Koss JR-900 User Manual

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Congratulations on your choice of the Koss JR/900 Cordless RF Stereophone System. Now you can enjoy the
Sound of Koss anywhere in your home- even outdooors-without the cord. The Koss JR/900 RF System
Includes:

1. KossJR/900S Stereophones (1)

2. Koss JR/900T Transmitter (1)

3. Koss JR/900A Adapter (1)

4. 3.5 mm male stereo plug to dual RCA stereo plug connecting cord.

5. DC male to DC male recharge cord

6. Adapter plug

7. 3.5mm Stereo Jack

8. NICAD Battery Pack

IMPORTANT INFORMATION. READ BEFORE USING!
Located on the side of the transmitter is a charger output jack that is used to recharge the internal battery of
the JR/900RF System
The NICAD(nickel cadmium) battery pack of the JR/900 must be fully charged prior to operation. An initial
charge of 24 hours is required to ensure the extended life of the NICAD battery pack. Be sure the
stereophone is in the "OFF" position. (SEE "To recharge the NICAD battery pack")

JR/900 OPERATING CONTROLS
Volume Control
Controls the level of the audio signal input to the transmitter. Adjust for the highest non-distorted level as
heard through the JR/900S stereophones.

ON/OFF Switch
Place this switch in the ON position when using the stereophones. The ON indicator will be red. Place this
switch in the OFF position when you are charging the battery or when the stereophones are not in use NOTE:
When the ON/OFF switch is in the ON position, the on indicator light will light even when recharging is
necessary.

Red LED/ Green LED
Red indicates the transmitter is operating. Green indicates the transmitter is charging when connected to
stereophones.

Recharge Jack
The charger cable plugs into the transmitter at the charger input jack and the stereophones' charger cable
input jack. This connection is made only when recharging the battery pack ( SEE " To recharge the NICAD
battery pack")

Left/ Right RCA input Jack
Use dual RCA connecting cord (#4) to connect transmitter to the audio output.

AC Input
Connects 24VDC, 150mA ac adapter to transmitter.

Channel Selector
The channel selector is pre-set at the factory. If you encounter interference the channel selector can be re-set

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to any of the following frequencies by moving the switches.

JR/900S STEREOPHONE CONTROLS
ON/OFF Switch
Place this switch in the ON position when using the stereophones. Place the switch in the OFF position when
you are charging the battery pack or when you are charging the battery pack or when the stereophones are
not in use.

Recharge Jack
Located at the bottom right earcup. The recharge cable from the transmitter connects here for recharging.

"ON" LED
Located on the right earcup. This indicates the stereophone is operating.

Volume Control
Located on the left earcup. Turn this split dual control that allows the left and right channels to be adjusted
together or independently.

Stereo/Mono switch
Located on the left earcup. The LED is lit green when the stereophone is receiving a stereo signal. The LED
is lit red when the signal scan is made. The red/green LED is not lit when receiving a signal and the
stereophone is switched to "mono."

Selector Button
Located on the front surface of the left earcup. Press this switch to make the receiver scan for the signal
being transmitted and then to lock that signal. Repeat this step if necessary.

TO CONNECT THE KOSS JR/900 TO YOUR SYSTEM

1. Plug the AC adapter into the wall outlet. Connect the AC adapter line out into the far left-hand input jack
marked "24V,0.15a" on the rear of the JR/900 Transmitter.

2. Connect dual RCA ends of the dual RCA to 3.5mm connecting cord to the left and right RCA input jacks
on the rear of the JR/900 Transmitter.

3. Plug the remaining 3.5mm end of the dual RCA to 3.5mm connecting cord into the headphone jack on your
audio or video source. The source should be off during the connection.
NOTE: If the headphone jack on you audio source is 1/4," attach the 1/4" adapter plug to the remaining 3.5
mm end of the dual RCA to 3.5 mm connecting cord before connecting to audio source.

4. Now are you ready to enjoy your unit:
A. Turn on the audio source
B. Switch on the JR/900 Transmitter. The red LRD located on the unit will glow to indicate that the unit is
operating.
C. Turn the Volume control on the JR/900 Stereophone to a low level and switch on the Stereophone. The
glowing red LED indicator will confirm that the unit is operating.
D. The LED on the left earcup will glow green when a clear frequency has been locked in, it glows red when
scanning for a signal. The red/green LED is not lit when receiving a signal. The red/green LED is not lit when
receiving a signal and the stereophone is switched to "mono."
E. Adjust the volume to the desired listening level.
F. Adjust level control on the transmitter for a non-distorted listening level.
G. Remember to always switch off the stereophone and the transmitter when the system is not in use,

TO RECHARGE THE NICAD BATTERY PACK
Your JR/900 Cordless RF Stereophone System is equipped with a rechargeable NICAD battery pack with a

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listening life of approximately 10 hours. The NICAD battery pack must be fully charged prior to operation.
An initial charge of 24 hours is required to ensure the extended life of the NICAD battery pack. When
charging, be sure the stereophone is off. These batteries are located inside the stereophone and do not need to
be removed to be recharged. The red/green LED on the stereophone will extinguish when battery power is
low. The unit should be recharged at this time.

1. Both Stereophone and Transmitter should be turned off.

2. Plug the AC adapter into the wall outlet. Connect the AC adapter line out into the far left-hand input jack
on the rear of the JR/900 Transmitter.

3. Plug one end of the DC male power cord into the DC input jack labeled "Charge" on the side of the
transmitter.

4. Plug the remaining end of the DC male power cord into the DC input jack, marked "Recharge" on the right
earcup of the stereophone. The LED on the transmitter will glow green, indicating that the batteries are
charging.

5. To maintain battery life, drain the battery once a month by leaving the headphone in the "ON" position
until the light goes off, then recharge 14-16 hours. Replacement NICAD batteries can be ordered from Koss
Corporation. Dial 1-800-USA-KOSS.
NOTE:Overcharging will not damage your unit. Maximum battery life is achieved after the fourth charging
cycle(Cycle is each time the battery requires recharging.)

If you choose to replace your NICAD battery pack yourself, please dispose of the NICAD batteries properly.

Trouble Shooting Guide

No Sound

1. Check installation.

2. Check volume controls on audio source and JR/900 Stereophones.

3. Check that audio source and JR/900 system are switched on.

4. Check adapter.

5. Check that battery indicator light is growing.

6. Check all connections.

Distortion or Background Noise

1. Switch between channels on the transmitter to determine the clearest signal.

2. Check audio source.

3. Check that battery indicator light is glowing.

4. Adjust level control on transmitter.

For additional service problems, call 1-800-USA-KOSS

FCC ID:L76-JR900S,L76-JR900T
This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions:(1)
This device may not cause harmful interference, and (2) this device must accept any interference received,
including interference that may cause undesired operation.

Radio and Television Interference
This equipment generates and uses radio frequency energy and if not installed and used properly, in strict
accordance with the manufacturer's instructions, may cause interference to radio and television reception.
The JR/900 Stereophone System has been tested and found to comply with the specifications in Part 15 of the
FCC rules, which are designed to provide reasonable protection against such interference in a residential
installation.
However, there is no guarantee that interference will not occur in a particular installation. If this device does

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cause interference to radio or television reception, which you can determine by monitoring reception whe
the JR/900 Stereophone System is installed and when it is removed from the sound system, try to correct the
problem with one or more of the following measures:
*Reorient the receiving antenna.
*Relocate the signal source with respect to the receiver.
*Relocate the signal source and/or the receiver so that they are on separate branch circuits.
If necessary, consult your dealer or an experienced radio/television technician for additional suggestions. You
may find the following booklet, prepared by the Federal Communications Commissions, helpful:

How to Identify and Resolve Radio-TV Interference Problems
Stock No. 004-000-0345-4
U. S. Government Printing Office
Washington, DC 20402

In accordance with Part 15, Section .21 of FCC rules, the user is cautioned that any changes or modifications
to the equipment described in this manual that are not expressly approved by Koss Corporation could void the
user's authority to operate the equipment.

The user is also cautioned, in accordance with Part 15, Section .27 of FCC rules, that any peripheral device
installed with this equipment, such as a modem or printer, must be connected with a high-quality shielded
cable to insure compliance with FCC limits.

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