*For anyone interested in this circuit. A subscriber Chief_Engineer told me that Big Clive had also reverse engineered a more basic form of this circuit (without over current and over temp protection) four years ago. He couldn't post the link but as channel owner I can so* ua-cam.com/video/rsYcjysPHwM/v-deo.html Say hi to Big Clive while you are there. 🙂
Excellent approach to this repair, and good of you to include the Netlist instruction. It takes a lot of time and patience to present these videos Richard. Thanks very much for sharing your skills. I look forward to the next episode! Brian
Further to my previous comment: If you look at BigClive‘s YT „inside an electronic halogen lamp driver, with schematic“ you see the basic circuit, without the protection and temperature control bits, that oscillates at high kHz within the 100Hz rectified mains envelope. That way the component size makes sense. If you reorder your components slightly, you will probably come out at much the same circuit.
Yeah, this was good! I now have another use for my LED tester. Think my method of reverse-engineering a circuit might be a little easier and quicker, but hey, really good. Real life jobs with information and details at this level are very productive for the recipient. Kudos!
Thanks Richard. Another excellent video and such a detailed analysis. I had learnt some electronics theory but watching your channel with your terrific teaching style has taught me electronics in practice and reinforced the theory. Thank you.
Heya, yess love these smaller circuits it's for me for now complicated enough o it's good to learn from these kinds of circuits. still I had to watch the working of the total shematics 2 some pieces 3 times to untherstand what you were explaning as I'm still learning. and I love to see differant practical applications making people more aware of there surroundings
Very good detective work, Richard! The approach with the CAD program also was a refresher for my part (some years since I've used them much) The circuit you arrived at seems very much similar to the ones I've seen in compact fluorescent lights (some years ago, at least, and with smaller switching transistors, mostly) They had the exact same looking toroid driver transformer
Great video. As I was thinking he ought to build a net list, boom, there it was. Takes patience to do this. I would have run off to the store and bought a new one. That said, some things are worth fixing, and this is one technique that can be quite helpful when all else fails.
@@LearnElectronicsRepair True... it's of academic value only. In the real World, this faulty item would be chucked out and replace with like for like... or if the customer was wise, upgrade every halogen heater/lamp in the premises with cheaper (in every regard) LED lamps... if they care about pissing money up the wall in power bills and the associated fire risk. Ever seen the diecast metal light fittings that use MR halogen lamps heat distort and the paint finish burn? As a licensed electrician I have, too many times!
Excellent video Richard - as always - but it looks to me as though this process, even for a relatively simple circuit, would take several hours to complete and I wonder whether anything other than the most expensive or rare circuit would actually justify such a repair technique and for multi layer boards it would be even more difficult. Thanks for posting - very informative.
@@humidbeing Honestly, I like the actual schematic Richard did much more than nets pointing to each others. However, your approach makes indeed more sense when using more complex diagrams (mostly when using digital busess) in my opinion. But it's all personal preferences...
@@humidbeing I would say that this depends on the type of device. For digital schematics (microcontroller, graphics cards and things like that) then a modular schematic with nets makes a lot more sense. For analog devices like power supplies and audio amplifiers a schematic with wires makes a lot more sense. I didn't have much of a mess of criss-cross wires in this one, and in fact if you noticed, I used nets for the drive to the main switching transistors because it made the schematic clearer to read. So I have to say, digital use nets, analog use wires and hybrid devices like an air-con controller or audio mixer with DSP section use a mixture of both techniques on the same schematic.
I'm not yet a big user of this kind of CAD, but have KiCAD and it seems a bit too extensive as I rarely produce schematics let alone design boards. However, I can see how to use this net list method to just clarify a set of components and their connections during a repair instead of just beeping out the traces and trying to keep it all in my head or scribbled on a bit of paper. Cheers.
I think what you've labeled as D4 the glass diode which is redish in color with the blue stripe. Maybe what's called a diac. Quite a few references out there on the web. Hopefully it is still good and you won't have to attempt to figure out what value it is supposed to be.
@@LearnElectronicsRepair Yeah... others seem to have made comment before watching the whole video. My first sight of it in Part 1 had me assume it was a diac. I'm curious as to where that very fine trace is located on the schematic. Is it a fusible link or just a trace to a test probe point for manufacturing QA purposes?
I was trying to tell you why I don't use google any more, but it seems that just mentioning another search engine gets the comment deleted by YT. It did, but then it came back. Strange!
Certainly enjoy the reverse engineering and your excellent explanation of how you think the circuit works. But I have to ask; why not just replace this power supply with one that will drive the lamp. I can’t be sure of the exact lamp that this devices uses, but if it is a halogen lamp, there are led bulbs available in this form factor that use much less power and will provide the same light output.
Without analysing further, I am wondering why they would go to all that effort to generate a 100Hz circuit from a 50Hz supply. That doesn‘t give you much benefit in the size of the required transformer and you might just as well just use a transformer directly to convert from 230 to 12V. My suspicion is that this should oscillate at a significantly higher frequency to be able to generate the 60W output with a transformer of that size. Now the challenge is to find out how the small Mosfet with the associated circuitry turns into an oscillator probably in the 2 digit kHz range. Hmm
yes but the 50Hz supply is the mains AC frequency. What is coming out of the bridge rectifier is pulsed DC at 100Hz. So where is the all the effort in doing that?
And then they didn't lol. That gets advertised on TV at the moment in the UK but I've never used it. FWIW I use Firefox as my browser and google to search for stuff. I've also used Tor.
*For anyone interested in this circuit. A subscriber Chief_Engineer told me that Big Clive had also reverse engineered a more basic form of this circuit (without over current and over temp protection) four years ago. He couldn't post the link but as channel owner I can so* ua-cam.com/video/rsYcjysPHwM/v-deo.html
Say hi to Big Clive while you are there. 🙂
Excellent approach to this repair, and good of you to include the Netlist instruction. It takes a lot of time and patience to present these videos Richard. Thanks very much for sharing your skills. I look forward to the next episode! Brian
You're welcome
Brilliant video, would like to see more of these reverse engineering to schematics tutorials, Ive learned so much from this one. Thanks Richard!
Further to my previous comment: If you look at BigClive‘s YT „inside an electronic halogen lamp driver, with schematic“ you see the basic circuit, without the protection and temperature control bits, that oscillates at high kHz within the 100Hz rectified mains envelope. That way the component size makes sense. If you reorder your components slightly, you will probably come out at much the same circuit.
Thanks for the info. It's reassuring I came up with the same basic circuit as Big Clive. I'll post the link in a pinned project as I can do that.
Richard, thanks for the tuition on Netlisting, most informative, as well as the whole reverse eng process. Great Video Mate !
Yeah, this was good! I now have another use for my LED tester. Think my method of reverse-engineering a circuit might be a little easier and quicker, but hey, really good. Real life jobs with information and details at this level are very productive for the recipient. Kudos!
That was Great!!!
Thanks as always
Always fun messing around with stuff like this.
Grand video. Love watching and leaning reverse engineering circuit boards. Thanks from Down Under 🇦🇺
Thanks Richard. Another excellent video and such a detailed analysis. I had learnt some electronics theory but watching your channel with your terrific teaching style has taught me electronics in practice and reinforced the theory. Thank you.
Interesting, very helpful approach for those one off cases that fixing a circuit is a must. Thank you for your effort.
Thank you so much Richard, you keep impressing me with your teaching skills. Just returned from the island ;)
Heya, yess love these smaller circuits it's for me for now complicated enough o it's good to learn from these kinds of circuits. still I had to watch the working of the total shematics 2 some pieces 3 times to untherstand what you were explaning as I'm still learning. and I love to see differant practical applications making people more aware of there surroundings
Very good detective work, Richard! The approach with the CAD program also was a refresher for my part (some years since I've used them much) The circuit you arrived at seems very much similar to the ones I've seen in compact fluorescent lights (some years ago, at least, and with smaller switching transistors, mostly) They had the exact same looking toroid driver transformer
Yes I've just been pointed in the direction of Big Clive as well. I put the link to his video in a pinned comment here
Great video. As I was thinking he ought to build a net list, boom, there it was. Takes patience to do this. I would have run off to the store and bought a new one.
That said, some things are worth fixing, and this is one technique that can be quite helpful when all else fails.
Agreed. The real takeaway from this video is learning how to do it, regardless of the value of item I was using as a guinea pig 🙂
@@LearnElectronicsRepair If the customer has lots of these, then building the schematic is gonna make life easy and a few quid in the bank.
@@sivoltage The customer would save more time and money replacing all the Halogen heaters with LED.
@@LearnElectronicsRepair True... it's of academic value only.
In the real World, this faulty item would be chucked out and replace with like for like... or if the customer was wise, upgrade every halogen heater/lamp in the premises with cheaper (in every regard) LED lamps... if they care about pissing money up the wall in power bills and the associated fire risk.
Ever seen the diecast metal light fittings that use MR halogen lamps heat distort and the paint finish burn? As a licensed electrician I have, too many times!
@@sivoltage True
Excellent video Richard - as always - but it looks to me as though this process, even for a relatively simple circuit, would take several hours to complete and I wonder whether anything other than the most expensive or rare circuit would actually justify such a repair technique and for multi layer boards it would be even more difficult. Thanks for posting - very informative.
Very good video, learned a lot.
Thanks for sharing
Once you had input all the components and net entries I was expecting the program to generate the schematic itself!
That would be nice
The components and net labels IS the schematic. You should make modular schematics. Nobody wants to see a mess of criss cross wires anymore.
@@humidbeing Honestly, I like the actual schematic Richard did much more than nets pointing to each others. However, your approach makes indeed more sense when using more complex diagrams (mostly when using digital busess) in my opinion.
But it's all personal preferences...
@@humidbeing I would say that this depends on the type of device. For digital schematics (microcontroller, graphics cards and things like that) then a modular schematic with nets makes a lot more sense. For analog devices like power supplies and audio amplifiers a schematic with wires makes a lot more sense. I didn't have much of a mess of criss-cross wires in this one, and in fact if you noticed, I used nets for the drive to the main switching transistors because it made the schematic clearer to read. So I have to say, digital use nets, analog use wires and hybrid devices like an air-con controller or audio mixer with DSP section use a mixture of both techniques on the same schematic.
That a nice and very informative video but i cut and jump one in while 😂
Perhaps consider the phasing of TR2 secondary windings, and how that drives the transistors and MOSFETs.
Some interesting and useful techniques here. Just one thing to add, save your work every few minutes, or has it got auto save?
Whoever designed this circuit was either brilliant or insane.
They put a dot to each winding of a transformer to indicate which windings are in phase or anti phase
I'm not yet a big user of this kind of CAD, but have KiCAD and it seems a bit too extensive as I rarely produce schematics let alone design boards. However, I can see how to use this net list method to just clarify a set of components and their connections during a repair instead of just beeping out the traces and trying to keep it all in my head or scribbled on a bit of paper. Cheers.
You're welcome. Give it a try and you will be surprised.
I think what you've labeled as D4 the glass diode which is redish in color with the blue stripe. Maybe what's called a diac. Quite a few references out there on the web. Hopefully it is still good and you won't have to attempt to figure out what value it is supposed to be.
You did watch the video, right?
@@LearnElectronicsRepair😂
I think the blue stripe on the diode indicates that it is a zener.
The blue stripe located in the centre of the device does not indicate an anode, as it would if it was a zener diode - The big clue it's likely a diac.
If you watched the video then you know what the blue stripe diode is because I proved it.
@@LearnElectronicsRepair Yeah... others seem to have made comment before watching the whole video. My first sight of it in Part 1 had me assume it was a diac.
I'm curious as to where that very fine trace is located on the schematic.
Is it a fusible link or just a trace to a test probe point for manufacturing QA purposes?
I was trying to tell you why I don't use google any more, but it seems that just mentioning another search engine gets the comment deleted by YT. It did, but then it came back. Strange!
Certainly enjoy the reverse engineering and your excellent explanation of how you think the circuit works. But I have to ask; why not just replace this power supply with one that will drive the lamp. I can’t be sure of the exact lamp that this devices uses, but if it is a halogen lamp, there are led bulbs available in this form factor that use much less power and will provide the same light output.
Given the output rating of 60W at 12V it would certainly be for one of those old power hungry halogen heater/lamps.
Without analysing further, I am wondering why they would go to all that effort to generate a 100Hz circuit from a 50Hz supply. That doesn‘t give you much benefit in the size of the required transformer and you might just as well just use a transformer directly to convert from 230 to 12V. My suspicion is that this should oscillate at a significantly higher frequency to be able to generate the 60W output with a transformer of that size.
Now the challenge is to find out how the small Mosfet with the associated circuitry turns into an oscillator probably in the 2 digit kHz range. Hmm
yes but the 50Hz supply is the mains AC frequency. What is coming out of the bridge rectifier is pulsed DC at 100Hz. So where is the all the effort in doing that?
It wasn‘t about the 100Hz, but how you get to the HF oscillation…
@@Chief_Engineer Take a look a the video I linked in the pinned comment, it gives a better description on the circuit operation than mine
Hi Rich. Check out M8p BSN20 Philips
SOT-23 MOSFET n-type
Sw, LogL, 50V, 173mA, 830mW, 8/15ns, 15(100mA)
That's the same one I identified in the video?
Google "the ultimate smd marking codes database" . Good resource. Paul
@@LearnElectronicsRepair Hi Rich. Have tried to reply a few times but it keeps getting deleted. ??
Hi, ur delivery and speech may need a bit of correction in terms of some repeated irritating voice overtone.
Else ur content is superb.❤
Very interesting and informative approach. I'm guessing Fenton, but correct me 😁
Normacot
@@LearnElectronicsRepair Close!
Just checking if mentioning duckduckgo gets my comment deleted by YT.
And then they didn't lol. That gets advertised on TV at the moment in the UK but I've never used it. FWIW I use Firefox as my browser and google to search for stuff. I've also used Tor.