Pioneer SA-508: Mains Hum On Left Channel
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- Опубликовано: 11 сен 2024
- This thing is so old (1979), that it most likely needs to be re-capped (shotgun replace all electrolytic capacitors). Honestly, I can't justify the time and cost involved to do this.
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I have one of these amps. I replaced the two large, 8,000 uf smoothing capacitors, one of which was visibly bulging. I used two ELNA 8,200 uf replacements because 8,000 uf caps are no longer made. These two caps smooth the rectified DC from the mains; they remove the AC ripple that causes hum. I also replaced the other electrolytics in the power supply. My amp now sounds far better, particularly the bass, and I'm very happy with it. Have fun. :)
That's fine, but the hum is only on one channel. The supply is common to both, so its not the filter caps.
One of my favourite things to do is replace the 1 capacitor causing the fault ;)
Also if the current ebay listings reflect what this thing is worth.... maybe worth another crack
That involves finding said capacitor causing the fault... lol. I checked all transistors in that stage, seemed fine, too. I don't own the unit, my housemate does; he said he'll decide if it's worth his time recapping it. I just gave him my opinion on what would fix it (I hope).
@@AstrosElectronicsLab I hear ya dude! There has to be someone on a forum or youtube channel who'd know exactly what part is causing the fault....
I guess you need in-circuit ESR-meter. It's much faster to test any old device with it.
I have an SA-608 and it has a slight buzz from the transformer (physical not in the audio). They're nice units and worth a tinker. Let me talk to your housemate and convince him to have it sorted out, LOL!
Could you have traced back from the L channel O/P with an oscilloscope to see where the ripple stopped & started?
The amplifier was repaired by someone else. One of the main filter caps was physically leaking. It's now working fine 🙂
@@AstrosElectronicsLabЗдравствуйте,хочу спросить у меня такой аппарат Pioneer SA 508, почему когда я его слушаю,у него звук металлический,аж уши устают,я его купил с рук, хозяин говорил что то менялось в нём,но не понятно, слушаю через акустику S-90B,но на полную мощь не включаю, где-то на без пятнадцати.Спасибо.
@@user-by4ds8fh2z I can't read Russian.
@@AstrosElectronicsLabso the cap leaked in such a way it caused noise on one channel? The filter caps affect both channels equally, with one smoothing the positive rail and the other the negative. If only using a voltmeter to troubleshoot, the best approach is to check voltages. Get the schematic from hifiengine. A lot of these schematics do show voltages making your life easy.
@@ctrlzyx2 already had the schematic. The left channel amp was closest to the leaky cap.