I made a followup explaining how and why I was fooled by the PSU, and how a faulty diode can measure good in diode mode 😋 ua-cam.com/video/j4Ow04xwzRM/v-deo.html
An interesting video for sure. This was the trigger for my LLC journey, so thanks for that too! Also is the suspect diode at 35:30 showing mains ~240v not 28v?
Another great video Richard. It's important to stress to the young players that you are never fault finding a reference design. These things have been built down to a price. Often they have cut more corners than a one armed decorator. Always follow your nose. If it does not make sense, don't give up.
Hi Richard, excellent diagnosis of the board. I would have checked one fundamental thing before power-up. You proved the 'fuse' in the mains socket is OK but didn't check it was a 'fuse'. Wouldnt be the first time I have found tin foil or wire used. Just saying on the point of safety to others watching. Thanks
Hi Richard, thanks for another interesting video. I came across your channel a while ago and have been an avid follower ever since. You’ve inspired me to delve deeper next time I have something electronic to repair. 😊 Much appreciated.
Fantastic stuff. You're not the only one to be caught by an odd failure. Back in the day Sanyo made a 14" T.V. After a few years, they would start blowing line output transistors. The cause was a 47K 2w resistor going high. In circuit, it would read about 49K. Close enough right?....No. Lift one end off the board, closer to 58K. We've all been there 👍. Cheers Pete' New Zealand.
Thanks for the great video once again Richard. Your series is really helping me understand how the supplies work. I appreciate that you take the time to explain not only the circuit, but its possible failure modes as well. Now i'm off to the follow up! That said, I noticed that the cap directly below the PWM IC, Just right of D8 appears to be damaged.
I've been given one of these (output of 24V 8A for a mobility scooter) that appears dead from the outside. All fuses and plugs check out. Time to open the beast up! I think I know what I'll check first... 😉 Perfect video at precisely the right time. Thanks mate!
35:29 - that's 236VAC not 23 volts. your eyes saw what they were expecting?! 39:52 - You're getting ready to install a 100v diode into a board that is supplying 236 volts! (let's see what happens). 40:55 - Wow! Nothing bad happened even though 236v (see 35:29) was applied to the 100v diode. I expected something worse. We still don't know why there's 236v where you were expecting 28v.
The downside to that is also that removing components to test them is also mainly not a good idea - some are very hard to remove/resolder and practically impossible to test out of circuit anyway. No one said this is easy 😉
Errmm... I think what I did here was methodical logical fault finding. Not just stab away at components until you find the dead part. 😉 In this case everything tested OK in circuit so good luck with the stabbing approach
Yeah It was rather good for dramatic effect that I happened to go down that route. It's just the way it goes when I hit record... anything could happen 😉
Nice1. I’ve seen quite a few double diodes blown. Possible reverse polarity destruction or some sort of v spike if not low end component or ware and tare.
I am very impressed by your skills! Thanks for sharing your knowledge and expirience. Keep going! Cheers from Germany and sry for my english :D A bit late but can u show a little review from the handheld oszi?
Hay that was pretty awesome repair I like this one thanks,no burn out components but a bad part makes one have to think that it’s not always pop out and say here I am.lol thanks again.
@@romancharak3675 That is true but I have seem a pair of diodes soldered to a little metal plate with a pin that goes to the centre hole before now. The little metal plate bolts to the heatsink
Hey Richard, my HP 630 is keep doing THERMAL SHUTDOWN, last year I changed it's thermal paste. Whenever I tries to do edit or do some CPU based task, it gets overheated and shutdown. My Laptop is 15 years old. (HP 630 pavilion) . What to do ?
Are you sure you applied good thermal paste? If yes I'd open it up and check if the surface of the CPU die is fully covered in thermal paste. Might be you applied too little last time. Also proper tightening of the heat sink is important for good heat transfer. Other possibility is the fan is not working properly, or the fin stack is blocked by dust. GL
Possible faulty heat pipe (if it has one) - I made a video on this topic but it was some time ago. Google found it for me (PS my early videos were not so high quality/resolution) ua-cam.com/video/7puj20oGlQg/v-deo.html
I have a HP650 that is of similar age that I used daily up until last year. Every couple of years I would have to clean out the heat sink grills as they would get fluffed up. The fan would be running but very little air flow. May be that.
@@ianhewitt1858 Quite possible if the CPU is overheating but the radiator/fan end is cool or cold. Once the special gas in the heat pipe escapes it is useless, basically. Test it like i did in that video - or use a thermal camera but I didn't have one back then
Interesting video once again. It would be a good idea to turn off your cell phone notifications while shooting all your videos. You don't seem to pay attention to it, but above all, neither do we. Thanks for sharing your knowledge.
No, you do not know that chip well, E1 & E2 are emitter legs of output drivers, NOT enable. The TL494 is an ancient chip, NOT intended for LLC operation, so that makes the charger an unusual design, or it is some other configuration, ...I suspect push pull, which is the most common use for this chip.
I clicked on this video hoping to possibly gain some knowledge that might help me to repair my own charger. But, I'm the type of person whos very impatient when ive got a task at hand to accomplish, and this dude is far to slow for me. Getting to the point is taking way too long. Get to it dude.
I made a followup explaining how and why I was fooled by the PSU, and how a faulty diode can measure good in diode mode 😋
ua-cam.com/video/j4Ow04xwzRM/v-deo.html
An interesting video for sure. This was the trigger for my LLC journey, so thanks for that too! Also is the suspect diode at 35:30 showing mains ~240v not 28v?
The best explanation of a power supply on the internet!
One of the greatest diagnosis/repair videos that I've ever seen on UA-cam!
Another great video Richard. It's important to stress to the young players that you are never fault finding a reference design. These things have been built down to a price. Often they have cut more corners than a one armed decorator. Always follow your nose. If it does not make sense, don't give up.
Hi Richard, excellent diagnosis of the board. I would have checked one fundamental thing before power-up. You proved the 'fuse' in the mains socket is OK but didn't check it was a 'fuse'.
Wouldnt be the first time I have found tin foil or wire used. Just saying on the point of safety to others watching. Thanks
Whatching this 2.45am UK it's an age thing !thanks again rich learning all the time 👍
Hi Richard, thanks for another interesting video. I came across your channel a while ago and have been an avid follower ever since. You’ve inspired me to delve deeper next time I have something electronic to repair. 😊 Much appreciated.
Fantastic stuff. You're not the only one to be caught by an odd failure. Back in the day Sanyo made a 14" T.V. After a few years, they would start blowing line output transistors. The cause was a 47K 2w resistor going high. In circuit, it would read about 49K. Close enough right?....No. Lift one end off the board, closer to 58K. We've all been there 👍.
Cheers
Pete' New Zealand.
You are an awesome teacher sir, not afraid to show failure and always checking to see if we have done our homework. Thanks a bunch
Thanks for the great video once again Richard. Your series is really helping me understand how the supplies work. I appreciate that you take the time to explain not only the circuit, but its possible failure modes as well.
Now i'm off to the follow up!
That said, I noticed that the cap directly below the PWM IC, Just right of D8 appears to be damaged.
Thanks Richard, I have learned more how these controllers work as to the enable pins and the ref voltage.
I've been given one of these (output of 24V 8A for a mobility scooter) that appears dead from the outside. All fuses and plugs check out.
Time to open the beast up!
I think I know what I'll check first... 😉
Perfect video at precisely the right time. Thanks mate!
This stuff is starting to make sense 👍
Yeah, that is the beauty of repetition. It sounds like you are getting close to the day the penny drops big style!
35:29 - that's 236VAC not 23 volts. your eyes saw what they were expecting?!
39:52 - You're getting ready to install a 100v diode into a board that is supplying 236 volts! (let's see what happens).
40:55 - Wow! Nothing bad happened even though 236v (see 35:29) was applied to the 100v diode. I expected something worse. We still don't know why there's 236v where you were expecting 28v.
Richard thank you for another awesome video always makes my evening when i see you got a new video out 😀
That's why testing important composants in circuit is mainly not a good idea 😊
The downside to that is also that removing components to test them is also mainly not a good idea - some are very hard to remove/resolder and practically impossible to test out of circuit anyway. No one said this is easy 😉
thouroughly enjoyed that one.
very well done :) your fault finding worked out in the end :) nice job Richard :)
The double Schottky diode is an upgrade. Now the PSU is more efficient. Leave it in.
Very interesting, one of the harder diagnoses but explained really well.
Excellent video
Nice to see a board working.
Good work. I'm no professional but I am from the same school of thought.... Just stab away at components until you find the dead part lol.
Errmm... I think what I did here was methodical logical fault finding. Not just stab away at components until you find the dead part. 😉 In this case everything tested OK in circuit so good luck with the stabbing approach
@@LearnElectronicsRepair Hey Rich I was joking ;-)
I had my 5p on the PWM ic........oooh that pesky diode!
@@TYGAMatt oops sorry, my apologies 🤐 Try the followup video
ua-cam.com/video/j4Ow04xwzRM/v-deo.html
@@TYGAMattI thought that chip powered up from the scooter battery. These chargers won't start if the battery is too low.
Hi Richard! Thanks for the video!
Nice find sir good job
Much more interesting this way as if you would have diagnosed the diode as faulty in the first place. Great example of logic fault finding. 🤗
Yeah It was rather good for dramatic effect that I happened to go down that route. It's just the way it goes when I hit record... anything could happen 😉
Great work, thank you.
Note - C22 looks damaged... 28:53
Great work 👌
Thanks Richard. Very enjoyable and educational. Best wishes.
Hi Richard thank you for your video
Good find and diagnosis :D Happy watcher :)
Nice1. I’ve seen quite a few double diodes blown. Possible reverse polarity destruction or some sort of v spike if not low end component or ware and tare.
It may be worth finding out what the customer is actually charging with this,there could be some battery connection problem the other end
Solid gold tutorial...cheers.
Great video! Shame on UA-cam for the excessive adds. The excessive adds almost made this video unwatchable.
Very good video 😁😁
Nice work on this one
Heya, wel that's nice how do you call that a ghost in the woods wel you solved it so that's good
I am very impressed by your skills! Thanks for sharing your knowledge and expirience. Keep going! Cheers from Germany and sry for my english :D
A bit late but can u show a little review from the handheld oszi?
Hay that was pretty awesome repair I like this one thanks,no burn out components but a bad part makes one have to think that it’s not always pop out and say here I am.lol thanks again.
Nice one. Thanks.
Nice repair!!
19:00 call that a "gap" in the PCB. I think the PCB designer forgot to use his brain when designing that PCB. Not much clearance.
Why not use two power diodes to complete the job that day? Leave a note inside of the diode replaced for future service.
Thank you
I sleep when watch this. Lol
Hi dickie couldn't you fit two single diodes instead as long as their polarities is the same and the amp value corresponds? Or am i thinking wrong?
Yes you could. Also you need fast switching diodes, not plain old silicon rectifiers, as the SMPS runs at high frequency.
@@LearnElectronicsRepair AND, you can't "heatsink" individual diodes.
@@romancharak3675 That is true but I have seem a pair of diodes soldered to a little metal plate with a pin that goes to the centre hole before now. The little metal plate bolts to the heatsink
Hey Richard, my HP 630 is keep doing THERMAL SHUTDOWN, last year I changed it's thermal paste. Whenever I tries to do edit or do some CPU based task, it gets overheated and shutdown. My Laptop is 15 years old. (HP 630 pavilion) . What to do ?
Are you sure you applied good thermal paste? If yes I'd open it up and check if the surface of the CPU die is fully covered in thermal paste. Might be you applied too little last time. Also proper tightening of the heat sink is important for good heat transfer. Other possibility is the fan is not working properly, or the fin stack is blocked by dust. GL
Possible faulty heat pipe (if it has one) - I made a video on this topic but it was some time ago.
Google found it for me (PS my early videos were not so high quality/resolution)
ua-cam.com/video/7puj20oGlQg/v-deo.html
I have a HP650 that is of similar age that I used daily up until last year. Every couple of years I would have to clean out the heat sink grills as they would get fluffed up. The fan would be running but very little air flow. May be that.
@@ianhewitt1858 Quite possible if the CPU is overheating but the radiator/fan end is cool or cold. Once the special gas in the heat pipe escapes it is useless, basically. Test it like i did in that video - or use a thermal camera but I didn't have one back then
It may be a generic PSU with standby but they never used it because they didn’t need it?
Any idea how it starts?
@@LearnElectronicsRepairstill watching the video LOL!
Nie jestem szukaj ale okej😅❤
Interesting video once again. It would be a good idea to turn off your cell phone notifications while shooting all your videos. You don't seem to pay attention to it, but above all, neither do we. Thanks for sharing your knowledge.
Really?
Just a joke Richard, how often do you shave your fingers?
If it was me I would have wacked that dud diode with a hammer just to release some built up tension.
Pagawa ako san lugr
escooter is how spanish speakers pronounce scooter
33 mins in, I am baffled???? Can''t wait to see what the fault is! :)
39 mins in, ...aaah, maybe the other diodes fooled things????
No, you do not know that chip well, E1 & E2 are emitter legs of output drivers, NOT enable. The TL494 is an ancient chip, NOT intended for LLC operation, so that makes the charger an unusual design, or it is some other configuration, ...I suspect push pull, which is the most common use for this chip.
I clicked on this video hoping to possibly gain some knowledge that might help me to repair my own charger. But, I'm the type of person whos very impatient when ive got a task at hand to accomplish, and this dude is far to slow for me. Getting to the point is taking way too long. Get to it dude.