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y1 gamma-1 DAC
Jun 20, 2009 at 4:54 AM Post #721 of 1,546
Quote:

Originally Posted by fishski13 /img/forum/go_quote.gif
i'm putting together a BOM for USB-to-S/PDIF only option. i wonder if this would work?: Digi-Key - 425-2605-5-ND (Sharp Microelectronics - GP1FMV31TK0F)


Yes, this one would work and the pin-outs are the same as the TOTX147PL, but the mounting holes on the board for this one are not compatible. This one doesn't use the snap-in plastic pegs and the two unused pins the TOTX unit has, but has two side-mounting tabs for which there are no holes on the PCB.

I'll check into the availability situation on the TOTX147PL (and TORX147PL) and report back. Meanwhile, those who are building γ1 USB-to-S/PDIF and full++ configurations might want to get together and make a combined order from Newark to split the surcharge.

Quote:

back to my ground problem, there's a reduction in the hum when both the optical and coaxial outputs from the Oppo are connected - optical to the y-1 and coaxial to my Benckmark DAC1.

the switching transients were related to the fact that with the Pioneer cdp connected (i was trying to find out if it was an issue with the Oppo), it happened to be plugged into a different outlet on a different house AC circuit. no issues when plugged into the same outlet/power strip.

i'm wondering if the ground problem is caused by the fact that my LM7805 ground reference is "upstream" from the CK2III PS ground and tied in at the PS ground before going to star ground? i'll try a ground loop breaker before i rip apart the PS board.


It's hard to figure out just what's going on in your setup, but this is what I would do:

- If you're using the +15V from the CK²III board and dropping it down to 5V with the 7805 regulator, then the 7805's ground should be tied directly to the CK²III's star ground, and run the +5V output to the γ1.
- Run one ground wire from the γ1 to the CK²III star ground (it shouldn't matter where you connect this on the γ1, as long as it's securely tied to its ground plane (the ground pad for the output jack is a good place for this).
- Isolate the USB connector's shell ground from the case, or you might run into a ground loop situation even if you use a ground loop breaker.
 
Jun 20, 2009 at 5:08 AM Post #722 of 1,546
thanks Ti.
 
Jun 20, 2009 at 7:35 AM Post #723 of 1,546
OK, here is the scoop. Toshiba is obsoleting the TOTX147PL with a "last buy" date of 8/31/2010. That's more than a year away, I don't know why Digikey has prematurely discontinued it. I will redesign the next batch of γ1 boards to also accommodate the Sharp GP1FMV31TK0F transmitter (and GP1FMV31RK0F receiver, even though there is not yet any indication that the TORX147PL would become obsolete as well).

Meanwhile, you can make the Sharp unit fit the existing γ1 PCB by drilling two 2mm diameter holes for the mounting tabs, scrape away a little of the soldermask on the bottom side ground plane around those holes, and solder the tabs to the ground plane. EDIT: For U5U, doing this drilling will break the bottom-side trace that runs from R7U to LEDU. If you're going to populate R7U and LEDU, you should cut away more of that trace around the hole, so that when you solder the GP1FMV31TK0F's mounting tabs it won't short the LED trace to the ground plane. You should then solder a separate thin wire (30 AWG is enough) to go from R7U to LEDU.
 
Jun 20, 2009 at 3:17 PM Post #724 of 1,546
the hummmm is history per Ti's grounding recommendation! i still hear some soft/well-attenuated white noise starting at 3 o'clock on the pot. none of the hook-up wiring is shielded and i have yet to put the aluminum cover on the chassis. as i said before, 11 o'clock is really loud so any residual noise shouldn't be an issue.
 
Jun 20, 2009 at 3:51 PM Post #725 of 1,546
Quote:

Originally Posted by fishski13 /img/forum/go_quote.gif
i'm putting together a BOM for USB-to-S/PDIF only option.
<snip>


Quote:

Originally Posted by wiatrob /img/forum/go_quote.gif
if anybody wants 'em please PM me. I have three...


Ffishski13, if you need only one, I can have 2 and you can have the third from waitrob? Otherwise if there are more people, we can make a group buy from newark. If we get ~ 30 (more than $100) they will waive the $20 handling fee.

Anyone else interested?
 
Jun 20, 2009 at 4:04 PM Post #726 of 1,546
Quote:

Originally Posted by TeraHz /img/forum/go_quote.gif
Ffishski13, if you need only one, I can have 2 and you can have the third from waitrob? Otherwise if there are more people, we can make a group buy from newark. If we get ~ 30 (more than $100) they will waive the $20 handling fee.

Anyone else interested?


i'm not going to be using the speced Hammond enclosure, i'm builing my own. Sharp has a chassis mount transmitter that i think will work for me mounted remote with short leads. i'd rather let someone who wants/needs the speced Hammond enclosure to have dibs on waitrob's generous offer. of course if there's no takers....
 
Jun 20, 2009 at 4:19 PM Post #727 of 1,546
If you chassis-mount the fiber-optic modules and air-wire them to the board, you should add a 0.1uF multilayer ceramic decoupling cap across VCC and GND, right at the module's pins.
 
Jun 23, 2009 at 2:29 PM Post #730 of 1,546
Quote:

Originally Posted by TeraHz /img/forum/go_quote.gif
Ffishski13, if you need only one, I can have 2 and you can have the third from waitrob? Otherwise if there are more people, we can make a group buy from newark. If we get ~ 30 (more than $100) they will waive the $20 handling fee.

Anyone else interested?


I would be interested in two. I only really need one though. If we were going to buy a bunch as a group I would go for two.
 
Jul 8, 2009 at 9:27 PM Post #731 of 1,546
One of my obsolete IC sources pointed me to 5 pieces of TORX147PL remaining at NuHorizons. I bought the lot, and have 3 that I'll send out at the cost of UPS shipping - roughly $5. One as a backup.
wink.gif
I'll have them tomorrow.

Also - first time poster, and I'd really like to thank Ti for an awesome product, and a painless purchase.
smily_headphones1.gif
 
Jul 8, 2009 at 9:40 PM Post #732 of 1,546
Quote:

Originally Posted by jh0n /img/forum/go_quote.gif
One of my obsolete IC sources pointed me to 5 pieces of TORX147PL remaining at NuHorizons. I bought the lot, and have 3 that I'll send out at the cost of UPS shipping - roughly $5. One as a backup.
wink.gif
I'll have them tomorrow.

Also - first time poster, and I'd really like to thank Ti for an awesome product, and a painless purchase.
smily_headphones1.gif



I would really love two of them, but don't want to be piggy and take one if there is a crowd waiting for them.
 
Jul 8, 2009 at 10:34 PM Post #733 of 1,546
I just talked to Digikey about TORX147PL, they are currently out of stock but are expecting about 2500 pieces to come in late September. That's a long wait, so I suggest those who are building γ1 Full or Full++, S/PDIF only configurations to pool tegether orders from an alternate vendor. Newark can get them from their Farnell UK affiliate but there is a flat service charge. Those in non-US countries can get them directly from Farnell.
 
Jul 9, 2009 at 5:32 PM Post #734 of 1,546
Just an interest poll... how many people here need TORX147PL and how many pieces? As I said in the previous post, this part is in stock at Farnell UK, and can be ordered through Newark with an added $20 flat fee, so if there is sufficient quantity then the handling fee won't be too bad. Newark can get it delivered in 7-10 business days.
 
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