M-AUDIO  Fast Track Pro repair - Page 1
Forum section: electronics / repair

author: z4ri0n
author_rank: Newbie
timestamp: April 01, 2017, 04:12:40 pm
content: Hello guys! this is my first postI found this m-audio fast track pro usb interface in a dumpster... just when I was considering to buy a focusrite scarlett, luky dayI opened it and found that the voltage regulator was literally cut in half, it is a UTC LD1117AL AD. I started to search for it but seems to be obsolete and no one sell it anymore.I tried to search for an alternative but didn't find a matchcan someone help me?thanks!

author: mcinque
author_rank: Unknown
timestamp: April 01, 2017, 05:22:44 pm
content: I would try identifying what ICs are connected to the power rails to see by their datasheets what voltage and current they require, just to have a starting point for a replacement.You could then remove the part and inject the found voltage to see if there is some short over the regulator before simply replacing it.

author: Vicus
author_rank: Regular Contributor
timestamp: April 01, 2017, 05:39:55 pm
content: It seems to be a standard ldo regulator. What's the problem? The pinout?https://www.sparkfun.com/datasheets/Components/LD1117V33.pdf

author: z4ri0n
author_rank: Newbie
timestamp: April 01, 2017, 11:46:00 pm
content: I tried to compare the datasheet with other regulators that are in production, but didn't found a good replacement.here the datasheet for the original regulator:https://protostack.com.au/download/LD1117_A.pdfis the A version 1A adjustable not fixed.here the board photos front and back:it require a 9V DC 500mA power supply, positive inside and negative outside.I'll try to remove it to understand in which configuration is installed, but I'n not good enough to derivate the complete circuit and do the math to modify it in case was not possible to replace it with an alternative.

author: senso
author_rank: Frequent Contributor
timestamp: April 02, 2017, 05:29:36 pm
content: An LM1117 in TO-220 will be a drop-in replacement, just find the output voltage, because pin 1(Gnd/ADJ) is ground on the bottom layer, probably either 5v or 3v3.

author: Gyro
author_rank: Super Contributor
timestamp: April 02, 2017, 06:04:42 pm
content: That's curious damage. The regulator has thermal and overcurrent protection, it looks as if there's a reverse polarity protection diode too. Maybe a severe input overvoltage?Looking at the bottom of the board, it looks as if that regulator might have been hand soldered before. Edit: Overheated during soldering?

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 02, 2017, 06:12:18 pm
content: Quote from: Gyro on April 02, 2017, 06:04:42 pmLooks like a botched repair attempt.It does NOT look like the original production soldering job.Mouser sells 50 different shades of LM1117.OTOH, I wonder if a fault bad enough to crack the regulator in half might be related to trauma elsewhere in the circuit?

author: OldNeurons
author_rank: Regular Contributor
timestamp: April 02, 2017, 07:11:17 pm
content: Here is a good quality picture of the board.https://get.google.com/albumarchive/102970072923818524447/album/AF1QipPc54qBu7rk-wDSpl2LNQGsX2p9kLvkGqmTRiUx/AF1QipPhU4SmJGwVpRJJ_vfCc4i2qfwkmqG7SIorj8k6Hope this will help.

author: mcinque
author_rank: Unknown
timestamp: April 03, 2017, 07:20:15 pm
content: It seems to me that LM1117AL (cracked on board, evident bodge repair attempt) is not an equivalent of LM1117L (mounted on original board): am I wrong?

author: Rasz
author_rank: Super Contributor
timestamp: April 03, 2017, 07:40:33 pm
content: all it takes is for that barrel jack to be 5.5/2.5mm type, user plugs his laptop supply and puff

author: mariush
author_rank: Super Contributor
timestamp: April 03, 2017, 07:41:38 pm
content: The 2 resistors below the regulator set the output voltage. On trace goes from those to the GND/ADJ pin of the regulator.The tab is Vout on LM1117, so you can check with the continuity function of your multimeter, the tab should be connected to the center pin as well.The pin to the right is the input pin.If you can't find a *1117 ,LM1085orLM1084should be pin compatible (they're 3A max for LM1085 and 5A max for the LM1084), they can work with higher input voltages (up to around 29v compared to most 1117 which cap at around 17v from memory) and they have same forward voltage drop (actually even better than 1117 chips at high currents, less than 1v at 1A, up to 1.3v at 3a compared to around 0.8v..1v at 0.8A for *1117 )I keep using *1117 because they're literally made by lots of companies and they use various prefixes.