help needed with nikko 230 distortion

J

james moffat

Guest
HI all!
I have a nikko alpha 230 amp that is distorting one channel <just
enough to annoy my ears>
and was wondering if anyone has any advise on what to check for / and
or replace to get rid of the noise.
If it makes any difference to the diagnosis the music is fine at the
headphones, and is only distorted on the left channel.
I have enough knowledge to make me dangerous, and some test
equipment<no o-scope>
so if someone is willing to help me learn a little more please blast
away.
thanks for your time
remove the spam to e-mail me.
james
If you really want to talk to me - just eat the spam
 
"james moffat" <kallispamta@shaw.ca> wrote in message
news:f3uca61pr4k5h2nbrl2mn0bec2vbv7v32v@4ax.com...
HI all!
I have a nikko alpha 230 amp that is distorting one channel <just
enough to annoy my ears
and was wondering if anyone has any advise on what to check for / and
or replace to get rid of the noise.
If it makes any difference to the diagnosis the music is fine at the
headphones, and is only distorted on the left channel.
I have enough knowledge to make me dangerous, and some test
equipment<no o-scope
so if someone is willing to help me learn a little more please blast
away.
thanks for your time
remove the spam to e-mail me.
james
If you really want to talk to me - just eat the spam
Click to expand...


I suppose that you've done the obvious, and swapped the speakers between
channels ?

Arfa
 
"james moffat" <kallispamta@shaw.ca> wrote in message
news:f3uca61pr4k5h2nbrl2mn0bec2vbv7v32v@4ax.com...
HI all!
I have a nikko alpha 230 amp that is distorting one channel <just
enough to annoy my ears
and was wondering if anyone has any advise on what to check for / and
or replace to get rid of the noise.
If it makes any difference to the diagnosis the music is fine at the
headphones, and is only distorted on the left channel.
I have enough knowledge to make me dangerous, and some test
equipment<no o-scope
so if someone is willing to help me learn a little more please blast
away.
thanks for your time
remove the spam to e-mail me.
james
If you really want to talk to me - just eat the spam
Click to expand...

Could be a bias problem, but if you aren't good with amps it would be pretty
easy to blow up the thing and cause a much more expensive repair.
That said, could be a bad bias transistor, flaky bias pot, open resistor,
etc.
Unless there were a common problem on this model which someone here just
happens to know about (and Nikko's aren't the most common amps by a long
shot) then real troubleshooting by a qualified technician is your best bet.

Mark Z.

Mark Z.
 
On Sat, 2 Oct 2010 02:01:07 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

"james moffat" <kallispamta@shaw.ca> wrote in message
news:f3uca61pr4k5h2nbrl2mn0bec2vbv7v32v@4ax.com...

HI all!
I have a nikko alpha 230 amp that is distorting one channel <just
enough to annoy my ears
and was wondering if anyone has any advise on what to check for / and
or replace to get rid of the noise.
If it makes any difference to the diagnosis the music is fine at the
headphones, and is only distorted on the left channel.
I have enough knowledge to make me dangerous, and some test
equipment<no o-scope
so if someone is willing to help me learn a little more please blast
away.
thanks for your time
remove the spam to e-mail me.
james
If you really want to talk to me - just eat the spam



I suppose that you've done the obvious, and swapped the speakers between
channels ?

Arfa
Click to expand...
swapped the speakers, changed the source , and used different wires
to make sure that it was in fact the amp the was the cause. the left
speakers on both the a and b outputs have the same distortion....
kinda like gargling......
thanks for your time.
me
If you really want to talk to me - just eat the spam
 
On Sat, 2 Oct 2010 06:40:06 -0500, "Mark Zacharias"
<mark_zacharias@sbcglobal.net> wrote:

"james moffat" <kallispamta@shaw.ca> wrote in message
news:f3uca61pr4k5h2nbrl2mn0bec2vbv7v32v@4ax.com...

HI all!
I have a nikko alpha 230 amp that is distorting one channel <just
enough to annoy my ears
and was wondering if anyone has any advise on what to check for / and
or replace to get rid of the noise.
If it makes any difference to the diagnosis the music is fine at the
headphones, and is only distorted on the left channel.
I have enough knowledge to make me dangerous, and some test
equipment<no o-scope
so if someone is willing to help me learn a little more please blast
away.
thanks for your time
remove the spam to e-mail me.
james
If you really want to talk to me - just eat the spam


Could be a bias problem, but if you aren't good with amps it would be pretty
easy to blow up the thing and cause a much more expensive repair.
That said, could be a bad bias transistor, flaky bias pot, open resistor,
etc.
Unless there were a common problem on this model which someone here just
happens to know about (and Nikko's aren't the most common amps by a long
shot) then real troubleshooting by a qualified technician is your best bet.

Mark Z.

Mark Z.
Click to expand...
the amp was free... so I am treating it as a learning experience
rather than "I must get it working" . If I am unable to repair it then
it will simply be tossed.
thanks for the advise , I will look into that.
me
If you really want to talk to me - just eat the spam
 
On Fri, 01 Oct 2010 18:16:56 -0600, james moffat <kallispamta@shaw.ca>
wrote:

HI all!
I have a nikko alpha 230 amp that is distorting one channel <just
enough to annoy my ears
and was wondering if anyone has any advise on what to check for / and
or replace to get rid of the noise.
If it makes any difference to the diagnosis the music is fine at the
headphones, and is only distorted on the left channel.
I have enough knowledge to make me dangerous, and some test
equipment<no o-scope
so if someone is willing to help me learn a little more please blast
away.
thanks for your time
remove the spam to e-mail me.
james
If you really want to talk to me - just eat the spam
Click to expand...

ok just to update and close this tread:
here is what I did to it.
opened it up
checked all fuses.
ran some professional cleaner all through it<it was very grungy>
tested it on some real speakers... still distorted.
replaced light bulb for display.....IT WORKS!!!!!....Kidding.
using some info I found from an Internet search I found the bias
settings and test sites, so I started testing....
switched on and waited till it was warm<hot>
tested working side and got a reasonable reading from it.
tested the distorted side and got no (ie 0) reading from it.
which indicated to me that there was no voltage going to that side.
went back and retested the fuses with a multimeter and found one to be
bad..... not blown just not working...
popped in a set of new fuses to that grouping and restarted waited
till warm, and retested the bias. very high.....so I adjusted the bias
on both sides back to the recommended mv. <the other side was slightly
off> and threw some music through it.......
everything works super now.
Am thinking of replacing the bias pots as they are a little touchy,
and contemplating\fighting the urge to replace the caps as they are
original and most likely dry.... but as they say if it works don't
f**k with it. Recommendations on replacing?

thanks for the replies I received they sent me in the right direction.
kallita

If you really want to talk to me - just eat the spam
 
"james moffat" <kallispamta@shaw.ca> wrote in message
news:8qd6b6l2va1ebt12futnoqab2d1c36qqb6@4ax.com...
On Fri, 01 Oct 2010 18:16:56 -0600, james moffat <kallispamta@shaw.ca
wrote:


HI all!
I have a nikko alpha 230 amp that is distorting one channel <just
enough to annoy my ears
and was wondering if anyone has any advise on what to check for / and
or replace to get rid of the noise.
If it makes any difference to the diagnosis the music is fine at the
headphones, and is only distorted on the left channel.
I have enough knowledge to make me dangerous, and some test
equipment<no o-scope
so if someone is willing to help me learn a little more please blast
away.
thanks for your time
remove the spam to e-mail me.
james
If you really want to talk to me - just eat the spam


ok just to update and close this tread:
here is what I did to it.
opened it up
checked all fuses.
ran some professional cleaner all through it<it was very grungy
tested it on some real speakers... still distorted.
replaced light bulb for display.....IT WORKS!!!!!....Kidding.
using some info I found from an Internet search I found the bias
settings and test sites, so I started testing....
switched on and waited till it was warm<hot
tested working side and got a reasonable reading from it.
tested the distorted side and got no (ie 0) reading from it.
which indicated to me that there was no voltage going to that side.
went back and retested the fuses with a multimeter and found one to be
bad..... not blown just not working...
popped in a set of new fuses to that grouping and restarted waited
till warm, and retested the bias. very high.....so I adjusted the bias
on both sides back to the recommended mv. <the other side was slightly
off> and threw some music through it.......
everything works super now.
Am thinking of replacing the bias pots as they are a little touchy,
and contemplating\fighting the urge to replace the caps as they are
original and most likely dry.... but as they say if it works don't
f**k with it. Recommendations on replacing?

thanks for the replies I received they sent me in the right direction.
kallita
Click to expand...

I'm a great believer in that old maxim "If it ain't broke, don't fix it". It
has served me well throughout my long career in electronic service. It is a
fact that electrolytics *do* fail, and the location / function of particular
caps as a contributory factor to their failure, is well known. So by all
means check them if you have an ESR meter, but I am absolutely against just
changing every electro you can find, just because it *might* be faulty. In
my experience, the 'shotgun' approach can easily result in giving yourself a
bunch more grief than you originally had. With the best will in the world,
no matter how careful you are, it is staggeringly easy to put a cap in
backwards or get a solder whisker, and DC coupled amps are notoriously
unforgiving of such errors ...

Arfa
 
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