Harman Consumer Group AVR75/85, Техническое руководство

Страница: 14 / 204

Service Bulletin #9705 for AVR85
Service bulletin # 9705 August 1997
To: All harman/kardon Service Centers
Models: AVR85
Subject: No audio output
In the event you receive an AVR85 with the complaint “no audio output” (even though the display is
lit up normally), perform the necessary steps listed below:
PROCEDURE:
1)
Make sure the receiver is OFF and unplugged; remove the top cover of the unit.
2)
Position the unit on its side, facing it so you are looking at the bottom cover, with the front of the receiver
facing left. The power transformer should be down, or nearest the work bench.
3)
Remove the front right “foot” of the unit; then with a sharp pair of dikes or wire cutters cut the (16) metal
connections on the bottom screen attaching it to the bottom cover. Remove bottom screen from unit; for
safety continue to cut all the remaining severed metal tabs from the bottom cover.
4)
Locate and discharge main power supply electrolytic capacitors C802 & C803 with a 10 ohm, 10 watt resistor.
At this point, C802 & 803 are at the top of the main PCB; The two leads to C803 can be identified by the
marking “-B” on the PCB; C802 is just above it. After discharge, check with voltmeter that capacitors have
less than 1 volt DC across leads to confirm that discharge is complete.
5)
See drawing; locate two areas of a poor solder connection due to an unintended mask, or dark-colored dot
that is partially covering the solder pad(s) where the leads come through. Unsolder the connection(s) with
solder wick. Clean & scrape, if necessary, with a small screwdriver the foil/pad area thoroughly and remove
any excess mask residue. Re-solder the connection(s) carefully to assure good connections.
6)
Turn the unit upright; locate PCB P714, the small vertical circuit board nearest the main heatsink. Unplug
and remove small molex connector J701 at the top of the board; then remove the four mounting screws and
metal tabs holding the top of the board in place.
7)
Remove the two locks to the two sockets, J714 and J716. Take care not to damage the lock or connector
while attempting to unlatch the PCB; then unplug and remove the entire PCB P714.
8)
Locate 10 ohm, ¼ watt resistors RH23, RH24, R745, R746, R747, R748; test with multimeter to assure they
are still 10 ohms +/- 5%. If values are different (indicating damage), replace as necessary.
9)
Return PCB P714 to unit; re-attach molex connector; replace 4 screws and mounting tabs. Replace top cover
of receiver.
10)
Re-attach the bottom screen to the bottom cover using 12 screws, (H/K# 51260306MO); the screen will be
upside-down compared to its former position when attached; replace the unit’s “foot”.
11)
TO TEST:
a) Plug in the unit; connect speakers to left, right, and center output terminals.
b) Turn the unit on; switch the unit to “Prologic” mode by use of the mode buttons on the front panel.
c) Press the button “TEST TONE” on the remote control. The display should read “FRONT L” and “TEST”
should flash.
d) Adjust the master volume, and verify test noise is heard from front left channel.
e) Press the button “CH SELECT” on the remote control to change to the right and center speakers, and
verify test noise is heard from each one.
f) Press the button “TEST TONE” on the remote control again to exit the test.
Model
Serial number
120V
Serial number
230V
Status Action
AVR85
MJ0011-01001
to
MJ0011-02500
MJ0012-01001
to
MJ0012-01500
Poor connections in
two areas on main
PCB
Clean & re-solder connections, check
or replace RH23,RH24,R745.R746,
R747, R748 if necessary
AVR85
MJ0011-02501 and
above
MJ0011-01501 and
above
Modified by factory NONE REQUIRED
1 4
Harman Kardon
Dolby Digital Audio/Video Receiver
AVR75/85