Arcam A65, A75 & P75 Service Guide, Fault diagnostics, Power supply test points, IQ settings

A65, A75 & P75 Service Guide

Fault diagnostics

	Fault	Action
	No power	Check mains fuse
		Check transformer connections
		Check power supply rails
	Stuck in protection	Check power supply rails
		Check protection circuit voltages
		Check for dry joints on o/p devices
	Intermittent audio on one channel	Check for dry joints around o/p
		devices
	Fails to respond to commands	Check supply to remote circuit
		Check IC Z900
		Check remote flex foil cable
		Check for dry joints on selector pcb
	Volume control rubs on front panel	Pull knob out from fascia
	Audio crackles on o/p	Check for component break down
		using hot air gun & freezer spray
		Check transformer connections
Power supply test points

Position	Voltage
LK125	+37 volts DC
LK126	-37 volts DC
LK271 or black speaker terminal	0 volts
LK303	+15 volts DC
LK301	- 15 volts DC
Q300 emitter	+38 volts DC
Q304 emitter	+38 volts DC
Q302 emitter	-38 volts DC
Q305 emitter	-38 volts DC
D910 emitter	+5 volts DC remote supply

IQ settings

Model	IQ setting	Comments - (22/01/02)
A65	37mV
A75	37mV
P75	37mV
A85	12mV	Set for 8.5mV cold, reset for 12mV when warm
P85	12mV	Set for 8.5mV cold, reset for 12mV when warm
A65 plus	12 to 15mV
A75 plus	12 to 15mV
P75 plus	12 to 15mV

Hints & tips

!To isolate a fault between pre and power stage remove C602 (left channel) or C702 (right channel).

!Always check and re-solder o/p device SAP15N and SAP15P pin connections.

!Replace Z900 IC if software version is below version 3 ( note version 82 is also ok ).

!Make sure R127 is not touching LK130.

!When replacing the top cover with a new top it may be necessary to re-drill the fixing holes.