DJ Hero Teardown

intro-thumbnailGame controllers are pretty sophisticated these days.  If you've seen the DJ Hero controller, you may wonder how it works.  There's a 45-RPM-record-sized turntable for "scratching" which rotates freely which includes 3 pushbutton switches on the rotating piece.  Obviously, the turntable rotation is read with some kind of encoder but how the switches are read is a mystery.  I recently came across one of these at the right price, so with screwdrivers at the ready, let's delve into the internals.

The platter rotates very freely.  With a good spin, it will rotate at least 10 turns before it slows to a stop.  There's no resistance from any mechanical linkage between the platter and the base.  The "controller" snaps on to the side of the turntable part through a somewhat complex mechanical linkage with includes a 4 pin connector.


DJ-Hero copy copy

Time to break out the screwdriver and see what's inside.  Torx-head screws are used to hold the HJ Hero together, so a multi-bit set is helpful.  I think there were nine screws holding this together - it looks like they expect it to take some abuse!  The picture below shows the inside view of the top of the assembly.  The bottom contains only the interface connector.  This was a bit odf a surprise.


six wires run to the top half of the enclosure.  Removing the four screwa around the center area allows the platter secttion to be lifted off.


Wow, that's hard to believe.  None of the active parts are located in the stationary part of the assembly.  A picket-fence around of the perimeter of the base for an encoder.


There's an optical gap sensor in the rim of the platter.


At the center of the platter is a slip ring assembly to permit transferring of power and signals between the rotating pieces.  This is actually surprising as sling ring technology used to be extremely expensive.


The next step was to remove some more screws to open the platter section.  Here's the top of the slipring assembly.  Yes, it looks like the same wires that go into the bottom but there's actually a contact arrangement in the assembly.


Not much else is visible except for a circuit board containing the optical encoder and a circuit board for the switches.




There are 4 conductors in the cable between the switch board and the encoder board makes sense.  Six wires lead between the encoder board and slip ring assembly.  Hmmm... I'm suspicious about what's happening on the encoder board.


Bingo.  A microcontroller was hiding on the bottom of the encoder board!  And look at that!  MCLR | VDD | GND | DAT | CLK... a standard PIC ICSP connector!  I suspect the micro is a custom-programmed standard 28-pin part.  This could lead to an interest project.

Posted: 7 years 4 weeks ago by bitfogav #11237
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Thanks for sharing Jon, I always wondered what was inside my DJ-Hero. So theres a microcontroller on the bottom of the encoder board? have you hooked up a pickit yet to see if you can identify or read the microcontroller?, Intrigued to see if its write protected?!
Posted: 7 years 4 weeks ago by majenko #11238
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It'd be interesting to connect a programmer to those pads and do a probe of the chip to see which it is.

The -I/SSO means it's ICSP, and in an SSOP package, so the ICSP should at least tell you which it is.

If you look on the Microchip it's listed in some obscure PDF catalog of part numbers, but it's not in the actual site as a part, so it may be a custom one (maybe a normal PIC that's pre-programmed?) just for them?

Go on - get probing!
Posted: 7 years 4 weeks ago by Jon Chandler #11235
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I haven't hooked it up...yet

I'm suffering from a severe case of eye allergies that has resulted in some corneal scuffing and an emergency trip to the ophthalmologist. Fortunately, the camera does a good job without much help from me and I think spell check caught all the errors in my writeup. Clear vision should return in a few days and I'll try it then.

There's also one detail I left out. The connector between the turntable and controller has 4 conductors. There's also an optical component in the mechanical connector arrangement. There are two circuit boards in the base...the first to the connector and the second to an LED or IR receiver. The mating face on the controller doesn't have a hole but it may have an IR-transparent lens.
Posted: 7 years 4 weeks ago by majenko #11234
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Hay fever? One thing we really don't have to worry about in this country this year ... :/
Posted: 7 years 4 weeks ago by bitfogav #11241
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Hay fever? One thing we really don't have to worry about in this country this year ... ]

Yup were still waiting for summer to start!
Posted: 7 years 4 weeks ago by Jon Chandler #11245
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Summer has been slow to start here too (Seattle) and my hay fever hasn't been so bad but a couple weeks ago it just went wild despite the usual treatments. Usually, adding nasal spray gets me through the worst times but not this time.
Posted: 7 years 4 weeks ago by W4GNS #11247
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Why did you people not ask! On the right coast we have had temps + - 100 degrees for a few weeks now, glad to share.
Posted: 7 years 4 weeks ago by Jon Chandler #11250
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Well, my efforts to connect the PICkit 2 didn't pay off. I tried it with Vcc set to 3.3v and again with Vcc set to 5v and both times received a "No Device Detected" error.

What I need to look at is what signals come from the 4-pin connector. Might as well let the original controller read the bottoms and encoder if I can read the output. No particular project in mind yet but the DJ Hero could be a useful nye face for some applications.
Posted: 7 years 3 weeks ago by Jon G #11297
 Jon G's Avatar
I love it when I open things up and see a PIC inside. Makes me feel like I'm a part of something larger. :p

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