Multi-Tap Transformer. DON'T HOOK UP EVERY WIRE !!

Multitap or Multi-voltage Transformers are commonly used to replace a bad OEM transformer but make sure that you connect it properly. Not all wires will be used. I try to explain some of that in this video so I hope that I can help you make sense out of them.
I am still working on learning this action camera so bear with me as I try to get better.
00:00 Look at Transformer
08:10 Voltage Checks

[@user-vb8jl6nf4k]

It’s very disappointing to see that you dive have at least 200k subscribers, very well explained and clear and very helpful to us technicians on the field

[@emduplessis9996]

Outstanding, concise explanation of transformer wiring and how they work! I have looked at over 50 videos and yours 'clicked' for me. Thank you so much for sharing your knowledge.

[@danomano733]

Thanks, clear and very well explained. Thanks for taking the time.

[@kennyw7453]

Great video. That issue at the end you mentioned about multi-tap transformers in packaged roof top units having the primary voltage wired incorrectly happens more than it should. When I did factory service for Trane that and units with the wrong 3-phase rotation were common when some mechanical contractors would not pay for factory start-up and do it themselves or not do it at all.

[@johnjennings487]

I fear that it is more of "us" not paying attention and trying to hurry to the next call.

[@ServiceOrchestramegastore]

Thank you for the video. for that very explanation I had to go through all the you tube.

[@ashleypopiolek6434]

Well said, Thank you for the knowledge

[@johnjennings487]

Thanks. Appreciate it.

[@user-jp8rk7pu2d]

Great info. Thanks.

[@Iisidjenejiirjrkgawdcv9888yyyt]

Thanks for clarifying that "Com" = Neutral. I had to wire one up for a 277 from a single phase of the 3phz provided. As to say, Ground and Neutral were the options. My brain said "Ground is ground!" so used the Neutral!!!! Ground always seem in my mind to be the "Safety Net" that stops electricity from killing us!!! (takes it down and minimizes it from going thru other paths.....or can)

[@johnjennings487]

Thanks for commenting. I has been a while since i have been on a 277 circuit.

[@PBS-nm1uu]

just found your site like how you teach, keep it coming .

[@johnjennings487]

Thanks.

[@georgebuck2269]

From Hammond transformer company. You must hook up the dual windings type transformer in phase or you will burn out the unit. In transformers with dual primaries and secondaries, do I need to hook up both? YES, The unit was designed to run both and if you use just one it will overheat and voltage regulation will be poor. In dual winding transformers, how do you hook windings up "IN PHASE"? To hook the windings in parallel, always hook the dot to the dot. To hook the windings in series, always hook the dot to no dot. This applies to primary and secondary windings.

[@johnjennings487]

I have seen some commercial units with a different transformer than what is typically used in our residential HVAC units. That must be one of those types that they are describing...never seen one with dual primary windings. I'll have to try and find one so I can learn about it. Thanks

[@georgebuck2269]

@@johnjennings487 The reason for dual primaries is that transformers are sold all over the world and most countries use 240 AC volts instead of 125 AC. It means they are dual use, 240 VAC for the world and 125 ACV for America and Canada. For 240 volts AC you hook the primary windings in series, so each section only gets 125 AC. For parallel (125 AC) if you wire the transformer out of phase it burns out the windings. For 125 AC you always wire them in parallel. You would first download the manufacturers PDF and find the dots and pin numbers on the schematic. Some of the pin numbers will be assigned a dot. For 240 vac series wired, the schematic shows to connect pins 2 and 3 together and connect the line voltage to pins 1 and 4. I used to buy small pcb transformers at flea markets for a dollar. And I burned out a few after wiring them out of phase. Remember dot to dot for parallel.

[@carlosg1165]

awesome teaching skills👍👍👍👍👍👍👍

[@johnjennings487]

Thank you.

[@shankarjadoo]

Thank you sir.

[@westbay5858]

Thanks for video. Any suggestions on to type of tape you removed (yellow) ....just regular electric tape or something better that sticks better?? Thsnks.

[@johnjennings487]

That yellow tape stuff was something that the factory wrapped the coil in. Some I've seen have it and some don't. I just took that off for the video "show 'n tell". I don't know that you would ever need to replace it or anything. Thanks for commenting.

[@simmonsjr25]

Awesome video. I will take this info into the lab.

[@johnjennings487]

I'm from Missouri...don't tell me - show me Bigg Dogg.

[@simmonsjr25]

@@johnjennings487 I will show you next time we in the lab. To easy. Easy money 💰

[@matthatesford]

Quick question. I've got a 120v microwave transformer, it's the only one I've seen with 3 taps on the primary winding. One tap for each end of the winding and one that splits and goes both directions in the winding. Having a heck of a time trying to get output. Xfer ohms out fine on the meter and good connections all around. But can't seem to verify power with any combination of line and neutral connections on the 3 taps. Thanks, solid video btw

[@johnjennings487]

I would think that the primary side would just be 2 taps or wires and the secondary side maybe has 3 wires? They do some different stuff with capacitors and I don't do a lot with them so I really wouldn't know what to tell you that is different than what you said. That's why I like HVAC...just a little simpler! Hope you get it though.

[@matthatesford]

@@johnjennings487 it is definitely on the primary side. 1 single tap on the secondary, with a couple wires from the heater winding but those are not used in my application. But no worries, I'll either get it or burn up the transformer, in which case I'm sure I've got another microwave laying around hahaha. Thanks for the reply

[@jackbrennan754]

Good video

[@johnjennings487]

Thanks.

[@larryyoungman1759]

Great video. Question I have a transformer has 2 X 120 Primarily which Are Blue, Black Wires. If I wire them in series should get me 240v It also has 2 Green Primary wires listed as 24v. We have 240v here so do I cap. The 2 Green wires of? The secondary wires are 24 out. Red Black?

[@johnjennings487]

Never seen one like that...what do you mean wire them in series. If you put have 240v power supplied to the transformer, one transformer wire will go to the L1 and the other transformer wire to the L2 of the source. You would need to individually cap each unused wire.

[@larryyoungman1759]

Yes 240v is what it needs and 24v out. However it has the green 24v Primary in as well as the Secondary 24v wires. It is aToroidal type of Transformer from a powered speaker that had the soft start blow so I am replacing it with a generic one.

[@nonsuch]

So, If I put 120v into a multi tap transformer, can I use the 240v tap as a step up? Even if it's low current, it could be rectified and voltage doubled to 500v and used in say a tube amplifier.

[@johnjennings487]

Should work. You are just limited to the wattage capacity on the 120v side (if i remember all my electrical stuff right!) Even if you stepped it up to 500v it would still be at the original wattage rating of the 120 side. I am not familiar enough with tube amplifiers but I like to tinker with stuff!

[@nonsuch]

​@@johnjennings487 Crap. I just realized if I did this, there'd be no isolation. It's the whole point of using a transformer! Duh 😂. I knew it was too good to be true. I was trying to get away from the step-up transformer costs and cheap out. They can get expensive.

[@shankarjadoo]

Thank you for your video. I have an old Colemans' heating furnace the old transformer has four wires one side white and black another side red and blue. new transformer S1-2940A3541 120V-pri 24V-SEC40VA York Goodman came with four terminals with no instructions. now I don't know which wire goes to which terminal. Please help me with the connections. Thank you. Dost K

[@johnjennings487]

The new transformer should have each side labeled somehow. The black/white on the old is 120v of course so one the new transformer it should be labeled as 120 or maybe primary. The other side for 24v red/blue should go to the new one labeled "sec" or 24. I hope this helps.

[@juliantrujillo8560]

What happens if I leave the 120 volts current supply line connected to the connection line of the transformer 240 or 208 volts for a long time thanks,nave a good day

[@johnjennings487]

If you put 120v on the 208/240 connection of the transformer -- should be no problem. It just puts out half of the voltage on the secondary. The other way however, 208/240 volts on the 120 connections of the transformer, will destroy the transformer!

[@juliantrujillo8560]

Thank you

[@franciskennedy1930]

4 plug transformer, top right 120 black wire, opposite white com. Bottom right yellow w/black strip on 24v opposite plain yellow com. I took pictures to make sure. The new transformer shut down and was extremely HOT! Any ideas?

[@johnjennings487]

It sounds like a short had taken out the original transformer. Did someone just find the unit not working and diagnose a bad transformer? If so, by just replacing the transformer it would not have fixed the problem...only give it another chance to strike! Sounds like you have got to find the low voltage short (possibility) that took out the original transformer before replacing it again. Am I close? If not...I plead the 5th!

[@brs.l.bs.p5159]

i have a questionve a 40 watt amp that has 2 transformers and im trying to use them to give my new stereo more power. one of them already has speaker wire plugs connected which are ( brown blue red orange and yellow) but also has a black and white with a two prong male end then on the other i only have two reds on one side and 2 blacks on the other how do i hook it up combined with a homemade amp i built

[@johnjennings487]

I don't have much experience with autos and speakers. I am afraid I wiuldn't be much help with this one. I would have to learn what you know first...

[@brs.l.bs.p5159]

@John Jennings it's really just the transformers using them to add more power but I'm an electricians help for years my dad owned his own company but they came out of an app that I took apart I like taking things apart and trying to build my own things. My project now is to get this super loud system building my own speakers and etc. But its two transformers I know nothing about. One is a single layered transformer I'm assuming and has 7 wires 5 in which are brown blue red orange and yellow which are all hooked up to a peaked wire plug and were labeled com,4u,8u,16u and 70v which would go from yellow being Com which is negative and brown being 70v. And it has a black and white wire connected to a two prong plug theat went to the power board then I have another Amp that has the two black wires coming from the top half of the transformer connecting to the twoprong power board also but then it has two red wires on the lower half

[@brs.l.bs.p5159]

@@johnjennings487 thanks for the reply though

[@alexanderthegreat3674]

I have a bad 4 wire transformer. Primary side has two black wires going in and had 120v on each one. And the secondary side has two red coming out at 24v. How would I wire this up with out a neutral?

[@johnjennings487]

If it is a 208/240v to 24v you wouldn't need a neutral at all. You would just just wire it to your L1 and L2 power (at the terminal bock inside your unit?). I am assuming since you said you have 120v on each leg. Neutral should only be needed if you are running 120v, not a 240.

[@travisrickard1154]

That’s my question on 220 single phase you have 110 and 110 so on the 220 wire you have 110 and what they call common you have your other 110 wire that what you mean on L1 and L2 line in . kind of confusing thinking it’s a ground

[@johnjennings487]

A lot of universal transformers have multiple wires (and even if you have one that isn't universal) and most everyone that I have seen has a 'COM' on the primary side along with something like 120= Black, 208=Orange, 240=Red, White=COM. The L1 side of your actual power supply (say 120 volt for a gas furnace) would be wired to the Black (because that is the L1 for a 120 on the transformer) and your actual neutral would be wired to the White because that is the COM on the transformer. The 'COM' is always wired to your L2 or neutral no matter what actual power supply you have in the unit. With your 240, you would use something like the red and black in my example. No neutral needed since it is a 240 circuit. Only have a neutral in the 120v power supply.

[@michaelnunez8983]

Dumb question how hot (temperature) do transformers get when energized?

[@johnjennings487]

I don't have an exact number but "warm" would be how I described it. If the windjings get too hot then the lacquer on them will burn off and you'll get that burnt electrical smell. I'll have to put a temp probe on a transformer and let you know...

[@frankeckert4901]

So how does 240 get wired?? There is no common, its 2 120 legs and a ground

[@johnjennings487]

On the primary side they list it as a common but it is just the "other side of power" for whatever power source you are using it on. For a 120 you would put the neutral on the "com" and for 208/240 you would put your L2 side to "com". It doesn't know any better 🤣

[@frankeckert4901]

@@johnjennings487 I really appreciate your time John.. So L2(120V) to com and then L1(120V) to 240V wire? I'm just wiring a 24v UV light in air handler.

[@johnjennings487]

That should do it. There are several "commons" in the HVAC realm. There is a 24v common, a COM on a capacitor, a COM on a relay, etc. In cases like a relay or capacitor or in your case, a multi-voltage transformer winding...the COM is just a indication of "no matter the supply voltage you are gonna use this terminal and then one of the other numbered ones." Kinda like everybody likes Chick-Fil-A...we all have that in common!

[@frankeckert4901]

@@johnjennings487 I just got breakfast there!!! Chicken egg & cheese biscuit... Thanks Again!!!

[@mikellandrum6673]

So the common wire goes to another power wire correct

[@johnjennings487]

Yes. The common wire in the primary side would connect to the neutral in a 120v circuit or the L2 in a 208/240 v.

[@mikellandrum6673]

@@johnjennings487 I think I hooked it up wrong. The heating element cuts on but not the blower. With it being different color wires it's throwing me off

[@johnjennings487]

Are we still talking about a transformer? Or is it a relay of some sort?

[@mikellandrum6673]

@@johnjennings487 the transformer. Guessing whoever had my house before me had to have it worked on some of the color wired are different

[@rosswilliams5339]

Mmmmmm inductance

[@pab6069]

18:16

[@charleslynch2938]

Why do all the videos have a tech with a southern accent?

[@johnjennings487]

I don't think I have a southern accent, everyone else has northern ears!

[@joeyravage4798]

WHAT??!! I just read the title?! ........I suppose this is for beginners....

[@johnjennings487]

Sorry about that Joey Ravage. This was one that i tried to put up for some beginners i had in a class. I tried to use the BIG WORDS so it would grab their attention since i don't wear bikinis!

[@joeyravage4798]

@@johnjennings487 I realized that after I was typing. Great video for the novices!

[@johnjennings487]

Appreciate it.

[@user-el1fv5pf5k]

Blurry during entire video. Gave up halfway through

[@johnjennings487]

it is an old one from the covid days and it was a cheap camera. thanks for trying though!