289 

 

No. 210 Poor timbre, low volume or noise jump when playing CD   

Malfunction Cause 

Solution 

 CD disk is too dirty or poor quality

①

 

Check CD disk surface, if it is too dirty or scuffed, then must be 

①
replaced. 

Check CD disk quality, if it is deformed or piratic, then must be 

②
replaced. 

 Loudspeaker poor contact or 

②
damaged 

Check loudspeaker ext

③

erior, whether it is damaged, as well as 

coil, whether it is burnt. Method: Measure the resistance by 
multimeter, and the normal value shall be 4 Ohm. If the value 
shows as infinite, then the loudspeaker was burnt and must be 
replaced. 

 Volume controlli

③

ng knob damaged 

Check CD player volume controlling knob, whether it is 

④
damaged. As well as track controlling, whether it operates 
correctly. And variable potentiometer of volume controller, 
whether it is seriously worn, Replace CD-player assembly when 
necessary. 

 Power supply unstable

④

 

Check voltage of CD

⑤

-player power supply, generally +B and 

GND voltage shall between 10V and 14V. When ACC and GND 
ignition switch locating at ACC or ON position, the value shall 
between 10V and 14V. 

Check CD

⑥

-player laser head serve motor driving voltage, 

whether it is in normal range. Maintain it when necessary. 

 Laser head is too dirty or aging

⑤

 

After CD disk was inserted, inspect by infrared illuminator, 

⑦
load motor action, when the disk positioned survey up/down 
focus action of laser head, whether it radiates red/blue beam. 
Check laser head component, clean laser head or replace 
CD-player assembly when abnormal. 

Poor timbre, 

low volume or 

noise jump 

when playing 

CD

 

 CD

⑥

-player inner power amplifying 

circuit malfunction 

Power amplifier is a component of the vehicle son

⑧

ic equipmen

with most malfunction rate. It is mostly caused by integrated
package puncture. 

Check power amplifier circuit supply voltage and load, as well 

⑨
as the transient peak voltage generated by motor, whether they 
are under normal value. Maintain and replace CD-player 
assembly when necessary. 

 

 
 

 

 

290 

 

Check laser head, whether it is too 

dirty or aging 

Check volume adjusting 

knob 

Check loudspeaker, whether it is 

poor conducted 

Poor timbre, low volume or 

noise jump when playing CD 

Check CD disk, whether it is too 

dirty 

Check CD-player supply 

voltage 

Check the voltage between each pin of 

power amplifier 

Replace CD-player assembly 

Inspect and maintain circuit or replace 

CD-player assembly 

Clean or replace CD-player 

assembly 

Maintain, modify 

Replace CD-player assembly 

Maintain, modify or replace 

Replace CD disk 

Normal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Normal 

Normal 

Normal 

Normal 

normal 

 
 

 

 

291 

 

No. 211 Low loudspeaker volume   

Malfunction Cause 

Solution 

Loudspeaker poor performance 

Loudspeaker poor performance, magnetic of alnico 

①
reduced. The sensitivity of loudspeaker is mainly 
determined by the magnetic of permanent magnet, the 
quality of cone diaphragm and the level of assembly 
process. Contact alnico with ferromagnetic and 
estimate the magnetism, replace loudspeaker when 
necessary. 

Loudspeaker circuit poor contact or short circuit. 

②

  Check loudspeaker and CD-player external 

connection, whether they are damaged. Measure with 
multimeter, the resistance shall be 0 Ohm, disconnect 
the connectors on both ends, and measure the 
resistance between connection and body (earth lead), 
of which value shall be infinite. If not, the circuit shall 
be maintained or replaced. 

Check loudspeaker exterior, whether it is damaged, 

③
as well as coil, whether it is burnt. Measure the 
resistance by multimeter, and the normal value shall 
be 4 Ohm. If the value shows as infinite, then the 
loudspeaker was burnt and must be replaced. 

CD disk damaged 

Check CD disk 

④

quality, whether it is piratic. Replace to

genuine CD disk. 

Check disk format or surface wearing level, and 

⑤
replace timely when necessary. 

Volume controlling potentiometer worn or 
damaged 

Measure the resistance between both ends of 

⑥
volume controlling potentiometer. Connect multimeter 
and rotate potentiometer slowly, meanwhile survey the 
resistance variation, if there is no change or shows as 
infinite, which indicates damage, then shall replace 
CD-player 

All or single 

loudspeaker low 

volume 

CD  -player inner power amplifier open or short 
circuit 

Check power amplifying circuit, measure the voltage 

⑦
between each pin by multimeter. Check the signal from 
front amplifying circuit. Mainly inspect the capacitance, 
resistance of power amplifying circuit, as well as the 
circuit and integrated package of circuit panel, whether 
they are burnt. Replace CD-player when necessary. 
power amplifying circuit, measure the voltage between 
each pin by multimeter. 

 

 
 

 

 

292 

 

Volume controlling potentiometer damaged 

Poor CD disk quatily 

Loudspeaker poor performance 

Loudspeaker low volume 

Loudspeaker connecting wire poor 

conducted or short circuit 

CD-player assembly inner short circuit or open 

circuit 

Replace volume 

potentiometer 

Check and maintain 

loudspeaker circuit 

Replace CD disk 

Replace loudspeaker 

Replace CD player 

Normal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Normal 

Normal 

Normal