Onkyo ARV401 Problem

Unit turns on but has no audio. I checked the speakers with another amp and they are fine. I tested the source for output I am using on my other amp and it is fine. I tried all of the inputs including CD, phono, tv/vcr; but still no sound at all. Not even a hiss at full volume. I pressed every button on the cotrols on and off and still nothing. I removed the cover, but can find no visible faults or burns. Any ideas, please?
 

bob91343

Member
2010-03-11 10:43 pm
The protection circuit is preventing the speakers from being connected to the amplifier. This means either the protection circuit is not working properly (rare) or one or both amplifiers have failed (likely).

Get a service manual and check for defective components.
 
Hi there.

Judging by what you said, the protection circuitry in the amp is kicking in and disconnectng the speakers to protect them. This can be caused by a number of things such as blown output transistors or other faults that may allow the amp to output DC into the speaker (this can sometimes blow the speakers).

To confirm that this is the case, power up the amp and listen to see whether there is a click after around 5 seconds. This is the sound of the relay inside the amp connecting the speakers. If it does not click, the speakers stay disconnected and no audio will be reproduced.

Also, when the amp powers up, does the display read anything like `protect` or do any lights flash. This would help to establish whether the protection is still kicking in.

The service manual may prove helpful later on in the process so here is the link: Onkyo ARV-401 Service Manual

Let me know the outcome and hopefully we can diagnose it from there.
 
I have located the souce of the click, and it is a relay. I am wondering why it takes 5 seconds to click. I remember that it always did have that pause when the amp was working properly. Anyway, maybe that relay is bad? I am familiar with how a relay works, and am considering jumpering it out to see if I get audio. Anyone think this is a bad idea?
 

bob91343

Member
2010-03-11 10:43 pm
I think it is a bad idea. Since you hear a click, it's likely the amplifiers and protection circuit are okay and I would look elsewhere for the problem.

There is no substitute for a service manual and an oscilloscope. Anything else and it's like you are trying to check your email while blindfolded.
 
In the service manual, it states that the relay will click after around 5 seconds after power up. This is when it connects the seakers, so if there was a problem, it would not connect the speakers and would not click.

The 5 second pause is to allow the amps and power supply to stabilise and prevent any nasty turn on thumps. If the relay clicks, it is highly unlikey that it is faulty as most relay failures come in the form of a faulty coil, not contacts.

As Bob said, you should look elswhere for the problem. I would try the preamplifier stages and/or the input selection and volume control section. It is unlikely to be the input switching section because the inputs are electronically switched but the preamp section could be a possible fault.

The service manual should provide some information on where the output from the preamp can be found. You could also try connecting a known working amplifier to the tape monitor/record output as this is usually just a levelled and properly adjusted ouput from the internal preamp.