Identify this SMD component please? - Page 1
Forum section: electronics / repair

author: fudmuffin
author_rank: Contributor
timestamp: August 03, 2019, 01:35:54 pm
content: Hello everyone!Can you identify the pictured component please? Unfortunately the package melted so I'm not sure what to replace with. I think the package is a SOT89-3.What I can read is as follows, (where ? represents part I can't read):A8?05A8?84(those last 2 '8' could be 'B', hard to know)The component is designatedU7in the circuit. I've also included a pic of the circuit.It's from an old CDROM drive that I'd like to repair (model is CREATIVE 52X CD5233E).Probably a 3.3v or 5v regulator but I wasn't really sure.edit to mention: the MIDDLE pin has continuity with the 5v input from the power source, and the other pins to GND (I assume there's a short).Many thanks in advance!

author: PA0PBZ
author_rank: Super Contributor
timestamp: August 03, 2019, 03:48:24 pm
content: KIC3201S-18 matches the pinout and has A8 as marking, this is a 1.8V 400mA regulator.https://pdf.datasheet.live/datasheets-1/kec/KIC3201S-43.pdf

author: fudmuffin
author_rank: Contributor
timestamp: August 03, 2019, 04:17:17 pm
content: Thank you for your suggestion, it may be itI also noticed thisAME8805 which even has the marking of A8805, but they come in a variety of voltages and none match the second line of the marking on my blown component of A8?84, it seems. Still not sure about the identification.I may have bigger problems, as when I removed the burnt regulator I've noticed the two side pads still have continuity to GND (one pad is 4R, the other is 0R), and this doesn't seem right, does it?I can't find any other broken components yet - perhaps a short in the large IC has caused the regulator to burn out. Anyone please let me know if you have any ideas but I think I will need to shelve this repair attempt and find a new challenge for tomorrow

author: fzabkar
author_rank: Super Contributor
timestamp: August 03, 2019, 05:06:28 pm
content: Could the second line be AEF34, in which case the part could be an AME8805AEFT 3.3V regulator (week of manufacture = 34)?BTW, U2 (socketed flash EEPROM ?) appears to have a burn mark in the centre. If you remove it, does the short go away? Is U2 a 3.3V part?

author: fudmuffin
author_rank: Contributor
timestamp: August 04, 2019, 01:15:11 am
content: wow - I think you may have identified the part, as it must be a 3.3v regulator. Thank you.Unfortunately removing the EEPROM did not remove the short between the 2 pads where the regulator sat.The large chip (MT1199E) is a 3.3v chip, and on closer inspection had the suspicious smell of having had something magical and smokey escape from it, though there is no outward sign of damage. In the intersts of science I removed the large chip and indeed the short was removed.I had hoped it would be an easy fix with a new regulator. There is even an seller on Aliexpress peddling the MT1199E chips if I wanted to continue, but In the interests of priorities I'm going to put aside the idea of repair on this one unless another similar unit dies from which I can grab a new chip from.Thanks all for the very helpful replies!

author: fzabkar
author_rank: Super Contributor
timestamp: August 04, 2019, 02:27:06 am
content: IC501 (MT1199E) : RF+DSP+ATAPI DECODER+µ-COMhttps://www.rom.by/files/MT1199E.pdfAFAICT the big IC is powered from both +5V and +3.3V.If the EEPROM is a 5V device, then I would expect that the PCB was killed by an external overvoltage on the +5V input.