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Old 07-16-2018, 08:24 AM   #1
Dannyx
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Join Date: Aug 2016
City & State: Constanta
My Country: Romania
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Question Guess this device...

Good day folks. I've got mission-impossible on my hands here again and what I mean by that is that someone brought in a little doohickey which I have no idea how it operates or what it really is. It looks homemade if I were to guess and the chap who brought it in said it's a remote operated switch installed in a vehicle (a truck or something) to cut the power on and off to a tachograph...it could very well be anything, doesn't matter. The thingy suddenly stopped working and now the vehicle is grounded because it can't run without a tacho. That's another thing I need to mention: smells to me like EXTREMELY illegal to disable the tacho at will whenever you please like that, since from my experience it should be working and keeping track of the journey constantly, but these guys apparently couched this thing somewhere in the dash, undetectable enough in the event of a control, yet still offering the possibility of disabling the tacho without damaging any seals or stuff like that.

The point is, what could it be ? It's a tiny thing as you can see. I went in as closely as I could with my ghetto macro lens. From my initial analysis, it's got a 5v regulator on, a mystery IC and 4 of THESE SSRs...apparently. It makes sense to a degree, but why there's 4 of these makes no sense.

Also, I have no idea what that mystery SOT 23 IC is and how this thing even interfaces with a remote, since I don't see any antenna...unless they chopped it when they removed it from the vehicle...if we could identify this IC, it would be easier to troubleshoot. I suspect it's this IC which actually failed. To spare you the squinting, says 06A5 on it...I could not find anything of the sort, let alone anything close to being a remote controller or something. I'm not entirely sure the guy brought in the "complete" system...it looks to me there should've been another receiver or something. I find it hard to believe simply pressing a button on that key fob remote miraculously interfaces with this thing....there's just not enough components :| I probed around the board and sure enough there IS 5v coming out of that SOP 5v regulator, but no reaction when I spam the remote.

Seems to me those SSRs have their diodes (LEDs) wired in series: cathode of one goes to the anode of the other...it's a mess...yes, it is double-sided.

What do you guys think ?
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