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Dannyx 07-16-2018 08:24 AM

Guess this device...
6 Attachment(s)
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 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" 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's a mess...yes, it is double-sided.

What do you guys think ?

stj 07-16-2018 11:14 AM

Re: Guess this device...
are you sure there isnt more boards?
i'm not seeing any RF stuff

Dannyx 07-16-2018 11:16 AM

Re: Guess this device...

Originally Posted by stj (Post 839275)
are you sure there isnt more boards?
i'm not seeing any RF stuff

Just my point. Like I said, I have no idea what it is or what it does...the guy didn't know either most likely...he just ASSUMED it's the thing immediately before the tacho.

CapLeaker 07-17-2018 06:26 PM

Re: Guess this device...
you surly don't have all of it. As stj said, there is NO RF anything on these 2 boards.
This was installed on a truck. What that truck driver does, is he is blocking the tachograph, but keeps driving and the tachograph thinks the truck is standing still. Truck drivers are only allowed to drive X amount of hours a day, then they have to have a rest period. Police checks the log book and the card of the tachograph. Because of this cheating device, the truck isn't really grounded, because if they hook up the tachograph as they supposed to, things work as intended. The owner of the truck just want's to make more $$$ keeping the truck rolling, while the actual driver should have a rest period.

The blocker blocks the 2 speed signals to the tachograph.

Google "tachograph blocker"

R_J 07-17-2018 08:18 PM

Re: Guess this device...
1 Attachment(s)
I found the fob here

redwire 07-17-2018 11:02 PM

Re: Guess this device...
It looks like a big fat relay switch.
The 4-pin SMT are ASSR-1218 solid-state relays (photo MOSFET) 60V 0.2A
The SOT-23 looks like XC6101 watchdog which could detect pulses, so it does look like a tachograph jammer

Dannyx 07-17-2018 11:32 PM

Re: Guess this device...

Originally Posted by CapLeaker (Post 839571)
you surly don't have all of it. As stj said, there is NO RF anything on these 2 boards.

It's really just one board, the same one front and back.
Yes, its probably not the whole thing, which I suspected from the very beginning...

Shock2cure 07-25-2018 09:00 PM

Re: Guess this device...
buck converter

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