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Old 7th Nov 2021, 3:51 pm   #145
DMcMahon
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Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 4,443
Default Re: Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

Sounds like you could do with a new replacement cartridge which sometimes will come with the push on connectors. Apart from the corroded connections causing a potential problem, the cartridge itself may be defective (in terms of giving a good output signal) as referenced in Post 82.

No guarantee though that a replacement cartridge will restore/give good normal sound, especially as the operational status of the homebrew kit was unknown from the beginning.

There are a number of other factors that may contribute to poor sound including :-

1. The low power supply voltage. The audio amplifier IC/chip on the PCB is believed to be a SL403, which requires an 18 volt supply, it may not perform well at the lower voltage. We still do not know what actual AC voltage is arriving at the bridge rectifier from the mains transformer 2 x 6.3V secondary outputs wired in series, request for measurement reference Post 121.

2. If the original braided co-axial cable has been replaced by a non screened cable then hum could result.

3. No system earth connection could result in hum, particularly if the record deck metalwork is not earthed, reference Post 137.

4. The PCB unsoldered 3 pins (one is the input from the power supply) reference Posts 79/80 with Posts 84/86 referencing 6 pins.

5. The smoothing choke maybe be dropping too much voltage and is not really required anyway so best to remove it, reference Post 137.

6. The output transformer which is believed to be there to match the amplifier output impedance of 7.5 Ohms to the 3 Ohm loudspeaker impedance (reference Post 110) if not correctly wired/configured could be an issue. Request for details of the transformer identification number reference Post 113.

7. The 2 wires connecting the volume control to the PCB if swapped over would effectively kill the sound, reference request for confirmation of wiring Post 59.

David

Last edited by DMcMahon; 7th Nov 2021 at 4:00 pm. Reason: Line # 7 added
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