The radio on my '96 has a nasty crackle when riding. Only happens with the left speaker. Doesn't matter what the volume is set at. I took the front fairing off and checked the wires...everything seemed tight. Speaker looked good. I played with the connectors and couldn't get the same harsh crackle sound. Pulled the radio and checked the internals and nothing appeared out of place and all the solder joints looked good. When the bike isn't running, it doesn't do it. I don't know if it's something loose in the radio that's affected by the vibration or if it's feedback from the electrical system. Seems to do it at all RPM's.
Anyone else had this problem? Any ideas of the cause?
To draw a food analogy (I'm a big fan of food...lol)....the sound is somewhere between bacon frying and popping popcorn.
I've checked all the wires and can't get the radio to make the sound without the bike running so I don't think it's a ground problem. Like I said...didn't see anything loose in there either when I opened up the radio.
When you can rule out ground and connector interface issues, such that your sure the problem is strictly from the radio unit itself, then the problem can be any of the following:
1) Cold solder joint or joint fracture; allowing intermittent contact
2) Dirt contamination within an audio control potentiometer
3) Moisture and dirt contamination across sensitive areas of the PCB with exposed solder links
4) Active or passive components (IC’s, resistors, capacitors, exct.) that have internal fractures or shorts
Cleaning away any noticeable PCB contamination or spray flushing potentiometers is an easy measure to start with.
To localize any of the other possibilities a heat gun and or freeze mist might reveal the trouble spot or component.
Beyond this, you’re obviously going need specialized equipment and expertise.
Could this be caused by electrical interference from the voltage reg or the stator or would that interference be heard in both speakers?
The other question is...my bike is a Classic but I believe it uses the same radio that the Ultra used in '96. If I knew which pins in the plug were what and could narrow the problem down to a bad output on the radio (since only the left speaker does it, I could swap the wires and see if the right speaker does it), then I could move the speaker pins to the rear speaker positions since the ultra had 4 speakers and the classic only has 2.
Vreg or ignition interference issues would be heard in both speakers.
If your radio issue was localized to just one of four power amplifier circuits, each designed to drive one of four separate speakers, your speaker output channel swap idea could work.
I was suspicious of the interference issue because the problem is only in one speaker. I think if I swap the wires, I should be able to narrow the problem to either the speaker itself or the radio output for that speaker. I can deal with either being the problem by upgrading the speakers or changing the outputs to the rear speaker pins (I'd have to figure out which radio plug pins are the rear speakers). Hopefully I'll have time this weekend to take the fairing off again and mess with it.