Marantz PM-80AF Marantz early representatives of the HIFI amplifier, has now done PM6003/7003/8004/7200 and other models, old machine quality, maintenance of small, got a lot of older fans still love little trouble sometimes, as long as they can in good repair also are reluctant to buy new machines, here are just a PM-80AF fault-checking process, for your reference.xt2service manual download site
Symptom: power on the output relay does not snap at times, sometimes suction works but the volume increased protection, protective shutdown can take a long time after reboot.xt2service manual download site
Working time measurement the midpoint of the supply voltage, the output voltage is normal. Checks for a long time without results, users after using for about a week, consumer reports has been difficult to boot, and then sent to a repair shop, which to repair search convenience.xt2service manual download site
Measurement output relay after taking a 24-volt 2 pin to ground, because it works directly for 24 volts to the coil of a foot, through transistor controlled the other foot on the ground. Description control no signal. This machine uses protection chip is very classical TA7317P,xt2service manual download site
xt2service manual download site
Is Japan Toshiba amplifier protection IC, internal, including detection circuit, overload detection circuit, switch mode power supplies DC detection circuit, power on the midpoint squelch, or gates, Schmitt Triggers, regulator circuits, circuit, relay drive circuit circuit protection features great sound, reliable performance. The IC combines external circuit, allows you to start up delay, shut down instantly disconnect the speaker circuit, the output voltage offset pipe protection, output overload protection, is widely used in all kinds of high school low end power amp.xt2service manual download site
The manifold blocks for the foot fault voltage is as follows:xt2service manual download site
1:0.65V 2:0V 3:0V 4:0V 5:-0.7V 6:23.4V 7:0V 8:135MV 9:3.2Vxt2service manual download site
Check TA7317P IC function as follows:xt2service manual download site
1. overcurrent detection, voltage detection ends. Amplifier work correctly when this voltage is -0.8V. when the PIN voltage is higher than 0.75V, the protection circuit, the relay releases.

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