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Hi, Can anyone help me ID a semiconductor? It's in a TO-92 package and has Motorola's logo on it and the following numbers on it:
SU
316
7939
This part is in a Sears 10A 12V automatic battery charger that I am trying to fix.

Well, the 7939 is almost certainly a date code, 39th week of 1979. Does this fit with the age of the equipment?
You say TO92, are we to assume that the device has three leads?
If so then probably a transistor or thyristor or some such device.
Will have a look through the possibilities.
Regards
Rob

The device has 3 leads. It seems to be an older battery charger. It's not mine; I am fixing it for another person in my community.

Probably devices, most likely first:-
2SC316 - Silicon, NPN, 30mA Ic, 300mW Ptot - package TO18, EBC starting from tab.
2N316 - Germanium, PNP, 500mA IC, 150mW Ptot - package TO5, EBC starting from tab.
2SA316 - Germanium PNP, 20mA Ic, 60mW Ptot, package TO5, EBC starting from tab.
BF316 - Silicon PNP, 15mA Ic, 150mW Ptot, package TO72, BEC starting from tab.
There is a U316 which is a junction N-FET but unlikely
As to which this is, I could not say. Could you be reading SC316 as SU316?
Regards
Rob

It's definitely an SU316. I checked carefully before I placed my first post as a google search didn't turn up anything useful. Also, I have never seen a Motorola branded part with part numbers 2SA, 2SB, 2SD, 2SD or anything similar.

Why not just do a little reverse engineering in that area to determine the circuit funtion its used for? It will probably end up that any garden variety device will work, as a battery charger rarely has critical components, and further yet, you may be able to get away with a 5 cent device for a replacement part. BTW why do you think its this device since you did not mention any troubleshooting procedures as yet?
Also 2S is the Asian equivilent of American 2N devices.

ken1,

Do you have the old Manual for it?
Yes,
Then look on the back pages for a schematic, and parts listing.
You may get lucky and find a parts listing.
Then you can try crossing it from the part number in the listing.
Or
Get the model number off the Sears 10A 12V Charger.
Then go to this Web address...
http://www.searspartsdirect.com/partsdi ... 114x00001a

See if they have a parts break down on it.
Yes,
Then look up the sears part number for that Motorola device.
Now check that Sears Part Number, and see if it has a cross to a NTE part number.

If the 12V Charger doesn't turn up.
It's to old, and Sears has discontinued parts for it.

If that is the case.
Rebuild the Charger, or just tell this person to buy a new one.

Good luck!


Signed: Janitor Tzap

Ken1 wrote:Hi, Can anyone help me ID a semiconductor? It's in a TO-92 package and has Motorola's logo on it and the following numbers on it:
SU 316 7939
This part is in a Sears 10A 12V automatic battery charger that I am trying to fix.

Ken, can you do a bit of reverse engineering?

If you could take the time to examine the board and hand draw a rough schematic, then scan it and upload it here, we will be more likely to figure this out.

Hmmm in a older battery charger, i can almost betchya its a dioad of some sort
not many battery chargers were smart back then..

I drew a schematic but cannot figure out how to post it.

Hi Ken,


Look under the big box you type in, it says "Add image to post".
Click that to upload an image. It will appear in your post.

I was going to say the same thing Bob said, that if you can draw
a schematic we might be able to recommend a replacement part.
I checked an old dated transistor cross reference and the only
part they had listed was SU110, and no others that started
with SU. I also checked SV and there was no SV316 either.
Not finding the part means we might have to try to figure out
how the circuit works and use a different part, or else redesign
the entire charger (sometimes not that hard) if you dont mind
building your own (new) board.

I don't see the phrase "add image to post" anywhere. Do I have to change some setting to get this to appear?[/quote]

Hi Ken,


There is a chance that you have to change your profile so that
you are using the board style called "FI Subsilver Shadow".
This might allow the image adding text to appear.
Im not sure about this, but you can try it or else someone else
who knows why you dont have this might reply here.

Hi, Updating my profile to Subsilver shadow worked!
Now, here is the schematic I drew last night:

This may be a programmable unijunction transistor (PUT), since it is providing a trigger pulse to the SCR's through a trigger transformer.

A PUT is actually a small integrated circuit that acts like an older part called a unijunction transistor, but with more consistent characteristics. The part you have might be a house number version on a 2N6027, which also comes in a TO-92 case. You shiuld be able to find a data sheet on the ON Semiconductor web site.