solder the damaged M51102L, solder the D7240P, connect with the soft wire according to Table 4, and finally at the D7240P input terminals 1, 6 pins and A 1μF/10V electrolytic capacitor can be connected in series between the previous stage (potentiometers VR 1 -E, VR 1 -D).
Table 4 M51102L and D7240P pin correspondence table
If the above examples occur after self-excitation, a 500-1000pF capacitor can be connected between the 1-2 and 5-6 pins of the D7240P to prevent oscillation and eliminate self-excitation.
The specific substitution method is: first cut the circuit of the printed circuit board 1-12 pin, solder the UPC1185H, and then insert the D7240P into the printed circuit board. According to Table 1, the pin of the D7240P and the pin of the original UPC1185H are soldered. Corresponding to the welding, carefully check that there is no short circuit and then turn on the power to work.
Example 2 A Kaige 4B25 car audio is silent when it is received and played.
After inspection, it was found that the AN7178 power amplifier integrated circuit block of the machine has been damaged. It can be processed according to Table 2 according to Table 2. However, it is not necessary to cut the printed circuit board, and only need to be slightly shaped (such as 5 and 6 pins are reversed, and the cross is made into a cross. Cross shape, but pay attention to insulation).
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