03-18-2017, 05:56 PM
Livin' the dream
Location: Plano Texas
Join Date: Oct 2016
Mein Auto: 1996 BMW Z3 Roadster
Business Radio Volume Control Fix - No parts required!
My first Z3 how-to. I'm so excited right now...
Problem: volume control on stock business radio works intermittently or not at all
Over time the volume control on my stock radio became unresponsive. I could turn it clockwise or counter-clockwise endlessly to no avail. Initially turning it a lot would eventually work, then I discovered putting side pressure on the switch while turning it would get a response. The side pressure would cause the contacts to connect. But this eventually wouldn't even help. I even tried telling it that it was a good switch, a pretty switch and eventually a POS switch, but no help there either.
Solution: I found several references where people replaced the POT (switch). None of the sources cited had them anymore. There is also a person who will fix it for you on eBay for under $100, but that requires mailing the whole radio unit to him and waiting for it to be mailed back.
The problem isn't with the switch itself, but with the contacts. Convertibles are inherently dirty and allow dust to circulate from all angles. The volume control isn't sealed very well and eventually this dust collects around the contacts and insulates them. The solution is to clean the contacts.
Procedure: It's been a few months now but essentially the process was, after disconnecting the negative cable from the car battery, to first remove the radio by opening the two screw covers on the outer edge of each side of the radio face. There is a small indentation that indicates where to pull. Might work with a finger nail but if not a small flat head screw driver will do the trick. The door is on a hinge and does not pop out, just swings open to reveal the hexagonal screws. Losten these and the radio will pull out far enough to reveal the wires in the back.
There is a wire cluster connector that took some finagling to get lose. Just a basic plastic harness that has plastic ear chatches you have to move enough to pull it off. I broke one of the ears in the process but the whole connector is so tight that I question the need for it in the first place. It's been three months since I fixed my volume control and it's still fine.
After removing all of the wire connections, remove the radio. You will have to open the metal cage to get to the switch and this requires twisting several metal T latches straight so they can be pulled back through. I took pictures of this and will add them later from my phone. The T ear connectors are also soldered so you have to first use a solder sucker before you can twist the T straight. I elected not to solder them when I reassembled everything in case a mere cleaning didn't suffice. I don't think solder is necessary either, but time will tell.
Once you open the cage, detach the POT from the main board by pulling the wire from the connector. No soldering is required here.
With the POT fully removed, get some contact cleaner solution, the kind that cleans corrosion on electric contacts, and flood the POT with the solution. I decided to fill a container with the solution and emerse the entire POT in it. I then placed the container in a jewelry cleaner of the sonic vibration variety and let it do its magic. My jewelry cleaner has a timer that maxes out at 480 seconds, so I ran it through several cycles. After this I removed everything, shook the switch over a paper towel, and then put it on top of clean paper towel and set it in the jewelry cleaner again to shake off any residual solution.
With the POT dry, reconnect the POT, button the cage back up with the T latches, reinstall the radio, reconnect the battery, enter the damned radio code, and rock and roll. Literally.
There are 10 types of people: Those who understand binary and those who have friends