Repair of a Hypex PSC2.400d plate amp with USB communication issue (solved)

[_Wim_]

Hi, just wanted to post about a simple repair I did last weekend so it might be helpful for others. From a friend I received a Hypex PSC2.400d plate amp, which would not communicate over USB any longer (USB communication is necessary for configuring the DSP). It did power up, but also no sound (probably because no filter was loaded, amp did work correctly when a signal was fed in directly using a siggen)

I first started to check the basics (voltages, bad usb connection, visually damaged components) but did not find any problem. The USB communication on this amp was handled by a PIC18LF2455. Next to the pic was a 5-pin header for programming. Tracing out the pins of the header gave the following results:
Pin 1(square on solder mask): MCLR
Pin 2: Vdd
Pin 3: Vss
Pin 4: PGD
Pin 5: PGC

This is the same pin-out of the pickit 3, only missing pin 6 for low voltage programming. The pickit 3 does however not fit directly, because some other components are in the way, so I needed to make an extension cable. On the Hypex website, you can downloaded the software for configuring the dsp (http://www.hypex.nl/downloads/product-downloads.html). As this software also allows you to update the firmware, it contains a folder with the HEX-firmware files. Using MPLab IPE and a pickit 3, I was able to successfully load the latest firmware (remark: amp needs to be powered on to do this, pickit 3 configured not to supply Vdd itself). After loading the firmware, the amp worked perfectly again.