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Pioneer SX-434

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nocturnal07

New Member
hello, i own a 36y old Pioneer SX-434 with a pair of also 36y old vintage speakers wich model i don't know atm (i have it noted down somewhere 'cause they don't say)

the reason i registed was to ask how to correct the fm tuner
(ex: 104.3fm radio was at 106.0 on the pointer), after a long afternoon i managed to figure myself and works like a charm now :thmbsp:

but since i'm already registed might aswell ask, i really love this thing and been in the family since it was bought together with the speakers, i opened it today, and the capacitors and boards all look clean and leak free, and lights are good, i use it regularly connected via aux. port to my mp3 and has a great sound, only some crisp on bass heavy music, wich i have to tone down the bass

is there anything maintenance wise i should do?
also it tends to heat up quite a bit, specially in the summer, any worries with that?

and finally is 15w per channel enough if i wanted some new speakers?
it's for a living room with 3.80mx5.0m (couch is roughly 3.5m of the speakers)

thanks in advance
ps: found this forum while looking for info on said amp
 
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For your viewing pleasure :


PioneerSX-434front.jpg



PioneerSX-434rear.jpg
 
Get some DeoxIt and give the pots and switches a good cleaning.

As for power, it really depends on the amp. I've got a Sansui AU555A rated at 25 watts @ 8ohms, and it powers my IMF TLS 50 II's just fine (big speakers) which are fairly power hungry (83db efficient). I'd say power wise it gives me the same impression that my Pioneer Elite VSX37-TX does, which is rated at 100 watts @ 8ohms.. so that's why I say it really depends on the amplifier.
 
they really are clean :p, box was never opened until today, i'll get some pics as soon as i get my camera, only problem are some scratches on the outside

well, im kinda of a newbie but learning on the audio world, is this amp any good?
im not looking for loud sound btw, looking mostly for quality sound

thanks to both, very nice paper :thmbsp:
 
ok, so i got the full system specs (found the 36y old proof of purchase)

bought in 1976 for what i would call a shitload of money back then:
1x Pioneer SX-434 Amplifier
2x Pioneer CS-E320 speakers
1x Pioneer SE-305 Headphones

both speakers have problem with the Woofer, where a loose cable that connects the woofer jumps a lot and makes weird sounds (ghetto fixed), and tends to distort on some heavier metal tracks

Headphones haven't been used in years but tried today and they work if i put the cable in a specific position on the phones
edit - phone cable is broken inside, common problem, easy fix, i like the sound of them
in comparison with my senheiser cx-300 II the cx win in bass by a mile, and have pretty good sound overall, but feels sorta condensanted, like all the sounds squeezed in, the Pioneer altought meh bass, has very nice high and mids, and a clear difference between them wich i liked

Amp, working great other than a few scratches:)

pics:
http://imgur.com/a/jpmHs#0
 

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Sounds like it needs a recap. I bought mine in April 1975. I've since recapped it, as it was getting muddy sounding, the high's were fading, and it was getting a bit of hum. Real easy to recap.

The amp alignment (idle current) is adjusted one of two ways. Cut the jumper or not. depends on the reading you get against what the manual says.

Unless you have speakers that are highly efficient, (>96db) you'll be pushing the 434 a bit hard in your 3.5m x 5.0m room. a 3M x 3m bedroom or study is a better environment for it. I run mine with Sansui SP-200's (98db) and it's fine in a 3.9m x 5.8m room.

It shouldn't get hot. The 434 is a fairly cool (temp) receiver. It'll get slightly warm when pushed. If it's running hot, recap it and check the amp alignment. Make adjustments as necessary. Shouldn't cost more than $20.00 parts wise(caps, and transistors if needed) from Mouser.

Larry
 
been alot busy lately to hop buy here, but sh*t hit the fan today :worried:

out of nowhere while listening to radio i get a chemical burning smell, couple minutes later i realize it's comming from the amp even tho it's still running on 1 speaker (the other was disconnected for unknow reasons, i didnt even notice until i checked), after disassembling everything and looking for burn spots i find nothingm but after i reconnect everything both right channels are down, but both left work, altought it enables me to hear music, the sound sounds like mono

any ideas what could have happened?
 
Ugh.

Well, I think you've cooked her.

I used to have a SX-424, slightly older but essentially the same unit. Excellent, warm sound.

I think you've been overdriving the unit, by the sounds of things. You have spoken of woofers moving rather dramatically and of some distorted sound. I don't know what you're using for speakers, either...the load that speakers place on an amp and how they are hooked up makes a big difference. Also, these amps do not tolerate having the speaker wires for + and - touch while the amp is on, so that may have played a factor in it's burning up.

You *may* be lucky. My 424 had fuses on the back for not only the power but for each speaker channel. If your 434 has them, replace them with the EXACT VALUE SHOWN ON THE FUSE. Do not substitute something that is 'close'.

If it's not the fuses, either have the unit serviced by a competent tech or yell for help here. It's worth fixing. Modern day equipment does not compare at all, unless you are prepared to drop a LOT of cash.

Never ever hook up the speakers with the power on. Always make sure the polarity is correct. If you hear distortion, turn it down...distortion means clipping, and it kills amps and speakers. If it's not loud enough, consider more efficient speakers. Always make sure that your speaker load does not dip below 4 ohms -- either use one pair of 8 or 4 ohm speakers, or two pair of 8 ohm speakers. Using two pair of mixed ohm between 8 and 4 could spell disaster. These are the basic rules of vintage receivers. Gotta remember that these were made back in the day when nothing was plug and play, where having some general audio knowledge was a pre-requisite to having a good stereo, and where everything was built by people, not robots and computers. As such, some care must be exercised.
 
A couple of nit-picks about common misconceptions.

Caps don't leak liquid, they leak voltage, you won't see anything.

There are only to channels, Left and Right. A and B, Main and Remote, 1 and 2 are just more connections to the same channel.


It sounds like you blew out one channel.
Where did the speaker wire get disconnected? At the speaker? So the wires could have been touching each other? That could blow out the output transistors/module.

Its going to need repair. Someone with skills and tools and knowlege.

A problem is that the SX-434 is not worth much, so paying a lot to repair it is questionable. But, if you are in a place where other things are rare or you have a special affection to this unit, that figures into the situation.

If you can repair it yourself, that helps, parts are not real expensive.
 
got a special affect for it, but no way im gonna drop money to fix it

atm only A and B left work, before i had one speaker connected to A right, and another to B left, the speakers are low power pioneer bought with the amp

ok, both channels working now after i swaped fuses (no spares and they're the same) but the right one sounds bad and distorted, completelely puzzled now
thanks for the help
 
small update
this thing was never open before, and it doesn't look like a burnt hole to me, but is that normal?

looks big :saywhat:
 

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nocturnal07 said:
small update
this thing was never open before, and it doesn't look like a burnt hole to me, but is that normal?

looks big :saywhat:
Click to expand...

Are you sure nobody was in there? That doesn't look like a factory mod to me...:no: Can you get a top pic of that area?
 
Can't say for sure, but besides that hole, looks like some possibly questionable solder joints in groups of three at bottom-left, bottom-center and bottom-right. Transistors replaced at some point perhaps...?
 
unless my older brother is lieing or my dad forgot, it was never open before since 1976, even if it was open, a soldering iron was never there, since both have 0 soldering skills (like me)

top pic like this, or the other side of the pcb?
 

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i very much doubt it came from the factory like that .. only way it would have is if someone was going to lose wages or be sacked for breaking it .
 
well, i'll dig into it further tomorrow, for some reason i can't push that piece out and take a pic of the other side, but the soldering on bottom, center/left/right are these in the next pic

no idea what they are
 

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nocturnal07 said:
well, i'll dig into it further tomorrow, for some reason i can't push that piece out and take a pic of the other side, but the soldering on bottom, center/left/right are these in the next pic

no idea what they are
Click to expand...

they are the main outputs and temp. sensor
 
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