Frank Pitochelli: Yep...did TV repair for 35 yrs...the FET transistors will have a junction short , iv'e seen when the fet's are in series sometimes it will only show shorted when the fet tries to turn on etc.... Drove myself crazy many times with FET'S......they are a good transistor, but, can be a pain in the butt !! good job !
RiaRadioFMHD773: Don't you hate how fets are chained so when one goes, often they all will.
Raul Schay: Hi Jerry... I have a pure sine power inverter that I used to run an air conditioner that used 450 watts without problems until the other day that will not turn on the ac compressor , the inverter is rated up to 1500 watts, I tested with a watt meter, and I load a toaster that used 1300 watts and it work with no problems , but will no turn the compresor ac no more. Do you have any idea what could be the problem? Thank you Jerry in advance !
Chuck Holder: Interesting lesson.but very slow
Victor Silva: If you don't have a light bulb you can use a bench supply that has CC mode.
vance byers: i am so grateful you shared this in spite of the mix up . i have been looking for the lightbulb tick in action for a while and now i have learned a lot about it even some from the comments section thank you
villigasruel: hahaha......LOL it's so funny
John Rose: i have the same problem as you have i did not think about the cabes being across have soon as i turn it on dead short think you for your tips and money john
jack hodges: The reason for using a filament light bulb and not a normal resistor is that the light bulb is a variable resistor.
If the current being drawn by the circuit is low then the filament will have a very low resistance so the circuit can operate normally. Only when the current drawn is high does the filament heat up and become a high resistance.
resistors dont do this so well.
Bob Bozanic: Hi ther Jerry This might be late to add, but at the beginning of the video you were on the right track and you almost got it. One thing you should have realised, when your lamp lit up,because of the” short “ you have used all of voltage available (reconnect and measure the voltage drop across lamp. I bet you will be reading 12V or 13.7V) If so, what was left for the inverter to fire up?Maybe 0.6-0.7V. It is like this. Sum of ALL voltages (drops) in a closed circuit must be equal to the supply voltage. So if your lamp "took” 12V what was to power your inverter?
John Ratko: I see by your magnifying-glass-alligator-clips device sitting on your bench that you must have been to the Harbor Freight store. Well, that's where I bought mine.
LearningZone: LOL. This is known as dig a whole mountain and get a mouse only! The polarity was creating a big trouble. Great work. I am sure you know the problem from the beginning of the video.
Ryan96se: don't feel bad dude. I've done stuff like this before. still interesting how you were able to check things out. You know if they were smart when they built the circuit they would have put a diode right on the power inlet terminals to prevent a short through the FET's but being made in China I'm guessing it would have added a few cents to the cost of manufacturing to add a reverse polarity protection circuit with a red light
MrBugsier5: If you want to draw 400 watts it wil draw 33 amps at 12 volt, so what the 7,5 fus does inthere i do not know!
NiHaoMike: For large AC loads, a hair dryer or space heater would be more compact than a bunch of light bulbs.
Paul Brace: Man your a pickle any expearenced engineer would have checked the polarity, a lot of circuits have a reverse polarity dioad in them to blow the fuse "hopefully" before any dammage is done, but a good video anyway. i also use a bulb on things i am repairing here in the uk we have 240v and a 100w works nice
Giuliano Damiano: In Few simple words, Thank you. This is a cool and helpful trick!!
H2GenerationX: I honestly love this. I don't know how many times I've made simple mistakes like this. But hey, that's how we learn! I'm glad I learned the LIGHT BULB trick! GENIUS!! I honestly never heard of that! Thanks. :)
12voltvids: Ha ha. Good for a laugh. I was thinking reversed power supply as soon as you got the .6 volt drop. The light bulb load was one of the first things I learned some 30 years ago when I first got into the repair business, and the second thing I learned was to keep one hand in my pocket when working on a live circuit. Only been bit twice, one time by an operating microwave power supply, some 2500 volts, and the second time by 30,000 volts from a second anode lead that was not attached properly to a picture tube by a junior tech that changed the CRT. I was performing a convergence job, and the lead popped off and dropped on my hand. It felt like I hit my thumb with a hammer. Fortunately I was wearing insulated shoes, and had my other hand in my pocket, so it just charged me up. I got almost as big a shock when I discharged the energy in my body! Talk about a major spark from my finger. (body charged up like a capacitor, just like static electricity only a bigger jolt!) Saved my life, that's for sure. Sure glad to be out of the electronics repair business.