Yamaha CA 2010 meters behaviour

copydex

Member
2008-11-12 11:54 am
Firstly, please excuse the novice question.

Just taken delivery of a Yamaha CA 2010 and before hooking it up to my system, plugged it in with no speakers or sources connected and turned it on to see if the lights all worked. They do but I noticed that the needle on the right channel VU meter is mostly flicking to about a 1/4 of the way across, and sometimes jumping all the way up to the maximum point. The left needle hovers around the 1/4 way point too but doesn't jump upto maximum like the right one does. They both go back down to zero after the right one jumps to maximum before both returning to the 1/4 way point and then repeating the pattern every few seconds.

My question is, does this sound like normal behaviour for when no speakers are attached to this amp, and could it suggest a problem that could endanger the speakers if I do connect them up? The volume is set to zero, by the way, in case that matters. I haven't got my multimeter to hand to check for DC at the speaker outputs but will do so when I get it back from my Dad.
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
Hi, nice find.
I guess you bought this via Epay or from somewhere you couldn't test it before buying.
It has a problem that may clear after running a while but can only get worse. Unless you are confident repairing mains operated equipment,
this is not something that can be tested fully or repaired simply. It could be anything from a bad relay contact to a badly damaged amplifier.

You will need a service technician to check it out in any case, if you want a refund and even that could be expensive.

It should be possible to hook up the good channel to a speaker but don't attempt to use the R channel or connect it to any speaker.
You could also operate the various switches several times to be certain you don't just have poor contacts due to its age and the likely time
in storage this amplifier has had. If you have cheap headphones, you might quickly plug these in to check any noise and what then
happens to meter activity.
This also operates the speaker switches in the socket but be warned that this could cause damage to them too.

You may be aware that amplifiers don't last forever and to keep an old one like this working properly, components will need replacing,
both for failure and routine maintenance reasons. Owners eventually realise this, then discover the repair cost and just sell them off.

The proper way to resolve the problem is with the seller, so contact them or their agent before opening the thing.
 

VaNarn

Member
Paid Member
2010-12-11 12:39 am
Ivanhoe
This model of amplifier is from a period when the smaller transistors had plating problems.The connecting legs tarnish and cause failure,noise being an indicator.It is advisable to replace all such transistors (it is likely that some have already been replaced).Definetly, a service technician should be sought.
 

copydex

Member
2008-11-12 11:54 am
Thank you for your replies.

Having now retrieved my multimeter I have been able to measure for any DC at the speaker outputs, and on both switch on and when idle (with or without a source connected), there is no DC to speak of there, which is good. Having an old pair of speakers to use like sacrificial lambs, I have gone as far as connecting them to the amp now and have music playing. Lovely, undistorted music, with no hums/rustles/static noises audible through the speakers, even with my ear close up whilst no music is playing and the volume at various levels. With speakers and source connected, and volume at zero, the left hand meter is no longer moving at all and the right hand meter is fluctuating between the 1/8 and 1/5 mark, and the right hand one no longer shoots up to maximum as it did with nothing connected.

Playing music through it, the meters move in harmony with one another as far as I can tell (allowing for differences in the left/right stereo signal replayed). Interestingly, if you switch the meters over from giving the wattage ouput to their tape monitor level usage, the right meter behaves in a similar fashion as if it was on wattage output, hovering at about the 1/8 from minimum mark. Would this suggest the meter circuit is at fault, do you think?

Regardless, as has been suggested, I will be contacting a local service guy I know to have a look at it at some point soon. Also, I should probably have said "taken ownership of" rather than "taken delivery of" in my initial post, as I didn't mean to imply that a seller is at fault here and that I should be seeking redress in any way.

Thanks again.