Amiga 600 Rev. 1.5 Distorted, Clipped audio fix

PCBA: 8514892315986004184316; Country of origin : Poland

Distorted and clipped audio may be the result of the capacitor’s fault, LF347M chip, broken traces, and vias in the vicinity of the LF314M chip.

 

The LF147 is an op amp with an internally trimmed input offset voltage and JFET input devices (BI-FET II). These JFETs have large reverse breakdown voltages from gate to source and drain eliminating the need for clamps across the inputs. Therefore, large differential input voltages can easily be accommodated without a large increase in input current. The maximum differential input voltage is independent of the supply voltages. However, neither of the input voltages should be allowed to exceed the negative supply as this will cause large currents to flow which can result in a destroyed unit.

DIAGNOSTICS: Old through-hole capacitors previously haven’t been replaced, broken trace between U15 PIN 8 and R332 has been found. R302, C301, C302, C3, and D57 components fault. On the pictures below you will find a location of the fault already marked in colors.

MAINTENANCE: All capacitor’s pads were inspected restored and cleaned using isopropanol. Broken trace between U15 PIN 8 and R332 has been restored. All broken components have been replaced i.a.w standard practices. Mainboard has been cleaned in the ultrasonic cleaner.

FAULTY BOARD

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