After startup, only 16 on power amplifier tube-lined on either side, each channel separately in circuit board Assembly. Left with scorch marks. Closer look: intermediate amplifier tubes have been burned, and the circuit board is have partial carbonization occurs, push tubes (C2073 and A940) has disappeared, and only a few residual foot remained in place.ESFservice manual download site
ESFservice manual download site
Remove the left channel of amplifier Board, local circuits have become unreadable. Had to remove all amplifier tube, remove the circuit board, use lacquer thinner wash and sort all damaged parts.ESFservice manual download site
ESFservice manual download site
Inspection method: available multimeter Rx10 blocked-in sequence to check for levels of three-level forward from deep-level tube, a triode (common 2N5551 and 2N5401,8550 and 8050, C2073 and A1943) damaged,ESFservice manual download site
ESFservice manual download site
With three tubes are connected resistor and capacitor should be checked. Prevent drift of diodes are often joint damage. For late-stage power amplifier tube and advance level and "temperature of WD" compensate the triode, circuit wiring are often severely damaged, only controlled sound reducing repair to the right channel. Circuit board part application of coking clean knife cut, repair the fly line should pay attention to current capacity, and tube current resistance (including power resistor) should also pay attention to correct. Sometimes if the damaged area is too large, it is recommended to give up maintenance, scrapped or changed treatment.ESFservice manual download site
ESFservice manual download site
The machine by the author is careful matching, repair damaged parts of the lines and devices. Replaced all power devices, before the machine, disconnect power from the Dianyuan secondary DC power supply, power voltage, 65V. Shutdown, 220V/100W of incandescent welding two one-meter long head, 30 seconds or so to discharge the capacitor array.ESFservice manual download site
ESFservice manual download site
Note: this step is critical, don't short circuit discharge with a screwdriver! As long as it is turned on to check, it must be disconnected from the mains of vision safe discharge of the capacitor array!

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