Pioneer QX-949 Quad amp....

Archived from groups: alt.audio.equipment,rec.audio.marketplace,rec.audio.tech,sci.electronics.repair (More info?)

Ahhh, finally something from my time and days. I will say at first, that I
have not worked on this model, but am extremely experienced with this era of
electronics. It seems you have a simple problem, since you can tap it and
it will work. I would say, also, it is a bad solder joint. Most of the
time on the older units, the ones with all the wires, they eventually work
them self's free from the years of being run. Meaning that the heat from
them running, and then cooling off, will eventually break them free from the
PC board. But first thing I would do is clean all the pots and switches.
Get yourself some tuner cleaner (preferably one with a lubrication agent in
it, you can usually find this at your local Radio Shack, or part store.) It
will clean them out, and if this isn't the problem, then at least you know
that they are clean when you do solve the problem. Sorry I can't be more
help, but with out it sitting in front of me, I can't see the actual unit.
Maybe someone else can look at the same pix I looked at and give a more to
the point answer http://www.classic-audio.com/pioneer/pics/i_qx949.jpg What
I would do personally, and remember, I am experienced at working on the
older units. But I would take the top off, and turn it on. Take a Dowel
rod, or something similar, that is non conductive, and LIGHTLY touch the
wires, and the individual PC boards, till you find the one giving you the
problem (Reason I say lightly is because if you tap too hard, it could
vibrate to the board or wire that is in fault). Then inspect them for lose
or broken connections. Now, like I said, it is hard to say exactly what it
could be, with out actually having the unit in front of me, but this is the
way I would go to trouble shoot the problem. HOWEVER, being that I don't
know your experience in electronics, I do urge you to use caution. And if
your experience in electronics is little to none, I urge you to take this
unit to a qualified tech, dispose of it in the proper manner, or just put up
with the problem till the unit expires.

That's my story, and I'm sticking to it,
hope that's helps.
Rick

"Deke" <denkell1@starband.com> wrote in message
news:sI5Bc.567$J82.264@fe25.usenetserver.com...
> This monster was recently given to me by a woman getting rid of her late
> husbands "junk". It hasn't been used for years, but it fires up, all the
> lights work, and the quad display works. All the controls are dirty,
> but they work. Problem is, the right front channel is weak until its been
> on about 5 minutes, then it pops on and off. I suspect bad solder joints,
a
> gentle tap on the top will bring the right channel back up for a bit.
Rear
> channels are functional also.
> Before I put it on the bench and get started on the basics, anyone have
any
> experience with these units? The last one I saw (while drooling heavily),
> was in the Navy exchange on Guam back in 72 or 73.
> Want to get it fully functional, and replace a Proton 930 in the computer
> room
> with the Pioneer. Any info on known faults or weaknesses would be
> appreciated.
> TIA
>
> Deke
>
>
> --
> "Any sufficiently advanced technology is indistinguishable from
> magic."
>
> Arthur C. Clarke (1917 - ), "Technology and the Future"
>
>
>
>

Archived from groups: alt.audio.equipment,rec.audio.marketplace,rec.audio.tech,sci.electronics.repair (More info?)

Thanks for the input Rick, I've been working in the electronics field, both
private and military, since the late 60's.
I'm really anxious to get into this amp, partially out of curiosity, and
because I want to revive the old beast. And I have several cans of Channel
Master "Shield" left (now illegal, but the ultimate cleaner/lubricant), so
the controls wont be a problem. I've ordered the service manual.
Just wanted any input from anyone else that may have worked on one of these.
Thanks again.

Deke
"Ricky Eck" <lizard7151971@verizon2.net> wrote in message
news:AC7Bc.4181$mG4.4046@nwrddc03.gnilink.net...
> Ahhh, finally something from my time and days. I will say at first, that
I
> have not worked on this model, but am extremely experienced with this era
of
> electronics. It seems you have a simple problem, since you can tap it and
> it will work. I would say, also, it is a bad solder joint. Most of the
> time on the older units, the ones with all the wires, they eventually work
> them self's free from the years of being run. Meaning that the heat from
> them running, and then cooling off, will eventually break them free from
the
> PC board. But first thing I would do is clean all the pots and switches.
> Get yourself some tuner cleaner (preferably one with a lubrication agent
in
> it, you can usually find this at your local Radio Shack, or part store.)
It
> will clean them out, and if this isn't the problem, then at least you know
> that they are clean when you do solve the problem. Sorry I can't be more
> help, but with out it sitting in front of me, I can't see the actual unit.
> Maybe someone else can look at the same pix I looked at and give a more to
> the point answer http://www.classic-audio.com/pioneer/pics/i_qx949.jpg
What
> I would do personally, and remember, I am experienced at working on the
> older units. But I would take the top off, and turn it on. Take a Dowel
> rod, or something similar, that is non conductive, and LIGHTLY touch the
> wires, and the individual PC boards, till you find the one giving you the
> problem (Reason I say lightly is because if you tap too hard, it could
> vibrate to the board or wire that is in fault). Then inspect them for
lose
> or broken connections. Now, like I said, it is hard to say exactly what
it
> could be, with out actually having the unit in front of me, but this is
the
> way I would go to trouble shoot the problem. HOWEVER, being that I don't
> know your experience in electronics, I do urge you to use caution. And if
> your experience in electronics is little to none, I urge you to take this
> unit to a qualified tech, dispose of it in the proper manner, or just put
up
> with the problem till the unit expires.
>
> That's my story, and I'm sticking to it,
> hope that's helps.
> Rick
>
> "Deke" <denkell1@starband.com> wrote in message
> news:sI5Bc.567$J82.264@fe25.usenetserver.com...
> > This monster was recently given to me by a woman getting rid of her late
> > husbands "junk". It hasn't been used for years, but it fires up, all
the
> > lights work, and the quad display works. All the controls are dirty,
> > but they work. Problem is, the right front channel is weak until its
been
> > on about 5 minutes, then it pops on and off. I suspect bad solder
joints,
> a
> > gentle tap on the top will bring the right channel back up for a bit.
> Rear
> > channels are functional also.
> > Before I put it on the bench and get started on the basics, anyone have
> any
> > experience with these units? The last one I saw (while drooling
heavily),
> > was in the Navy exchange on Guam back in 72 or 73.
> > Want to get it fully functional, and replace a Proton 930 in the
computer
> > room
> > with the Pioneer. Any info on known faults or weaknesses would be
> > appreciated.
> > TIA
> >
> > Deke
> >
> >
> > --
> > "Any sufficiently advanced technology is indistinguishable from
> > magic."
> >
> > Arthur C. Clarke (1917 - ), "Technology and the Future"
> >
> >
> >
> >
>
>

Archived from groups: alt.audio.equipment,rec.audio.marketplace,rec.audio.tech,sci.electronics.repair (More info?)

The speaker relay contacts may need cleaning. This model uses those little
blue Sanyo coupling caps in the tone/pre and main amp input areas; they had
lots of problems with those.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Deke" <denkell1@starband.com> wrote in message
news:sI5Bc.567$J82.264@fe25.usenetserver.com...
> This monster was recently given to me by a woman getting rid of her late
> husbands "junk". It hasn't been used for years, but it fires up, all the
> lights work, and the quad display works. All the controls are dirty,
> but they work. Problem is, the right front channel is weak until its been
> on about 5 minutes, then it pops on and off. I suspect bad solder joints,
a
> gentle tap on the top will bring the right channel back up for a bit.
Rear
> channels are functional also.
> Before I put it on the bench and get started on the basics, anyone have
any
> experience with these units? The last one I saw (while drooling heavily),
> was in the Navy exchange on Guam back in 72 or 73.
> Want to get it fully functional, and replace a Proton 930 in the computer
> room
> with the Pioneer. Any info on known faults or weaknesses would be
> appreciated.
> TIA
>
> Deke
>
>
> --
> "Any sufficiently advanced technology is indistinguishable from
> magic."
>
> Arthur C. Clarke (1917 - ), "Technology and the Future"
>
>
>
>

Archived from groups: alt.audio.equipment,rec.audio.marketplace,rec.audio.tech,sci.electronics.repair (More info?)

The headphones are run off of the main amp - as they are in most amps. Just
limiting resistors added. Doesn't eleiminate main amp or relay problems.

Try tapping on the relay, when you get the chance, and see if that affects
your problem.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Deke" <denkell1@starband.com> wrote in message
news:ZHfBc.595$J82.36@fe25.usenetserver.com...
> Alan and Mark Z.....Thanks for the input. I'm forcing myself not to even
> crack the case until I get the service manual, plus there's a reel to reel
> spread out on the bench right now, and its a small bench.
> Judging by its weight, 52 pounds, I think my first project will be to a
make
> a wooden jig to hold it at a good angle to get to the bottom of the main
> circuit board.
> I noticed the right channel sound cuts off using headphones, so its
probably
> in the pre-out section. Have to wait to get the schematics to see what
the
> commonalties are.
> Thanks again! Now to get the Sansui SD-7000
> out of test mode, put back together, and off the bench.
>
> Deke
>
>
> "Mark D. Zacharias" <mzacharias@yis.us> wrote in message
> news:2jl8prF12orm0U1@uni-berlin.de...
> > The speaker relay contacts may need cleaning. This model uses those
little
> > blue Sanyo coupling caps in the tone/pre and main amp input areas; they
> had
> > lots of problems with those.
> >
> > Mark Z.
> >
> > --
> > Please reply only to Group. I regret this is necessary. Viruses and spam
> > have rendered my regular e-mail address useless.
> >
> >
> > "Deke" <denkell1@starband.com> wrote in message
> > news:sI5Bc.567$J82.264@fe25.usenetserver.com...
> > > This monster was recently given to me by a woman getting rid of her
late
> > > husbands "junk". It hasn't been used for years, but it fires up, all
> the
> > > lights work, and the quad display works. All the controls are dirty,
> > > but they work. Problem is, the right front channel is weak until its
> been
> > > on about 5 minutes, then it pops on and off. I suspect bad solder
> joints,
> > a
> > > gentle tap on the top will bring the right channel back up for a bit.
> > Rear
> > > channels are functional also.
> > > Before I put it on the bench and get started on the basics, anyone
have
> > any
> > > experience with these units? The last one I saw (while drooling
> heavily),
> > > was in the Navy exchange on Guam back in 72 or 73.
> > > Want to get it fully functional, and replace a Proton 930 in the
> computer
> > > room
> > > with the Pioneer. Any info on known faults or weaknesses would be
> > > appreciated.
> > > TIA
> > >
> > > Deke
> > >
> > >
> > > --
> > > "Any sufficiently advanced technology is indistinguishable from
> > > magic."
> > >
> > > Arthur C. Clarke (1917 - ), "Technology and the Future"
> > >
> > >
> > >
> > >
> >
> >
>
>
>