I've got a remote helicopter that I'm trying to fix for a co-worker. I've found that one of the ICs on a board is fried. There are 3 identical ICs in a row and it looks like they have the following markings: A symbol that kind of looks like a fancy A, 99268, and CA6T1S. I've tried searching Digi-key for these part numbers. 99268 returns a DC to DC power supply, but it has 10 pins instead of 8 like the part I have. There's also 3 smaller parts, that I think are transistors. It looks like they are marked with 80C. Can anyone help me identify these parts? Thanks.

 

I think I figured out what the IC is. It looks like the number on it is NOT 99268, but 9926B which according to Digikey is a MOSFET DUAL N-CH 20V 6.2A 8-SOIC. Now, can anyone tell me a way to ID the accompanying, what I assume is a transistor?

 

it might be the same part as the sot23 beside it..?

 

I'd be willing to bet they're the same, but I can't figure out what they are. Looks like the markings might be 8 or B, D or 0, and a C or 3. Thanks for helping me ID the package though. That will help narrow it down a bit.

 

BDC or 8DC

 

I pulled out the magnifying glass today and the marking is indeed BDC with a sideways 26 at the end. Still trying to track down exactly what the part is though.

 

I pulled out the magnifying glass today and the marking is indeed BDC with a sideways 26 at the end. Still trying to track down exactly what the part is though.

aye, on the smaller packages its a right pig! or if theyre made by texas instruments! ti oddly omit letters from the chip id, even on bigger chips.. then when you search, nothing appears on the ti website or google.. very annoying.
out of interest, have you tried getting in contact with OEM? they might be able to supply schematic and bill of materials or new board?

 

I have not tried to contact the OEM. These parts are on an RC helicopter controller board. You can buy a new one for $50, but if I can figure out what this part is I'm sure I could fix it for much cheaper.

 

do you know what this does? got a picture of the other side?

 

I'm pretty sure this board controls the motors for the heli. There are 2 sets of chips to control the angle of the propeller and 1 to control the speed of the propeller. Here's a shot of the back of the board though.

 

yeh i reckon its a mixer circuit too, means you can use two controls and it sorta mixes them in the right proportions.. i guess, you could find out what that sot23 does? plug the board in, and probe it? see if its a mosfet or transistor?

 

I tried probing these things a little today. when all the joysticks were in the center all 3 pins read -1V. when I moved a joystick one way it looks like one pin went to -1.2V and the other 2 went to -0.8V Still not quite sure what I'm looking at, but I'm thinking it's either a PNP transistor or a schottky diode.

This list shows a marking code of BD* (* indicates SOT23) is a BCW61D PNP transistor.

This PDF shows B0C is a HSMS-2810 schottky diode.

When I get a chance I'll see if I can't probe the voltage between each pin on this chip. It's kind of hard though since they're so small.

 

i think that things basically a mixer.. it allows the mixing of two channels (e.g.: X,Y) and means instead of having to push diagonally to go forward (e.g. on a rc car) you can push forward.. makes the controls more logical.. anyway.. replace them.. maybe buy them and see if a) they look the same and b) same ids on the top! good find on the lists, i should check that out! very helpful to be able to reverse engineer or like you have, find replacements!

 

Here's what looks like another good SMT reference
http://www.s-manuals.com/smd

 

favouriting that! make sure you put those links in the offtopic bit.. or projects bit.. its called datasheets. its DAMNED useful!! good fine batman

 

http://forum.allaboutcircuits.com/showthread.php?t=3246