I have a digital ESR meter but I never know I could used it in other way just like what you did in this video. Thanks for sparing some time to share us your skills sir.
this is nice. thank you. I been back to watch this video several time. I also have the toneohm, which, I am in the process of making my own leads since its leads are crazy expensive, I am yet to learn how to use it though.. but I have found using a good thermal camera, though expensive but is a very effecting and fast way in finding shorts. I would call thermal camera, short finder for dummies.
One can also pour some Butane on the suspect component. The S/C will obviously generate some heat, which in turn will cause the Butane to evaporate (boil) at a rapid rate in comparison to the normally operating components. Of course a Power supply is used for the power source as described in this video. The Current (I) may have to be increased to 5A so that enough heat is generated, As the S?C component is already defective 5A will not be of a concern, and power rail components are quite durable for obvious reasons. For those just learning, it is important to understand how Power rails work, and how lower voltages are derived from the source power rail(s) Not knowing that would be chasing one's own tail and wasting time. Good luck everyone.
Great video, thanks! There's a potential (little) goldmine out there if you can get the "throwaways" before the "scrappers". And if they are repairable. I bet most are.
Great way to test for shorted components BUT that's IF you have more than one of the same component [with which to compare it with - like three similar values diodes]. But how can this work, when the components are of different values to each other AND altogether different components? Ex: a transistor, a cap [tear shaped - tantalum], an electrolytic cap, few resistors and maybe a diode. What can you possibly achieve test-wise with this method [ESR meter]? You would never be able to find the shorted component. But I have so much more to learn about electronics [I'm a complete NOOB in this field] so, PLEASE correct me if I'm wrong - I truly am trying to learn. Your videos have been a great source of education for me. Thank you kindly.
Hey, you can just supply this troubled PCB not with ordinary high input voltage but with low voltage and high current capability power supply. And just use your fingertip to locate a shorted component(s) by its temperature. )) Any advanced multimeter needed, but ATC 300W power supply in tact is strongly recommended to have in your workbench.
Gustav Kirchhoff would turn in his grave if he saw this video...... Those components are in parallel , the voltage drop across the components will be identical as you are measuring rail to rail. They will be passing different currents depending on their resistance but the voltage drop across the rails will be the same no matter where you measure. The more sensitive you make your meter readings, the more you will think that a few millivolts here or there mean something when they actually dont.. There is a reason why components in parallel need to be unsoldered to check, and this is a good lesson in why.
omgffsification Technically speaking the only voltage drop you really see in this example is from the shorted diode. The other diodes direction are not in the conduct mode, and capacitors do not pass DC. I should have used slightly different words to describe this example.
When diodes go bad they generally short out and their resistance goes down as the diode junctions become fused together. This test is showing me which diode has the lowest resistance reading within a few thousandths of an ohm.
Hi Dave , I to enjoy finding shorts to ground, and use two different approaches depending the mood i' m in 1st is my home made milliohm meter, other more recently is a circuit I found on the web current source .25 of a watt at 3 volts, so I use that method you used, works well, to practise on I have some old tv boards, which I know have faults, so I quite moment & I try these things out, I haven't yet tried out the ESR meter, but may well Paul M0BSW uk
There have been time in the past where I actually used the most simple and cheapest piece of test equipment I have. With a current limited supply and a little bit of current I used my finger to find who's getting hot... ;-)
We have a variety of ways to accomplish the same end result when looking for shorts to ground. Sometimes I use a lazier temperature probe, or I freeze spray the whole board until it turns white, and then watch to see which components are the fist to defrost. Louis Rossman made a video where he poured alcohol on his circuit board, and then watched to see which area of the board evaporated first.
LoL that is kinda funny, I thought you were gonna say where the alcohol starts sizzling... Yeah we are a creative group sometimes. More then most other groups....
Have any idea how I can force yt to put up your newest videos? I go out of town and upon returning yt seems to "retire" subscriptions to the back burner. I imagine just finding and watching a few is the only way.
I would think a component shorted to ground would have no voltage drop across the component. Doesn’t the shorted component just become a low resistance wire, therefore no voltage drop across it .
Your correct about a shorted component becoming like a low resistance wire, but if you measure across the component input wires with a voltage applied to the component you will see more of a voltage drop than you would with a non shorted component.
Think about this concept. You attach a 10 volt battery to Two parallel wires that are 5 feet long, and at the end of the 5 foot stretch of wires you attach a 1 ohm resistor. If you measured your battery voltage right at the battery terminals it would read higher than the voltage you would read across the resistor due to the voltage drop across the resistor. If you did this same experiment using a 10 ohm resistor you would have less of a voltage drop, and you would read a higher voltage than you would using the 1 ohm resistor. I hope this example helps.
I am wondered when looking at your demo when you turn ON DC power supply and connected to a short circuit that you made it by your own. I think it would feedback and blow power supply if you leave it for a certain time. THX,
Yes it could be a problem if your asking the power supply to deliver more amps than it can handle. My power supply can deliver up to 3 amps with out there being a problem to my power supply. If your power supply can't handle what ever current a short circuit produces, you can add a resistor in series with the device your attempting to repair. You resistor will probably get hot if your device has a short so you may need a high wattage resistor.
it is exactly you need to mention in your demo, if there are someone do not know would cause lot problem. Also, You forgot to let reader know the method measure Diode by reversing the lead of DVM, Thanks,
it is cheaper to replace circuit board some time than spend time and money locating tbl. keep this in mind when cust is paying by the hour you can shaft him one time but he want come back
That depends on how much resistance the shorted component has once it goes bad. As a general rule when a diode goes bad it will have less than One ohm of resistance, so it's about the same as a piece of wire.
The voltage drop across a wire is very small, but it is never zero volts. All wires have resistance. That's why this technique works. Shorted components often have more voltage drop than a wire does.
+VINCENT ONGALA Most of the time you can test diodes which are in circuit, but sometimes you must remove them to know if they are shorted due to the surrounding components on the board . Anytime you remove a diode which appears to be shorted it's always a good idea to test them out of circuit to make sure your test results were not effected by surrounding components. Most of the time a shorted diode will have less than 1 ohm of resistance, so when I get a bad reading using the diode check function of my multimeter I switch my meter over to the ohms function so I can get more information about the nature of the short in terms of how much resistance the diode appears to have in circuit. If the ohms reading is 10 ohms or more I generally assume the diode is probably okay, but when in doubt pull them out to double test.
@@GrantsPassTVRepair Had to troubleshoot a part that was drawing curent on an old PC board. There are some 40+ ICs. Some were getting hot, others not. But by using a ohmmeter, i was able to locate the problem in the memory area. After removing the memory chips, the problem was gone. The memory chips were not getting very hot.
You said the diodes are in parallel so if one is shorted then they all are?? My question is what reason would they be in parallel if they all fall short when one fall short.
@@irishguy200007 I don't recall saying that all of the diodes will be shorted just because one of them was bad. My point was that one shorted diode is in parallel with other diodes it can make it appear as though all of the diodes are shorted. Unless you have a sensitive meter it will be difficult to figure out which one of them is actually bad.
Longer leads on a ESR meter just doesn't work. The meter gives you an error message when trying to calibrate to "0", probably due to the capacitance of the cables themselves? That's why all ESR meters that I know of, have short leads (too short, yes :)
@@Cubasenet33, You are correct, the ESR meter leads do add capacitance, hence they are short. I tried adding longer leads to mine as an experiment, and it does change your readings.
Being a former PHILIPS Engineer, you will notice when you L00K closely at the CORPORATE Logo, that it is PHILIPS and not Philips. There is a huge difference between the two. CORPORATE names are always in the ALL CAPS , because a CORPORATION is a DEAD entity. The word CORPORATION itself derives from the Latin CORPUS meaning CORPSE Hence all the CORPSES you wil find in the cemetery have their name in the ALL CAPS on the grave stone. Mixed Case Names are for the Living Breathing souls, A Given Name - given by the parents and a Family Name to link to the Family. Such things as FIRST NAME LAST NAME SURNAME are CORPORATE fiction names, given for the purpose of conducting Commerce. Hence why all your commercial and Legal DOCuments are in the ALL CAPS and is Admiralty Law. DOCument is also an Admiralty term linked to the DOCK where the SHIP is tied. CitizenSHIP is also an Admiralty Law term as is DOCtor This is not commonly taught in school. One would learn it after studying Law for a few years Take a look at what is written on Airforce One - and HOW it is written Because the UNITED STATES OF AMERICA is a CORPORATION registered in 1778 by King George III and is owned by the CROWN It is not the same as The United States of America - which are the 50 States WASHINGTON DC is in a way a Separate Country with its own Laws. The 50 States are Franchise operations of the Parent. WASHINGTON DC will NEVER be a State despite attempts to make it so. These people attempting this either do not understand or are simply playing games with the naive people for some undisclosed agenda. Look at the BOEING logo .. It is not Boeing. Most people are not very observant, and walk around with their eyes closed and ears blocked
Great video and explanation. I thought I seen a video of someone looking for a short with a battery maybe it was a 9 volt and a multi meter. Is it possible or even safe to do?
TakeTheNarrowPath GloryIsHisName I suppose you could use a 9 volt battery if you added a 27 ohm resistor to drop the current a little, but it would sure be hard on the battery..You might see the power drop so quickly that your reading might be undependable. It would be better to build yourself a small power supply out of an inexpensive transformer, a resistor and a bridge rectifier.
Also, if the short is low enough resistance, you can likewise inject a voltage of much less than the voltage than the power supply and boost the current output until the shorted component heats up enough to actually feel with your finger (no using expensive freeze spray. I work repairing cable boxes for Comcast and have been able to repair a very high percentage of boxes this way. I Have used the milli ohm method as well as the ESR Meter as well as injecting voltage and tracing with the milli volt meter, too. All have their place and merit. With Shorted chip components on a highly concentrated board with as many as 10 decoupling chip caps on a power supply line all across the PCb, it could be anywhere on the entire board. Hands down the injecting low voltage at higher current and merely feeling for heat is the most effective. I haven't had one case in hundreds of repairs where I have ever damaged the upstream or downstream components. This is mostly with buck supplies.
Thanks for this information. I would imagine a cheap thermal camera would help this process? I’ve had my eye on the “flir one pro” for a while now. at $400 I think it would be invaluable on the electronics bench, in automotive repair, even checking the HVAC/energy leaks in your home. A friend of mine has a cheaper model… And it immediately identified the bad wheelbearings on my vehicle in broad daylight because they were warmer than everything else. The flir one pro is pretty much the minimum priced thermal camera and resolution that one would want for electronics. Sure the $100 models work fine... but to really get down and see the smallest SMD packages and such… I think $400 is worth the extra price.
mister kluge Thanks a ton for the info! They’ve tried so many different terminal cameras… Are you referring to the “seek“ thermal camera? I know they’ve showed a few very nice thermal cameras but they are out of my price range. Closer to $1000....Where the flir one pro phone attachment is only about 400. And with a macro lens added… Can REALLLYYYYYY see tiny parts even the smallest SMD components clear as day. and the diy macro attachment is only a few dollars. AND makes small components 10 times clearer! Thanks for your time!
HULL GUITARS USA Did you end up getting the camera yet by chance? In a total novice with this stuff but I end up doing it often enough to make 400$ worth it, especially if it works for other applications. HVAC, home electrical, and car maintenance alone would justify it if it’s useable on a larger scale. I’d imagine it is, if it’s able to pick up the much higher resolution of electronics.
@@hullinstruments how about one of those cheap laser temperature guns? you could do the same thing with the low-volts high-current and scan the components. and those are like 30 bucks
You need to know something about the trace geometry to accurately pinpoint the short using this method. You need to measure the voltage drops across the traces. I start by connecting the negative lead of the DMM (mV mode) to the point where the current source's negative terminal connects to the PCB. Then begin probing further from negative connection point until the voltage stops increasing. As long as the voltage continues to increase, you are following the flow of current. As soon as it stops increasing and levels off, you've passed the short. If you have a layout viewer, it really helps. Using this technique with boards that have power planes is more difficult. You'll need a high precision DMM to measure micro-volts of change on top of the millivolt voltage that is actually across the shorted component. You may need 6-digits of precision to do this. The relative (delta) button won't help because the meter will use the appropriate scale for the total voltage ("trace voltage drop" + "shorted component voltage drop"). You are only interested in the trace voltage drop. I suggest using a good cad viewer that allows you to highlight nets and has coordinates so you can calculate distance. I've used this technique to get me within about 1/2 inch of a shorted cap between Vcc and Gnd on boards with hundreds of bypass caps on them. I also use thermal LCD paper and cold spray to try to locate the shorted part thermally.
In India, we mostly use rosin paste and 3.3v with few good range of amps (current) and volts depends to the supply line or supply track. And we easily find the shorting component. There are many ways to locate the shorting component and those are effective too.
I was just searching to see how to put a multimeter to millivolts and seen this video. I finally see how diode measured to find if they aren’t working. Video is beyond excellent.
Thanks very much for sharing. I too use my ESR meter for finding shorts but you've intrigued me with the short sniffer that I saw it costs quite an insane amount of money. 10 minutes later, I have one up and working just great, it's just a prototype of course but more or less I made myself and idea of what values of components I have to use. If you need any help, just ask. Cheers :)
I just watched a video by a guy called "creative Lua" and he has a cool little circuit with a LM317 a 10 turn pot and resistor, oh and a small cap. but it allow's you to turn you meter into a milliohm meter. CHECK IT OUT IF THIS INTERESTS YOU "CREATIVE LUA" IS THE CHANNEL, HE'S A GUY FROM CHINA BUT IT HAS ENGLISH SUBTITLES WITH THE CAPTIONS TURNED ON. BUT HE GOES OVER EACH STEP IN MAKING IT VERY WELL AND GIVES YOU A SCHEMATIC AND DEMO ETC!! HOPE THIS HELPS SOME OF YOU WHO LIKE THIS VIDEO LIKE I HAVE....
Thanks much Grant you remind me of my uncle who had the 1st TV repair shop in the north Adirondacks.That was circa 1950? He was a communications guy in the Marines on Okinawa ww2
Dave, I was hoping to see a really informative video, but you spoilt it by having it all OUT OF FOCUS. Also, I need to read your multimeter setting position and you had an elestic bungee across the selector knob obscuring the view. What a shame. Keith 😞
Complete NOOB here. Great video BUT, it seems to me like it’s like many others, in that, it assumes that you have, a general idea of where the shorted component might be. I haven’t found ANY videos, which actually explains how to determine where a short might be, or for that matter, IF what you are dealing with, is actually a short. I mean, every electronic failure isn’t ONLY a short. It could be an opened component, or a non-oscillating crystal, etc, etc. What if the device you are are trying to fix, shows no signs of damage, or burns/darkened areas on the pcb, what do you do then? You can’t just assume, that it’s a short. Sometimes, the issue can be something simple, that you just overlooked OR a super difficult one to figure out, and what/how do you start then? What/where do you start, when the device you are going to work on, shows no damaged components or pcb? That’s the kind of video, I would like to see.
another excellent video. although in my experience finding a short to ground is a lot tougher than you have shown especially if you have a bunch of smt noise caps or the short is between layers.
I'm not sure I understand what you're looking for... Every measure you did had different values for different diodes. You KNOW one of the diodes is bad in this case, but the only indication you have for which one it is would be the one with the lowest value in whatever measurement you're doing. But if you don't know if it's a diode or a capacitor (or any other component, for that matter) that is the culprit, how would this help you? You haven't really located the short, because to even use the technique, you must know which component type you're looking for. And even then, it only works if all of the components of that type in the circuit has the same value. And even then, you can get "false positives" because of the natural difference in the readings.
This procedure is designed to help you find a shorted component where there are multiple components which share the same power supply output. it's not going to tell you if a diode, capacitor, IC, or transistor is open, but if one of these components is shorted such as a diode it will have the lowest voltage drop of all the components you test. I hope this helps.
Thank you so much. unfortunately, my bench power supply doesn't control current that accurately so I created a simple constant current supply circuit that I use now for this method.
very good most helpfull tip haow can you check for a winding short in a transformer do you have to use a micro ohm meter and know what a good one would read?
I do have a micro ohm meter, but when I test the primary side of a transformer I often use the my blue ring coil tester. Here is video on how they work. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Ky2T1-n_Fks.html
Nice job. I'm working on a small board with a short somewhere. I'm going to apply a small voltage (3 D batteries, 4.5v) with a small current limiting resistor and try to get closest to the short with digital voltmeter readings OR allow more current and feel for a hot component.
Short-Circuits (in their natural state) on PCB's have already done the damage to the equipment! I am an amateur (self-taught over 50 years). I can say that Grants Pass TV repairs have taught me that you can check out 'shorts' by the use of a DMM on the milivolt scale. I have followed the same procedure as shown in this video, and that is - to first determine WHICH CIRCUIT BOARD is faulty. Sometimes, there are five or six separate PCBs in a Home Theatre System. Narrow down the fault to just one specific PCB. Write down every step that you take! Magnification of the PCB and its' components is a must! Look for the obvious first. I do this by powering-up the suspect PCB independently, with the same voltage / current that is rated for the particular Board. I will not reduce the voltage (or current), because a 'short' is present. Remember that the Board cannot suffer more damage! At this point (when the suspect Board has been disconnected from ALL other Boards and Feeds), the 'short' begins to show itself........... Yes, components (even the printed copper track) will get warmer than others, because many other parts of the circuit are not being fed with their correct voltage - due to the 'short'. Have a smoke, have a coffee - but leave the suspect Board powered for 5 minutes. THEN, pinpoint every component such as diodes, capacitors, resistors, voltage regulators and transistors etc WITH A LASER BEAM. I am talking about the (very cheap) Hand Held Laser Pyrometer. The Laser Pyrometer detects the smallest amounts of heat (from or near to the shorted component), and you will definitely see results! As an amateur, I have had many hours of frustration and heartache in trying to detect a 'short'. I have no idea why all of the professionals have never mentioned this method of heat detection on You Tube. In many cases, it isn't possible to detect small amounts of heat with the human hand - from many components that have radically shrunk in size - and mass - from two or three decades ago. If I was a professional Electronics Technician, a Laser Pyrometer would be a very important part of my arsenal. Thanks to Grants Pass for a great Tutorial. Greetings from Australia.
hi, is there a difference between a bad diode and a shortened diode when checked with a meter what i am asking would a shortened diode measure as bad with a meter ? thank you
I don't quite understand your question, but I think you meant to say shorted diode rather than shortened diode. ;-). When the short out they generally become like a piece of wire with almost no measurable resistance. Less than 1 ohm.
Great video !! And tips in the comments! When I first stared out in my 20's, my boss had a Weston 7 digit ohm meter to find shorts on boards. Boy did that work like a Champ ! 35 years later, I see this great idea using the mV meter approach !! Especially the HP concept in the comments !! I'm so grateful and embarrased I didn't think of it ! This concept in this video should get an award ! Thanks again for making this video and bringing out further comments here with further tips !
Not sure you should be touching all the components like that. You obviously know what you're doing, but your viewers may not... Freely and carelessly touching live capacitors will end up getting someone hurt.
If it's a shorted part other than a diode, the same technique can apply, but unless you have a schematic, or a pinout of the part, it can be more challenging to isolate which part or parts have gone bad, When transistors go bad their terminals often short out between them, so using an ohm meter can also help you isolate the problem by looking for shorts between the transistor terminals. Having a schematic can help you understand what's likely to be a shorted part if you measure a low resistance path to ground on a component terminal that should show an open relative to ground of your power supply, and learning to read schematics can be a time saver if you happen to have one for the device you're trying to repair, and knowing which parts are more likely to fail can also be helpful. The parts which mostly commonly fail are diodes, transistors and ICs. It's been my experiences that electrolytic capacitors rarely short out, but sometimes the small surface mounted capacitors are known to short out.
That's exactly my problem. I have a short on the board I'm working on, but I suspect the issue is a ymf292f sound chip, for which I can't find a schematic or a replacement! Thanks for the response.@@GrantsPassTVRepair
91% IPA (isopropynol aka isopropyl alcohol)pour on suspect components then inject voltage and you will know what is shorted by how quickly it evaporates. Much cheaper than thermal cameras
Actually, there is one thing here VERY WRONG. Measuring with current is ok, but 0.25A is TOO MUCH - that could've fried your diodes! Most diodes work on currents around 20mA (LED diodes for example) and that is a level you should have. In this example you where lucky that the diodes you had there where power diodes, but on laptop motherboards and elsewhere, the diodes are much more sensitive and they can get fried with as low current as 50mA. Of course, a short to the ground means that the power will go through the short and not through the diodes, but once the short is gone, all that power would go to those diodes. Another safe thing (except limiting current) would be to try to find the short by limiting the voltage to 0.25 V - at this voltage most of the diodes just don't work and no harm will happen to them even if the short will be eliminated. At 0.25V only thing that works is passive components (and shorts) - and those can handle that voltage no problem, so you don't have to limit the current so much when you are at 0.25V.
Yes there are some components such as LEDs that can easily be damaged with 0.25 of an amp, but If you insert a low voltage directly across one of the electrolytic capacitors on the circuit trace in question, and apply the correct polarity your not likely to damage anything. Especially when you consider there is already a short dragging your voltage way down below normal operating voltages. If I see an electrolytic capacitor on the circuit trace I'm testing with a working voltage printed on the side, I think it's fair to assume I can safely apply 10 percent of that voltage and probably much more without causing any additional problems. Even if the short were to open, as long as you don't exceed the normal operating voltage of the circuit and you apply the correct polarity it should be fine.
I think this is the most professional method to isolate the shorted component. I want to know about if this method can be applied to computer boards. If possible, can u make some video on that?
What a fantastic video! Over my self-educated time spent (100's and 100's of videos and some books), what no one ever said/wrote was that in repairing electronics, it all comes down to OPENs and SHORTs; with SHORTS being the "variable" cause ... meaning that there can be a SHORT ...or... a PARTIAL SHORT that's causing the problem. Once that became apparent, troubleshooting changed to "much easier" to diagnose. I have a Zapper, built a LeakSeeker, have injected voltage, and and and. This video from 7yrs ago ... I wished I had discovered earlier. It added a very valuable approach ... inject a small voltage and then look for a voltage drop in the mA's (or maybe even uA's if you can). Brilliant. Thanks for this video.
Thank you for the comment. It's always nice to hear when someone appreciates on of my videos. We had a period where bad capacitors kept repairmen fairly busy due to a manufacture error known as the "capacitor plague", but that's not so common anymore, so other than bad eeproms and leaky parts, I suppose shorts and opens do make up the bulk of repairs. All the best.
