[sdiy] help with uQ repair

[ASSI]

On Thursday, 23 February 2017 15:24:26 CET Julian Schmidt wrote:
> I have a broken microQ in the workshop right now.
> It arrived with a scrambled LCD that only showed garbage.

Main board uC not booting up correctly.

> after opening it up I saw someone butcher the D-Flipflop (bend and
> shorted pins)
> after replacing it the unit boots again, waldorf welcome screen, os2.2,
> then preset name.

That means the uC now boots and finds valid data in Flash.

> yay!
> 
> bad news is the unit immediately freezes. No buttons and encoders do
> something. :(

The uC runs all communications and deals with encoders, LCD and LED.  If it 
freezes then it's either getting a lot of unexpected things to do or it has 
crashed again.  Once it has booted it would initialize the DSP and send it the 
preset data in Flash, but it seems that's not succeeding.

> I tried the firmware update but on reveiving the sysex data the power
> button makes a quick flash, 4 or 5 vertical bars appear in the LCD and
> then nothing happens. Pingpong chaselight on the Inst. 1-4 LEDs and the
> message "please play back dump" or something like that in the screen.

If the uC doesn't run stably, I would not risk a firmware update over MIDI.  
If anything goes wrong during the flashing of the new firmware there's no 
going back.

> In factory test mode all buttons, LEDs and encoders work.
> Audio out test does not work (silence on all outs)
> and the DSP test fails.
> it only shows:
> 
> 1:----- 2:----- 3:sig!

Hmm.  I think if it isn't a voice extended unit it should only show a DSP on 
slot 1 (the two additional slots are for the voice expansion).  Is it possible 
that this unit had its voice expansion removed?  Depending on the main board 
version you might need to move some jumpers or even zero-Ohm resistors in that 
case.

> and repeatedly flashes "DSP REBOOT" every second.

So the DSP is not starting up correctly.  That also explains why the firmware 
doesn't load, since it's loaded into the DSP SRAM before getting flashed.

> So my guess is that I have a broken DSP.

The more likely culprit is the DSP SRAM.

> Is it worth it to try and replace the DSP? they are still in stock at
> digikey.

I guess it'd be easier to just get another microQ.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

Factory and User Sound Singles for Waldorf rackAttack:
http://Synth.Stromeko.net/Downloads.html#WaldorfSounds