SOURCE: NAD C350
Take a ohm meter and measure resistance from emiter to collector should have a few kilo ohm on output transistor.
If no ohm meter available , remove output transistors from circuit.
note position of transistor . you have a NPN and a PNP for each channel.
Replace fuse and power up. If fuse blows check bridge in the power supply.
80% of the time output transistor burn and blow the fuse.
before replacing output transistors check driver transistors they probably burnt also
SOURCE: Nad amp failure
Solution if all fuses checked out OK and +/-40V are present on main PCB DC connector from power supply:
Check for +37V and -37V on small sub-power supply PCB - mounted vertically on the main power supply PCB. (next to ribbon cable connector is a layout with voltages.) If the +/-37V are missing check (replace) C501 (0.1uF) on the small power supply PCB for leakage, but also check (replace) R401 (2R2) and R402 (2R2) on the main power supply PCB. Both resistors are fuse-resistors and will have gone open circuit when C501 has gone leaky.
SOURCE: Nad c350 no power at all
Solution if all fuses checked out OK and +/-40V are present on main PCB DC connector from power supply:
Check
for +37V and -37V on small sub-power supply PCB - mounted vertically on
the main power supply PCB. (next to ribbon cable connector is a layout
with voltages.) If the +/-37V are missing check (replace) C501 (0.1uF)
on the small power supply PCB for leakage, but also check (replace)
R401 (2R2) and R402 (2R2) on the main power supply PCB. Both resistors
are fuse-resistors and will have gone open circuit when C501 has gone
leaky.
SOURCE: NAD C270 amp won't switch from red power/protection to green.
The AH may denote "slo-blo" style as opposed to Fast-acting
A fast-acting fuse will look like a single strand of wire ( maybe wiggly looking) ..A Slo-blo will have an element in it and a spring
SOURCE: nad 304 amplifier no output, relais not willing to
The 2 BIAS resistors of 47kohm, R333 R334, replaced with new 1W resistors. 1 resistor was totally open and 1 resistor was 55k.
It were 1/2W resistors, replaced them with 1W resistors. Very low cost repair for a High End amplifier. Should live for another 10 years.
Regards
Marc
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