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4ZDservice manual download site
And like a lot of work, and repairs amplifiers when there are a lot of methods and experience needs to summarize, here's sharing some experiences for everyone, in order to learn.4ZDservice manual download site
(1) control in kind, drawing machine (schematic diagram of power amplifier section (see Figure 1), figure out the principles and components of the circuit parameters.4ZDservice manual download site
4ZDservice manual download site
(2) take full advantage of resistance measurement method, current and voltage laws, once on the road measurements of all the components in the circuit, an analysis of the related parameters determine, tend to smooth out damage components.4ZDservice manual download site
(3) using the three-step safety power trial method, power up test machine, respectively. First of all, in order not to damage the speaker and power tube, try machine wouldn't pick up the speaker system in the push-pull between the output and ground (that is, between points c and d in Figure 1) pick up a 20~50 ohm/20~50W wire-wound resistive dummy load. Next, disconnect the level at the end of any of the two electrodes or power transistor without prior installation of power transistor Q212~Q219. Reserved drive tube Q210 and Q211 complementary push-pull output (if the thrust tube emitter with the midpoint between the emitter resistance, should be temporarily installed two 100~270 ω, 0.5W resistor, after the commissioning of demolition). Then the amplifier power 220V input threaded a voltage regulator,4ZDservice manual download site
4ZDservice manual download site
Starting from 50V to amp power supply and monitor outputs midpoint voltage (voltage between points c and d). OCL circuit, the voltage should read 0V ± 0.5V, OTL circuits should be half the supply voltage. If the midpoint voltage does not conform to the normal, should immediately stop checking. At this time due to the lower power supply,4ZDservice manual download site
Normally does not cause damage to the components. If the midpoint voltage, you can gradually increase the power supply voltage, while monitoring the midpoint voltage, observing the color, smoke-free components, simultaneously with a hand push tube temperature. If the mains up to normal power output voltage remains constant in half an hour, driving coils no temperature rise or no deterioration discoloration of components, it means that the security power on commissioning the first step done, you can proceed.
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