555 multi-purpose repair circuit diagram

The overhaul has the following features: online judge diodes, transistors is good or bad; test TTL logic level or a high impedance state; can output 37MHz, bar television signal 74MHz, 148MHz; the output 465kHz, 930kHz, 1395kHz AM signal. As illustrated, 555 and R5,
555 multi-purpose repair circuit diagram - schematic

R6, C8 composition astable multivibrator, the output added to the VT1, VT2 and so many were, as a test signal (200Hz). When the output is high, VT2 off, VT3 conduction; low, VT2 conduction. VT3 deadline. Test diodes, transistors, from LED1, LED2 luminescence, the tube can be judged good or bad. VT1, L1, L2, C1 ~ C7 and 555 point-frequency oscillators signal generating circuit. K2 "1" at, CZ1 output of the AM signal 465,930,1395kHz to repair radios, tape recorders, etc; K2 is set to "2", CZ1 TV output 37,74,148MHz bar signal for high frequency maintenance head and channel section. CZ4 public places.

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