5,6V?
That is too high. Set the placid to give you 5,15-5,20 and at least 50ma Shunt. Dont worry about frying the B3 by sourcing too much current. The B3 will not be affected by higher shunting. The shunted current is converted to heat by the placid.The worry is overheating the placid, but you are fine with shunting 50-80mA. Basically the placid allways draw enough current for the B3 at all times, and by doing this there is no delay from the power source when the current is needed.

Then on to the dac.

Do the lights on the front panel switch light up when you select an input now?
You should try without the front panel switch with dil at SW2:1 to on with SW2:2 to off for input 3(C on the sp-dif module) and SW2:1 to on with SW2:2 to on for input 4 (D on the sp-dif module). From what I read that is where you had connected your two sources.

Then you should also have both sources connected and turned on (dont know why it makes a difference, but....apparently when fully populating the sp-dif board, you have to either have a source connected and turned on, or some other fiddling). I ended up with using only one source through the 4ch input board and wish I had ordered the single (wich was not awailable when it was ordered).

From the manual (read it very carefully over and over until you think you understand, then ask to make sure you understood it correctly.


The B3 is very complicated, but then again that is what the DIY community asked for (the flexibility of the ESS chip).
My B2 was put together far easier, I had to help a few friends after they had built their B3 based on my recommandation, but I think I know a little about what the fall-pits are now. Or at least enough to try again with new projects.

The current build went smoothly after a lot of troubleshooting by others on their dac`s here and elsewhere in advance. I got a lock on my first try, but then again I only have one sp-dif source (and input populated on the 4ch input card) connected and tested at that time.

Now I`m off for a few hours. Time for some zZz`s

Best regards
Gunnar

HI All,

Can anyone advise me on how to do a cold DC check on the buff III DAC between earth and the DAC output in order to acccertain if the chip is serviceable (or any other checks?)

regards

Sawman

Hi Gunnar,

Sage advice indeed mate--, Din dong, hi Russ H i Brian!, any advice on Cold DC checks or othere wise regarding a BUFFIII DAC with no lock light, I am running (have) run out of idears.

Thank you Boys

Thanks for getting back I am also a very busy person!!-- So I appreciate the reply.

Here are some photos, I have tested the connectivity of each 20 strands of the ribbon and they buzz out ok, the top connector was left off (it broke actually!) but servers as a good test point for scoping SPDIF outputs and checking 5 volts are getting in, I can confirm that in accordance with the integration guide (with regard to the pin outs) there are serviceable SPDIF inputs and what looks like a TTL (smaller) level waveform leavening the 4 input SPDIF board to the DAC

The PSU is 5.25 v/ Shunting 50mA (and has also been replaced with a bench PSU for confirmation) still no lock LED, just the mute LED on.

Also I replaced the 4 wires from the input selector switch as the connector wires were getting frail with all the testing, as I said to Gunnar I had initially put the 4 wires on the “front “ of the header (pins 1/3/5/7) but r read the integration guide and correctly placed them on pins 2/4/6/8, I also notice IC 8 is a bit warm, but I guess that’s normal for an active device.

I have also removed IC 8 and force inputs 1 and 2 from the 4 input SPDIF card via the DIL input switches in accordance with the integration guide, with no luck, presently IC 8 is inserted and SW1/SW1 are all off And I have two serviceable SPDIF inputs in A and B inputs on the 4 input SPDIF board.

The LEDS on the 4 way input selector switch all light and LEDS 1 to 4 follow the switch as the poles are changes (so appears normal?) I have tried all 4 inputs (a/b/c/d) on the input SPDIF card and switched them with the selector switch but no lock LED indication. (yet

I am fairy confident that TTL level SPDIF are arriving at the DAC header.

CHEERS

Hi Gunnar,

Here is another photo, think there correct

But i dont mind being wrong

cheers

john

Edited by user Wednesday, September 12, 2012 11:29:22 AM(UTC)  | Reason: additional comment

AH Ha!

you got me! , I don’t know if my mistake will make any difference (are they just 1:1 isolation transformers? dont know if Russ or Brian can correct me here?) but I will reorientation them correctly tomorrow (at work at the moment!) keep em coming!

Thank you Gunnar

John

Hi Brian,

Thought not (Phew!), thanks for that.

regards

Sawman

Hi Corpius, thank you for replying.

I. have tried with only 1 source and with 2 sources also (I currently only have 2 sources)

2. I have done cold DC checks on each of the 20 strands, all buzz out OK.

3. sw2:1 and sw2:2 are currently both off and have been tested in that configuration (I have also tried different bandwidth and SPFIF bypass-all switches are currently Off)

4: I have tried sw2:1 and sw 2:2 to select two inputs separately.

5. Here its 230v

Personally i am convinced a Serviceable TTL level signal is leavening the 4 input SPDIF card to the DAC.

Keep em coming!

Regards
Sawman

Hi Corpius,

I have tested with out volume control and with link provided no joy.(no lock LED. mute LED remains on)

I have scoped the SPDIF in to the 4 input SPDIF module and out on to the header of the DAC, I can also confirm that the 4 way switch switches the waveform where they should be in the DAC input pins, so TTL SPDIF is getting to the DAC OK, the problem must be on the DAC then?

Cheers

Sawman

Hi Russ, thank you for replying:
(What I believed I saw)
(with reference to page 7 on the Buff integration guide—again with respect to INA/INB/INC/INC inputs and on J1 (output to ribbon cable) I scoped between pins 3-4/5-6/7-8/9-10 as I switched the 4 way selector switch I was able to follow the input to the corresponding output on J1.
I confirmed the waveform I was scoping on the output was related to the input as I disconnected the USB DAC input i was able to see the output waveform disappear (so I was attempting to confirm that what I was scoping on the output was associated with all four inputs respectively)
I also have used the dip switches to select input a known good SPDIF signal between INA.1 and INA.2 (used the dipswitches sw2:1 and sw2:2 to select one of the inputs without the input selection board connected) as suggested by Corpius
I have scoped D1 on the DAC (with D1 selected on the 4 input selector switch at that time) and observed a " squarwave " across the D1 Pins which disappeared as I disconnected the USB SPDIF input)
That’s why I think i have an input to the DAC. (I am not saying I am right but that’s where I think the evidence leads me?) ---And I right in thinking I have overlooked something basic?? . (..I am even now wondering if I have fitted the Trident correctly?..Please see attached picture (just to confirm that)..I am baffled

Thank you
Sawman

Edited by user Saturday, September 15, 2012 7:29:47 AM(UTC)  | Reason: Not specified