Hello all,

So I've had a rather disconcerting night. I finally got my IVY-III and Buffalo+accoutrements assembled and was so excited to finally power up for the first time! I double checked each board top and bottom for mistakes and then assembled like so:

SPDIF4--->SIDECAR--->BUFFALO--->IVY

Left the IVY unpowered as I haven't built my placids yet and got my bench DC supply set up for 5.25V to power the Buffalo. All hands on deck, annnnnnnnnnd it works! Mute led lit solid, Lock led off, 3 tridents showing two LEDs each, and the AVCC as well. Great. Leave it powered for a second while moment of self-pride is enjoyed. Power off and disconnect. (no pics, but it DID happen)

But wait, I forgot to add the input selector switch! Already built, just need to add the cable header, great. Solder the 4 connector pin to the "small box" area on the backside, make the cable and test for integrity. Done. Connect to switch header and to the corresponding pins on the Buffalo (4 pins on the inboard side of the i/o header closest to power terminal)

Power it on again to see if i get LEDs on the switchboard. Everything happened fast but i believe the following occurred:

1. switch leds all lit up but in a flickering kind of way
2. while examining switch module, i see a telltale puff of smoke in my peripheral vision and a popping sound, knew something had blown.
3. immediately switched off power and disconnected the switch module

After cursing for awhile and doing a cursory google/forum search, I mustered up the courage to power it up again without the switch module attached to see if i was well and truly f*cked.

Well, now I've got at least 3 burnt out LEDs (including MUTE apparently), who knows what other fried comps., and I'm too scared to hook anything else up to it without getting some idea of what happened first. I can only guess that I shorted out the power supply from the DAC to the switch board and ruined at least a couple of the supplies or something? I don't know if the DAC itself is fried and im scared to hook something up to see if i can get a lock; also the disappearance of the mute led is troubling.

I should note a few things. At this point I hadn't made any adjustments to the DIP switches, they are all as set by the factory (hadn't changed for sidecar, etc.) . I also hadnt attached the volume control pot and the PB4 was not jumpered. I also used my own LEDs for lock/mute. I believe I followed all the setup instructions for the B-III to the letter.

I've attached photos of the items in question, along with the regulator readings im getting. Any help would be appreciated, it would be great if I could just replace a couple SMD LEDs, or even a Trident or two rather than the whole friggin' thing.


wiring-small.jpg (245kb) downloaded 34 time(s). switch-small.jpg (236kb) downloaded 30 time(s). voltages-small.jpg (280kb) downloaded 25 time(s).

Well, I definitely burned out D1 on both AVCC and the 1.2V Trident, and probably my yellow mute LED.

I'm 99.999% sure that I didn't overvolt the input, since I powered up successfully for at least several seconds the first time. Also, my supply is a digital one with a readout and an aux on/off switch so you can read the voltage out before turning on the output. I had it set at 5.23V cuz I couldn't nudge it to 5.25.

Since the adding of the switch module caused the burnout, my thought is the only failure mode would be that I shorted VDD to ground thru the selector by reversing the cable on one end. I have since tested the switch board standalone and it seems to be working fine.

Now, assuming that I put VDD on ground how screwed am I probably? Is it likely that I've burnt the Sabre, or would the power supplies have protected it by burning out first somehow? $120 for new regs would be an easier pill to swallow, but I'm worried that if they got damaged the regulator internal to the dac board is probably shot too?

Ok, I have disconnected all the supplies from the BIII and tested them in isolation with the supply Vd at 5.25V.

I'm getting:

Trident1: Vout=3.31V, both LEDs lit. Good.

Trident2: Vout=3.32V, both LEDs lit. Good.

Trident3: Vout=1.197, D1 dead, D2 good. Good?

AVCC (Vd=5.25V, DVCC=0V): AVCC1=0.7V, AVCC2=0.7V, D1 Dead, D2 good. Probably need to replace, but i tested without 3.3V present on DVCC, is this ok or does supply need DVCC to output properly?

Can someone with a more intimate knowledge of the buffalo board tell me what I should be checking next? I thought that there was a built-in supply for peripherals as well? Can/should I check this before I reinstall the regs?

I assume if AVCC is toast then that would account for the lack of MUTE light, right? Or is that portion of the chip fed from DVCC?

Actually AVCC being out will cause all sorts of mischief - that looks to be the root of your problem.