Hi guys!
Sorry for reviving an old thread, but it's incredible that Line6 has never released to this date a version that has digital outputs. What is more incredible is that all the other manufacturers also don't care about digital outputs on their digital wireless systems.
Digital effects processors are on the rise, most offer such incredible performance that it just makes more sense than using the analog counterparts. The vast majority offer digital inputs (mostly SPDIF, some offer AES also) so it really makes no sense to use analog signals to transfer digital signals. The major reason: D/A and A/D conversions add some delay. Two minor reasons: you need to think about your gain settings (i.e. signal levels), also the signal quality is always slightly degraded.
So after a lot of digging about wireless systems for instruments, retrofitting the missing components on the G90 looks like the most cost effective solution for now.
After looking more closely at the PCB traces from the picture provided in the previous posts, the pinout of U28 don't match what was previously suggested (TI DIT4096). We can see that the transmit pins are on pins 25 & 26. Also, U28 is a transceiver IC, not a transmitter IC. So after some more digging it looks to me that U28 is actually a Cirrus Logic
CS8427. Y6 and Y5 look to be DIP-8 half size precision oscillators for 22.5792 MHz and 24.576 MHz respectively but the pinout doesn't seem to perfectly match (VCC and GND look inverted...).
I have tried to figure out the U27 IC but no luck on that. It looks to be some kind of input selector for switching between AES and SPDIF inputs. Since this is for digital input, it can be ignored...
Some have suggested that there might potentially be an issue regarding the firmware support for the missing components, that could be true since if U28 is the CS8427 than it's used in software mode (pin 24, looks like it's connected to GND). Nevertheless, since they did not bother on removing the pcb traces, there is a chance that they did not bother on altering the firmware (also possibly no need to...).
Figuring out the remaining components regarding capacitors and resistors should not be too difficult, there is an evaluation board for the CS8427 called CS8427EB and accompanying
datasheet that has relevant circuit diagrams with values for these components.
So if I ever get my hands on one of these units, I'll let you know if the digital output can be retrofitted. In the meantime, if someone is interested in retrofitting a digital output on their G90, please let me know! The only tricky part is figuring out which oscillator goes where, but since there are only 2 ways it's not a huge issue. There would also be a need to make a hole in the metal chassis for the AES connector, but for testing purposes a XLR cable can be soldered to the pcb instead.
Since I spent most of today thinking about this I hope someone out there will find this useful. If so, please get back to us on how it turned out!