Just posting this here so I don’t loose it if the Presonus forums die/change again.
Original post can be found here: http://forums.presonus.com/posts/list/4528.page
Device was powered off. 3-4 hours later, when powered on, it acts as if the power switch is being pressed on and off at a very rapid rate.
The power/sync light as well as the phantom power lights/buttons blink on and off in sync with the signature on/off popping through my powered monitors.
Problem occurs with or without firewire cable.
When I dump video from my camera via firewire it interferes with the FS Project (my only sound device), so I have gotten into the habit of just turning the FSP off before beginning the video capture process and then reconnecting the FSP after the camera's firewire is disconnected. This has always worked flawlessly.
Since I verified my FSP was out of warranty, I opened it up to see if I could figure it out. While getting some voltage readings on the power board, I accidentally shorted two legs on an IC and bam, the problem is fixed. I was able to recreate this fix when the board messed up again so I can verify this is probably the problem. The FSP has been running great for 3 days nonstop since.
FSP with the top cover removed.
Closeup of the power supply board.
Short these two legs together with a metal object.
The IC discussed is a 4N35. $0.21 at mouser.com http://www.mouser.com/Search/Refine.aspx?Keyword=4n35
YOU ARE PUTTING YOURSELF AT RISK FOR ELECTRICAL SHOCK AND/OR DEATH WHEN YOU MESS WITH THE INSIDES OF DEVICES LIKE THIS. I AM NOT RESPONSIBLE IF YOU GET SHOCKED AND/OR KILLED.
Just a quick bumpdate,
This area recently got hit by some very bad weather and the power was surging on and off for a while. My FSP is on 24/7 all the time and this finally took it out to where it doesn't really power on, but it does still respond to shorting that IC, even though it no longer resolves the issue.
I would occasionally run into the same problem, so I left the cover unscrewed and enough space in my rack so that I could stick an ink pen in there to short those IC's legs together and get it up and running again.
Note that I never once had the FSP fail while using it during tracking or mixing, it only failed in windows while surfing the web etc, no recording related issues.
I got a replacement for the suspected IC a long time ago but never put it in, I may go ahead and try that while trudging through my hundreds of other unfinished projects. haha.
Also, these things are going amazingly cheap used nowadays, so fortunately, I have another one as a backup, but I still need two to feel comfortable live tracking and giving me more options for drums.
I reflowed that joint and it didn't solve the current issue. I replaced the IC and now it works like it did before, I still have to short the legs on the IC, so obviously there is something else wrong, but I've been using it like this for a while now and there are no performance issues or anything like that, just a small inconvenience when turning the unit on.
After a few more power outages (common here), the FSP was out of action again. I hooked up a momentary switch to the optocoupler mentioned previously. When it has problems turning on, I can manually toggle the optocoupler until it works right, then it syncs via firewire and stays that way until the next power outage. Check the optocoupler's data sheet for the pinout etc... It's just a switch, so wire your physical switch to it's respective pins.