From: No.Spam@No.Where.com
"Zack" wrote in message news:i03g6k$624$1@new
.eternal-september.org...
> Fred wrote:
>
>>
>> "Zack" wrote in message
>> news:i00qho$phq$1@news.eternal-september.org...
>>> if you think that is old, I have an AX-630 which drops one or both
>>> channels
>>> intermittently. During the dropout, the audio is low and distorted with
>>> mostly just buzzing. Increasing the volume sometimes breaks through the
>>> distortion and the problem goes away for a time. The unit has an AST
>>> pack, so replacing just the amp (which otherwise sounds great when it is
>>> working) would require new speakers.
>>>
>>> Any ideas what might be wrong with it? Reseating the wires external and
>>> internal does not seem to result in a fix. Mostly happens while using
>>> the tuner, a TX-400U - which had a bad solder joint on the output that
>>> was fixed a few years ago.
>>
>>
>> Hey Zack,
>>
>> You say it mostly happens while using the tuner. I assume that's because
>> you mostly listen to the radio. But if it also happens when listening to
>> other
>> sources like CD, the problem has to be in the amp. So here's a plan:
>>
>> First thing to do is attack the switches & controls with Caig De-Oxit D5.
>> Push button switches often require removal of the front panel so you can
>> spray de-oxit into the switch where the shaft from the button enters the
>> switch. Spray and then cycle the switch 8 or 10 times.
>
> This sounds like a good idea.
>
>> Pots only need de-oxit if they scratch or cut out when rotated from limit
>> to
>> limit. If they're doing that, they need to have the de-oxit sprayed in
>
> The controls are in remarkably good shape and don't have any noise when
> rotated. Kudos to Yamaha on that front.
>
>> De-oxit is powerful stuff. You don't have to flood the area for it to
>> work - a
>> quick blast will do ya if it's aimed right. Given that both channels are
>> cutting out individually, it's about a 98% chance the de-oxit is going to
>> solve your problem if you do it right.
>>
>> But if that doesn't do it, then it's a matter of finding the bad
>> connection by visual inspection, mechanical shock (a tap here, a tap
>> there), thermal shock (freeze spray, heat gun), and/or good old fashioned
>> signal tracing with a
>> scope or signal tracer while the unit's misbehaving. Comparing the same
>> point in the bad channel with the working channel will tell you if what
>> you're seeing or hearing is OK or not.
>>
>> Keep in mind it's possible the bad connection is inside a transistor or IC
>> - freeze spray is good for finding that kind of problem.
>>
>> It really helps to have a schematic so you can see where the signal goes
>> next if de-oxit doesn't fix it. Given its age, you can probably find the
>> service manual for your amp on the internet in pdf form, possibly for a
>> few $ from
>> one of the many service manual purveyors out there these days. Google is
>> your friend.
>
> Ironically, Yamaha has since released a DSP amp with the same ID that has
> loads of chips and gagdetry my unit does not have. Makes Google harder to
> use.
>
> Thanks for the tips, they are something to try!
Zack,
I don't know what Yamaha's policy is concerning service info for non-warranty
servicers; I've been doing warranty work for them since they first went into
the
consumer audio business. You might be able to get the service manual from
Yamaha for a few bucks if you wind up needing it. It's worth a phone call or
an
email to find out.
Fred
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
|
