identify component

[glinjik]

hi please someone tell me what this is i dont think its a zener its quite big about 1cm in length markings like a resistor it sits right beside a transformer in a smps shows ol in resistence on fluke could it be a fuse? shows nothing on diode mode got me baffled no doubt whoever identifies it will think dumb newbe 

[Andreas]

G = GDT? (Gas discharge tube)

https://uk.rs-online.com/web/p/gas-discharge-tubes/5258844/

with best regards

Andreas

[glinjik]

thank you guess ill have do some investigating now 

[Gyro]

That's weird, I've never seen these parts [Edit:in this package] queried before and then they pop up twice within a few days, from different sides of the world!

https://www.eevblog.com/forum/repair/troubleshooting-what-seems-to-be-a-germanium-diode/

(Although they seem to have different markings / voltage ratings).


P.S. The PDF datasheet in Andrea's link appears to show colour coding.

[glinjik]

https://en.wikipedia.org/wiki/Gas-filled_tube

for anyone interested here’s the wiki on this innocent looking component turns out to be very impressive

[glinjik]

i think my next obvious question is how to test the little сука

[Gyro]

If it measures open-circuit then you should be fine - it's when it is shorted that you need to worry. 

[PPS]

Hello guys.
I need your help with the with indentifying of this transistor.
It is on the small PCB which adjusts the rotation speed of the Dewalt 707 miter saw.
Cant find this marking anywhere.

marking
on the top - 18 508
on the bottom - BSGZ348
as I can read
look at the pic

[amyk]

Some clone of IRFZ34?

[gubezon]

Hello PPS.

It's hard to be sure about whether this is a three lead TO220 style package with a lead broken off? Or is it a two lead device? (It could be a diode for instance.)

Please confirm is the package damaged with a leg (lead) pulled/snapped off?

Hello guys.
I need your help with the with indentifying of this transistor.
It is on the small PCB which adjusts the rotation speed of the Dewalt 707 miter saw.
Cant find this marking anywhere.

marking
on the top - 18 508
on the bottom - BSGZ348
as I can read
look at the pic

[SeanB]

You can see it is a TO220 3 lead device with the one leg missing, probably blown off when the die decided to turn to smoke, but not enough pressure to blow the top entirely off.

[gubezon]

You can see it is a TO220 3 lead device with the one leg missing, probably blown off when the die decided to turn to smoke, but not enough pressure to blow the top entirely off.

My old eyes 

I'll go with that.

I offer this next insight to the original poster. I don't know everything about the DW707, but I tried to research it to the extent that I could.

It appears to be a single speed saw, 240VAC. You mentioned

...
It is on the small PCB which adjusts the rotation speed of the Dewalt 707 miter saw.
...

Just for the sake of argument, let's say it is actually a single speed saw.

Now the mystery device can become a half wave rectifier, which in a lot of simple designs is used in the NC part of the trigger switch (they are two pole SPST -- one pole NO, the other NC).

When you press the trigger switch the rectifier is disconnected from the stator and the motor starts and spins up normally.

When you release the trigger the diode is reconnected to the stator,  and the magnetic remanence field is rectified as the stator sets up a magnetic field via rectification in the diode. It's not the fanciest way to provide "regenerative" braking, but it can slow down the armature a lot faster than otherwise, and based on the numerous patents and prior art referenced in the patents, I suggest that you may be looking at a remanence brake component, which *could* just be a half wave rectifier.

Dewalt doesn't provide an electrical schematic of their saws generally, but if you search patents online, there are a lot of examples where patents have been issued to Black and Decker (Dewalt) and other tool manufacturers that leverage the technology and some really elaborate and simple ways (some with multiple diodes, transistors, FETs, and other passive components like capacitors and so on.)

All the way back in the 1960s, one of the first (if not THE first company) to use an electronic brake in a saw was actually Rockwell:

https://en.wikipedia.org/wiki/Electric_motor_brake

Hope this helps.

Good day to all!

[wasedadoc]

PPS has double posted.  https://www.eevblog.com/forum/repair/help-with-the-with-identifying-unknown-transistor/

Better answers there.