As some commenters have pointed out, there are flaws in my design and the schematic I drew is not exactly correct. Please check the additional resources I've listed in this video's description if you're looking to build one of these yourself. The goal of this video was to show a general demonstration of how it works - not how to build one. Thanks!

@albertarider5070

2 жыл бұрын

Great channel, glad I came across it. I have to second JoeJ8282's comment below. The way your receptacle is wired (actual wiring, not the schematic) you have the hot and neutral reversed on the lower receptacle labelled "amp". This presents a dangerous risk of putting 120v hot to the chassis of the equipment under test. Solution is simple, just break the "busbar" jumper piece, add a short jumper wire and revise the "amp" receptacle wiring. The audiokarma link you provided shows the correct wiring on back of the receptacle. Regards and keep up the good work!

@Eduardo_Espinoza

Жыл бұрын

As someone who doesn't know about electronics, I agree with you @AlbertaRider after reading @JoeJ8282's comment. Now I don't understand why @AH-Fix-It didn't just pin @JoeJ8282's comment instead of extra hoops to his website. 😔

@SDsailor7

5 ай бұрын

Ok, So what wattage bulb do I need to get? My stereo is a 40 watt max output? Also what type of light bulb can I use? Incandescent bulds are hard to come by nowadays can I use a halogen bulb or LED? Very interesting and informative video Thank you

@SDsailor7

4 ай бұрын

Those two jumpers go from where to where? Also does it matter from what side of the outlet you cut the tab? Do you cut it from the hot side or the neutral side? Also where do you connect the ground on the switch and outlet? Thank you. Very interesting and informative video 👍

OK, I like the general idea, and I'm gonna have to build one of these testers myself, however, I am an electrician by trade, and I see one minor, (potentially major?), flaw in your design there of the actual wiring of the test hookup box itself... The way you have that wired, the lamp is fine and safe, but the outlet that you plug the amp/receiver/equipment under test into is wired backwards as a result of the way you did it there, and you have the "hot" lead going THROUGH the lamp bulb and then coming back from the lamp on the lamp's neutral wire, so then the hot is now going to the "neutral" lead on the amp's power cord, which in many cases with more modern equipment, that usually doesn't matter too much because the transformer primary is oftentimes totally isolated from the rest of the circuit, however, on some older/vintage equipment the neutral wire is sometimes tied to the chassis of the equipment, at least through a resistor and sometimes directly, and since the way you wired that test box outlet up sends hot to the neutral terminal of the amp outlet, you could potentially get shocked when touching the chassis of certain older equipment, and of course that is a major safety hazard!... To fix that potential issue with certain equipment potentially shocking you when you touch it, you should break the tab on the neutral side of the outlet also and then take the "neutral" (white/silver colored screw) of the LAMP outlet and wire that instead to the "hot" (black/brass colored screw) of the AMP/EQUIPMENT outlet, then take the amp outlet's neutral terminal (white/silver screw) and go back to the neutral of the main input wire/cord. On a 120 volt outlet the neutral is always the longer slot, and with a 20-amp outlet like you have there, the neutral is the slot that looks like a sideways T, and the hot terminal is always the shorter slot. If you fix that minor thing as described above then you will always have the polarity correct on both the lamp AND the equipment under test, which is very important for safety!... At least as long as the cords plugged into both outlets are polarized anyway, (i.e. with the neutral blade of the plug wider than the hot blade so it can only be inserted one way), OR else if plugging in a lamp or equipment without a polarized plug, (with both plug blades narrow and of equal size), then you would have to just pay attention to which way you insert said (unpolaraized) plug into the outlet so that the neutral side of the outlet always goes to the neutral wire of the plug/cord, (which is usually marked with either a white stripe or more often ribs or ridges), and then the hot side of the outlet, (narrow slot), always goes to the hot wire/side of the plug, (which in most all cases with most 2-conductor power cord wires, the hot is the one without the ribs AND it usually also is the one that has the writing or imprinting on it as to the guage of the wire, etc.), and so by always checking that, AND having your outlet box wired up correctly, then you'd never have any issues for a potential shock hazard. Because if you've actually never gotten shocked yet with the way you have that test outlet box set up now, then you've gotten extremely lucky! Hopefully you see this comment and understand it, AND you can fix/properly wire your test outlet box before you ever get shocked by touching the chassis of a piece of equipment, (due to the way your tester is currently MISwired), because we can't lose a great channel for us people who love to fix vintage gear, due to you getting injured or worse! I will help you with a further, more detailed explanation, to get your test outlet box wired correctly if you need further clarification of anything I said here, so if you have ANY questions about anything I said above OR about why it is absolutely necessary/essential to fix for your own safety, then feel free to ask me anything at all about it and I will walk you through it step by step IF you need the help! I actually hope I DO hear from you in a follow up reply, AND that you got your tester outlet box fixed the way I said, because electricity can be very dangerous if you ever touch the hot lead of 120 volts or higher, as I'm sure you already know!

@Texan1048

Жыл бұрын

These vintage units have non-polarized plugs so that is a non-issue

@JoeJ-8282

Жыл бұрын

@@Texan1048 Sometimes yes, if they're a fully isolated unit or device, (which many are), but if you really pay attention among ALL electronic components, there are just as many, (probably even more), devices with polarized plugs as there is with non-polarized ones, so in order for this dim-bulb testing device to be totally 100% safe for ALL devices and components that you may plug into it, it really needs to be wired correctly, with proper hot/neutral polarity on the outlets, otherwise there runs a slight risk of electric shock with some devices that rely on that proper plug polarity for safety!

@Texan1048

Жыл бұрын

@@JoeJ-8282 agree, have to be familiar with what you are dealing with

@MikeyAntonakakis

Жыл бұрын

Thanks for this! I just built one and watched this video to compare what I did, mine is a little different - thankfully I think I built exactly as you described it. I am using a 2-gang metal box. One of the gangs is a dual switch/output combo, which is where I will plug in the amp. The other is a regular dual outlet, where I will plug in the bulb. I broke the tab on the switch/output combo to completely separate them. My wiring is like this: hot from power cord -> switch -> hot terminal of double outlet -> lamp(s) plugged into double outlet -> neutral terminal of double outlet -> hot terminal of single outlet (on the combo switch/outlet) -> neutral terminal of single outlet -> neutral of power cord. Of course all pieces are grounded including the box. Thanks again!

@vernonbosshard9317

Жыл бұрын

He doesn't have anything labeled so you don't know, this isn't a physical diagram. He has the source labeled as a battery anyway. Yea on the amp plug you want line and Neut to be on the correct side with a ground, that's intuitive. Ground to protect the tester case and if the amp has a ground.

Thanks bro. Been going thru a bunch of my “regular’s” for audio channels because i needed guidance on a current limiter, and your upload appeared near the too. Have not caught anything from you recently and i forgot how good you are at breaking down the knowledge. Appreciate your shares

use of correct traditiotional filament bulb is paramount...great channel...thank you..I will continue to watch and enjoy...

It's always funny when people talking about electrical safety, but build something with a metal enclosure, and don't use a powercord with earth wire. If the hot wire becomes loose inside that metal box and touch the metal box, your RCD won't trip. If you then also touch the metal box, then you get a serious zap. It's good that you use a device like a Dim Bulb Tester, for protecting the device that you connect to it, but you should also protect yourself in the first place and think about the safety of your viewers that gonna copy your unsafe way of working with electricity.

It is really a simple mechanism,,,but very important,,and very nicely described and presented

Just a suggestion, break off both tabs on the outlet and run a jumper wire from the Neutral side of the dim bulb socket over to the Hot side of the item test socket. That way you preserve the Hot, Neutral, and Ground positions at the item test socket. Basically plug in an outlet tester in the item test socket and verify it passes the checks (no reversed Hot/Neutral) then you know it's good.

@JoeJ-8282

2 жыл бұрын

Yep, that is actually an absolutely essential thing that he MUST do as soon as possible, or else he is going to eventually, sooner or later, get shocked by having the hot (running through the bulb and back to the tester outlet) and then connected to the neutral wire of the equipment under test through that unbroken tab on the neutral side of his test outlet there as it is currently wired... I certainly hope he sees either your comment or mine about this exact same thing, and he makes the appropriate changes to his tester outlet box before he gets shocked by touching the chassis of some piece of equipment he's testing out that has the incoming neutral power cord wire connected to the chassis of said equipment, as some vintage gear is wired that way, I've seen it in years past! We definitely don't want to ever see him get hurt by getting shocked!

@jordanch68

2 жыл бұрын

@@JoeJ-8282 Yes. there's KZread videos about making these and the one I followed pointed that out. Mine looks the same as his with the exception of the reversed hot/neutral and I also added two neon lamps to mine. One lamp comes on when it's plugged into mains and the other will come on with the switch is thrown indicating AC is present at the item test socket.

@Eduardo_Espinoza

Жыл бұрын

Excellent point using a socket tester! :DDDD

you are really professional in your work god bless you I love to see your videos ....

There is tons of tons of this video on youtube , But this is the best i shown !! Thank You !

I've been using one for 40+ Years 🔆 saved my butt more than once over the years

Great demonstration and explanation.

Great demonstration. Just signed up to channel. Been rediscovering audio last two years and have been on a vintage audio kick as well as older higher end units. I’m a tinkerer. Rebuilt a few receiver and have fixed quite a few simple fix gems I picked up for peanuts. Flip some units and get better gear etc. looking forward to more videos. Just built a few raspberryPi streaming dacs as well recently and ditched the costly Bluesound node I had. I’m a real mix of old tech and new tech. My wife thinks I’m crazy. I think maybe we all are a bit lol.

@kordta

2 жыл бұрын

Last couple of years I've been back to hi-fi and stuffed a room full of amps and speakers. I think I need a new house to make room for all that stuff! So I guess we are all a little bit shifted!

Ahhhh, thanks for that! I've been wondering what that is, finally found this explaining it.

Great demonstration! Love your videos. I'm brand new trying to learn all I can even though I'm decades in age ahead of you :). If possible, can you make a video outlining all the hazards of working on a vintage receiver? There are videos here and there about electrical safety while working on these units but none I've found that's comprehensive. Thanks! Ed

Well done....my good man! Thank you.

Hi and thanks for posting this video. I am building a current limiting device right now because I have a coffee machine that is suffering from an internal short due to a water leak inside. In order to find the leak, in this incredibly crowded coffee machine I want to protect my circuit breaker on my switchboard before switching on again. My coffee machine draws 5 amps at 240 volts though, so will have to add additional protection inside the box I will build, by including a 5 amp fuse in line with the active supply. That reminds me, there is no 'positive' or 'negative' mains power in your house supply, it's an alternating current. So your drawing would be more accurate if you labelled the wall outlet 'Active and Neutral' or 'Hot and neutral'. I haven't read all the comments, so someone may have already said that. Cheers from Australia.

this is especially useful for really old amps with capacitors that don't have rupture grooves, if those explode they explode hard, i still have a nice dent in my ceiling from a little one that exploded on me.

Good evening my friend from Greece I saw the video with the Dim Bulb Tester: and he saved me, please I have seen the awesome work you do with the amplifiers, my wife's dad has a Marantz PM350, 40 years old, he burned his electrical fuse of the transformer changed it but burned it again, told me if I can look what it has, I opened it and found another 2 fuses the 3.5 amps inside burned out, I put it in the power with the Dim Bulb Tester: and the lamp turned on, I changed everything the transistors and capacitors, when I tried it, it played very well, but the transistors were very hot after five minutes, you did not rest your hand on them, when I connected it to the Dim Bulb Tester and opened the amplifier, the lamp lit up and flashed then it remained on continuously with low brightness but the transistors did not heat up and everything was fine. please can you help me with any of your ideas to find the short circuit, i would appreciate it very much. otherwise I see myself leaving the Dim Bulb Tester permanently on, thank you in advance from the bottom of my heart, I hope I did not tire you, and another question, does it matter that I turn on the amplifier without the speakers.

Very Nice work, thanks for sharing

Great Channel!!! I've only been subscribed for like a week and I already get excited for notifications! I was gonna comment on the Marantz that had a chia pet inside it and bring up the frequently debated topic of dust being conductive, but it seemed too redundant lol. But when I saw the ls swap project I seriously thought we may be brothers... my mom swears im not adopted though. Keep up the great content!

@classicwefi

2 жыл бұрын

Ls swap the roadmaster?

@Blowncapacitor84

2 жыл бұрын

@@classicwefi I think it might be easier in the long run. Changing on the optispark and water pump every hundred miles is getting expensive. Although, sloth from the goonies told me its really hard "gigitty" to LS swap em so... we'll see.

Very insightful, as one of your aforementioned total idiot end users, I appreciate all the help I can get...

I liked the proactive anti-troll disclaimer about strain relief on the power cord on the current limiter.

Great tutorial.

They should use a dim bulb tester in Washington DC lots of dim bulbs there :)

Awesome tutorial

Thank you for the good video, the 2 prum plug can be connected in anyway?

nice one, you just got one more subscriber

THANK YOU, Could you make more Vids explaining all the New Tech items for People that are Afraid to ask Questions? Such as DACs, Streamers, Blu Tooth Items Etc. Thanks, you do a great Job telling it without all the Technical "Wording" or at leat Explaining what those Words Mean.

Hello I enjoy you videos, what brand speakers is on the bench in the backgrounds ?

yes very useful thing. i used mine to test if what a repaired is gonna blow or not. by the way it is not positive and negative in mains AC. is live and neutral

Great demonstration but.. What happened if you connect the dim bulb to monster amplifier that main transformer is about 4 ohm and the amp is completely OK is the dim bulb will light when you turn it on?

I like the drawing where it say 120 Vac on top and then B+ right underneath it, lol.... After all B+ is an old DC voltage term, but he's working on an AC circuit. He just wasn't around in the old days.

What happens if I mistakenly connect a 120v device to a 220v outlet? This DBT saves from short circuit and burn the inside transformer?

My unit I built is wired just like yours. The power is running thru the bulb but the switch seems to do nothing. What could be the problem ?

Where do you guys get your incandescent bulbs?

One important thing to note: When you are working with a mains system that is grounded/earthed, you MUST provide earthing to the AMP outlet AND the metal case of the box the outlets are mounted in- otherwise in case of failure you have mains voltage at the case- also leakage currents from the DUT (device under test) are not able to go via earth and will be present on any metal surface that can be touched...

@kcuhc84

Жыл бұрын

I couldn't understand why the metal box was not grounded.

Handy tool for preventing fires

Elegant solution.

I used to have one but relocated to SEAsia, now I can’t even find an incandescent bulb. Is there a solution not aware of?

I don't understand?? There is no negative hooked to either piece, so how can they work?

Thanks 👍

You’re the best.

A current limiter drops voltage when challenged for current. The brighter the bulb gets, the less available voltage across the receiver's AC power input.

I wish this video was out a year ago when I recappped my 2220B. I used a DBT and the bulb would faintly glow then glow brighter when high volume in a song came. Other than that the bulb would be slightly warm but no visible light. Is this normal or should I tear apart my marantz and find the culprit short? I figured it was fine during the rebuild process because it was pulling more current for the audio but I was never 100% sure. I’d love to hear your response.

@AHFixIt

2 жыл бұрын

Completely normal

Very interesting

What is really important and it was not mentioned ( but it is implemented in your design ) that you have to have switch on BOTH: HOT and NEUTRAL wires and switch both not just one or another. This is to prevent obvious safety issues. So for People who planing to build this: !!!! please use DOUBLE POLE light switch !!!!

@peterlarkin762

2 жыл бұрын

Using one with a single pole switch for ages. It's very obvious now that you say it.... DEFINITELY should have a switch on both live and neutral. Thanks!

Do you have your amp plugged into the dbt while taking measurements like dc offset and bias? If so, does it not throw the measurements off? Or, if it does skew measurements, it's so little that it doesn't matter?

@AHFixIt

2 жыл бұрын

DBT is just to confirm there's no shorts. Set bias and offset on regular power.

@SDsailor7

2 жыл бұрын

@@AHFixIt What speakers are those in the background? They look like klh or optimus1 Great video very interesting and informative. Thank you

@iThoughtUHad2Bitch

2 жыл бұрын

@@SDsailor7 If start the video from the beginning and look at the right speaker, there is literally a sign on it that say they're KLH 17 speakers xD

Hi Aidan, Please help me build this. There are some coments (jordanch68 etc) about the way you cut the bussbar on the outlet, reversing hot/neutral. Is this true, seems like it might be? Then what type of switch is it?? --- 3 way?? -- with the brown wire you used - the visual of the video has me unsure how you wired it all up. Thanks for you help. Regards, Jack

@AHFixIt

2 жыл бұрын

Hi Jack, this video wasn't intended to be a "how to build" video, it was more of a very rough "how it works" video. If you look at the video's description, I've included two links that go to more detailed "how to" instructions that should answer your questions.

Can I ask what it means when you plug your amp into a DBT and the bulb comes on bright then dims down? The amp supposedly works fine. But the tester bulb lights and dims. Is that bad?

@AHFixIt

2 жыл бұрын

Perfectly normal. An amp draws the most current when power is first applied because the filter capacitors need to charge. That charging causes high current draw (bright bulb) and when they're charged the amp draws a much lower current (dim bulb).

@theaveragesimmer4780

2 жыл бұрын

@@AHFixIt you’re the best! You’re teaching us all, that’s important. Thank you.

Genius!

I have perfectly good working DBT but when I use it on a Kenwood-Trio KA-4002 it does NOT light up at all. The Kenwood was given to me but obviously does not work. Anyone know why the bulb is not lighting up at all? I checked it on another amp and tester is OK.

@AHFixIt

Жыл бұрын

Not every unit will light it up. Some pull very low current at idle. Try playing some music and it may light up as the volume is increased.

@danc2014

9 ай бұрын

The fuse could be blown on the amp and not draw any power. The light is protecting too much power by limiting the max current available

If they are in series and there is a massive current flow thru the bulb then the same flow must be 5th the stereo. Series!

nasty current means drawing a short?

You wired it like a dim bulb.

Need yours email. I got a marantz 2115b, transister capacity was burnt after 5 minutes plug in. Can you repair?

You show a SPST switch in your schematic, but that looks like a DPST switch in the tester. Please correct me if I'm wrong.

@AHFixIt

2 жыл бұрын

The schematic is oversimplified in order to help illustrate the point. You are correct, it's SPDT

@TomcatSTL

6 ай бұрын

@@AHFixIt Actually, a DPST Switch (double-pole, single-throw) is in use.

May also be used as a ( temporary ? ) ballast for many types of gas discharge tubes .... and .... essential when discovering the windings of an unmarked transformer ... ( accidental connection to a 6 Volt winding just results in a bright bulb ..( tried - n - tested ) ................. DAVE™ ..........

Too bad you didn’t go into a bit more detail on the jumper wires in the box. Not sure what you did there.

DPST switch is used.

what would be the wattage of the bulb?

@AHFixIt

2 жыл бұрын

Good question. It depends on how powerful the device under test is, or how much current it draws at idle. I keep a 100W bulb in mine. Some people use 60W. For much bigger stuff like a Marantz 2500, you might want to step up the wattage to 150 or 200.

@mohimadvani6425

2 жыл бұрын

@@AHFixIt . thanks for the quick reply. 👍

@srtamplification

2 жыл бұрын

Size your bulb to under the fuse rating of the device under test. For example if the DUT has a 1A fuse, you would want to use a bulb under 120W, because with a short circuit on the DUT, the bulb will draw 1A through the circuit and would probably blow the fuse. In this case a 60W, 75W or even a 100W would do just fine. For a 2A fuse, you could go all the way up to a 200W bulb if you wanted. for a 0.5A fuse a 40W bulb would be good. As long as you are only using it to determine if you have a short or not, then you don't have to worry about the voltage being dropped across the bulb and how that will affect the DUT. I know people that keep their DUT on the bulb at all times, but they have done the calculations based off the bulb used to know what the voltage readings should look like based off of that.

Can't believe that metal box is not earthed!

great, I think I've thrown out all my incandescent bulbs. Is everyone using a 100w?

Good old bulb (with a filament) are gone now... all replace by leds!

Still astonishes me that America likes metal boxes like that. Here in Australia, that would have to be plastic to be safe and legal.

@stephengentle2815

2 жыл бұрын

A metal box would be OK as long as it's properly grounded. But yeah, it astonishes me to see that with no ground lead, super dangerous! Having the sockets like that would be totally illegal also - firstly, again, because again, earthing - the sockets don't have a protective earth connected to their ground pins, but secondly because you could just plug any old appliance in series with the device under test. Theoretically I think you could produce a legal dim bulb tester here, but you'd want an RCD breaker on it, and probably you'd need to put a bulb bayonet/screw mount socket on the box itself and wired internally, instead of the socket for the external lamp.

Hi Aidan, OK, My mistake. Thanks anyway. Regards, Jack

@AHFixIt

2 жыл бұрын

I'm glad it inspired you to try building one, though. I hope it works out!

I've never in all my 45+ years as an electronics/computer/network technician used one of these. It's why we have fuses. The results can be misleading. The light bulb will not go on if the fuse in the DUT (device under test) opens, giving you a false sense that the device is OK. And potentially dangerous if you have a transformer-less piece of equipment with one side of AC line tied to the chassis.

ac has no b plus

I could use this on some people I know 🤣💥

@insolentstickleback3266

2 жыл бұрын

@@chanslorvalorum6905 You might need an Australian Shepherd to keep them in line. ; D

I love DIY tools, this is awesome! But you should make sure and use an LED bulb, it's more energy efficient. 😉

@Silverface1987

2 жыл бұрын

I believe LED bulbs are different resistances. You could also use different watt bulbs for different equipment you are working on. It Has to be an incandescent bulb.

@JoeJ-8282

2 жыл бұрын

LED bulbs do NOT work as series connected, (i.e. current limiting), resistors. It is the actual filament of an incandescent (only) bulb itself that acts as the resistor needed for this type of tester, because if the current going through the bulb is relatively low and therefore safe for the equipment under test, then the bulb will not glow, (or only glow for a short period of time during the intitial charging of the power supply capacitors in the amp/etc. under test, and then once those caps are fully charged then the bulb will slowly fade out and go off), however, if the current drawn by the equipment under test is too high, due to an internal short or other major malfunction in said equipment, then the lightbulb will stay lit, indicating a problem with the equipment under test, because if the equipment being tested draws too much current, due to a fault, then the filament of the incandescent bulb will heat up and start to glow... But an LED bulb doesn't use a filament, it uses internal electronics to light the LEDs in it, of which are of a very high resistance, (usually in the megohm range), which will never pass enough current through it to power ANY equipment, even if the equipment is working totally fine. That is why this kind of tester ONLY works properly with an incandescent bulb. You can also change the wattage of the incandescent bulb to pass relatively more or less current, depending on what the equipment under test may need to operate at all. Higher wattage incandescent bulbs will pass relatively more current in a series wiring configuration like these testers use, and a lower wattage bulb will only allow a relatively lower current to pass before lighting. When using one of these type testers it's best to start out with a relatively lower wattage incandescent bulb first if you have no idea if your equipment under test is working or not, that way you send as little of current to said equipment as possible at first, reducing the chance of further damaging it if something is wrong with it.

@Monocog007

2 жыл бұрын

@@JoeJ-8282 but.. are you sure? Have you even tried it first?

@SaturnV2000

2 жыл бұрын

"Have you even tried it first?" is NOT even a valid question. An LED bulb WILL NOT WORK in this application. They function on an entirely different principle.

@SaturnV2000

2 жыл бұрын

Coincidental that Kirchoff's Law, (which every first-year engineering student is taught) applies here. If the device under test has a dead short, a voltage drop equal to the full applied AC voltage appears across the light bulb, therefore causing it to light.

why WTF?

Don't be so sensitive

Your drawing was totally inadequate for the mods you did inside the box. Your mumble-jumble explanation needs another drawing. Please provide one.

Its funny to me that so many youtube producers plagiarize the work of others without ever giving any credit to those who actually did this first. The dim tube tester concept goes back to at least the 1930's when guys were repairing radios. The concept probably goes back to the 1800's when electrical principals were being experimented with. I'm not sure who first came up with and called this device a dim bulb tester but it surely was NOT the multitude of techs and wannabe techs who watched another video and made their own video without even a hint of the credit being given to someone else. SHAME