Hi,

I've encountered with a strange problem. Vehicle is an X-Type estate of late 2004. Stereo system is MMM1 (Denso unit from Mondeo).
When I start my car, radio works just fine. After 5-10 mins of driving, static on all stations. Even on FM transmitter station (which is 2-3 metres away from antenna and even closer to radio unit). Sometimes after 30 mins of driving, sometimes even less, sometimes more, static dissappears and radio is functioning again. Antennabase was replaced 2 days ago (OEM part from XJK Ltd). With old base, there was no working frequencies at all.
So, could it be faulty alternator or is it something inside the radio unit itsself? Because I am thinking, whether not enough power from alternator, or one condensator is faulty (which could be why it is functioning after start). Or could it be bad grounding on stereo?

Thanks.

 

Hi, Wares!

The most likely cause is some corrosion under the antenna housing causing a bad ground connection. Remove the antenna, clean up the connections, seal it back up, and you should be good to go.

 

Hi,

Thanks for reply.
Antenna is new (+base). So there could be no corrosion at all. Roof mount was also clean.

 

Is your rear defogger on? Sometimes that can cause static.

 

Please tell me, what do you mean by defogger? Front-rear windshield heater, windshield blower or antenna filter?

 

Rear defroster. Rear window with the wires running through it.

 

Wares, did they replace the antenna coaxial cable? (or pigtail a new section in at the end?) If water has infiltrated the cable, that can keep the signal from getting in, as well.


The "works after half an hour" thing has me thinking, though...perhaps there is a cold solder joint on the board that only acts up whne the board is cold; as the board warms up, the joint settles down and makes a good contact again. I'd suspect the capacitor right where the antenna connection meets the circuit board, or the center connection from the antenna connector itself.


Is it only on FM, or is MW wiped out too?

 

Hi,

Sorry for very late reply.

I replaced antenna base (yes, the pigtail looking thing on the roof, where antenna screws in). This helped to get better reception on radio signals when working, but didn't fix everything.

Now that I have more knowledge about electronics, I am suspecting cold solders on the unit itsself too. I can't test MW, since in here, no radios are playing on amplitude modulation, but I think, it's not working aswell.

When I get time, I tear radio unit apart and see, what's wrong.

 

I would look right where the antenna connection meets the printed circuit board; it is a point that would flex pretty easily.