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Left Channel sound problem on my system

N

naimforce

Active Member
So the other day when listening to music all of a sudden it sounded as if the speakers had blown (they haven't)...
At first everything sounded as good as it usually does and then out of nowhere it was as if the speakers had blown as there was a lot of distortion etc..

So the first thing I did was check the speakers using another system and they are fine.
Second was turned off the system and waited for a few hours and then back on and pressed play and it sounded like it was working but then quickly the distortion was back, when changing balance to the left side it has distortion but the sound (music) is still coming from the right side inc distortion? then when changing balance to the right the distortion is there but the music seems to be lower than normal but then there is still distortion coming from the left (but no sound (music).
Third is when turning the volume up (and its not even close to third of the way) the left side cuts out completely and the right side then sounds louder and clearer and appears the distortion goes (difficult to hear at that point if there is some but I think there is) but there is still distortion coming from the left side allbeit quieter.

I've been doing some research and have opened up the NAP 250 and checked the earth connections as I saw in another thread this could be an issue and I did find a loose spade connector so sorted that out but it has made no difference I have also checked the snaic and that appears to be ok.

The system is as follows:


Naim Nac 52 / Supercap
Naim CDS1 / CDPS
Naim Nap 250

So if the volume is left pretty low both sides seem to keep going but distortion is there in both sides and when changing the balance to the left the right side still has music coming out? and then when the balance is moved to the right the distortion only is still on the left, if the volume is turned up this will then cause the left side to cut out causing the right side to be much clearer and louder but with lower distortion from either side.
So even when the balance is only on one side there is still distortion and/or music from the other side.
The usual pops and noises from the system through the speakers upon initial turning on are still there and the humming.

I'm assuming the NAP 250 is the issue but as yet have not been able to change to another amp (waiting to borrow/use my friends NAP 180).

Pic of the NAP 250:
https://drive.google.com/file/d/1IP5-Nyzf3Z46RrTYOTnmLlbiwFh60Nih/view?usp=drivesdk

Note: the NAP 250 was serviced in 2006 having had a complete service - 22 capacitors, 4 diodes and 4 3r3 resitors.
 
If you were to swap over the 2 grey signal leads inside the 250 and the problem remains the same ie the same speaker/channel on the 250, then its the power amp and if the problem swaps to the other channel its the preamp. Switch everything off and fully rotate the balance and volume pots 30 times or more each way to clean them. The first place to look at the 250 is the small blue axial cap on the regulator pcb.
 
Pete MB&D said:
Have you tried unplugging and reconnecting everything?

Pete
Click to expand...

I haven't unplugged and reconnected everything but I did unplug and reconnect the cables from 250 to supercap and I also tried the CDS on different inputs on the NAC52 , while troubleshooting the snaic's last week.
 
hp1 said:
If you were to swap over the 2 grey signal leads inside the 250 and the problem remains the same ie the same speaker/channel on the 250, then its the power amp and if the problem swaps to the other channel its the preamp. Switch everything off and fully rotate the balance and volume pots 30 times or more each way to clean them. The first place to look at the 250 is the small blue axial cap on the regulator pcb.
Click to expand...

I am going to be testing the 250 on my friends system tomorrow so will try what you have suggested then.
Thanks for help
 
You are welcome, there is plenty of leg visible on those 63v 10uf caps so if you have no meter to test them then buy some new ones and cut the old ones right by the cap then you can solder new ones to the sticky up legs just to get the 250 working without taking it all apart.
do them on both channels one at a time and be absolutely sure of the polarity.
 
Well a bit of a disaster test wise as we have somehow managed to break my friends system when connecting the supercap to his system prior to connecting the 250 :(, his system now has no power to the left channel.

I will take mine apart another day and try those suggestions you have made (assuming my system is not even more broken than it was), just to be ultra safe can you confirm the capacitors you are referring to are the 2x blue ones below the 2x yellow 47uf 40vcc ones and I take it they will need to be like for like (manufacturer etc..) for sound purposes etc..

https://www.digikey.co.uk/product-detail/en/vishay-bc-components/MAL202138109E3/4066PHCT-ND/263269

And this is what the distortion sounds like:

https://drive.google.com/file/d/1IjunNVCdWXaNuXIVNQuhjRWTc5AGblA9/view?usp=drivesdk

(And only used that track as it shows the distortion much better than what I would normally listen too!!)
 
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