Coz,
Many thanks for your detailed appraisal of the fault - and my apologies for taking so long to reply (a very busy start to 2022).
I have performed only basic tests on the expansion board, but it does appear to have the 5v, 3v3 and 2.5v rails working. I also have the schematics.
I haven't yet had chance to hook up my data analyser to look at the SPI messaging. I'm not convinced it will uncover anything that I can compare to what a working solution - perhaps some basic handshaking, but given the main DPS24 menus acknowledge the ADAT expansion, I'm guessing this initially works.
Testing my ADAT expansion on another DPS24 still appears to be the most logical step. The FPGA is on a socket, so my original programmed version could be copied/tested on your expansion card - that in itself sounds like it could be useful for your situation. I shall try to send a private message with my email now...
Akai DPS24 ADAT expansion card woes: no audio
Moderator: Moderators
Re: Akai DPS24 ADAT expansion card woes: no audio
-
- Anthony gilbert
Poster - Posts: 16 Joined: Wed Dec 23, 2020 10:17 am
Re: Akai DPS24 ADAT expansion card woes: no audio
Keen to further investigate the provision of power to the ADAT expansion card, so here's an update:
The Expansion ADAT GP1F32T (TOSLINK Transmitter) LEDs switch off after initial boot-up, which seems contrary to what other people are experiencing. Is this a result of the expansion card itself being powered down, post-boot?
In short, it appears not.
For one, the schematics suggest the DPS24 doesn't have a modular set of 5v supply rails for option cards. Next, I have added a breakout to the 9-pin ADAT sync D-Sub. This proves the ongoing existence of the 5v rail, as well as some periodic serial-out on pin-9. Interestingly, this serial-out data first passes through an AND gate with a PWRGDB as the enable. PWRGDB (Power Good) appears to work as a general enabler across several external facing I/O including the MIDI jack. The use of "Power Good" is used in other Akai products, and seems to rule out the idea of high power consumption (failing component) shutting options off.
So, we have 5v power, component tested 3v3 and 2v5 regulators, expansion board system recognition (handshake) on boot, PWRGDB enabled, and the FPGA pin 139 generating serial streams to the 9-pin ADAT SYNC D-Sub.
The expansion board on the face of it appears healthy, but with the transmitter LEDs still going off after c. 5 seconds from boot. They are controlled directly from the FPGA pins 117, 118. Puzzling, but more investigation to follow.
P.S, made an error in a previous reply when I called the socketed IC the FPGA. It is merely a generic array logic IC.
The Expansion ADAT GP1F32T (TOSLINK Transmitter) LEDs switch off after initial boot-up, which seems contrary to what other people are experiencing. Is this a result of the expansion card itself being powered down, post-boot?
In short, it appears not.
For one, the schematics suggest the DPS24 doesn't have a modular set of 5v supply rails for option cards. Next, I have added a breakout to the 9-pin ADAT sync D-Sub. This proves the ongoing existence of the 5v rail, as well as some periodic serial-out on pin-9. Interestingly, this serial-out data first passes through an AND gate with a PWRGDB as the enable. PWRGDB (Power Good) appears to work as a general enabler across several external facing I/O including the MIDI jack. The use of "Power Good" is used in other Akai products, and seems to rule out the idea of high power consumption (failing component) shutting options off.
So, we have 5v power, component tested 3v3 and 2v5 regulators, expansion board system recognition (handshake) on boot, PWRGDB enabled, and the FPGA pin 139 generating serial streams to the 9-pin ADAT SYNC D-Sub.
The expansion board on the face of it appears healthy, but with the transmitter LEDs still going off after c. 5 seconds from boot. They are controlled directly from the FPGA pins 117, 118. Puzzling, but more investigation to follow.
P.S, made an error in a previous reply when I called the socketed IC the FPGA. It is merely a generic array logic IC.
-
- Anthony gilbert
Poster - Posts: 16 Joined: Wed Dec 23, 2020 10:17 am
Re: Akai DPS24 ADAT expansion card woes: no audio
As a quick update to this tread. I have decided with a heavy heart to finally part company with my DPS24. I have put the advert in SOS readers ads, and at a price which reflects the issue with the ADAT expansion card. Everything else is pretty damn good. I'm sure I will miss it!
-
- Anthony gilbert
Poster - Posts: 16 Joined: Wed Dec 23, 2020 10:17 am
Re: Akai DPS24 ADAT expansion card woes: no audio
The ADAT protocol runs at clock frequencies well within the capability of any half decent digital scope to analyse (like my Siglent SDS1202 200MHz scope) and I would have been tempted to rent one for a few days to troubleshoot (as they are somewhat north of £300 to purchase).
[or see if there's a grey-haired electronics enthusiast like myself in your local area!. ]
Scopes like this can decode a number of protocols but in any case their triggering options are sufficiently powerful compared to analogue scopes that you can generally get a good idea of what's going on.
[because if nothing else you can set it for a one-shot trigger and it has indefinite persistence on the display with zoom and scroll.]
They are generally a much better proposition than logic analysers because they tell you whether there's noise on the signal, whether the rise and fall times are good, whether there is ringing on the transitions, whether the logic high and low levels are within tolerance etc.
Albeit you would probably want to probe the signal by using an optical receiver such as the devices on eBay for around £20. (I'm assuming you only have optical out, not familiar with the DPS24).
Otherwise without proper test equipment it's frustrating and futile, unfortunately, there are things like this where a DVM is just not enough.
If it's any consolation, a scope like the Siglent would have cost the equivalent of a decent family car a few decades back, and if you have an interest in electronics design it becomes an invaluable tool.
[or see if there's a grey-haired electronics enthusiast like myself in your local area!. ]
Scopes like this can decode a number of protocols but in any case their triggering options are sufficiently powerful compared to analogue scopes that you can generally get a good idea of what's going on.
[because if nothing else you can set it for a one-shot trigger and it has indefinite persistence on the display with zoom and scroll.]
They are generally a much better proposition than logic analysers because they tell you whether there's noise on the signal, whether the rise and fall times are good, whether there is ringing on the transitions, whether the logic high and low levels are within tolerance etc.
Albeit you would probably want to probe the signal by using an optical receiver such as the devices on eBay for around £20. (I'm assuming you only have optical out, not familiar with the DPS24).
Otherwise without proper test equipment it's frustrating and futile, unfortunately, there are things like this where a DVM is just not enough.
If it's any consolation, a scope like the Siglent would have cost the equivalent of a decent family car a few decades back, and if you have an interest in electronics design it becomes an invaluable tool.
Re: Akai DPS24 ADAT expansion card woes: no audio
Anthony gilbert wrote: ↑Mon Sep 18, 2023 12:26 pm As a quick update to this tread. I have decided with a heavy heart to finally part company with my DPS24. I have put the advert in SOS readers ads, and at a price which reflects the issue with the ADAT expansion card. Everything else is pretty damn good. I'm sure I will miss it!
Hi have you sold the DPS24 now? I would be interested if you still have it. Email me on andy_simmons@yahoo.co.uk Thanks in advance!