Question about NAD C370 2-Channel Amplifier

1 Answer

One (right) preamp blow! I've located the problem to the right C160 module. When disconnected everything seems fine. Diodes and transistors are apparantly ok measured onboard as are all resistors and nothing seems "burnt". Power on and the output is nearly 33 volts - the healthy channel app. 0 volts

Posted by on

  • 2 more comments 
  • Rommel Cana
    Rommel Cana Oct 01, 2010

    then here are additional things to check:

    same withe driver transistors

  • jacob_r Oct 05, 2010

    Well, thank you petraman7! I was working on it while you posted, The Amp is up and running by now. It turned out only "upper" output transistor was blown. It really had me puzzled for a while as the diode characteristics of that transistor was identical to that of the healthy channel. I changed all transistors by the way just to be sure and a single electrolyte capacitor as well.

  • jacob_r Oct 05, 2010

    Hi Petraman7 Actually your input arrived to me 1 hour "post festum".
    Your solution was the right one though. So the helpful rating is there for everyone ...else!

  • jacob_r Oct 05, 2010

    Hi Palaboy7
    The "C160 module" is just the name for the an input stage in the preamp section - not too much heat generated here I think. (Got schematics from



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert who has answered 1,000 questions.

  • Master
  • 1,175 Answers

transistors are not ok on the C160 module.
replace all the power transistors and emitter resistors for that channel. and are good for transistors

Posted on Oct 04, 2010

  • Scott Frye
    Scott Frye Oct 05, 2010

    glad I could help



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Sa 606

Dave , If that fuse is blowing , there is a problem in the power supply or output section. If you have a meter that can test diodes / transistors. please check the output transistors first. Most likely one or more are shorted. If they check ok , you should check the power supply diodes .You can order new ones from a number of online stores by simply putting the part number into google. Hope this helps ?

Apr 20, 2014 | Pioneer Audio Players & Recorders

1 Answer

Behringer EP2500 drawing large current when powered up

If you are pulling the transistor that drives the final and the problem goes away, is the driver bad? Is the power supply a multi channel isolated unit? Could the channel for that side be bad?

May 18, 2013 | Behringer EUROPOWER EP2500 Amplifier

1 Answer

NAD Electronics 7020e 4A fuse keeps blowing on power up

Well you are on the right course. I suspect you think the problem is in the power supply and it's probably not. I think that what's gone is either a transistor (or more) or an IC amp - if it uses one - on the main power amp stage. Look at the devices on the heat sink. I think that's where you will find your shorted device.

Nov 28, 2012 | Audio Players & Recorders

1 Answer

Denon AVR2106 One output channel shorted and blown. 2 power transistors shorted, emitter resistors and base resistors blown Have replaced all, including bias transistor I think bias is still wrong (no...

I would also replace 2sa992 (2pcs) and 2sc1845 on preamp board- sometimes they look ok when you test them by regular meter. Check 1.2 kOm and 4.7ohm resistors at preamp pcb. Check diodes on output pcb (could be smd type, connected from base of output transistors to emitter i think)

Sep 07, 2011 | Denon Audio Players & Recorders

1 Answer

Samick sga 120 amp keeps blowing fuses. Replaced all rectifier diodes and tranformer seems to be working fine. Any suggestions?

The fault may not be in the power supply area! The other area of blame is the main amp section. Suspect any of the devices on the heat sink (also any device in the power supply with an heat sink). Transistors can be tested easily with this problem. An Ohm Meter on the resistance setting, on the terminals (even in circuit) of the transistor, will act like you have touched the test probes together. Just like a piece of wire, because that's what it has become and why they blow the fuse!

May 15, 2010 | Audio Players & Recorders

1 Answer

A small 2.5 amp fuse keeps blowing. It is located at the back of the unit just after the ac inlet

When a fuse blows suspect an overload in the power supply or power amp section.
For culprits in the power supply check the transformer, large capacitors, rectifier, voltage control semi-conductors, diodes.
In the amp section any semi-conductor on the heat-sink.

Semi-conductors - transistors and IC's are the biggest cause of fuse blowing. They become short-circuit acting like a piece of wire!
Because of this transistors and diodes are easy to spot with an Ohm Meter, as it will be like you have just touched the probes together.
Very often they have holes, or damage, or have burnt up with this kind of fault.
If it is a fault on the main amp section, check your speaker wiring as the + & - wires could have touched to cause it.

Apr 18, 2010 | Pioneer A509R Amplifier

1 Answer

Samick sga 120 amp keeps blowing fuses. replaced all rectifier diodes and tranformer seems to be working fine. any suggestions?

Fuse blowing is due to excessive current drain and the the first clue is the blown fuse itself. If the fuse blows with a flash a bang and splatters copper across the inside of the glass you have a hard blow caused by a dead short on the power supply, check for power switch flashing over internaly. Short circuit main filter capacitors. Shorted turns in power transformer primary winding. If fuse just separates check for short on output transistors C to E. Try isolating fault by disconnecting LT pos/neg supplies to output stage. Also check for partial shorts on speakers and speaker wires using an analog ohm meter on low ohms setting.

Mar 27, 2010 | Audio Players & Recorders

2 Answers

My receiver shuts off after 3 seconds.

Between the ground and the "PRD" pin of the CPU, there are three diodes: D503, D504 and D505. The first two seem to be useful to protect the CPU itself against any over-current. In case of short circuit or similar, these 2 diodes can easily blow out, and force to "0" the pin 139 voltage of the CPU ("PRD" pin, dedicated to detect any abnormal DC voltage from output transistors)
This is the reason why the protection circuit shuts-off the unit, even if the faulty power transistors have been replaced

Diodes are normal surface-mounted 1SS355: I've replaced them with two 1N4146, and everything works perfectly now.
Diodes are located in the "Function" board, at the left side of the unit: they are easily accessible

I've realized that the problems seems to be extremely common for this model, so I hope that this hint will be useful in several cases

Oct 28, 2009 | Yamaha RX-V1500 Receiver

1 Answer

Won't turn on

If the output module(s) has/have not failed (you need to know a bit to check this), then the power supply problem is probably traceable to a failed capacitor that caused the further failure of a switching transistor.
Locating this problem requires some electronic knowledge and at least a (digital) multimeter.

About the only thing you can do by eye is look for cans, normally mounted vertically on the board, mostly with the aluminum of the case visible at the top and shrink-wrapped sides that have values printed on them.
If you see any that have cracked tops or deposits on the board nearby, these may have caused the problem but the major component that is causing the fuse to blow is/are diodes or switching transistors on the AC side or shorted diodes on the DC side.

Because the failure might be related to bad capacitors, not having any way to check them pretty much precludes do-it-yourself repairs.

Replacing a blown fuse is sensible; replacing it twice is futile.

Jun 14, 2008 | Koss KS2503 System

1 Answer

No output to speakers mackie 808s power mixer

I can hardly even tell what you're talking about because you don't use any punctuation.

Jun 10, 2008 | Audio Players & Recorders

Not finding what you are looking for?
NAD C370 2-Channel Amplifier Logo

Related Topics:

264 people viewed this question

Ask a Question

Usually answered in minutes!

Top NAD Audio Players & Recorders Experts


Level 3 Expert

5126 Answers

The Knight
The Knight

Level 3 Expert

74198 Answers

Larry Stiles
Larry Stiles

Level 2 Expert

287 Answers

Are you a NAD Audio Player and Recorder Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides