Faults can be tricky. One of the more interesting I have seen on YT lately, was on the Buy It Fix It channel, where a Milwaukee Vacuum had a defective SMD fuse. When testing with a meter in Ohms range, it was fine, but when under load, it did not pass any actual current. That is why I love watching this type of videos to get more ideas for where to look for for faults, when nothing is just black or blown to give clues
My money is on dry solder joints. Take in a couple more defective units and microscope the large solder terminal joints. The slightest trace of a hair crack or black colour around the terminal is the telltale. This is especially true for equipment working in vicinity of chloride swimming pool water.
I've seen this sort of thing so many times. My brain rightly or wrongly tells me that even though it's now working it's not fixed because you didn't actually replace a part or repair a broken trace or dry solder joint. Enjoyed the videos though, thanks once again for sharing and I'm glad this kinda thing happens to other people too. 👍👍
lol lose solder joint?! My guess is that the power supply is putting out an amount of heat significant enough to compromise the solder joint. Thermal expansion and contraction over time. And time always wins.
I had a very similar experience with an Amazon fire TV 21W PSU, its circuit is very similar but with 15v output. After removing all the electrolytic capacitors to test them and re-soldering them back in. It miraculously started working again and still is two weeks later after heavy use. My money is on the soldering iron heat rejuvenating one of the electrolytic capacitors or that ceramic startup capacitor is intermittently faulty.
I know of no mechanism by which heating could "rejuvenate" an electrolytic capacitor. There are ceramic capacitors that will slowly age to lower capacitance due to changes in the ceramic itself. Heating the ceramic above a certain temperature will restore the original capacitance and restart the aging process. It is very bad practice to solder SM ceramic caps with an iron, though sometimes there is very little alternative. The tip of the iron should never be allowed to touch the cap directly. Thermal shock from an iron can cause cracking.
Had this 'magic fix' happen occasionally. Generally caused by the heat of the soldering iron temporarily clearing the fault. Suggest replacing that SMT VDD reservoir capacitor you soldered the wire to at 11'55". Might be one of the nearby components of course but bets are on that smt cap. Possibly problem is now heat sensitive??? try heat / chill to see what happens. On a Different topic, failing Poly-fuses behave differently after being re-soldered. They do weird things and are appearing in many supply's nowadays. Love ya videos, good work.
At 2:54 and 3:33 it looks like the connector pin at the lower left corner of the board is perhaps somewhat starved for solder on the top side. That _may_ be indicative of a problem with the plating through the hole (very rare, but it does happen). Since the actual electrical connection is on the top of the board, it might account for the restoration after those pins were mucked about with to attach the wires for testing. It looks to me like the board may have been done by reflow soldering the SM components on both sides, with the through-hole components manually soldered. There isn't great gobs of excess solder on the SM parts on the bottom which argue against wave soldering of the entire bottom side. The through-hole pins _might_ have been soldered with a sort of micro wave machine that actually moves around to makes a little fountain of solder under individual pads. "Transformers" like that are almost invariably wound with magnet wire that isn't stripped before being soldered, the exception being when "triple insulated" wire is used. The magnet wire is insulated with one or more polymers (e.g. nylon and polyester) that more or less evaporates when the pins are dipped into a solder pot. Sometimes a flaky joint is made. Handling of a board can temporarily restore a flaky joint.
I'd freshen up all the solder joints, clean and tighten connectors. I've had quite a few ''mystery'' fixes like this where the fault goes away after desoldering / soldering things and disconnecting / connecting plugs, terminals etc. on the board.
Richard I just watched part one again and I do not believe you checked that AC was actually reaching that switch mode board. It looked to me like they had cut the legs off flush to the board after it was soldered, seen plenty of dry joints caused by that practice.
maybe something to do with the ribbon cable,? ribbon cables and their connections can be finicky. Yes I suspect the ribbon cable only lights up things and the display on top, and worked the controls if I remember correctly... Intermittent weird stuff like this is often times interesting, I would reflow a lot of the solder joints especially on capacitors and then put it back into service and see what happens, it would be nice if there was a way to simulate what it does with some kind of load and let it cycle...
A solenoid works on my bench top when I put 24VAC to it. When plugged into the control board, I see 24VAC across the terminals…but the solenoid doesn’t open. What would you look for?
This was more than likely a Cold Solder Joint. I see this quite often. Things just aren't connecting, it's basically an Open Loop, but visually it looks normal. At the chemical level, there is no bond, no electrical connection. What you did was de-solder, re-solder wires on. So the act of refreshing/changing the solder is the solution. Probably the pool water corroded the solder joints over time? Or just plain old age.
My theory: I have discovered that sometimes a circuit board can get 'Stuck' in a specific state that hinders the operation of the unit! Powering up and down does not shift it, it remains how it was. But - if you isolate power to just that board while powered up and reconnect it, it resets to it's correct state! Example: I had a CDJ (Professional DJ CD player) and it was stuck in Reverse! Powering up and down didn't help. But when I dis/reconnected the board that controls the playback. It cleared it up and normal play could resume. I wrote a more detailed essay on this occurrence if anyone's interested? I call it Logic Loop!
Yeah I hope to have several more and similar ones to repair soon. I need to go buy some wide guage heatshrink before I give it back, I don't have any big enough at the workshop
@zedcarr6128 @zedcarr6128 I asked exactly the same question in part one video, though your translation is more literal and not taking into acount the order of words in Spanish is different to English, so it actually says 'Broken Jungle Mother' 😉And don't even get into how Spanish speakers pronounce 'Jungle ' 😂
I learned the term PFM while in the Navy in the 70's and it was used often when maintaining analog and digital electronics and things would magically just start working in the midst of troubleshooting some fault. It stands for Pure F**king Magic.
Faults can be tricky. One of the more interesting I have seen on YT lately, was on the Buy It Fix It channel, where a Milwaukee Vacuum had a defective SMD fuse. When testing with a meter in Ohms range, it was fine, but when under load, it did not pass any actual current. That is why I love watching this type of videos to get more ideas for where to look for for faults, when nothing is just black or blown to give clues
I enjoyed that too.
My money is on dry solder joints.
Take in a couple more defective units and microscope the large solder terminal joints.
The slightest trace of a hair crack or black colour around the terminal is the telltale.
This is especially true for equipment working in vicinity of chloride swimming pool water.
I've seen this sort of thing so many times. My brain rightly or wrongly tells me that even though it's now working it's not fixed because you didn't actually replace a part or repair a broken trace or dry solder joint. Enjoyed the videos though, thanks once again for sharing and I'm glad this kinda thing happens to other people too. 👍👍
Going to go for a dry joint on the PSU either on the AC in or the DC out. It's the only real explanation surely.
No, it could be a strange static voltage on the chip that took time to go away or went away while he was probing everything.
American A&P here. You’re a pleasure mate! Teach us lot to be safe, great example u are you!
lol lose solder joint?! My guess is that the power supply is putting out an amount of heat significant enough to compromise the solder joint. Thermal expansion and contraction over time. And time always wins.
It may be faulty caps. When you wiggle and bend them they start to feel better. But still it's better to change them.
I had a very similar experience with an Amazon fire TV 21W PSU, its circuit is very similar but with 15v output. After removing all the electrolytic capacitors to test them and re-soldering them back in. It miraculously started working again and still is two weeks later after heavy use. My money is on the soldering iron heat rejuvenating one of the electrolytic capacitors or that ceramic startup capacitor is intermittently faulty.
I know of no mechanism by which heating could "rejuvenate" an electrolytic capacitor.
There are ceramic capacitors that will slowly age to lower capacitance due to changes in the ceramic itself. Heating the ceramic above a certain temperature will restore the original capacitance and restart the aging process.
It is very bad practice to solder SM ceramic caps with an iron, though sometimes there is very little alternative. The tip of the iron should never be allowed to touch the cap directly. Thermal shock from an iron can cause cracking.
I’m glad you hooked the power supply circuit back with the test wires before installing it in again. I would have done that too out of pure curiosity.
Yeah it seemed the most sensible thing to do in the circumstances 😉
Had this 'magic fix' happen occasionally.
Generally caused by the heat of the soldering iron temporarily clearing the fault.
Suggest replacing that SMT VDD reservoir capacitor you soldered the wire to at 11'55".
Might be one of the nearby components of course but bets are on that smt cap.
Possibly problem is now heat sensitive??? try heat / chill to see what happens.
On a Different topic, failing Poly-fuses behave differently after being re-soldered. They do weird things and are appearing in many supply's nowadays.
Love ya videos, good work.
A fine example of PFM.
At 2:54 and 3:33 it looks like the connector pin at the lower left corner of the board is perhaps somewhat starved for solder on the top side. That _may_ be indicative of a problem with the plating through the hole (very rare, but it does happen). Since the actual electrical connection is on the top of the board, it might account for the restoration after those pins were mucked about with to attach the wires for testing.
It looks to me like the board may have been done by reflow soldering the SM components on both sides, with the through-hole components manually soldered. There isn't great gobs of excess solder on the SM parts on the bottom which argue against wave soldering of the entire bottom side. The through-hole pins _might_ have been soldered with a sort of micro wave machine that actually moves around to makes a little fountain of solder under individual pads.
"Transformers" like that are almost invariably wound with magnet wire that isn't stripped before being soldered, the exception being when "triple insulated" wire is used. The magnet wire is insulated with one or more polymers (e.g. nylon and polyester) that more or less evaporates when the pins are dipped into a solder pot. Sometimes a flaky joint is made. Handling of a board can temporarily restore a flaky joint.
I'd freshen up all the solder joints, clean and tighten connectors.
I've had quite a few ''mystery'' fixes like this where the fault goes away after desoldering / soldering things and disconnecting / connecting plugs, terminals etc. on the board.
Richard I just watched part one again and I do not believe you checked that AC was actually reaching that switch mode board. It looked to me like they had cut the legs off flush to the board after it was soldered, seen plenty of dry joints caused by that practice.
Heat on the board when you soldered the jumper wires onto the capacitors fixed something?
The ground pin on the chip looks like it's barely soldered onto the pcb. The hole pcb could probably benefit from a reflow.
maybe something to do with the ribbon cable,? ribbon cables and their connections can be finicky. Yes I suspect the ribbon cable only lights up things and the display on top, and worked the controls if I remember correctly... Intermittent weird stuff like this is often times interesting, I would reflow a lot of the solder joints especially on capacitors and then put it back into service and see what happens, it would be nice if there was a way to simulate what it does with some kind of load and let it cycle...
Heya, could this be an intermintend fault or was it just a lose contact or bad soldering that you solve by resoldering that lose contact who will tell
That's why we call it "F", "M"!
If you have a battery-powered oscilloscope would it be safe to probe as this would be issued from mains ground?
A solenoid works on my bench top when I put 24VAC to it. When plugged into the control board, I see 24VAC across the terminals…but the solenoid doesn’t open.
What would you look for?
The only thing i can think is that there was some bad connection somewhere?
Me too but it is such a simple PSU and I had it under the microscope a lot during the videos
This was more than likely a Cold Solder Joint.
I see this quite often.
Things just aren't connecting, it's basically an Open Loop, but visually it looks normal.
At the chemical level, there is no bond, no electrical connection.
What you did was de-solder, re-solder wires on. So the act of refreshing/changing the solder is the solution.
Probably the pool water corroded the solder joints over time? Or just plain old age.
My theory: I have discovered that sometimes a circuit board can get 'Stuck' in a specific state that hinders the operation of the unit! Powering up and down does not shift it, it remains how it was. But - if you isolate power to just that board while powered up and reconnect it, it resets to it's correct state! Example: I had a CDJ (Professional DJ CD player) and it was stuck in Reverse! Powering up and down didn't help. But when I dis/reconnected the board that controls the playback. It cleared it up and normal play could resume. I wrote a more detailed essay on this occurrence if anyone's interested? I call it Logic Loop!
Magic Spit. Final answer.
You killed the gremlin.
maybe it was a broken solder joint ?? and now you solder the wires that joint has been fixed only thing i can think of !
They diagnosed those kinds of faults in airplanes way back during WW2.
The problem was Gremlins.
looks like you have to get the other not working units from the customer for Part 3 !
Yeah I hope to have several more and similar ones to repair soon. I need to go buy some wide guage heatshrink before I give it back, I don't have any big enough at the workshop
Broken solder joint, it happens more with lead free junk
Interesting hehe 😮😊
The magic pixie fairies often visit my house.
Why has it got ''Broken Mother Jungle'' written on it? 🤔
@zedcarr6128
@zedcarr6128
I asked exactly the same question in part one video, though your translation is more literal and not taking into acount the order of words in Spanish is different to English, so it actually says 'Broken Jungle Mother' 😉And don't even get into how Spanish speakers pronounce 'Jungle ' 😂
Comment for the gods
It just wanted to be touched by a technician... 😂
Dry joint
It is VOODOO 😱😱😱
🤣🤣🤣🤣🤣🤣🤣🤣
Richard , which skills didn't have you???
Santa fixed it
Some Things Fix Themselfs..lol
It's the worst outcome of repair attempt. You can't give it back to customer as repaired item and charge him for repair.
Bad solder joint.
Boop
Richard: it's kilohm amd megohm. Only two syllables. No 'a' in the middle.
Because the second syllable of kilo is lo and is a schwa that is an indistinct
vowel sound and is pronounced 'uh',so we say ki-luh-ohm.👍
He can say it how he likes
bullshit xD
A fine example of PFM.
Public Financial Management / Personal Finance Management? That's all google tells me 😵💫
I learned the term PFM while in the Navy in the 70's and it was used often when maintaining analog and digital electronics and things would magically just start working in the midst of troubleshooting some fault. It stands for Pure F**king Magic.