No Plug in the machine reset beeps, no display , each function key is invalid, but the furnace glass turntable rotation.7vuservice manual download site

Although the above expression is uncontrolled . But glass plate rotating machine is powered instructions , failure to be in the computer control panel. Remove the computer control panel , because the screen about two rows of pins in the computer control panel welding welding surface , affecting the observed alignments and testing as well as welding , it is best to display temporarily removed, pending troubleshooting and reassemble . Specific removal method is:7vuservice manual download site

The stained rosin copper wire or multi-strand copper braid shield cable , with electric iron . On the left or right on the screen and slowly pulling the pin , solder pin will be sucked very clean , and when each pin solder After all suck . It is easy to remove the display. Early computer control panel measuring low-voltage transformer secondary.7vuservice manual download site
 7vuservice manual download site

Normal , and then measure the microprocessor IC1 (TMP87PH46N) of +5 V power supply is normal, crystal pin ( 19 ) feet to 0.5V, (21) feet of 1.9V to normal, but the reset ( 18 ) feet to the left there is not normal 1V ( The above data is measured MF47 type pointer table ) .7vuservice manual download site

From the analysis of test results , causes the machine does not work should be caused by abnormal microprocessor reset . Because the reset exception . Microprocessor fails to work properly, the machine can not implement the original program and operational control. Referring to the drawings reset circuit , reset circuit measuring Q11 (A1015) e extremely 5V, b extremely 4.9V, c extremely 1.9V. e b voltage pole and essentially flat , indicating that not Q11b-e junction is shorted Zener diode ZD2 (3.9V) open. Upon further examination. ZD2 tube body was found a fine cracks appear , measuring its already open. After replacing ZD2, microprocessor IC1 (18) feet of the reset voltage at power- instant transition from the 0V → 1.5V → 4.5V, 4.5V then when it reaches steady . At this time machine back to normal , troubleshooting.

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