AudioSource AMP300 Troubleshooting

[mukerjea]

Hello Everyone. I am new to this forum.

I have basic knowledge of electronics and can desolder and solder nicely. I still work on vintage tube radios. So “Gurus" at this site please help me step by step to troubleshoot this AMP and repair?

Thanks in Advance.

I have this AudioSource AMP 300, which has developed following problem:
Upon powering up, it turns on with Blue light. Sound is great on both*channels*for about 1-2 minutes then it clicks off sound but the light remains Blue. If I re-power the Amp again it plays for 1-2 minutes and clicks off again.

I did check the AMP, disconnecting all the speakers and inputs. Still relays trip after 1-2 minutes.

Couple of things I noticed:
1. Even after the relays trip the Blue Light remains blue.
2. It is happening irrespective of selection of speakers A or B or A+B. Or even without selecting any speaker set.
3. There is a switch at the back for Trigger - Auto ON - Manual.
When the switch is on Trigger (Light is Red which is OK),
when it is on Manual (Light is Blue which is OK too).
But when the switch is on Auto ON (Light should be Red as no signal is coming in but the light remains Blue)
Looking forward to bring this AMP to life with your help.
Thanks,
Ash

 

[bullittstang]

First thing to ask is...are you using Input 2, don't know why but AS default input is 2. If you're using Input 1, it tends to act sporadically similar to what you are indicating. I would power it off, switch to Manual power on the back and ensure your RCAs are in Input 2.


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[nigelwright7557]

Does the amp have a fan ?
1-2 minutes sounds like something warming up and tripping the protect.

 

[mukerjea]

First thing to ask is...are you using Input 2, don't know why but AS default input is 2. If you're using Input 1, it tends ....

Yes I am using Input 2. It was working for my Home Theater 7.1.4 ATMOS set up as pair of Height speakers.

 

[mukerjea]

Does the amp have a fan ?
1-2 minutes sounds like something warming up and tripping the protect.

NO it doesn’t have cooling fan. Yes it seems something is warming up even without any load and input.

 

[mukerjea]

I just did one more test:
I put the DMM probes to the speaker outputs.
Speaker Right Channels A or B set shows DC (+)3V slowly goes up to (+)6V
But strangely:
Speaker Left Channels A or B set shows DC (-)3V slowly goes up to (-)6V
Then, I tested Mono Bridged mode too.
That is also showing DC -3V slowly goes up to -6V

I checked up with my other AMP300, there all voltages are (+) on all Speaker Channels.
Any advice?

 

[r_merola]

Did you tried to ask service manual? We can help more with it.
Regards
Ronaldo

 

[mukerjea]

Can anyone help me to get a Service Manual for AudioSource AMP300?
Thanks

 

[r_merola]

Dear Mukerjea,

Normally in the user manual exist a support contact e-mail. You can enter in contact with them asking service manual and informing your product model and serial number. Please, remenber you will lost warranty.
I tried to find your service manual in web without sucess.
Regards
Ronaldo

 

[mukerjea]

Thanks a lot Ronaldo.
I did try contacting AudioSource and also, tried Google but with no luck.
The company doesn't respond may be because this Amp 300 was purchased in 2007 and is discontinued by the company.
Regards,
Ash

 

[bullittstang]

Have you checked the input voltage(120 or 220V AC), the transformer voltage (should be 44.5 at Brown/Black/Brown) and secondary voltage (20.5 at Blue/Black/Blue) and then the regulated DC at the amp boards (63vDC) on both sides (i.e. 2 sets of red/black/yellow). Might be too easy, but maybe its on the PSU side.

 

[r_merola]

Ash
as your integrated is discontinued, i suppose will be easier to get service manual or at least schematic from factory.

Bullittstang
as this integrated has some logic with the inputs with the audio signal I suppose the failure can be around this logic. Something simple as a defective elco.

Regards

 

[mukerjea]

Have you checked the input voltage(120 or 220V AC), the transformer voltage (should be 44.5 at Brown/Black/Brown) and secondary voltage (20.5 at Blue/Black/Blue) and then the regulated DC at the amp boards (63vDC) on both sides (i.e. 2 sets of red/black/yellow). Might be too easy, but maybe its on the PSU side.

Hi

I checked the voltages, these are more or less what you mentioned. Only thing is that
Transformer wires are Blue/Black/Blue are 46.9V and 47.0V
Secondary wires are Brown/Black/Brown are 21.5V and 21.5V

Regulated DC on both set of Red/Black/Yellow are DC (+) 64V and DC (-) 64V on both set.

See the attached images if I have done it correctly.

Thanks

Ash

 

[mukerjea]

Ash
as your integrated is discontinued, i suppose will be easier to get service manual or at least schematic from factory.

Bullittstang
as this integrated has some logic with the inputs with the audio signal I suppose the failure can be around this logic. Something simple as a defective elco.

Regards

Hello,
Thanks for helping me troubleshoot this AMP.
I tried contacting Factory, but they don’t respond.
I managed to get the schematics from an earlier post on this site.
Please have a look at the schematics and advise me accordingly.
Regards,

Ash

 

[r_merola]

Murkerjea

Are both channels off?
There is RL01 in power board that can turn off both power amplifier and is controlled by a logic control board.

If only one channel is off, please check dc voltage in amplifier output(inside amplifier). It can be the cause of your failure detected by the logic board. Do not connect speaker boxer and be very carrefull measuring output voltage. It is difficult to find a easy point do do this measurement following your pictures.

If you do not fell confident to do those test do not make it. Any mistake can destroy a channel.

Good luck
Ronaldo

 

[nec3]

What is the voltage at pin-2 of CNA02 socket, when it works good and goes muted (in MANUAL position) ?

What is the voltage at pin-7 of IC303B ?

 

[mukerjea]

Murkerjea

Are both channels off?
There is RL01 in ..... make it. Any mistake can destroy a channel.

Good luck
Ronaldo

Hi Ronaldo,
Yes both the channels go off. But as I had mentioned earlier,

I put the DMM probes to the speaker outputs.
Speaker Right Channels A or B set shows DC (+)3V slowly goes up to DC(+)6V
But strangely:
Speaker Left Channels A or B set shows DC (-)3V slowly goes up to DC(-)6V
Then, I tested Mono Bridged mode too.
That is also showing DC( -)3V slowly goes up to DC(-)6V

I checked up with my other AMP300, there all voltages are (+) on all Speaker Channels.

And when the Amp trips, all the channels read DC 0V.

Secondly, if need be, please have a look at the pic. attached and let me know where you want me to check the DC Output voltage. Are these the “yellow-Black-Red” wires sockets?
Thanks

 

[mukerjea]

What is the voltage at pin-2 of CNA02 socket, when it works good and goes muted (in MANUAL position) ?

What is the voltage at pin-7 of IC303B ?

Hi nec3,
Voltage at pin-2 of CNA02 socket, when it works good and goes muted (in MANUAL position)
Remains at DC (+)11.85V in both condition.
Please see the pic, if I have done correctly.

Secondly, sorry to ask you a silly newbie question.
In which section will I find this IC303B and which one will be Pin-7.
Once, I put DMM Red probe on pin -7, where should I put DMM black probe in circuit?
Thanks

 

[nec3]

Yes, you did correct.

IC303 A and B are in the same package.

You will check the voltage between 7 and the ground (GND).

An externally hosted image should be here but it was not working when we last tested it.

Edit:

Find the IC303 first on the PCB. The dot at the left is Pin-1.

Edit-2

I can see IC303 here:

Just be careful not to make short with other pins accidently.

 

[mukerjea]

Yes, you did correct.

IC303 A and B ....... short with other pins accidently.

Hello,
Thank you so much for your time.
So I should check the voltage between Pin7 and Pin4? Am I right?
Thanks
Ash