Hello,
Last week I picked up a nice Kenwood KA-3500 40watt intergrated amplifier in pretty good shape.
Upon using it a bit more, I noticed a bit of distortion at high volume, more so in the left channel. I checked the DC offset at the speaker terminals, and the L channel said 100 mV, while the R was 25 mV. I understand this isn't so good for the L channel at least, but unfortunately this amp doesn't have any DC offset adjustments. Am I right in saying that to fix this I'd have to replace the output transistors?
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On a related issue, in the service manual I found the section on BIAS adjustment, and I read online how it can affect the DC offset. So I hooked up my voltmeter to the test points, and I got 4 mV on the L, and 8 mV on the R. In the manual it says should be 40 mV.....(!). Is there something wrong here? I tried carefully adjusting them, but they only go to 30mV with the pots fully on, this doesn't seem right to me.
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I compromised at 20 mV BIAS for both channels, and now the DC offset is 50 mV for L, and 5 mV for R, which is better, less than half what they were. I'm wondering, will I damage anything doing this, should I put them back to where they were?
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The service manual is on site here.
Let me know if you want me to upload an english copy of the Owner's Manual, it has a better schematic in it all on one page, easier to read.
I've also included some pictures. They're not my actual unit, but mine is exactly the same, but less dusty.
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Thanks for reading this. Many thanks in advance, and have a peaceful Palm Sunday! :taps2:
Bellarmine
Sziasztok!
Most került hozzám ez a készülék, bekapcsolás után szól rendesen. Egyszer csak elkezdi kiírni ATT ON, de ekkor meg le némítja a rádiót. Ezt ismétli folyamatosan, most átnéztem de semmi elváltozást nem találok benne. Merre keresgéljek az előlapban, vagy az alaplapján?
Üdv mindenkinek!
KDC-W312 tip. cd-rádió E-99 hibakódot produkálja.Nem pörgeti a lemezt olvasáshoz.
Merre induljak!
Szép estét mindenkinek!
Tisztelt Szakik!
Egy ismerősöm fordult hozzám ezzel a kéréssel, hogy milyen módon (módokon) lehet ezt itthon beüzemelni.
Kiindulási alap hogy a legegyszerűbben és a legolcsóbban.(meg persze legyen üzembiztos)
Ehhez kérnék tippeket.
Amerikai eredetű készülék, 120V 60Hz, rajza a itt a tanyán, 13 oldal a táp rész.
Köszönettel D A