Basically, my head unit has 2 slots on the front for a microSD and a full-size SD card. The full-size SD card contains the software and maps for the sat nav unit. The microSD card is for music, aka fill up with MP3's. The music feature has always been buggy e.g. sometimes you'll listen and then the music stops and restarts from the start of the track. I've always thought it was because of a cheap SD but I'm starting to think there's an electrical fault, especially as the music player is totally independent to the sat nav from a software perspective (And hardware?), so I doubt they're even sharing the same bus, the only thing they're sharing is the same ribbon cable from the sockets to the board perhaps?

Say I put the microSD first and start playing some music. If I then put in the SD for the sat nav software, the music will instantly stop playing, the software will reset and start from Track 1 on the microSD. Second, say I'm listening to some music, and I decide to load the Sat Nav software (So not even touching the SD card), the same result. It seems that whenever there's a burst of data from the sat nav side of the unit, there's a fault, like the two SD's are fighting, resulting in the music restarting or in one or two cases the whole thing crashing. Now this one has completely stumped me as I've owned dozens of sat nav style head units before and never had this issue with music SD card. If I remove the sat nav SD and just listen to MP3's it'll play all day, won't crash at all. However, if I've inserted the sat nav SD card, and start playing music, it's only a matter of time before it crashes. Sometimes this is one song, sometimes this is two or three, but it will inevitably crash.

So, what do we think? Are the SD cards not receiving enough power to supply the necessary data at the correct speed? Is it a wiring fault, perhaps they're sharing a ribbon cable that isn't able to cope with the amount of data? Alternatively, could it be because I'm using one very fast SD card and one slower SD card? Has anyone had this before?

Thoughts, opinions, and advice would be brilliant.

sure it will crash, since your microSD card is the second card. the primary card, the gps need to stop the music for start the voice guide. just use gps or music player at same time. or you can try to to swap those 2 cards content.

No, that is not true. The software is able to dim the sound of music from the SD card. This is a standard on most of these units.

Could be a power issue, a drop in power when the gps card is accessed causes the media card to be unmounted briefly, or a data bus issue.

Or more likely it's rubbish software from lazy developers

Fatboy, any idea how I could solve the power issue?

I'm not sure how the software would be messed up, the two are independent right? There should be no way in which the two even know they are there. I can only assume because the two cards are so close they're sharing the same power source. Is there any way I can increase the power going to that destination?

You could check the power with a decent multimeter, you'd probably need an avo needle style meter as a digital one probably wouldn't react fast enough to see the voltage drop. If that's the case you're gonna have to play around with the componants leading to the card readers, if that's possible, you don't want to be playing with anything surface mounted.

It could be a faulty unit...

I'm feeling like that. Unfortunately, no warranty, so will just have to grin and bear it, and perhaps sell it when I find a decent Android unit.

I do like the pure Android 4.1 unit double din, but the only issue is they've got no TMC and they go obsolete too quickly