Pioneer DDJ SX doesn't power on

[maybepanic]

Hey
I have got a Pioneer DDJ SX DJ controller with an I suppose you'd call it intermittent fault. It doesn't power on (no leds light up, not recognized via USB) but draws some current (.7 amps). It has done this before and by disassembling, bit of cleaning while I was inside and reassembling it the fault just magically went away....
I was able to find the service manual (on elektrotanya) but sadly at least the troubleshooting part (Section 5/Page12) is of little help to me. For example what is meant by output from the DSP PCB Assy (3. point in the first flow chart)? Where is that supposed to be measured, do I have to measure it with all boards attached?
I measured what I could of the graphs (shown on page 49 in the manual) with my oscilloscope, but they seem unremarkable and I can't see how I can test the other test points since I'd have to connect the PCBs (with numerous cables) and in doing so can't access those test points anymore.
Does the magic disassemble + reassemble fix hint at something maybe? This is just illogical and weird to me and I suspect bad voodoo.
Any input would be appreciated.

[Audiorepair]

I measured what I could of the graphs (shown on page 49 in the manual) with my oscilloscope, but they seem unremarkable

Does this mean you have measured some points and there is activity similar to the service manual plots going on?
i.e. the machine is running somewhat?

[maybepanic]

Yeah there are test points marked in the boardview in the manual with screenshots of the signal on the osci. They all seem to be present +5, -5, +15, -15, 3.3 but the controller shows no outward signs of life, no flashing leds, no usb activity when plugged in.

[Audiorepair]

Are you possibly overthinking this?

Change the USB socket, most times this works.

[maybepanic]

Sadly not. There is a whole "boot-up" led blink sequence that should go off when powering it on, regardless if its connected via usb or not. From what I gather the controller gets all the power it needs but seems to get stuck at some point during initialization.

[Audiorepair]

Yes, silly me, this isn't USB powered is it.

[maybepanic]

Ahh sorry should have mentioned that probably. Its got a 5V external PSU, USB is only for data. I am currently testing with my bench power supply to get the current readings.

[james_s]

After checking voltages I would look for the reset pin on the microcontroller or microprocessor and see what it's doing. It's possible that the reset circuit is getting stuck or is not working at all.

[krisskross]

After checking voltages I would look for the reset pin on the microcontroller or microprocessor and see what it's doing. It's possible that the reset circuit is getting stuck or is not working at all.

I know this is a old topic but its left hanging with no ending, so just curious if you managed to fix it? Cause im having the same issue with sx2 and suspect the reset pin as well. Did you manage to sort it out? If u did, what have you replaced?

[darkspr1te]

Try to see if your device will go into service mode,
Hold shift+deck1 and power on, channel power leds 2/3/4 will show firmware version (1=1 etc)

if you only get FX assign 1 blinking then it's a firmware issue, if you get FX2 assign blinking then it's USB controller error

hope this helps

darkspr1te

[maybepanic]

Sorry all didn't get any notifications about the replies and had to put the unit in storage, that thing is just too damn big, then forgot about it.

[maybepanic]

Your tip is probably on the right track. The unit has four crystals one of them is not oscillating and it is next to one of the stm8s207mb micro controllers. The rest pin of this one is doing weird stuff. See atachment.

[maybepanic]

Yeah I tried to get it into service mode before even taking it apart. It doesn't seem to react to any inputs.

[maybepanic]

To give this topic some closure: My best guess was and still is that one of the stm8s207mb 's memory got corrupted. You can buy those chips for about $5 but obviously you'll have to program them. I was able to extract the "updater.bin" file with 7zip from the "DDJ-SX_UpdaterApp_v1.07_2.jar" I got from the pioneer website.
So far so good but the file is 172KB and the micro controllers only have 128KB of EEPROM each. So my guess was it has to be somehow split between them. As for the actual programming: There are two headers on the pcb "CN9", "CN10" from what I could tell those are the ports you could use to program them. But they use the "STM8 SWIM communication protocol" which I think is proprietary to STMicroelectronics. STMicroelectronics sells programmers, but when I made this topic I had 0 experience with programming micro controllers (apart form an Arduino) and I felt that this whole project was and maybe still is far above my pay grade. Too many questions and too little skill on my side.

Sorry for the late replies all, just wanted to give some more info on this topic. Maybe it'll be of use to someone else.