[Forte]

Start reading here if you haven't already BantamDAC Checks and Setup.

You should be getting 3.3vdc for IC1 and 4.75vdc for IC2 so it looks like you have a problem with IC2 and maybe IC1 as well.

Try to resolder the regs to make sure you have a good joint, FWIW I actually found these regs harder to solder than the DAC.

 

[Juaquin]

I can confirm that the BantamDAC works on:
Mac OSX Leopard
Mac OSX Snow Leopard
Vista 64-bit Business
Windows 7 32-bit RC

I actually HAVE to use the Bantam on my MacBook Pro when running Windows 7 because Apple hasn't fixed their audio drivers to work with 7 yet.

 

[MoxMonkey]

so got around to actually trying to get it to work today

reflowed the regs, still both read 3.0 replaced them with another pair i had making sure to check part numbers that mouser sent me and still the same

at this point i'm at a loss as my pc will just list "Unknown device" but still light the LED

 

[tomb]

Quote:

Originally Posted by MoxMonkey /img/forum/go_quote.gif so got around to actually trying to get it to work today reflowed the regs, still both read 3.0 replaced them with another pair i had making sure to check part numbers that mouser sent me and still the same at this point i'm at a loss as my pc will just list "Unknown device" but still light the LED

Maybe post a pic or two and let us take a look?

Meanwhile, just to make sure:
1. You're measuring the voltage at IC1 by measuring the ends of C11 (should be 3.3V)?
2. You're measuring the voltage at IC2 by measuring the ends of C13 (should be 4.75V)?
3. Did you install C16 at the R8 position and left the R7 and C16 positions un-populated? (The red BantamDAC PCB says C16 at two positions - it should go at the R8/C16 position.)
4. Does the LED light? (Never mind - you said it did.) If so, what's the voltage across R9? Or, the voltage from the bottom end of R9 to Ground?

 

[MoxMonkey]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Maybe post a pic or two and let us take a look? Meanwhile, just to make sure: 1. You're measuring the voltage at IC1 by measuring the ends of C11 (should be 3.3V)? 2. You're measuring the voltage at IC2 by measuring the ends of C13 (should be 4.75V)? 3. Did you install C16 at the R8 position and left the R7 and C16 positions un-populated? (The red BantamDAC PCB says C16 at two positions - it should go at the R8/C16 position.) 4. Does the LED light? (Never mind - you said it did.) If so, what's the voltage across R9? Or, the voltage from the bottom end of R9 to Ground?

Turns out I had forgotten C16 but that's now in place in R8. Doesn't change the reg voltage, both still measure 3.0v, the LED reads 2.65v

 

[tomb]

Quote:

Originally Posted by MoxMonkey /img/forum/go_quote.gif Turns out I had forgotten C16 but that's now in place in R8. Doesn't change the reg voltage, both still measure 3.0v, the LED reads 2.65v

So, is the voltage across R9 about 2.35V?

If you get that voltage across R9, then you have 5V from your USB. If so, it sounds like IC2 is a TPS9333, not a TPS93475.

How about the pics?

 

[MoxMonkey]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif So, is the voltage across R9 about 2.35V? If you get that voltage across R9, then you have 5V from your USB. If so, it sounds like IC2 is a TPS9333, not a TPS93475. How about the pics?

Sorry for the delay, had a busy couple days and had to find a camera that would take decent closeup shots.

ImageShack -

For measuring R9, where should it be measured from? If I measure right across R9 I get 0.36 (which may be off as my meter is running on low battery)

 

[tomb]

Quote:

Originally Posted by MoxMonkey /img/forum/go_quote.gif Sorry for the delay, had a busy couple days and had to find a camera that would take decent closeup shots. ImageShack - For measuring R9, where should it be measured from? If I measure right across R9 I get 0.36 (which may be off as my meter is running on low battery)

Assuming your meter is OK, that measurement across R9 explains a lot. The voltage leg for R9 and the LED are taken directly from the USB power connection - no regulator involved. This means you're only getting about 3V (2.65 + 0.36) from your USB power connection. You should have 5V.

EDIT: Looking at your pics, you've wired the USB cable incorrectly. Refer to this page on the BantamDAC website for proper color coding the wires to the proper holes:
http://www.diyforums.org/BantamDAC/B...ACcabledac.php
You have the green and red wires reversed.

 

[MoxMonkey]

awww, i had looked at that page when wiring it up yet somehow mixed them up.

i'll swap it tomorrow after work and let you know

 

[MoxMonkey]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Assuming your meter is OK, that measurement across R9 explains a lot. The voltage leg for R9 and the LED are taken directly from the USB power connection - no regulator involved. This means you're only getting about 3V (2.65 + 0.36) from your USB power connection. You should have 5V. EDIT: Looking at your pics, you've wired the USB cable incorrectly. Refer to this page on the BantamDAC website for proper color coding the wires to the proper holes: BantamCableDAC You have the green and red wires reversed.

finally got around to fixing the USB cable and that did it.

 

[tomb]

Quote:

Originally Posted by MoxMonkey /img/forum/go_quote.gif finally got around to fixing the USB cable and that did it.

That's great news! Glad to hear you got it working!

 

[Forte]

Have a problem with my latest Bantam DAC build.

Plugged in the USB cable to check voltages were okay before wiring it up to my Carrie amp but the LED did not light up and there was a small wisp of smoke from underneath the board near the USB terminal. No voltage present anywhere on the board and after unplugging the board and inspecting it there are scorch marks at each end of L3. Have unsoldered L3 and the pad nearest to C8 has come loose from the board.

All parts seem to be in the correct place and orientation, any ideas what may be wrong?

 

[tomb]

Quote:

Originally Posted by Forte /img/forum/go_quote.gif Have a problem with my latest Bantam DAC build. Plugged in the USB cable to check voltages were okay before wiring it up to my Carrie amp but the LED did not light up and there was a small wisp of smoke from underneath the board near the USB terminal. No voltage present anywhere on the board and after unplugging the board and inspecting it there are scorch marks at each end of L3. Have unsoldered L3 and the pad nearest to C8 has come loose from the board. All parts seem to be in the correct place and orientation, any ideas what may be wrong?

I hate to say it, but it sounds like something came into contact with L3 and shorted it. Is it possible a stray wire/frayed wire, or the case came into contact with L3? Usually, C8 is the part that sticks out the most on the bottom of the board, but L3 has a connection directly with the charged positive of C7 that's right at the edge of the board.

 

[Forte]

It wasn't cased up, just held in my helping hands so I could check voltages so no direct short to L3, have had a look over the board with a jewelers magnifier and have found a solder bridge from one leg of IC1 to C15 near the C7 cap, could this have caused the problem?

What apart from L3 could have been damaged from this, anything else?

 

[tomb]

Quote:

Originally Posted by Forte /img/forum/go_quote.gif It wasn't cased up, just held in my helping hands so I could check voltages so no direct short to L3, have had a look over the board with a jewelers magnifier and have found a solder bridge from one leg of IC1 to C15 near the C7 cap, could this have caused the problem? What apart from L3 could have been damaged from this, anything else?

Just guessing here, but I doubt that would've caused it. Maybe you should check for a bridge around the left USB connector tab and L3 - or perhaps the tab is not totally secure and could've flexed into L3? Is it possible one of the helping hands' alligator clips could've touched this area?

As for how much is damaged, that's pretty hard to predict. I'd begin by replacing L3 and seeing if that fixes it - assuming you continue to check for solder bridges and contact points. If that doesn't fix it, then check the voltages for IC1 and IC2 next, and proceed from there.