Hello.
Integrated amplifier NAD 3140.
Power amplifier works fine.
Pre amp fuse F1 blown.
With 60w bulb on fuse F1 pre Amplifier works but the sound if very low.
SM
NAD 3140 SERVICE MANUAL Pdf Download | ManualsLib
Integrated amplifier NAD 3140.
Power amplifier works fine.
Pre amp fuse F1 blown.
With 60w bulb on fuse F1 pre Amplifier works but the sound if very low.
SM
NAD 3140 SERVICE MANUAL Pdf Download | ManualsLib
Last edited:
if F1 blown, check the supply voltages, +/- 45v, +/-25v,
( if +/- 25v abnormal you can disconnect it from the preamp to measure the voltages.)
if not ok,
Check The Regulator Circuitry
check AC voltages after F1, F2.
to locate the fault. unplug and
check the bridge rectifier D805, C805, C806,
use diode mode to check all the transistors,
check capacitors, resistors, diodes, zener, if their values changed.
( if +/- 25v abnormal you can disconnect it from the preamp to measure the voltages.)
if not ok,
Check The Regulator Circuitry
check AC voltages after F1, F2.
to locate the fault. unplug and
check the bridge rectifier D805, C805, C806,
use diode mode to check all the transistors,
check capacitors, resistors, diodes, zener, if their values changed.
The regulated power supply of the 3140 runs pretty hot. There will likely be some heat damaged electrolytic capacitors in the area that need to be replaced during the repair.
Ok,I replaced D805.
Amplifier power on,fuse F1 ok no blown.
If I there is great sound but low,not distorted.
if i press the soft clipping button it is almost inaudible.
Diode SLC is off, even if I press the button SLC on rear panel.
Only power and soft Clipping LEDs work.
Vumeter no work.
IC402 is absent on display PCB.
Amplifier power on,fuse F1 ok no blown.
If I there is great sound but low,not distorted.
if i press the soft clipping button it is almost inaudible.
Diode SLC is off, even if I press the button SLC on rear panel.
Only power and soft Clipping LEDs work.
Vumeter no work.
IC402 is absent on display PCB.
Last edited:
make sure
+/- 45v, +/-25v, of power supplies ok,
+/-50v, +6v, -6v, in the soft clipping circuit ok,
+25v, -25v in the power amp input buffer circuit ok,
it looks this amp need maintenance.
clean all the switches, clean all trim pots, check solder joints.
change the input coupling caps of power amps,
C601, C603, C607, C647, C649, C611, C631, C633, C637, C655,
( same with other channel. )
( front end buffer amps, tone amps, speaker eq. amps need to change coupling caps also.)
may be its best to change all of the capacitors as its been serving many years.
check all the diodes, resistors, when you have free time.
IC 402 is needed to buy from the web.
+/- 45v, +/-25v, of power supplies ok,
+/-50v, +6v, -6v, in the soft clipping circuit ok,
+25v, -25v in the power amp input buffer circuit ok,
it looks this amp need maintenance.
clean all the switches, clean all trim pots, check solder joints.
change the input coupling caps of power amps,
C601, C603, C607, C647, C649, C611, C631, C633, C637, C655,
( same with other channel. )
( front end buffer amps, tone amps, speaker eq. amps need to change coupling caps also.)
may be its best to change all of the capacitors as its been serving many years.
check all the diodes, resistors, when you have free time.
IC 402 is needed to buy from the web.
Speaker EQ knob was bad,fixed
Now the sound is ok.
But soft clipping knob push the sound is very distorted.
if IC401 in place whether the indicators of left channel should light up, or without IC402 anything it does not work ?
Thanks
Now the sound is ok.
But soft clipping knob push the sound is very distorted.
if IC401 in place whether the indicators of left channel should light up, or without IC402 anything it does not work ?
Thanks
Last edited:
when soft clipping knob pushed the sound would distort,
-- check the soft clipping circuitry as I mentioned #14,
voltages, diodes, caps, resistors... for errors,
this procedure should be familiar to you as you'd fixed your A1 by your self and done a good job.
IC402 is for led driver only, without it only that channel led won't light up .
-- check the soft clipping circuitry as I mentioned #14,
voltages, diodes, caps, resistors... for errors,
this procedure should be familiar to you as you'd fixed your A1 by your self and done a good job.
IC402 is for led driver only, without it only that channel led won't light up .
check R203, R205,
check VR201, 200k is for adjusting the input level.
check D203,
check D201, a 22v zener,
check IC 401 pin 8 for +22v, pin 1 to ground,
you must have music output to activate the led (vu meter) to light up.
no led would light up when idle.
check R201 470r 2w, it connects to +50v.
check VR201, 200k is for adjusting the input level.
check D203,
check D201, a 22v zener,
check IC 401 pin 8 for +22v, pin 1 to ground,
you must have music output to activate the led (vu meter) to light up.
no led would light up when idle.
check R201 470r 2w, it connects to +50v.
