What regulator is U13 on the SB3?

[Holyghostfire]

I know this powers a few chips and not only the hex buffer chip. I was going to raise the pin on the buffer chip to supply a super reg, but I have heard of bad reports doing it. If I could have the name of the reg then I can figure out what is going on so I can replace it with a super reg. Maybe Sean could help me out on this one. Thanks a bunch.

[Holyghostfire]

I was testing the voltage on each pin for U13 and four pins read 3.3v and the other pin being ground. Is this a regulator? What purpose does it serve? Hopefully someone can answer this question. Thanks again.

[seanadams]

U13 is a logic gate! It's part of the failsafe blanking circuit for the display. The 3.3v supply is U18.

In any case it's not possible to wire in a different power supply just for the HCU04, without lifting its pins. What is your end goal here? If you want to hook up a super regulator somewhere, you are best off using it to power the DAC's 5V rail, because there's nothing else in the system that would particularly benefit from it. If you want to get less jitter over s/pdif, consider implementing a slave clocking scheme where the master clock originates from the DAC. Any jitter that might be removed by cleaning up power rails will pale in comparison to what is being introduced by the s/pdif connection.

[devodave]

I was interested in possibly lifting the U18 supply (3.3 v) and replacing it with a super regulator. This was done by Nuuk in the Decibel Dungeon. I am planning on an improved 5.0 v supply as well as possibly another super regulator on U15. I will be feeding a seperate DAC, so my plan was to disable the power to the headphones, the stereo amps, and the PCM1748. I have not however been able to identify what exactly U18 is to obtain a data sheet. It is labeled as IR (International Regulator) with "101033," but I have had no luck with the searches.

[metropole]

Did anyone find more info about the 101033?

I would have expected that one pin would show 5VDC. However, everything is close to 0VDC. What is the path from the 5V supply to this circuit?

Trying to repair my SB3...

[Astralix]

Hi metropole,

the IR shortcut is from Internation Rectifier, you can find their parts here:
http://www.irf.com/indexsw.html
But the code you tell is probavly not the regulators name but a LOT number or datecode. Unfortunately none of the pictures show the part in detail.

EDIT
Sorry, you where right, it is an IRF1010-33 (Datasheet http://www.irf.com/product-info/datasheets/data/iru1010-33.pdf) a 3.3V/1A linear regulator.
But there are two other switching reglators near by it, as I can see from the photo http://myweb.tiscali.co.uk/nuukspot/decdun/SB3/sb3_psu_section.jpg
One is on the left, check the Diode D14 for beeing ok and one is only partly visible above. I can only see L7. Hey, we really need two high-res photos from top and bottom side of that area of the device. Even on multilayer PCBs power is routed often only on top and bottom.
/EDIT

There seem to be several regulation parts below the DC jack. One is a switching DC/DC (8-Pin SO case near the indurctor) there is another ON Semi part and probably the mentioned IR. May be you can put another high-res photo online?

Best regards and happy new year ( 1.5h to go for the old one)
Ulrich aka Astralix