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
halihó, hoztak egy kenwood kdc-5090ry tipusú autórádiót, amely a kijelzőn bekapcsolás után WAITING 4 (gondolom) hibakódot ír ki. Az elért forrasztásokat átforrasztottam, majd egyszer bekapcsolt. Azóta akármit csinálok vele, hiába, csak a kijelzön lévő hibakód (?) van. Estleg ha tudtok valamit erről, megköszönném.
Hello, I am in a repair KENWOOD KRF-X9995D.
Let me know if anyone is aware of how to reset the processor.
That is about a year ago I had the same problem with another amp of the same model!
So this is the second unit can not repair!
The main flaw is that the accumulation of around 1F 5.5V had spilled acid. was also in the same thing happened! ie it shows mute, but going into test mode, (having pressed the key "INPUT SELECTOR DOWN" and "POWER", the analog input works (but only in TEST).
Any help?
Thank you
KT-3300 analóg régi tunert javítok. Sajnos a kf ic meghalt benne, de a felirata elég furcsa / 6088s 4402 / tudja valaki mi lehet ez és mivel pótolható?