What's this please? (Component Advice)

[Andy Watson]

Ok I need help with this one. I got a Fluke 83 series I

Is this any help? It gives a "simplified power supply schematic".
http://assets.fluke.com/manuals/83_85_87smeng0500.pdf

[orbiter]

Ok I need help with this one. I got a Fluke 83 series I in auction that won't turn on. I had almost given up having checked all the usual stuff like fuses etc which are all fine. Until tonight I was bored checking random part values and noticed there was only 68ohms resistance between the positive and negative battery terminals. Hmm I wonder why it wouldn't start. After removing several items that tested bad in circuit, but were fine out of circuit, I came across this. It's clearly bad (roughly 50 ohms across every terminal), I am guessing that it is a bjt of some sort but my googlefoo is failing me. I apologize if it's easy but my laptop is off for warranty repairs so I'm limited to phone searches. The item doesn't have a designator number on the silk screen but it was located top right beneath the LCD.

Thanks guys and gals for your help. Hopefully I can save another device from the trash can.

Sent from my EVO using Tapatalk

Not had time to look through the 80 series schematic but the 702 device is indicating on the following site as an N-CH Mosfet

http://www.marsport.org.uk/smd/mainframe.htm

[AndersAnd]

my googlefoo is failing me.

You need to improve your lacking googlefoo a lot then, because 702 is a very easy marking to find using google. 
Simply google 702 SMD marking or include the housing type SOT23 and google 702 SOT23 marking, or simply just 702 marking.
Then you will get plenty of hits for 2N7002, which is probably the most common of all SMD MOSFETs. Very cheap and easy to find, so you're lucky if this is the only thing broken. It's also a device that's easy to damage.
Be careful when replacing it. MOSFETs are very easy to damage by static electricity. And it can just get partly damaged so you might not be able to tell it's damaged right away.

But other than goggling marking codes, the other place to start out looking for SMD codes is simply looking in a SMD codebook like the one mentioned in the post above. There's a number of different ones to check, for example:

http://www.systek.ru/marking.php
http://www.marsport.org.uk/smd/mainframe.htm
http://www.s-manuals.com/smd
http://www.angelfire.com/electronic2/rch/smt.html
http://elektronikjk.republika.pl/s1.html

PDF SMD codebooks:
http://www.electroschematics.com/wp-content/uploads/2013/04/SMD-code-book.pdf
http://www.siongboon.com/projects/2013-09-22_reverse_engineering/doc/SMD-2012-sample.pdf

[PedroDaGr8]

Ok I feel retarded now. I saw the links last night to 2n7002. For some stupid reason my brain though 2nXXXX is to92 must be a Google error from using the words 702 and mosfet.  I blame the bourbon Thanks a bunch guys I've bookmaked those sites for future reference. I didn't know they existed.

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[AndersAnd]

2N7000 is the leaded TO-92 version of 2N7002. Almost the same MOSFET, both 60 V N-channel, but different housing and a bit different current and power handling capabilities etc.

2N7000 / 2N7002 / NDS7002A datasheet https://www.fairchildsemi.com/ds/2N/2N7000.pdf

2N doesn't tell anything about the housing type. The first digit just tells how many P-N junctions it has. So in the American JEDEC naming system 1N is for didoes and 2N is for BJTs, Triacs, SCRs, JFETs or MOSFETs (but not dual-gate).
Here's a post I made in another topic about the JDEC naming system: https://www.eevblog.com/forum/chat/555th-video/msg335916/#msg335916

[PedroDaGr8]

Thanks that was actually really informative.

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[TheBay]

SMD Diode identification, EPP 47 is all that's marked, Becker Indianapolis BE7920

Picture attached, was taken with mobile phone, do not have a digital camera handy.

https://www.dropbox.com/sc/krzm94a01vecd4o/qermgHRZSY

Picture here:

[peter.mitchell]

SMD Diode identification, EPP 47 is all that's marked, Becker Indianapolis BE7920

Picture attached, was taken with mobile phone, do not have a digital camera handy.

Picture here:
www.useasmallerpicture.com

Does this seem appropriate:
http://www.vishay.com/docs/88407/tpsmc68tpsmc47a.pdf

[TheBay]

Thank you for this, makes some sense I wonder if excess voltage supplied i.e. 24v caused it to go S/C

This is the logo on the device, who is the manufacturer?

SMD Diode identification, EPP 47 is all that's marked, Becker Indianapolis BE7920

Picture attached, was taken with mobile phone, do not have a digital camera handy.

Picture here:
www.useasmallerpicture.com

Does this seem appropriate:
http://www.vishay.com/docs/88407/tpsmc68tpsmc47a.pdf

[peter.mitchell]

Thank you for this, makes some sense I wonder if excess voltage supplied i.e. 24v caused it to go S/C

This is the logo on the device, who is the manufacturer?

SMD Diode identification, EPP 47 is all that's marked, Becker Indianapolis BE7920

Picture attached, was taken with mobile phone, do not have a digital camera handy.

Picture here:
www.useasmallerpicture.com

Does this seem appropriate:
http://www.vishay.com/docs/88407/tpsmc68tpsmc47a.pdf

That logo is for  General Semiconductor, who are now owned by Vishay Technology, the above mentioned company.

The device is a TVS, it is designed to go short circuit to clamp voltages to a specified level, this one, marked EPP states 23.1v maximum working voltage, and 25.7v-28.4v breakdown voltage. Whilst designed to withstand high currents for short periods of time (to clamp the voltage), expectedly, it will be damaged under exceptional stress for extended periods.

The wikipedia page is quite helpful in regards to this device. http://en.wikipedia.org/wiki/Transient-voltage-suppression_diode

[TheBay]

That explains my assumption, some vehicles are 24v obviously so this goes short to take out main fuse to save damage to the unit.
Maybe someone jump started the vehicle it came out of.

Have seen that logo a few times but had no idea what manufacturer it is, I've found the part on RS

Thanks again,
Dale

Thank you for this, makes some sense I wonder if excess voltage supplied i.e. 24v caused it to go S/C

This is the logo on the device, who is the manufacturer?

SMD Diode identification, EPP 47 is all that's marked, Becker Indianapolis BE7920

Picture attached, was taken with mobile phone, do not have a digital camera handy.

Picture here:
www.useasmallerpicture.com

Does this seem appropriate:
http://www.vishay.com/docs/88407/tpsmc68tpsmc47a.pdf

That logo is for  General Semiconductor, who are now owned by Vishay Technology, the above mentioned company.

The device is a TVS, it is designed to go short circuit to clamp voltages to a specified level, this one, marked EPP states 23.1v maximum working voltage, and 25.7v-28.4v breakdown voltage. Whilst designed to withstand high currents for short periods of time (to clamp the voltage), expectedly, it will be damaged under exceptional stress for extended periods.

The wikipedia page is quite helpful in regards to this device. http://en.wikipedia.org/wiki/Transient-voltage-suppression_diode

[AndersAnd]

Have seen that logo a few times but had no idea what manufacturer it is,

Just like there's SMD marking databases online, there's also semiconductor logo databases available.

E.g. these ones:
http://www.dibsplace.com/design/ICLogos.htm
http://www.elnec.com/support/ic-logos/
http://how-to.wikia.com/wiki/How_to_identify_integrated_circuit_%28chip%29_manufacturers_by_their_logos
http://www.chipdocs.com/logos/logotypes.html
http://www.classiccmp.org/rtellason/logos/semiconductorlogos.html
http://www.dialelec.com/semiconductorlogos.html
http://www.westfloridacomponents.com/manufacturer-logos.html
http://freespace.virgin.net/matt.waite/resource/logos/

Only the last of the above links doesn't have the GS logo and the associated General Semiconductor name, but only show an older star logo for GS.

[TheBay]

Some useful info there, thanks

Have seen that logo a few times but had no idea what manufacturer it is,

Just like there's SMD marking databases online, there's also semiconductor logo databases available.

E.g. these ones:
http://www.dibsplace.com/design/ICLogos.htm
http://www.elnec.com/support/ic-logos/
http://how-to.wikia.com/wiki/How_to_identify_integrated_circuit_%28chip%29_manufacturers_by_their_logos
http://www.chipdocs.com/logos/logotypes.html
http://www.classiccmp.org/rtellason/logos/semiconductorlogos.html
http://www.dialelec.com/semiconductorlogos.html
http://www.westfloridacomponents.com/manufacturer-logos.html
http://freespace.virgin.net/matt.waite/resource/logos/

Only the last of the above links doesn't have the GS logo and the associated General Semiconductor name, but only show an older star logo for GS.

[cubemike99]

BTC 0207-010F

All I know is that it is the chip inside the Brymen-257/Greenlee-510A. Thanks.

[AndersAnd]

BTC 0207-010F

All I know is that it is the chip inside the Brymen-257/Greenlee-510A. Thanks.

BTC is most likely short for BRYMEN TECHNOLOGY CORPORATION, which is the full company name: http://www.brymen.com
So it's probably some kind of custom chip, and datasheets or other documentation is usually not available for custom chips.

[cubemike99]

BTC 0207-010F

All I know is that it is the chip inside the Brymen-257/Greenlee-510A. Thanks.

BTC is most likely short for BRYMEN TECHNOLOGY CORPORATION, which is the full company name: http://www.brymen.com
So it's probably some kind of custom chip, and datasheets or other documentation is usually not available for custom chips.

Would a small company like Brymen really have custom chips? I was thinking it's a common DMM chip simply rebranded. Oh well.

[timelessbeing]

How do I identify these diodes (schottky, zener etc.), and what do the stripes mean?

[AndersAnd]

How do I identify these diodes (schottky, zener etc.), and what do the stripes mean?

Have you measured the diode forward voltage with a multimeter? Easy way to tell if it's silicium, schottky or germanium diodes. And you could reverse bias them with a resistor in series to measure if it's zener didoes.


Edit: Diode color codes: http://www.crystalradio.net/cal/diodeid.shtml
If these codes are used with two digit type:
White - Yellow = 1N94
Brown - White = 1N19

Or maybe it's the opposite, if you star reading from the other end.

[timelessbeing]

With my DMM, I measure nothing ("1") in either direction.

[AndersAnd]

With my DMM, I measure nothing ("1") in either direction.

At the DMM diode setting?

[timelessbeing]

Yes, and I know it works because I can test other diodes.

[SeanB]

Those are not diodes but are spark gaps. The clue is the resistor like inside with the ring cut all the way around the middle. They are going to be open circuit till you reach the break over voltage, probably around 90V or so.

[timelessbeing]

Aha! Thanks you SeanB.

[Terabyte2007]

I look parts up all the time, but I can't find this one at all! Any ideas???

It came out of a power supply so my guess is a regulator or dual schottky diode of some sort.

Sorry, the print is faded. Hope you can read it!

[SeanB]

N channel mosfet?