[Office Partner Information Center] I believe that the average user has used the fax machine, but once the fax machine has a problem, most people will not handle it, especially those fax machines with English interface, which will bring more maintenance difficulties to the user. Let's take a look at five ways to repair it yourself!
Analysis and maintenance: According to the analysis of the fault phenomenon, the machine can automatically receive the fax, indicating that the communication part circuit and the other device are fault-free. Therefore, first check if the "START" button is normal and the check result is normal.
Then power on for self-test, press the “FUNCTION†function key → number “7†key → “TEL/DIAL†key (4 times) → “*†key, and the machine enters the device test mode. Then press the number “3†button → “START†button to start it automatically, and automatically print out the RAM data and function parameter table. Look closely at the function parameter table and find that its parameter values ​​have all been initialized to the initial setting state, and the fax machine has been automatically reset.
Therefore, it is judged that the power supply circuit of the equipment in the machine is faulty, and the power supply circuit mainly includes components such as a POW1 battery component, a triode Q7, a Q8, a reset switch SW2, and the like. This circuit is mainly used for uninterrupted power supply to the RAM to ensure that its data parameters and clock signals are not lost due to power failure.
According to the analysis, first check the voltage of the POW1 battery pack with a multimeter, and the inspection result is normal. Then check whether the SW2 switch position is normal and the contact is good. Under normal circumstances, the SW2 switch is located in the “ON†block. Using the multimeter "R × 1" block along the SW2 soldering piece to test the continuity of the printed circuit board, the test found that the "ON" end of the soldering piece due to long-term in a humid environment and mold. Replace it, reset the function value, and troubleshoot.
Symptom 2: A Ricoh FAX188 fax machine, the copy is all black.
Analysis and maintenance: According to the fault phenomenon, first check whether the LED array in the CIS device is lit, and the LED array test function can be used for self-test. Press: "FUNCTTON" function key → number "6" key → number "1" key → number "9" key (2 times) → number "5" key → "YES" key. Then press the number “1†key → number “0†key → “YES†key → number “0†key → “START†key, and the LED array should be lit.
However, the LED array was not illuminated. Then check if there is +24V voltage and whether the GLED is low. Use a multimeter to detect the 9th and 10th pins of the connection device CN6 on the motherboard, and find that there is a +24V voltage output, while the 9-pin GLED terminal is always at a high level.
Carefully check the 1st and 16th pins of the driver QA2R and find that the first pin can transition from low level to high level at startup, while pin 16 remains unchanged. Therefore, it is judged that the drive is damaged. After replacing the TD62003, the fault is eliminated.
Symptom 3: A Ricoh FAX188 fax machine, the copy is too dark, and some places are all black.
Analysis and overhaul: According to the working principle of the fax machine, the above phenomenon occurs when the light emitted by the LED array is weak or the device in the analog image processing circuit is damaged.
According to the fault phenomenon, the LED array test is first performed, and the LED array is normally illuminated. Then check the analog image processing circuit. The analog image processing circuit of this type of fax machine is mainly composed of an operational amplifier TL082 analog switch, HC4053 and peripheral circuits.
The TL082 is used to amplify the video signal from the CIS device. The HC4053 automatically adjusts the gain of the amplifier by selecting the analog switch in the device. If the analog switch is damaged, the video signal output will be too high, causing the copy copy to be blurred. After inspection, the HC4053 was found to be damaged. After replacing the device, the fault was eliminated.
Symptom 4: A SUNTECH STFAX188 fax machine, according to the user's reaction, the machine often has the following phenomena:
1. Press the “FINE†button for about 5 seconds. When the “START†button is pressed after 5 beeps, the self-test is not performed.
2. Press the “START†button after booting to not start.
3. When sending and receiving faxes, press the “START†button, the called user can not hear the signal (9600bps), and does not take paper; when sending, after the user sends a signal (9600bps), press the “START†button and no response.
Analysis and overhaul: Since there are no ready-made drawings and more problems, this will bring certain difficulties to the maintenance work. Based on past maintenance experience, we can start from the following three aspects:
1. Check the assembly quality of the whole machine, whether there is open circuit of the plug-in, poor contact, and weak soldering of components.
2. Observe whether the components in the machine are overheated, smoked or burnt.
3. Check if the DC output voltage is normal.
After careful inspection, it was found that the circuit board was welded firmly, reliably, and the assembly quality was good, and there were no burnt components. Check the working status of the power supply in the machine, and calculate the power supply requirements according to the supply voltage requirements of the known components. Such as: 74 series TTL circuit chip needs to supply +5V voltage.
Tested with a multimeter, it was found that there are ±5V, -12V, ±24V supply voltages on the motherboard, but no +12V supply voltage. When the power is turned off, the ground resistance R11 of the +12V voltage terminal of the main board is measured to be 90Ω. Obviously, there is no +12V supply voltage due to the short circuit. Remove the boot cover and directly measure the DC voltage output of the switching power supply with a multimeter. There is still no +12V supply voltage.
After careful inspection, it was found that the printed circuit board copper foil on the filter capacitor C24 (2200uF/16V) was broken, so that the +12V voltage was open and there was no DC output voltage. At the same time, the capacitor C24 is soldered to the two-pin solder joint. After the solder is melted, the C24 capacitor is closely attached to the printed circuit board. After soldering, the inverter is restarted and the fault is eliminated.
Symptom 5: The copying of a copy of an OF-17 fax machine is superimposed and the cutting distance is short.
Analysis and overhaul: Remove the cover and carefully check that the root of the first driven axle of the transmission part of the pulse motor assembly is broken due to long-term wear. Since this type of facsimile machine is manufactured in Japan, accessories such as pulse motor components are difficult to purchase on the market and are expensive.
According to the characteristics of the transmission part of the pulse motor assembly mainly composed of plastic parts. Adhesive bonding and inserting steel studs at the break to increase strength. After the adhesive is bonded for 24 hours, it is fully solidified, reinstalled and turned on, and the fault is eliminated. After more than half a year, the effect has been very good.
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