Phonic Firefy 808 Issues - Page 1
Forum section: electronics / repair

author: Stef123
author_rank: Newbie
timestamp: July 29, 2023, 06:51:28 am
content: Hi,i´m Stef, 47 Years old, from Germany :-)i have a quite delicate Problem with my recently bought Phonic Firefly 808 Universal (Firewire/USB) from 2012, which i got in non working condition and getting Schematics / a Service Manual for this thing, as well as for other devices based on the BridgeCo DM-Series (DM-Series was also utilized by Terratec, M-Audio etc, in fact more or less any Audio Interface which incoorporates Firewire), looks very impossible.Well, it was said by the seller that it cannot be recogized by USB any longer (incoorporates FW and USB at the same time), and a close inspection revealed that the D+Trace of the USB Port was "flying"around; no idea how that could happen; i think it was a misleading try to change the USB-B Port itself. Means that i had to make a new connection, which i eventually did. But it looks like as the Firefly "resets" for each two seconds, because the Power light dims down for a short amount of time - before it does that again in a repeated loop.Oscilloscope shows that the Voltage on the CPU PCB drops for a short period. So hooked up a logic analyzer to something "what seems to be a 4-Pin debug port" - no idea which Format it has, i suppose serial, and it outputs something (not really useful), but repeatedly does that for each two seconds; every time the Power LED dims shortly.USB D+ and D- is low all the Time, even with a computer connected, which in conclusion cannot be right. They go,as far as i can tell, straight into the Main DM1500 ASIC, which seems to boot a stripped down Linux Kernel from Flash. Of course there is also no Datasheet of that ASIC anywhere available, because the Swiss Company Archwave, which bought BridgeCo around a decade ago, closed Business at the very beginning of 2023. So i suppose even gettting a replacement part is not simple.So the question is: Whats happening here. As for my own experience of programming Microcontrollers for +30 Years, it -might- be possible that the integrated USB port of the ASIC changes State from unconfigured to something that does not "quite" like 3.3 / 5 Volts being pulled directly to GND in case of a defect, but i assume that should happen right after power up - and the ASIC itself doesnt get hot at all, but seems to run (otherwise i wouldnt get "debug data" out of it, in whatever format it is). A diode Test reveals at least no short circuit between GND and the USB Data Pins.I suppose the CPU tries to switch something on - hence the Voltage drop - but idk exactly where to search without schematics. If the CPU PCB is removed, it stays "on". No blown Caps, burn traces or something else is visible at all. Maybe one of the voltage regulators cannot keep up with the power required???Any help - and probaly someone which can share additional information about that specific DM-Platform, at best a Service Manual for the Firefly, is greatly appreciated !Best regards!Stef

author: Swake
author_rank: Frequent Contributor
timestamp: July 29, 2023, 04:32:19 pm
content: Assuming you did not create a short with the USB repair (better to check with multimeter in diode mode)Is the power supply still OK (under load)?Can you isolate it from the rest of the circuits and test it (with some load)?