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Old 12th December 2015, 08:14 PM   #1
moss99 is offline moss99  United Kingdom
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Default audiolab 8000p has no output

Hi all , was wondering if you guys could help me out with your expertise ,.

I have an audiolab 8000P for my rear speakers (so never really driven hard) a few weeks ago i noticed the power led was out and found the fuse was blown , i replaced the fuse , power light came back on and i didnt think any more of it until i watched a movie ,,.. !! .. no sound from rear channels .
anyway i have taken the covers off and all looks ok ive taken some pics and some voltage readings from the main output transformers ,, again see photo (sorry about the crudeness of paint , lol ) anyway, not too sure where to go from here ,, ? IMG_6145.jpg

IMG_6148.jpg

IMG_6149.jpg



any help appreciated ..
thanks
mark.
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File Type: jpg IMG_6153 (1).jpg (793.1 KB, 173 views)

Last edited by moss99; 12th December 2015 at 09:13 PM.
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Old 12th December 2015, 09:10 PM   #2
moss99 is offline moss99  United Kingdom
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these are the voltages IMG_6153 (1).jpg
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Old 12th December 2015, 09:59 PM   #3
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Location: Belgrade RS
Check SM: Audiolab 8000P Manual - Stereo Power Amplifier - HiFi Engine
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Old 13th December 2015, 11:27 AM   #4
moss99 is offline moss99  United Kingdom
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ok . i have schematic file . but not too sure what i should be checking
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Old 13th December 2015, 11:28 AM   #5
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First check DC voltage on output stage.
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Old 13th December 2015, 11:46 AM   #6
RM is offline RM  Norway
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Most of the problems with this amp is the fact that the two transistors responsible for the voltage amplification is NOT fittet with a heatsink. As a result they run VERY HOT, and eventually break down. I can`t see the number, but one is a 2SA1209 and the other 2SC2911. Replace with 2SA1358/2SC3421, AND add heatsink.

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Roar
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Old 13th December 2015, 11:50 AM   #7
moss99 is offline moss99  United Kingdom
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do you mean at the speaker terminals ? there is .112 dc on right channel and .351 on the left
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Old 13th December 2015, 11:54 AM   #8
AndrewT is offline AndrewT  Scotland
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I'm fairly sure the 8000p has a DC servo to control the output offset.
That tl071 is probably the servo opamp. check the schematic.

0.112Vdc and 0.351Vdc is far too much from a servo.
How are you measuring the output offset. There should be just one voltage from a mono amplifier.
There must be a fault.
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Last edited by AndrewT; 13th December 2015 at 11:57 AM.
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Old 13th December 2015, 11:54 AM   #9
RM is offline RM  Norway
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As it is a servocontrolled amplifier. it should be very close to 0VDC.
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Old 13th December 2015, 11:57 AM   #10
moss99 is offline moss99  United Kingdom
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is it fixable ?
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