[Avro_Arrow]

  First time on Head-fi, because I can't seem to find this information anywhere.

 
Does anyone know where can I get one (possibly more) Carrie v2 boards? I have a AMB Mini3, and this Carrie amp interests me greatly!
I read through the whole thread, so my hopes are low (really low), but if someone has one and whishes to be charitable, I'm sure we can get along

 
Thanks anyway!

If you have some patients, there should be a new version coming out.
Like many of use who like to design things, Joneeboi's free time is in
short supply.

 

[joneeboi]

Hey folks,
 
As Avro mentioned, I am indeed kinda busy. Marriage and work and vacation taking up my time in the last few months, but as the dust has started to settle, I want to move forward with the design. First step is actually getting the PCBs, but I want to double check that my design makes sense. I let my obsessive side take over previously, and now I need to just get it moving. I'm almost never on head-fi to browse, but I do get email notifications on PMs. Trying to at least stumble toward the finish line, but this water break has lasted long enough.

 

[KimLaroux]

So... after a long break, I finally got around to debugging my Carrie.
 
I took the TL750L10 off the pcb to test it on a bread board. With an input voltage of 14.7 V and an output current of 30 mA, the output voltage reads 13 V. Does this mean the regulator is dead?
 
I've never experienced such a behavior from an LDO.
 
Either way if current is flowing trough it, I don't see why my Carrie is not operational. I'll try resoldering the LDO in and do more tests on the circuit. I wish I had spares to compare... This IC is one of the few I didn't get a spare of. Silly me.

 

[KimLaroux]

The LDO back in, I get 1.87 V on its input and 1.84 V on its output. I'm guessing there's a short somewhere but being mostly a trough-hole board I have no idea where to look. Not to mention the LDO doesn't get hot... Maybe it detects a short and shuts down, but then why is the input 1.87V?!?

 

[joneeboi]

What's the DCP's output reading?

 

[KimLaroux]

  What's the DCP's output reading?

 
2V, like the input of the LDO. I tried removing the LDO and the DCP did output enough voltage, around 14V if I remember right. It just falls for 2V when I put the LDO in.

 

[KimLaroux]

I got a new desktop computer running Windows 7 so I'm giving this another try...

If I plug my GrubDAC alone in the USB port, without the carrie, it's recognized and I guess works fine. (I don't have plugs connected to its audio output so I cant test it)

I think the problem is with the Carrie. Here's why I think so:

I added a power switch between the carrie and the dac. When I plug the DAC in with the switch open, the DAC is recognized:

1460.483019] usb 6-2: new full-speed USB device number 52 using uhci_hcd
[ 1460.669007] usb 6-2: New USB device found, idVendor=08bb, idProduct=2707
[ 1460.669011] usb 6-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 1460.669014] usb 6-2: Product: USB Audio DAC
[ 1460.669017] usb 6-2: Manufacturer: Burr-Brown from TI
[ 1460.701071] input: Burr-Brown from TI USB Audio DAC as /devices/pci0000:00/0000:00:1d.0/usb6/6-2/6-2:1.2/input/input19
[ 1460.701346] hid-generic 0003:08BB:2707.0009: input,hidraw5: USB HID v1.00 Device [Burr-Brown from TI USB Audio DAC ] on usb-0000:00:1d.0-2/input2

But the moment I close the switch to power the carrie...

[ 1528.953037] hub 6-0:1.0: port 2 disabled by hub (EMI?), re-enabling...
[ 1528.953045] usb 6-2: USB disconnect, device number 52
[ 1531.042021] hub 6-0:1.0: connect-debounce failed, port 2 disabled
[ 1533.246020] hub 6-0:1.0: connect-debounce failed, port 2 disabled

I'm thinking my Carrie+GrubDAC combo is pulling too much power off the usb port. I tried bypassing the switch using my DMM and it tells me the carrie is pulling 40 mA. I'm having a hard time believing this, after reading the math behind this whole project. How much current should I expect my carrie to draw?

 

[Avro_Arrow]

It might not be the idle current that is the problem, it's probably the start up surge.
Try powering the grub and th Carrie off different ports.
 

 

[KimLaroux]

And with the huge capacitor banks on the carrie, it's to be expected. I'll try powering the carrie straight off an ATX PSU. This should answer the question.

 

[KimLaroux]

Meh. Very meh.
 
I thought for a moment the problem could be the capacitor bank being too big, but even directly powered from an ATX PSU all I get out of the DCP - and the LDO - is 2.7 V.
 
I removed the LDO and the DCP outputs 24V. I'm hoping it's just the LDO that is blown, so I'll order a couple of spare ones and see.
 
But this time I'm soldering socket pins into the LDO PCB holes. I'm done with desoldering and resoldering this part.

 

[KimLaroux]

Anyone has got one or two TL750L10CLPR to spare? I don't feel like paying 20$ of shipping for a 0.82$ part. =/

 

[KimLaroux]

Ok I give up. Plan B: Is it safe to replace the 750L10 with a 78L10? The later has a current capability of 100 mA compared to 150 mA for the 750L10. I searched the thread but can't find a consensus on how much current the Carrie draws.

 

[Avro_Arrow]

Give it a try and I'll cross my fingers for you.

 

[KimLaroux]

  Give it a try and I'll cross my fingers for you.

 
Lol. If you see a big mushroom cloud East of your place, and that I never report back, you'll know the experiment will have failed. 
 
No but seriously. If I don't get more data on the specifications of the Carrie I won't fool around and order the 750L10. It's just twice the price.

 

[Avro_Arrow]

 

 
Lol. If you see a big mushroom cloud East of your place, and that I never report back, you'll know the experiment will have failed.


 
No but seriously. If I don't get more data on the specifications of the Carrie I won't fool around and order the 750L10. It's just twice the price.

Other than having to charge up that big a55 cap bank, it's just a three channel CMoy.
I think the 100mA should at least get it running. Just add up the quiescent current
for the three channels and add in how much current you think you may draw under load.