andypugh2000

Hi guys....

have an Alpine CDM 7871R fitted to my scooby and whilst driving today it decided to lose all sound from all four speakers, I switched it off for 5 mins then back on again and it worked for a further 90 seconds before losing sound again.....

When its switched off for 5 mins then back on again there is some interference in the front right channel, the music will then play spot on for 90 seconds then go again etc etc....

Any ideas?? the head unit is 2 years old, my money is on its blown something inside or could it be a short in the door wiring??

Thanks in advance

Andy

BigRed

Could be a problem with a speaker OR cables, unit is going into protection mode by the sound of things.

Does this problem occur no matter what the volume is set at?? Is the unit getting very hot??

Check ALL the wiring to the unit and wiring into the doors for any damage or scuffed insulation. Also check the ISO block is properly inserted into the stereo. Another cause could be a dry solder joint, if you have the guts to open up the unit yourself and have a dabble then check the solder joints towards the ISO connection points and also around the power amp chip legs and caps.

andypugh2000

Hi Bigred,

Have had the lid off the unit but nothing visible, it started working ok again today after about an hour of driving, before that it was just silent from cold

I have checked all wiring behind the unit but not to the doors, the interference was from the front right hand side speaker so maybe thats my starting point.

Thanks for your help

BigRed

Deffo loose connection, check the front right first, any corrosion on terminals??, or could it be the cold weather getting to it, condensation ETC

Dry solder joints can be hard to spot,unless on HT circuits, magnifying glass required sometimes.

Could you plug the units into a mates car, see if it still plays up(if it does you know the units at fault). Or have you got a decent 12v supply to soak test it on?

andypugh2000

I will give it a test this coming week and see what happens as it managed to play for an hour without a problem, a week of bumpy back roads and changing weather should throw something up..

Andy

andypugh2000

Just to let you know I took the door card off the drivers door and found the lugs on the speaker were shorting out on the door frame.

All sorted now thanks