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Old 31st December 2011, 02:55 PM   #1
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Default Kenwood KAC 848

I powerd this amp up and checked for output.

Out of the B channels i get no sound

Out of the A channels i also get no sound so i checked to see if there was any DC on the outputs..


When i checked the speaker termianls for DC my meter was all over the place from 4 voltd of dc to 1 volt to 3 volts to 4 volts The DC on the output terminals just keeps pulsing all over the place .


Any ideas?
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Old 31st December 2011, 05:44 PM   #2
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Set all bias pots fully counter-clockwise. Measure the DC voltage across all of the emitter resistors. Do you find any with more than 0.000v DC on them?
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Old 31st December 2011, 05:45 PM   #3
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A lot of the kenwood amps have problems with broken solder connections on the bias transistors. Check those.
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Old 31st December 2011, 06:12 PM   #4
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Set the bias pots full counter clockwise and measured the voltage across the emitter resistors all of them have 0 volts across them..


I reflowed the solder on all of the bias transistors..


Amp still does the same thing
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Old 31st December 2011, 08:22 PM   #5
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0v isn't the same as 0.000v. Do you read 0.000v on every one of them?
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Old 31st December 2011, 08:27 PM   #6
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no 1 of them is pulsing voltages across it
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Old 31st December 2011, 08:39 PM   #7
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Ok replaced the emitter resistor that had pulsing voltage across it...


Now i get 0.000 V across everyone of them..


Amps speaker terminals still pulse DC voltage
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Old 31st December 2011, 09:44 PM   #8
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Was the resistor out of tolerance?

If not, the replacement should have the same voltage across it. Re-check.

If it was not out of tolerance, it may have told you which channel is causing the problem.
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Old 31st December 2011, 09:47 PM   #9
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Yes it was out of tolerance
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Old 31st December 2011, 10:31 PM   #10
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If no emitter resistor has any voltage across it, pull the rectifiers to see if the amp will power up.
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