Pioneer SX434 Tuner Repair

[@martyjewell5683]

Interesting repair video on the little Pioneer. The SX-434 was my first "component" receiver in 1975, it was swell. All the basic features for quality sound and "thrusting" 15wpc, it was quite good for a small apartment with efficient speakers. Gotta love that mid '70's blue back lit dial scale and red STEREO lamp. It just oozes nostalgia. I currently use an SX-434 in my 900+ cu/ft kitchen system. It powers a Nakamichi BX-1 cassette deck and two pairs of speakers; Synergistics S12B and Boston Acoustics A-40's. The SX-434 easily drives a 4 ohm load. Nice looks and a heavy sucker weighing in at nearly 20 lbs, it's freakin' boss.

[@ChasLarge]

Yes, a nice little amp. In fact, it bounced back after being sold as one of the PHONO Pre-amp transistors had failed.

[@martyjewell5683]

@@ChasLarge- still though, that these SX-434 receivers are nearing the fifty year old mark I think they still perform quite well if kept in good working order. Even in an averaged size room, used with efficient speakers, if you keep the volume reasonable the SX-434 can be very satisfying. All it needs is a strobe, lava lamp and black light, fuhgeddaboudit.

[@rebokfleetfoot]

had one like that in the 80's, i had a very good FM receiver

[@ChasLarge]

The FM receiver in this model were very good, being passive components all in metal cans.

[@DrHarryT]

I repaired one similar for a girlfriend in the mid 80's. it had a power board on the top in the middle behind the display and a power regulator transistor [TO-220] that developed a cold solder joint on one of the legs.

[@ChasLarge]

Yeah, DJ's were common in these earlier PCBs, soldered by passing the board over a hot bath of solder.

[@norfenden]

Hi Chas, I've got one of these and the R channel (on both Phono and AUX settings) has become distorted (especially with an increase in volume)... L channel fine .... I've tried swapping out cables and speakers - but problem still persisting on R channel - any ideas? I've tried pressing Tape Monitor switch in and out a few times to clean pod - but again - no luck! Cheers!

[@ChasLarge]

Is it distorted on the Radio as well?

[@norfenden]

From what I can pick up on AM it doesn't seem to affect radio@@ChasLarge

[@ChasLarge]

ODD. The inputs all go through the FUNCTION Switch, so I would have expected the Radio to be affected in the same way. Have you cleaned / deoxified the function switch contacts? Check for loose wires there too.

[@norfenden]

I'll open it up tonight and have a look tonight - though I am a complete novice! Is there a way I can share a video with you of the audio?@@ChasLarge

[@ChasLarge]

@@norfenden you can email it to me: [e-mail]

[@RobertHewitt-fy4eg]

Hi i've brought a pioneer SX 434 working FM and AM both speakers working fine but only left speaker working when switching to phono for turntable any idea thanks

[@ChasLarge]

Mode selector switch contacts.

[@RobertHewitt-fy4eg]

Thanks for the reply back i'll clean contact's i've also going to replace bulbs one of them has blown

[@sami1773]

Hi , i have Pioneer SX 434 but the "stereo" light bulb doesn't work. The light bulb is not faulty. I don't hear stereo sound but mono in FM. It could be HA1156 ? what do you say? Thank you. Sam

[@ChasLarge]

It is possible, have you checked the working voltages? Do you get a strong signal on the meter for an FM stereo station? I would be inclined to check the primary rf amplifier transistors like the one I found in the video, they can go low gain.

[@sami1773]

@@ChasLarge Ok , yes I get a strong signal on the meter FM. I need to control the tensions better...Thank you. I hope to let you know news

[@sami1773]

@@ChasLarge I replaced the HA1156 integrated circuit and the stereo works! ok thanks