Greetings All, I have an old reciever/amplifier, the Pioneer SX-434. My folks bought it back in 1973 or '72. I think. Anyway, it sounded great when I was in high school and then later when it somehow migrated to my house in the early '80s. Somewhere along the way it was relegated to the garage and then the basement in my new house. It has not been powered up in years, at least 15. But it worked great then. Now it has a chance to provide me with listening pleasure once again. In my machine shop. I need new speakers, I gave the old ones away. But before I hook up new speakers and plug in the iPod, is there anything I should ckeck first? Should I open it up and look for stuff coming out of electrolytic capacitors? Should it be run at a low volume for a period of time? I would love to have the thing working for me again. A little nostalgia. My dad, who will be 80 in a couple months, would be delighted to hear it when he comnes by to visit. He doesn't even know I still have it. Thanks, Eric
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Some friends who restore old equipment, insist that you should use a VariAC (Variable Auto Transformer) to bring the AC power up very slowly. This allows the electrolytic capacitors to reform.
Yes, some old components may have deteriorated, but quality of components used in the 70s was much better than of components from earlier years. You may need to spray some contact cleaner on switch contacts and inside volume controls, but chances are fairly good that it will work OK.
You might consider a place to put it where it'll be reasonably out of the way of metal chips, cutting fluid/coolant, etc.
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
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, 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
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. (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
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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.)
A general inspection won't hurt. The capacitors on something this old probably won't be physically leaky, but looking is cheap.
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.
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