JBL S4HC Synthesis Four
JBL Loudspeaker Troubleshooting/Repair Tips
Most customers prefer to do simple loudspeaker repairs themselves. By following the steps below, a majority of loudspeakers can be returned to
their original factory performance with minimum effort. Choose the example that best describes the problem you are experiencing.
Problem 1: No sound or distorted sound from one loudspeaker in a pair (or set)
Connect the dead/distorting loudspeaker to a different amplifier channel (one that had a functioning loudspeaker connected to it). If it functions
normally, the problem is not loudspeaker-related. If the loudspeaker still makes no sound or sounds distorted, a wire may have become loose
or disconnected, the network (also known as a crossover) may be defective, the drivers (woofer, tweeter, etc.) may be defective or, in very rare
cases, all may be defective.
Refer to the wiring diagram and exploded view below. The network is a small circuit board found on the inside of the terminal cup, or mounted to
an inside wall of the enclosure. It sends low-frequency sounds to the woofer, high-frequency sounds to the tweeter and, if applicable, mid-frequency
sounds to the midrange driver. Make sure all wires are secure and connected. Look for components on the network that look burnt, “bulged,”
or abnormal. If everything looks normal, connect the network to the drivers from another matching loudspeaker. MAKE SURE you attach the
correct wires to each driver – mid- and low-frequency sounds can damage the tweeter! If there is still no sound or distorted sound, the network
is defective. If there is clean undistorted sound, the drivers are defective.
Problem 2: No sound or distorted sound from one or more (but not all) drivers in an enclosure
Remove the problem driver(s) from the enclosure and make sure all wires are secure and connected. If they are, proceed with the following test:
Woofer or midrange driver – Connect the driver’s + and – input terminals directly to the loudspeaker wires from your receiver/amplifier and play
some music at a reasonable volume. If the driver now sounds normal (produces a clean, undistorted sound), the network is most likely defective.
Tweeter – Replace the tweeter with a functioning tweeter from another loudspeaker. If the tweeter now functions normally (produces clean,
undistorted sound), the original tweeter is defective. If the replacement tweeter also sounds distorted or produces no sound, the network is
most likely defective.
Problem 3: Loudspeakers distort, rattle or pop at higher volumes
This is usually NOT a loudspeaker problem. Common causes are too much power (playing the loudspeakers too loud and causing them to distort),
an amplifier with not enough power (the amplifier can’t produce the required volume without distorting), excessive equalization (turning the tone
controls too far clockwise, and/or engaging the loudness/bass boost button on your receiver) or some combination of the above. If only one
loudspeaker is exhibiting the problem, and you’re confident that it’s not caused by too little power/too much power/excessive equalization, see
solutions for Problems 1 and 2.
WIRING DIAGRAM
EXPLODED VIEW
(8)
(2)
23
8
S4HC Cabinet – Not for Sale
HIGH-FREQUENCY
TRANSDUCER
335663-001
NETWORK
338527-001
26
24
7
(4)
14
MID-FREQUENCY
TRANSDUCER
336327-001
21
(6)
25
(4)
12
11
15
16
19
9
20
22
LOW-FREQUENCY
TRANSDUCER
335899-001
LOW-FREQUENCY
TRANSDUCER
335899-001
(4)
10
(6)
18
17
ITEM
NO.
ITEM
NO.
DESCRIPTION
QTY.
PART NO.
DESCRIPTION
QTY.
PART NO.
1. Survey Card
2. Owner’s Manual
3. Warranty Card
4. Mounting Bracket
5. Top & Bottom Pads
6. Outer Carton
7. Tweeter
8. Woofer
9. Midrange
10. Woofer Gasket
11. Midrange Gasket
12. Tweeter Faceplate
13. Tweeter Bezel Gasket
14. JBL Logo
15. Terminal Cup Ass’y
16. Cup Ass’y Gasket
17. Grille
1
1
1
4
2
1
1
2
1
2
1
1
1
1
1
1
1
6
331384-001
338636-001
338322-001
337722-001
337826-001
338635-001
335663-001
335899-001
336327-001
335657-001
335656-001
335695-001
336613-001
48003-01
19. Flower Pot
1
1
4
334072-001
338527-001
908302-012
20. Crossover Network
21. Screw (midrange) PB, HXS,
#6 x .75," ZNC
22. Screw (network) PB, PPH,
#6 x 5/8," BLK
23. Screw (woofer) PB, HXS,
#6 x 1," ZNC
24. Screw (tweeter) PB, HXS,
#6 x .75," ZNC
25. Screw (input cup) PB, HXS,
#6 x .75," BLK
26. T Nut 1/4 x 20
27. Screw (bracket mounting) MS,
PPH, 1/4 x 20 x .75" BLK
28. Screw (S4HC installation) MS,
PPH, 8-32 x .375" BLK
4
8
4
6
903401-010
903802-016
908302-012
908301-012
8
8
339051-001
900501-012
336616-002
336773-001
337598-001
333249-001
8
900201-006
18. Grille Retainer
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