Sugden A48 - right channel weak... - UK Vintage Radio Repair and Restoration Discussion Forum

ultra-radio · 21st Jul 2019, 1:14 pm

Hello Gurus,
I'm after a little help with a Sugden A48 amplifier. I've recapped all the tropical fish caps that were split and the Smoothing caps which had exploded all over the insides.

However, when I test the amp, I notice that the balance control loses the right channel when I push the sound fully to the right. I can still hear some small signal coming through, but I'm at a loss as to what can be causing this.

Does anyone have any experience with this amp and willing to help me through this tricky issue please?...I'm a noob but willing to learn.

I've servisoled the pots and there is no hiss or crackle anywhere...and when the sound is balanced I do get a really nice sound through my Dovedale 3's.

I'm confused.....

Regards and happy listening,
Dave

ultra-radio · 21st Jul 2019, 1:44 pm

Circuit drags attached...

vaslejean · 21st Jul 2019, 2:42 pm

Hi,

Vintage carbon type potentiometer tends behave oddly from time to time, ask anyone owning vintage quad 33 preamplifier. Your's seems to go beyond the carbon track deposit layer or having very low conductivity at it's end. If you can still balance the sound output I would not bother with it

ultra-radio · 22nd Jul 2019, 3:27 pm

Thanks for this. I'll give it one more blast with contact cleaner in the hope that something improves, but assuming I can get the sound properly balanced, I won't bother with it.

21st Jul 2019, 1:14 pm	#1
ultra-radio Retired Dormant Member Join Date: Aug 2015 Location: Leeds, West Yorkshire, UK. Posts: 8	Sugden A48 - right channel weak... Hello Gurus, I'm after a little help with a Sugden A48 amplifier. I've recapped all the tropical fish caps that were split and the Smoothing caps which had exploded all over the insides. However, when I test the amp, I notice that the balance control loses the right channel when I push the sound fully to the right. I can still hear some small signal coming through, but I'm at a loss as to what can be causing this. Does anyone have any experience with this amp and willing to help me through this tricky issue please?...I'm a noob but willing to learn. I've servisoled the pots and there is no hiss or crackle anywhere...and when the sound is balanced I do get a really nice sound through my Dovedale 3's. I'm confused..... Regards and happy listening, Dave

21st Jul 2019, 2:42 pm	#3
vaslejean Tetrode Join Date: Jul 2006 Location: Montréal, Canada. Posts: 78	Re: Sugden A48 - right channel weak... Hi, Vintage carbon type potentiometer tends behave oddly from time to time, ask anyone owning vintage quad 33 preamplifier. Your's seems to go beyond the carbon track deposit layer or having very low conductivity at it's end. If you can still balance the sound output I would not bother with it

22nd Jul 2019, 3:27 pm	#4
ultra-radio Retired Dormant Member Join Date: Aug 2015 Location: Leeds, West Yorkshire, UK. Posts: 8	Re: Sugden A48 - right channel weak... Thanks for this. I'll give it one more blast with contact cleaner in the hope that something improves, but assuming I can get the sound properly balanced, I won't bother with it.