Threshold SL-10, trouble in MC input

Mywing · 23rd October 2008, 01:43 PM

Hi all,
My SL-10 works perfectly in all its functions: line, monitor, MM phono input ... except the MC phono input. It's some time using the MC phono, the right channel produces a strong buzz-uhmmm, as if the turntable's ground is not connected, but only on right channel!. I'm not an expert in repairs but since the trouble is only at one section, perhaps with your help I might be able to identify the cause. The noise is the same in all three positions of impedance.
Here is an inside attachment...

Mywing · 23rd October 2008, 01:45 PM

...and schematics.

Thaks so much for help.

Mywing · 24th October 2008, 10:15 AM

Any idea?

analog_sa · 24th October 2008, 03:48 PM

This should be really easy to fix. First of all inspect and resolder all solder joints in the MC section - input jacks, connections to pcb, pcb itself. It may even be an almost broken wire. It is less likely that the electrolytics are to blame but it certainly wouldn't hurt to replace them - they are all way past their prime. The 4.7uF caps will deserve really good quality replacements - BG-N will be very suitable.

Mywing · 24th October 2008, 06:08 PM

Preamp has been recapped recently with Elna Silmic II. Maybe one of them has blown...
I'll check them and all solder points.
Thanks for help.

Zen Mod · 24th October 2008, 06:12 PM

Quote:

Originally posted by Mywing
Preamp has been recapped recently with Elna Silmic II. Maybe one of them has blown...
I'll check them and all solder points.
Thanks for help.

blown caps - not likely ;

cold solder joints or defective transistor in input

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24th October 2008, 10:15 AM	#3
Mywing diyAudio Member Join Date: Mar 2007	Any idea?

24th October 2008, 03:48 PM	#4
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	This should be really easy to fix. First of all inspect and resolder all solder joints in the MC section - input jacks, connections to pcb, pcb itself. It may even be an almost broken wire. It is less likely that the electrolytics are to blame but it certainly wouldn't hurt to replace them - they are all way past their prime. The 4.7uF caps will deserve really good quality replacements - BG-N will be very suitable.

24th October 2008, 06:08 PM	#5
Mywing diyAudio Member Join Date: Mar 2007	Preamp has been recapped recently with Elna Silmic II. Maybe one of them has blown... I'll check them and all solder points. Thanks for help.

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