Car Audio.

[thesameguy]

Got back together with Joying. They are definitely angling to do nothing, but sticking with it so I'm not upset.

This afternoon I decided to take apart the head unit, and found a tiny cable is likely the issue with the display. The mainboard connects to a daughterboard with a small, delicate cable that has obvious physical damage. Messing with this cable alternately scrambles and unscrambles the display. I tried flattening it and reinstalling it, but no dice - little jolts scramble the display. I now understand the previous and apparently random problems, so that's progress. I was able to adjust it so that I could do a firmware update hoping to restore the antenna function but no dice. Still no antenna. Everything else works great, though. Being the contingency thinker I am, I am trying to decide whether I'd be okay with a new cable and a discount in exchange for a non-functioning antenna trigger. I could use the amp trigger - all I lose is the ability to lower the antenna when not listening to the radio. It's not world-ending - lots of stereos are like that.

My new bench power supply is awesome. Set at 14v I was able to run the stereo indoors in a science-y way. At full tilt - installing firmware for example - power consumption maxes out at <.8a, which is not much. It generally sits around .4 or .5a. I assume if the speakers were connected that number would go up, but at "idle" that's not a lot of power. When turned off - which isn't actually "off" but "sleep," consumption is .008a at 14v. It's tangibly more than none, but not a lot. It's kind of impressive that an instant-on Intel CPU can "run" at that power. I was also able to take some temp readings. The heat sink (it's passively cooled) hangs out at 90F pretty much non-stop, and I'm not sure whether that goes up with the amp running. That's well within the CPU's tolerance, but I do worry a bit about it staying within tolerances when it's 140 degrees in the cabin. Once this is sorted, I may install a small fan to circulate air. There's plenty of room to do that.

I am waiting for the next step from Joying, but it was a productive night. I'm tired now though.

Edit: I like this relationship I have with the seller. They sent me a picture of the mainboard and highlighted a leg of a voltage regulator and asked for a meter at that spot. "Can you test here?" Hells yeah I can. Let's solve this. Far better than a defective Pioneer stereo I got where Pioneer lead with "Have you connected it to both power and negative ground?"