Jensen JHD1120 operation manual Care and Maintenance Troubleshooting, Ignition, Interference

JHD1120

CARE AND MAINTENANCE TROUBLESHOOTING

•Keep the product dry. If it does get wet, wipe it dry immediately. Liquids might contain minerals that can corrode the electronic circuits.

•Keep the product away from dust and dirt, which can cause premature wear of parts.

•Handle the product gently and carefully. Dropping it can damage circuit boards and cases, and can cause the product to work improperly.

•Wipe the product with a dampened cloth occasionally to keep it looking new. Do not use harsh chemicals, cleaning solvents, or strong detergents to clean the product.

•Use and store the product only in normal temperature environments. High temperature can shorten the life of electronic devices, damage batteries, and distort or melt plastic parts.

Ignition

The most common source of noise in reception is the ignition system. This is a result of the radio being placed close to the ignition system (engine). This type of noise can be easily detected because it will vary in intensity of pitch with the speed of the engine.

Usually, the ignition noise can be suppressed considerably by using a radio suppression type high voltage ignition wire and suppressor resistor in the ignition system. (Most vehicles employ this wire and resistor but it may be necessary to check them for correct operation.) Another method of suppression is the use of additional noise suppressors. These can be obtained from most professional mobile electronics retailers.

Symptom	Cause	Solution
No power	The vehicle’s accessory	If the power supply is properly
	switch is not on	connected to the vehicle’s acces-
		sory terminal, switch the ignition
		key to “ACC” or “Run”
	The fuse is blown	Replace the fuse
No sound	Volume is too low or system	Adjust volume to audible level
	is muted
	Wiring is not properly con-	Check wiring connections
	nected
The operation keys do	The built-in microcomputer	Press the RESET button
not work	is not operating properly
	due to noise
Cannot tune to radio sta-	The antenna cable is not	Check antenna cable
tion, auto-seek does not	connected
work
	The signals are too weak	Select a station manually

Interference

Radio reception in a moving environment is very different from reception in a stationary environment (home). It is very important to understand the difference.

AM reception will deteriorate when passing under a bridge or when passing under high voltage lines. Although AM is subject to environmental noise, it has the ability to received at great distance. This is because broadcasting signals follow the curvature of the earth and are reflected back by the upper atmosphere.

10