Technics SU-V560 problem

lame_zany · 1st November 2011, 10:50 PM

Hi folks

My mate was after a good solid amp with a phono stage and plenty of inputs for not much money, so I suggested he look at old technics amps. He ended up buying a SU-V560 for not much money, but it had a problem - when powered on, the 'Voltage Control' light comes on, but the 'Current Drive' light does not. Nothing from the speakers or headphones. Not even a hum. Not wanting to mess around with it, he sent it back, and bought another. When it arrived, it turned out to have exactly the same problem..

I know these amps have a protection circuit, but it is supposed to 'reset' when the amp is powered down, and back on. Both the 560's never got past the 'Voltage Control' stage.

Is it coincidence? Or have I missed something very obvious?

Any help would be much appreciated!

Cheers

Tim

Ian Finch · 2nd November 2011, 10:26 AM

The SUV series amps are no straightforward AB class amps at all. The lights refer to the small class A amps and then the big class B ones that switch in - if the potentials stabilise correctly. If this doesn't happen, you have a lot more problems than any fixit should touch, believe me. The terms voltage and current drive are quite misleading but ok for users to understand something of the warm-up cycle. They are generally great sounding amps but check the operating principles and schematic first before trying anything. Experienced audio service guys usually give up when they come across these. It takes specialist knowledge, equipment and experience - if you can indeed obtain the special modules or ICs likely needed.

It's just possible that normal function could be restored by checking both power supplies and then replacing parts like the electrolytic caps that deteriorate, giving incorrect supplies and operation but this is a long-shot I think.

Just read the recent threads on SUV Z45 and SUV50 to get an idea of some of the difficulties there and maybe learn why they were cheap.

lame_zany · 2nd November 2011, 04:27 PM

Thanks for the reply.. I'm sure whatever is wrong is outside of my technical abilities then! I just found it too much of a coincidence that 2 could have the same issue.. A shame because I have always found them to be great sounding amps.. with associated difficulties

Cheers

1st November 2011, 10:50 PM	#1
lame_zany diyAudio Member Join Date: Feb 2009	Technics SU-V560 problem Hi folks My mate was after a good solid amp with a phono stage and plenty of inputs for not much money, so I suggested he look at old technics amps. He ended up buying a SU-V560 for not much money, but it had a problem - when powered on, the 'Voltage Control' light comes on, but the 'Current Drive' light does not. Nothing from the speakers or headphones. Not even a hum. Not wanting to mess around with it, he sent it back, and bought another. When it arrived, it turned out to have exactly the same problem.. I know these amps have a protection circuit, but it is supposed to 'reset' when the amp is powered down, and back on. Both the 560's never got past the 'Voltage Control' stage. Is it coincidence? Or have I missed something very obvious? Any help would be much appreciated! Cheers Tim

2nd November 2011, 10:26 AM	#2
Ian Finch diyAudio Member Join Date: Apr 2010 Location: Coffs Harbour, on the east coast	The SUV series amps are no straightforward AB class amps at all. The lights refer to the small class A amps and then the big class B ones that switch in - if the potentials stabilise correctly. If this doesn't happen, you have a lot more problems than any fixit should touch, believe me. The terms voltage and current drive are quite misleading but ok for users to understand something of the warm-up cycle. They are generally great sounding amps but check the operating principles and schematic first before trying anything. Experienced audio service guys usually give up when they come across these. It takes specialist knowledge, equipment and experience - if you can indeed obtain the special modules or ICs likely needed. It's just possible that normal function could be restored by checking both power supplies and then replacing parts like the electrolytic caps that deteriorate, giving incorrect supplies and operation but this is a long-shot I think. Just read the recent threads on SUV Z45 and SUV50 to get an idea of some of the difficulties there and maybe learn why they were cheap. __________________ regards

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2nd November 2011, 04:27 PM	#3
lame_zany diyAudio Member Join Date: Feb 2009	Thanks for the reply.. I'm sure whatever is wrong is outside of my technical abilities then! I just found it too much of a coincidence that 2 could have the same issue.. A shame because I have always found them to be great sounding amps.. with associated difficulties Cheers

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