Service_Bulletin_2011_no_21_Unstable_18V_circuit.pdf

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SERVICE BULLETIN
(2011-02-01)
Page 1 of 8
Technical Service Bulletin No. 21
Created by: Lab.gruppen AB Service Department
Date: 2011-02-01
Reference no: C…X models
It is highly recommended to implement this service bulletin as preventative maintenance if the
unit is serviced for another issue.
Affected models
Following models are affected by this technical service bulletin:
C20:8X, C10:8X, C10:4X & C5:4X
Affected boards/modules
Describe which boards/modules this technical issue affects.
AICO4B08a-F01 or earlier.
AICO4B08a-F02 or earlier.
Symptom
Amplifier may refuse to start up.
If it starts up and there is no Audio on any channel.
Solution
AICO4B08x-FXX
1. Measure +18V across C407 & - 18V across C405.
2. If +18V across C407 & - 18V across C405 is ok, then nothing is damage and follow
service bulletin 21.
3. If zero, measure resistance between pin 2 & 3 at U403.
If reading below 100 Ohm then U403 is broken and in need of replacement.
4. Measure resistance across D422 and D423. If reading below 100 Ohm replace D422 &
D423.
AICO4B07x-Fxx or earlier.
1. Measure +18V across C407 & - 18V across C405.
2. If +18V across C407 & - 18V across C405 is ok, then nothing is damage and follow
service bulletin 21.
THIS DOCUMENT IS CONFIDENTIAL. IT MAY NOT BE REPRODUCED WITHOUT THE WRITTEN PERMISSION OF LAB.GRUPPEN AB AND TC Electronic A/S
2005 Lab.gruppen AB, Faktorvägen 1, S-434 44 KUNGSBACKA, SWEDEN |.
Document type:
Created:
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SERVICE BULLETIN
(2011-02-01)
Page 2 of 8
If zero, measure resistance between pin 2 & 3 at U403. If reading below 100 Ohm
then U403 is broken and in need of replacement.
Measure resistance across C407 and C405 if below 100 Ohm then there are several
damaged integrated circuits.
Note! When service bulletin 10/14 is not implemented can U403 cause damage to several
integrated circuits. AICO boards may need to be replaced. Contact Lab.gruppen for spare
parts.
Service Log Information
Write “Technical Service Bulletin no.21” in column “Repair Remedy” besides other normal
repair information.
Instruction
Part No.
1N4004
Description
Diode Power 1n4004
Amount Info
1
1
Pos
See
instruction
See
instruction
470n200VX7R Capacitor Ceramic 470n 200V X7R 10%
10%5
5mm
1.
“New “components in Schematic.
THIS DOCUMENT IS CONFIDENTIAL. IT MAY NOT BE REPRODUCED WITHOUT THE WRITTEN PERMISSION OF LAB.GRUPPEN AB AND TC Electronic A/S
2005 Lab.gruppen AB, Faktorvägen 1, S-434 44 KUNGSBACKA, SWEDEN |.
Document type:
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SERVICE BULLETIN
(2011-02-01)
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2.
Remove the screw from the bottom and top cover. Remove
the cover.
3.
Remove screws from the side panels.
THIS DOCUMENT IS CONFIDENTIAL. IT MAY NOT BE REPRODUCED WITHOUT THE WRITTEN PERMISSION OF LAB.GRUPPEN AB AND TC Electronic A/S
2005 Lab.gruppen AB, Faktorvägen 1, S-434 44 KUNGSBACKA, SWEDEN |.
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SERVICE BULLETIN
(2011-02-01)
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4.
Remove screws from the rear panels.
5.
Form diode, cut legs and solder according to picture.
Make sure that diode is close to pcb as possible.
THIS DOCUMENT IS CONFIDENTIAL. IT MAY NOT BE REPRODUCED WITHOUT THE WRITTEN PERMISSION OF LAB.GRUPPEN AB AND TC Electronic A/S
2005 Lab.gruppen AB, Faktorvägen 1, S-434 44 KUNGSBACKA, SWEDEN |.
Document type:
Created:
Page:
SERVICE BULLETIN
(2011-02-01)
Page 5 of 8
6.
Note! Please note the direction of the diode. Incorrectly
mounted major damage can occur.
7.
Form capacitors legs according to picture.
8.
Cut of legs according to picture.
THIS DOCUMENT IS CONFIDENTIAL. IT MAY NOT BE REPRODUCED WITHOUT THE WRITTEN PERMISSION OF LAB.GRUPPEN AB AND TC Electronic A/S
2005 Lab.gruppen AB, Faktorvägen 1, S-434 44 KUNGSBACKA, SWEDEN |.

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