tone defeat "ON" on my Pre-amplifier from Denon, only one channel works

[eddy2003]

When switching the tone defeat on "ON" One channel doesn't work. I
suspect a faulty Opamp. Sound can still be heard but tone control is
only available for one channel. The switch measured OK. The amp I expect
is a 2068AD JRC 9302 (8 pins)but cannot find any information about it.
Is there a replacement part for it. I believe the IC is manuafactored by
NRJ (New Radio Japan) but their website doesn't give me the answer as
well.

Any help welcome. I don't have a replacement manual.

Ed
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[Jerry Greenberg]

eddy2003 wrote:

>When switching the tone defeat on "ON" One channel doesn't work. I
>suspect a faulty Opamp. Sound can still be heard but tone control is
>only available for one channel. The switch measured OK. The amp I expect
>is a 2068AD JRC 9302 (8 pins)but cannot find any information about it.
>Is there a replacement part for it. I believe the IC is manuafactored by
>NRJ (New Radio Japan) but their website doesn't give me the answer as
>well.
>
>Any help welcome. I don't have a replacement manual.
>
>Ed
>
>

You have to give them a call on the phone, and order the origional part
from them. This is their own, and I doubt you will find it anywhere else!

--

Jerry Greenberg GLG Technologies GLG
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[Sofie]

eddy2003:
There is a good chance that the problem is a bad "tone defeat" switch or a
bad electrolytic in the tone circuit..... before tearing things apart,
verify that the switch is really working.... and check the electrolytics.
If you really suspect the bad CHIP you can first swap it with the good
channel to verify that the chip is actually bad AND that the rest of the
"bad" channel works OK with the replacement chip from the "good" channel.
Then if the culprit really is the chip then you can step up your search for
a proper replacement.
That is the beauty of working with stereo amps...... there is redundant
circuitry that can be used in your troubleshooting procedures.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
--------------------------------------

"eddy2003" <eddy2003.n...@web2news.net> wrote in message
news:3522...@web2news.com...

[eddy2003]

Thanks Jerry and Sofie.

I did measured the switch and remove the cables and the connectors. As
the switch measured OK so I could only conclude that it might be the
Opamp. Measuring the resistors for L+R didn't gave me any result. Now
the good part. In awaiting the answers of the group I put all cables
back and switch it on again, and it WORKED again. It therefore looks
like it was a bad contact over the years corroded (did I spell this
right ?)

Sometimes the solution is so simple.

Thanks to all and this great newsgroup !

Sofie wrote:
> eddy2003:
> There is a good chance that the problem is a bad "tone
> defeat" switch or a
> bad electrolytic in the tone circuit..... before tearing
> things apart,
> verify that the switch is really working.... and check the
> electrolytics.
> If you really suspect the bad CHIP you can first swap it
> with the good
> channel to verify that the chip is actually bad AND that
> the rest of the
> "bad" channel works OK with the replacement chip from the
> "good" channel.
> Then if the culprit really is the chip then you can step
> up your search for
> a proper replacement.
> That is the beauty of working with stereo amps......
> there is redundant
> circuitry that can be used in your troubleshooting procedures.

--