Blown Q1, any ideas what it was or what will work?

[centrion1956]

Hello everyone, I'm out of my comfort zone with this one and need assistance from the hive mind. I have an Olympus DP11 microscope camera that I just purchased and they said it had a burnt smell coming out of it, so they really discounted the price for me. Hoping it would just be a bad cap or something simple and straight forward to repair I took a chance. I took it apart and found a transistor popped on the power supply board (probably the wrong wall transformer was plugged into it). There are no schematics or any help from Olympus or any support companies, so my question is: What would be the assumed transistor replacement? Here is some of the information;

Input voltage- 6.5v 1.5 amp
Form factor- SOT89 SMD (approx) 4.5mm L x 2mm W  and stands about 2mm tall on the board
Identifying marks- A large capital "N" on the top left side. No other visible or detectable numbers printed on it
The Q2 next to it is ever so slightly smaller and has a very faint capital "N" on the top left side and has a capital "Y" printed on the top right side. No other visible or detectable numbers printed on it
Please see attached photos

Thanks a Million !!!

v/r

Joe

[helius]

From the code book, all the parts starting with 'n' with SOT89 package are NPN with the same pinout. Any of them will probably work if the threshold voltage is close enough to the original part.

[Chris56000]

Hi!

I'm fairly sure, from looking at your photos,  that both Q1 and Q2 will be of the same type, so if you can identify the less–burnt one Q2 you'll identifiy the other one!

One of those little LCR–T1 ebay testers is your friend, and if you want to repair a lot of surface– mount you can get a little maroon–cased one specifically made for surface–mount components!


Chris Williams

[centrion1956]

Thanks Helius and Chris56000 !!! I was also looking at the code book earlier and went back to my photos and started messing with the parameters and saw a capitial "N" on the top left side of the Q2, so that made it an "NY" on the Q2. Now that you said that I just went back to the code book and the only NY SOT89 is made by TOS. Thinking they are possibly a matched complementary set and the only other SOT89 that is made by TOS is an "NO". That means it's either a matched complementary set of an "NO" and "NY" together or it's a pair of "NY"'s. The NO is a 2SA1213O pnp power hfe 70-140 and the NY is a 2SA1213Y pnp power hfe 120-240. Both (if I'm reading the code book correctly) are compatible with a 2SC2873. Please slap me if I'm way off in left field somewhere.

Thank you !!!

Joe

[centrion1956]

I went back again and worked harder with the photo enhancements and I think I definitely see an anomaly that looks like a "Y" in the burnt area, so Chris56000 is also spot on along with Helius. It's a pair of "NY"s.
You guys are the best !!!

Joe

[fzabkar]

The NO is a 2SA1213O pnp power hfe 70-140 and the NY is a 2SA1213Y pnp power hfe 120-240. Both (if I'm reading the code book correctly) are compatible with a 2SC2873. Please slap me if I'm way off in left field somewhere.

2SCnnnn is NPN, 2SAnnnn is PNP.

Consider yourself slapped. :-)

[centrion1956]

Good catch fzabcar, this is straight out of the book " NY  2SA1213Y  Tos  P  SOT89  power hfe 120-240 comp 2SC2873" am I reading wrong or is the book wrong? So do you agree with the call that they are probably two 2SA1213Y?

Thanks,

Joe

[helius]

I believe the code book uses "comp" to mean "complimentary", not "compatible". Yes, 2SA1213Y, or a substitute like 2DA1213Y-13. Use parametric search for collector current=2A, case=SOT-89 or SOT-89-3, polarity=PNP, emitter-base voltage=5V or -5V

[centrion1956]

That absolutely makes sense now. I remember reading it somewhere before that the complementary to the "NY" is the "MY" and when I looked up the 2SC2873 earlier it was "MY". I didn't make the connection before now... * slaps forehead* dooooo!!!

Thanks again !!!

Joe