#1767

Рет қаралды 3,972

IMSAI Guy

5 ай бұрын

Episode 1767
$11.50 on Aliexpress but what exactly is it?
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Пікірлер: 46

@romancharak3675 5 ай бұрын

The voltage accuracy is not so important. The main use is for checking the strips of LEDs inside Flats Screen TVs. The LEDs on those strips fail open or short. This tester lets you see where the fault is by illuminating the Strips, if they light up at all.

@Godunjoify 5 ай бұрын

There must be a timer in there to switch the current from 20 to 50. Very cool to test zene Diodes for a short period of time.

@mikeselectricstuff 5 ай бұрын

That's so much less sketchy than one I got a while ago, which was a non-isolated capacitive dropper mains supply, with a single pole mains switch and non-polarised mains plug.

@Edisson. 5 ай бұрын

Hi Imsai, it's a handy helper, I have a similar one, it also has two V/A displays, but instead of the main switch you have on your tester, I have a small programming button. Using the button and short-circuiting the test cables, you can select a certain mode of operation, or leave the tester in automatic operation. My model is produced in an even better (more expensive) version with the possibility of testing backlight sources in the TV. You can try short-circuiting the test leads for a while to see if you have the option of a fixed setting made differently - for example, short-circuiting during operation, or short-circuiting and switching on, a dot on the display indicates the change of program. Nice day 🙂 Tom

@Digitek_Electronica 3 ай бұрын

Thanks for the approach to the circuit. I needed to know the value of resistors R22 and R23, 1K and 10R, respectively.

@TheElectronicDilettante 5 ай бұрын

Get proper probes. If those are the ones I think they are, the conducting core is comprised of about 6 strands of copper thread. Will make great filaments.

@Dennis-uc2gm 5 ай бұрын

Bought a common one that was selling a couple years ago to troubleshoot a backlight issue on a large flat screen, but I found they make a great zener diode tester. 👍

@IMSAIGuy 5 ай бұрын

Good tip!

@robinbrowne5419 5 ай бұрын

(At 11:25) That's 50mA. Holy cow. I wouldn't stare directly at the lamp at 1A. I know this from experience because fiddling with LEDs is one of my favourite hobbies. I have made the mistake of turning on a super bright LED while it was pointed at my eyeball. Several times. Lol.

@Broken_Yugo 5 ай бұрын

i wear sunglasses when messing with power LEDs for this reason.

@robinbrowne5419 5 ай бұрын

@@Broken_Yugo Very wise 👍 It's amazing how bright they can be.

@MrMersh-ts7jl 5 ай бұрын

Ive seen this only used by xtaytonyb during his transistor explanation video, part 2 i believe. Used it for demonstrating reverse breakdown.

@paulstaf 5 ай бұрын

I have a similar tester I use to test TV backlights. It is very handy for that purpose.

@paulstaf 5 ай бұрын

NOT JETSON, J-E-S-T-O-N. 🤣

@TheDigitalAura 5 ай бұрын

I have an earlier iteration of this which comes in a slightly smaller form factor. It's been useful, but I'm always very wary of using it. Mine is very much sealed closed.

@bob_mosavo 5 ай бұрын

Thanks 👍

@frankowalker4662 5 ай бұрын

Handy little device. (if a bit dangerous)

@mixguru9669 5 ай бұрын

It is JESTON not JETSON 😂

@jimomertz 5 ай бұрын

If it had said Spacely Sprockets, you would know to run away quickly. 😮

@IMSAIGuy 5 ай бұрын

Spacely Space Sprockets, Inc.

@dilbertnewton6864 5 ай бұрын

This is why I support DAM, (Moms Against Dyslexia)

@IMSAIGuy 5 ай бұрын

@@dilbertnewton6864 that's right, in my reality, it is JETSON!

@robinbrowne5419 5 ай бұрын

It's weird that in The Jetsons (which is set in the future) the TVs and Video Phones (of which there are many) all have the rounded corners and bulbous glass screens of CRTs and also have these weird circular antennas. Lol. Welcome to the future :-) 📺 📺 📺 📺 📺

@craigs5212 5 ай бұрын

Interesting tester, it was really hard to find the data sheet on that DU8613

@rorymacleod8488 5 ай бұрын

Seems like a great little accessory >>. how bout chip pf the day on DU8613 ?

@Broken_Yugo 5 ай бұрын

I think these are just for finding dead LEDs in the panel without disassembly, or confirming good LEDs and bad PSU.

@HAUNTED-HAM 5 ай бұрын

Wonder if you had a diode you didn’t know you could use to establish volt rating?

@Broken_Yugo 5 ай бұрын

Theres a different cheap box from china just for that, claims 2700V, look for "transistor breakdown tester".

@chrisgroenewegen3756 5 ай бұрын

Now I really have to smile…..

@0MikeG 5 ай бұрын

Maybe the 300 V is for testing cold cathode lamps.

@SeanBZA 5 ай бұрын

No, series LEDE strings in TV sets. 50mA is standard current, and to get the brightness you put lots of LED's in series. Series as the aluminimun board will easaily withstand 300V, and you can use very thin cables to connect, as they also will handle 300V, and with 50mA you only need to use a thin cable and save copper. Running them off say 12V your current would be a few amps for the backlight, needing thick copper cables, and much thicker PCB traces, to carry it. Both cost money to put in.

@0MikeG 5 ай бұрын

Makes sense. Have took a few older laptops apart where cold cathode tube are used. I guess LED makes more sense these days.

@SeanBZA 5 ай бұрын

@@0MikeG Cold cathode tubes need around 3kV to start them conducting, then draw a constant current of around 10-50mA, with a voltage drop across them of roughly 90V, though that voltage rises with age as the cathodes wear. They need to be run with a constant current, as the voltage drop decreases with increasing current, till the electrodes melt through the glass with enough current. The ends sputter material onto the glass with use, which is why they go black there with age, and eventually refuse to start and keep running with the 200V the power supply can put out. The CCFL driver senses the voltage across the tube, and will shut off when it exceeds the limit set by the CCFL manufacturer, so you will have the backlight light up for 10 seconds on power on, then turn off, as the driver attempts to run the tube, and after 10 seconds the timer that disables voltage sensing times out.

@simontay4851 5 ай бұрын

So how much did it cost?

@IMSAIGuy 5 ай бұрын

$11.50

@robinbrowne5419 5 ай бұрын

It's weird that a modern TV still has 300V inside it. You would think that they would use white LEDs for the backlight. But no. The wizards, in their infinite wisdom, decided to use high voltage fluorescent tubes instead. See. It really is wizardry 🧙‍♂️ and us mere mortals 🤷‍♂️ are left scratching our heads. Lol.

@IMSAIGuy 5 ай бұрын

no, this is not for fluorescent tubes, the LED backlights are many LEDs in series that can add up to fairly high voltages. while this tester can go as high as 300V the LED backlights are probably much lower

@robinbrowne5419 5 ай бұрын

Oh ok. But why they would have to put many LEDs in series and not in parallel is equally puzzling. I guess they can get more even brightness from the LEDs because they all have exactly the same current, and they can save 0.1 cents on the resistor for each LED which would be needed if they are in parallel. But this theory is probably wrong too. Lol.

@IMSAIGuy 5 ай бұрын

what voltage comes into the TV? it is more efficient to stay high.

@robinbrowne5419 5 ай бұрын

@@IMSAIGuy True 👍

@absurdengineering 5 ай бұрын

@@robinbrowne5419It’s not about saving money on resistors. It’s about not wasting energy. And using fewer resources - lighter copper if you use 300V and connect the LEDs in series. TV switching supplies have a winding for the LEDs. It can be fairly thin wire. It really is about the lowest parts cost solution and that’s not a bad thing. If you can use less copper by clever design, who cares about it being 300V. It’s inside the box. Low voltage high power takes lots of copper or it’ll waste energy. It takes energy to refine copper. The less you use, the better overall.