DIYbanter - Advice sought Pioneer SX-434

wrote:
Now it has a chance to provide me with listening pleasure once again.
In my machine shop.

You might consider a place to put it where it'll be reasonably out of
the way of metal chips, cutting fluid/coolant, etc.

But before I hook up new speakers and plug in the iPod, is there
anything I should ckeck first?

Here's what I'd do...

Take off the lid and just look around. Tilt it and see if any loose
stuff falls out - parts that belong in there, or old wasp nests, or
anything like that. See if anybody spilled something in it a long time
ago.

Use a "can of air" pressurized duster and gently blow out the dust that
has probably accumulated, using short bursts on the valve. Do this to
the circuit board(s) on the inside, and also shoot a little air into
the connectors on the back panel, especially the RCA jacks. If you
don't have a "can of air" already, get whichever one is cheapest at the
general store or office supply store. Don't use a shop air hose for
this job.

Operate all the controls - bass, treble, volume, the speaker switches -
a few times through their full range. They might be stiff at first but
then get a little easier with use; that's OK. If something is really
incredibly hard to get moving, don't force it - but you may have to
work on or replace that control or switch.

Hook up some speakers. There are scans of the original sell sheet at
http://www.audiokarma.org/forums/sho...d.php?t=446830 , which shows
that the headline was "15 W x 2", and the fine print is 15 W into 2
speakers at either 4 or 8 ohms each.

Hook up a few feet of any kind of wire to the "hot" terminal of the 75
ohm antenna connection. Hang the wire up in the air if you can.

Turn the volume all the way down. Put the source selector on "FM tuner"
and set the speaker switches so that your speakers should be on. Put
everything else in the middle of its range.

If you want to be really careful, wire up a light bulb socket in
*series* with an outlet. Plug the receiver into the socket, then start
with a 40 W or so incandescent lamp in the socket. (Compact
fluorescent, LED, and regular fluorescent won't work.) If the lamp goes
full bright the second you switch on the receiver, there is probably
some problem in the receiver. Otherwise, switch off, and try maybe a
100 W lamp. If that one is OK, then power the receiver as normal,
directly from the wall outlet. Details at
http://www.repairfaq.org/sam/tshoot.htm#tshslt . (This is the cheap
alternative to using a Variac.)

Hopefully it will come up and you will get either a radio station or
static out of the speakers. Tune in a station if needed and see how it
sounds.

Try the bass, treble, and volume controls over their ranges. If any
of them produce a "scratchy" sound in the speakers, make a note of it.
Turn off and unplug the receiver and use some control cleaner on those
controls... sometimes it's easiest to get it in there from the back
side of the control, sometimes from the front. See
http://www.repairfaq.org/sam/audiofaq.htm#audnisc for more.

The selection of control cleaner is just like selecting motor oil or
cutting oil - ask 10 people, get 12 answers, and 4 of the 10 people will
be ready for a fistfight or worse with another 4 of the 10 people. :) I
don't do this for a living, but I use some "TV tuner cleaner" from Rat
Shock, and it seems to do OK the few times I have used it. (There will
now be 10 posts saying I am an idiot for using that cleaner in this
application.)

Should I open it up and look for stuff coming out of electrolytic
capacitors?

A general inspection won't hurt. The capacitors on something this old
probably won't be physically leaky, but looking is cheap.

Should it be run at a low volume for a period of time?

I wouldn't turn it up full blast one second after you turn the power on,
but if it runs OK at moderate volume, then crank it on up. You might
run it for an hour or so with the volume at 1/2 to 2/3 of full and check
that nothing is getting "too hot" and that it doesn't start behaving
strangely.

Matt Roberds