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qeyservice manual download site
qeyservice manual download site
CPU normal work, except power powered outside, its initial of end 52 feet (INH) must heightening level, 55, and 56 feet internal circuit and the add-ins 75kHz Crystal vibration XT, and C84, and C85 composition of clock circuit oscillation normal, reset end 48 feet by low variable high of reset pulse and the CPU internal circuit and the program normal, only all meet above work conditions, CPU to normal work.qeyservice manual download site
Thus, the specific cause of failure of the machine does not work more, but they boil down mainly supply disorder (low voltage or 0V) and CPU both normal operating conditions are not met. Testing CPU52, 36 and 53 feet, 3839 pin voltage is 0V, can confirm that the failure is caused by CPU and power supply voltage. Along the power Jack DCJACK, R45, Q21, R46, Q20, then, plug-A11 and A12 terminals (ground) terminals in order to troubleshoot, find connector A11 pin wire broken from the bottom, cause the CPU without power. Welding system A11 attachment test again, the machine working, and troubleshooting.qeyservice manual download site
qeyservice manual download site
Discussion: 1. Printed circuit board connection plug-in after several rounds of folding, can easily lead to line breaking, fault focus is circuit breaker part. In addition, when the CPU supply voltage measured at the low end, first check the power supply filter capacitors C62,C63, C89, C90, there is no breakdown and leakage; 2. This machine uses the group power supply, certain parts when the circuit when power is lost, according to the analysis of sequence lookup, such as led and LCD display to normal, but when speakers and headphones are silent, we should check for open circuit, R48, Q24, failure. Power control (Q20-8550, 9012 substitution available) and other circuits, nearly all 9000 series transistors are used, are characteristic parameters and domestic replacement pipes are shown in table 1, reference for overhaul; 3. The machine has a special "crash" failures, mainly shows no display, press the power key will not power on; or screen display, press the operation key is no effect or turn on properly after listening to radio programs, but you cannot shutdown aberration. General reason is that when you replace the batteries or external power, a mistake; or suffered external strong radio interference (such as lightning), resulting in CPU chips inside the machine program into "endless loop" status, no acceptable external manipulation directives. Solution is very simple, has a lower part of the machine in the power Chamber specifically excluded "crash" fault protection function keys-the "restore" button, gently pressing this button, radio can be back to normal.
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