Soundstream Ref.405 turn-off pop only in subchannel

gisewhcs · 29th June 2010, 02:54 PM

Because I can't change the topic, I started this new threat.
It somehow starts here: Soundstream Ref.405 railvoltage at sub-ch.

The Problem is described there, I have a Ref.405 with a turn-off pop only in the subchannel.
Bad chassis ground or the radio can't be the problem, as I already tested another radio and checked the ground connections.
I read something about a relais in an old threat about a MC245 and Perry said there was something similar in an threat about a Ref.705, but I can't find that one!

I hope somebody already had similar problem with a Ref. amp and can offer some tricks.

Perry Babin · 29th June 2010, 03:03 PM

It was probably the MC245 that I was thinking about. Too many amps... too few working brain cells.

Does it pop with no signal input?

Does it pop no matter the position of the various switches?

What is the DC offset before and after the pop?

Do any of the op-amps in the sub channel have any significant DC offset (more than a few millivolts)?

gisewhcs · 29th June 2010, 03:35 PM

I will test the things you mentioned in the next days.
I will have to take the amp out of my girlfriends car first.
And I believe she will not be very happy without music...

But I don't believe that it will be caused by one of the switches,
because I set the subchannel now to fullrange (active x-over in HU) and it got it's own input, it's no longer daisy-chained from the other inputs.
That were all switches in the subchannel, right?

I had another closer look at the schematic, and saw a 100µF/16V cap right in the input for the subchannel,
if this one dried out/shorted itself, whatever, could that be the culprit?

And do you know the value of the mini-el-cap on the FEB?
The schematic lists a 100µF/16V cap somewhere there, but I don't believe that such a small cap will have 100µF.

Perry Babin · 29th June 2010, 05:47 PM

There is a 10uF on the FEB board. The 100uF is on the main board.

I asked about the switches because, often, the switches will rout signals through other op-amps and if the noise is only in one position, it can help you narrow down the problem.

29th June 2010, 02:54 PM	#1
gisewhcs diyAudio Member Join Date: Sep 2007	Soundstream Ref.405 turn-off pop only in subchannel Because I can't change the topic, I started this new threat. It somehow starts here: Soundstream Ref.405 railvoltage at sub-ch. The Problem is described there, I have a Ref.405 with a turn-off pop only in the subchannel. Bad chassis ground or the radio can't be the problem, as I already tested another radio and checked the ground connections. I read something about a relais in an old threat about a MC245 and Perry said there was something similar in an threat about a Ref.705, but I can't find that one! I hope somebody already had similar problem with a Ref. amp and can offer some tricks.

29th June 2010, 03:03 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	It was probably the MC245 that I was thinking about. Too many amps... too few working brain cells. Does it pop with no signal input? Does it pop no matter the position of the various switches? What is the DC offset before and after the pop? Do any of the op-amps in the sub channel have any significant DC offset (more than a few millivolts)? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

29th June 2010, 05:47 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	There is a 10uF on the FEB board. The 100uF is on the main board. I asked about the switches because, often, the switches will rout signals through other op-amps and if the noise is only in one position, it can help you narrow down the problem. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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29th June 2010, 03:35 PM	#3
gisewhcs diyAudio Member Join Date: Sep 2007	I will test the things you mentioned in the next days. I will have to take the amp out of my girlfriends car first. And I believe she will not be very happy without music... But I don't believe that it will be caused by one of the switches, because I set the subchannel now to fullrange (active x-over in HU) and it got it's own input, it's no longer daisy-chained from the other inputs. That were all switches in the subchannel, right? I had another closer look at the schematic, and saw a 100µF/16V cap right in the input for the subchannel, if this one dried out/shorted itself, whatever, could that be the culprit? And do you know the value of the mini-el-cap on the FEB? The schematic lists a 100µF/16V cap somewhere there, but I don't believe that such a small cap will have 100µF.

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