Pioneer SX434 Tuner Repair
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PIONEER SX 434 Tuner Amplifier
PIONEER SX 434 Tuner Amplifier Repair.
This vintage Tuner Amp from Pioneer was made in the 1970s and was a very popular unit. Comprising of AM/FM Stereo Tuner, Amplifier with TAPE, PHONE and Auxilliary inputs, it was put to good use for many years until the FM Tuner part failed. The customer stored it away and bought a newer mini hi-fi. Having a clear out, he brought this to me for renovation and sale on e-bay.
Having repaired a few of these before, I discovered the FM front end mixer amplifier transistor had failed, going open-circuit. Fitting a more modern replacement transistor brought the FM back to life. I had also to replace the failed STEREO indicator bulb. I checked the electrolytics and found the ones in the power supply circuitry were leaking so replaced them with new. The rest of the unit checked out A-OK so I put it for sale on e-bay where it went very quickly.
The service manual for this unit did not describe the means of replacing the bulbs so I wasted a fair bit of time removing the front panel in an attempt to get at the bulbs, then discovered two screws were holding in the metal lamp holder behind the front tuning scale, removing these gave me full access. I've left that part in the video in case it helps anyone wishing to take that part off, but speeded it up.
Hope you enjoy the video.
Chas
Please Like and Subscribe to the channel: @chaslarge
You might also like to support me on Patreon: https://www.patreon.com/bePatron?u=43...
MUSIC:
Google Library:
Find Your Way Beat - Nana Kwabena
Can I Tell You a Secret - TrackTribe
GRAPHICS & ANIMATIONS:
End: https://pixabay.com/users/tommyvideo-...
SUBSCRIBE BUTTON Pixabay
https://pixabay.com//?utm_source=link...
CONTENT:
00:00 Introduction
00:30 The main fault, no FM Reception
01:15 A look at the FM front end circuitry
02:46 Introduce noise into the signal path to test the demodulator input
05:20 Checking the volts on Q2
06:48 Remove Q2
07:50 Test Q2 out of circuit
08:45 Finding an equivalent replacement using old equivalents books
11:00 Making the replacement fit by extending its legs
14:30 Testing the radio after fitting the replacement
15:35 Deciding whether to replace the Electrolytics in the power supply
16:40 Discovering the failed STEREO indicator lamp
17:22 Beginning diagnostic tests
18:18 Yes, the bulb has failed
18:30 Beginning to waste a lot of time removing the front panel to change that bulb. It's not necessary.
20:50 EUREKA! I just need to remove the bulb housing behind the front tuning dial. Why was this not in the Service Manual?
22:47 Removing the bulb housing and testing
24:10 Removing the bulb and fitting the replacement
33:04 Testing if it lights up now - YES!
33:28 Wrapping up the repair. Thanks for watching.
This vintage Tuner Amp from Pioneer was made in the 1970s and was a very popular unit. Comprising of AM/FM Stereo Tuner, Amplifier with TAPE, PHONE and Auxilliary inputs, it was put to good use for many years until the FM Tuner part failed. The customer stored it away and bought a newer mini hi-fi. Having a clear out, he brought this to me for renovation and sale on e-bay.
Having repaired a few of these before, I discovered the FM front end mixer amplifier transistor had failed, going open-circuit. Fitting a more modern replacement transistor brought the FM back to life. I had also to replace the failed STEREO indicator bulb. I checked the electrolytics and found the ones in the power supply circuitry were leaking so replaced them with new. The rest of the unit checked out A-OK so I put it for sale on e-bay where it went very quickly.
The service manual for this unit did not describe the means of replacing the bulbs so I wasted a fair bit of time removing the front panel in an attempt to get at the bulbs, then discovered two screws were holding in the metal lamp holder behind the front tuning scale, removing these gave me full access. I've left that part in the video in case it helps anyone wishing to take that part off, but speeded it up.
Hope you enjoy the video.
Chas
Please Like and Subscribe to the channel: @chaslarge
You might also like to support me on Patreon: https://www.patreon.com/bePatron?u=43...
MUSIC:
Google Library:
Find Your Way Beat - Nana Kwabena
Can I Tell You a Secret - TrackTribe
GRAPHICS & ANIMATIONS:
End: https://pixabay.com/users/tommyvideo-...
SUBSCRIBE BUTTON Pixabay
https://pixabay.com//?utm_source=link...
CONTENT:
00:00 Introduction
00:30 The main fault, no FM Reception
01:15 A look at the FM front end circuitry
02:46 Introduce noise into the signal path to test the demodulator input
05:20 Checking the volts on Q2
06:48 Remove Q2
07:50 Test Q2 out of circuit
08:45 Finding an equivalent replacement using old equivalents books
11:00 Making the replacement fit by extending its legs
14:30 Testing the radio after fitting the replacement
15:35 Deciding whether to replace the Electrolytics in the power supply
16:40 Discovering the failed STEREO indicator lamp
17:22 Beginning diagnostic tests
18:18 Yes, the bulb has failed
18:30 Beginning to waste a lot of time removing the front panel to change that bulb. It's not necessary.
20:50 EUREKA! I just need to remove the bulb housing behind the front tuning dial. Why was this not in the Service Manual?
22:47 Removing the bulb housing and testing
24:10 Removing the bulb and fitting the replacement
33:04 Testing if it lights up now - YES!
33:28 Wrapping up the repair. Thanks for watching.
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