Fluke PM3370B Solder Joint Inspection
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- Опубликовано: 1 фев 2022
- An optical and digital camera inspection of a possible dodgy solder joint on the Fluke/Philips PM3370B conbiscope, and how lighting and different cameras can show a joint differently.
Also an explainer on PTC vs NTC thermistors.
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Yep, twas me who sent Dave about the possible unsoldered SMD cap on the underside.......as a viewer we can't minipulate the board in our hands to get a better view so not surprised it's probably fine.......
Great audience participation though Dave, keep it up whoop whoop!
What I normally do in situations like that is put a finger on the joint and wiggle the part, so I can feel if there is any movement.
do you still have all your fingers?
I really like that you make these types of repair videos, you create an environment where a lot of people come in share their opinions on what might be wrong or not, you even go and test for those, it is discussed, etc.
The "created" process is pretty good.
I have come to believe that any solder joint can start to look suspect if you look at it with enough magnification and light. On another note, I once had an issue on a double sided PCB where the connection through a via from one side to the other would open when the PCB heated up and close when it cooled down. Soldered a piece of wire through the via on both sides and problem solved!
That is definitely not a fault I would expect... I would have just troubleshooted until I found the lost connection between parts and probably run a jumper half a mile long between the ends lol
@@whatevernamegoeshere3644 It was actually the trace which supplied Vcc to a ROM. Pretty random failure mode for sure.
Wow, I had the same problem of failing vias with an Acer monitor. Took me ages to question the vias and confirm that. Several were failing on the LED driver board. I ran some bare wire through each via, soldered to scraped traces nearby on each side. Monitor has worked since.
We finally picked up a Mantis compact for our lab after hearing your opinions on them for years, gotta say you weren't lying! It's a nice bit of kit.
0:44
"But unfortunately it hasn't failed"
You don't hear that too often 😆
Glad I wasn't the only one who zeroed in on that joint. :) Never hurts to reflow very old joints when something on the board was causing the shutdown and all the components check out OK.
When the +58V shuts down it is probably caused by the thyristor V1213 being triggered.
It is connected between the +58 and -58 and is used for shut down.
It is triggered by the TPDOWN signal on page 5.6-11.
This signal can be triggered by several different faults as described on page 5.6-4.
It is also triggered by the Power Fail circuit.
Try interrupting the AC power for about 1/2 second and see if the scope shuts off.
This will simulate an intermittent power switch.
Maybe it is something else besides the switch.
It sure looks like the thyristor V1213 is being triggered.
Hint: If you tap a PCB on the edge when the instrument is active, e.g. with the back end of a screw driver or an isolated mallet, you may find any dry contact.
If it is a high voltage or high current joint, consider darkening the room and tap the PCB a few times, probably you will see the dry contact(s) sparking.
Another issue: dry contacts aren't always visible. Sometimes a tiny hole in the solder causes air into the joint (over time), causing oxidation INSIDE the solder joint. When you wiggle the component, the joint will look OK, but it still isn't. The oxidation also breaks the strength of the copper/tin joint, which is a layer of bronze a few microns thick. This will finally (over more time) make the entire joint break visibly.
These tiny holes are cause by bad soldering, usually by insufficient flux materials, or holding the soldering tip too long to the joint, or even heating the tin instead of the solder joint.
That solder joint looks good to me in the alternative lights. But I have had solder joints that looked good and I could only detect the issue by using a multimeter while poking the component. Reflow helped.
certainly don't need to have a wiggle on to be bad. Thing can be mechanically perfect but there's a crack that goes all the way through, and oxidation in the crack makes an open connection.
Sometimes even the video encoding may cause things to look like they're moving when In reality they're not.
This is very common in e.g. Louis Rossman's board repair videos. This can happen when the video encoder isolates objects in a frame and keeps them separate from the background. If the background starts moving (or is skewed or zoomed) and the isolated objects remain intact, this will create an "illusion" of movement.
With a polarizing filter you can get rid of reflections on metal parts.
Thanks for the extra mile you went on this, Dave. Always appreciated!
Thank you Dave for the follow up!
Thanks for getting back to that Dave. I learned something :)
most comprehensive investigation into a dry joint ever. Must admit when I saw the original clip I thought it looked dry.
People will be always critical doing any sort of technical video. It comes with being techs though as we're always trying to fix things lol!
I would re-solder the main switching transformer and any related inductive elements - I've seen the tiniest ring cracks develop in the solder on these types of components.
I have not read all the comments but it bears repeating “dryer then a dead dingos donuts”👍
1:05 "[As] dry as a dead dingo's donger"
@@gblargg 👍
Really interesting to watch. Much more interesting than a TV detective series LOL. Will he find the cause of the fail...? Maybe in the next episode... I would bet also on a bad soldering junction. Those could be microscopic. After 30 years of heating up, cooling down and mechanical stress. Solder is not made to give a lot mechanical support, so any heavier component (if not properly mechanically supported) could be a suspect (that is from a mechanical stress point of view, thermal can cause every solder to fail, but maybe less probably to be the actual cause). I still remember a medium size CRT color television, a re-branded Philips, back in the days, after an almost 2 thousand km auto ride when arrived not working. An visual inspection showed an less then hair size round break of solder under a bigger electrolytic cap. My eye sight was much better then LOL. Re-soldered and we were back in business. Winner winner chicken dinner LOL
Aside note on NTCs: I was confronted with NTCs for inrush limiting that failed in low temperatures. In the cold the NTC resistance dropped so low that the startup current peak caused the max pulse power dissipation of the NTC to be exceeded which broke it. A larger type of NTC fixed the problem.
But an NTC's resistance increases in the cold, so the initial current would be even lower.
@@cpm1003 Oh yes, indeed, my mistake, the NTC resistance got too high in the cold. The problem wasn't the inrush current but a constant current demand that caused excessive dissipation in the NTC before it could self heat.
But I am very surprised about HOW clean the scope is inside. Just wow.
To be on the sure side i would disconnect the end of ntc and run large current across joint to see if it played up.
Ha ha ha, not even 2 minutes into video & already 2 referances/Phrases that are my favourite "Dave-ism's" lol.
1- Input!1 "Need more Input Stephenie? Input, more Input?" ha ha
2- "As dry as a Dead Dingoe's Donga"
OMG! His vobabulary is just fantastic
Great, at least we now know, that this was just a camera angle and lighting trick! 👍
A dry joint does not require any mechanical movement. Solder joints need to be done at the coldest possible temperature that achieves "wetting". Higher temperatures (which you need sometimes) cause the solder to crystallise (internally - still looks good) as it cools. The crystal lattice interfaces can) and do oxidise) - this gives you a dry joint - which can be/is temperature sensitive - so just resolder all joints if you have an intermittent fault. This is common on joints that have "large" heatsink component to them - so connectors - thick wire terminals (relatively). "Wiggle" it would hardly expose ANY faults - except when things are almost falling apart.
Maybe re-engineer one of those circular camera lights to sweep around the LED ring, so the light angle is changing constantly even if the view isn't. (Think _Knight Rider's_ Kit or _Battlestar Galactica's_ Cylon, but scanning in a circle.) Could make it easier to spot stuff like that without having to reinspect the same board over and over.
so glad you brought up the NTC stuff seems to be very popular in power-supply circuits 🤩you should get the ultra low 6.5 digit ohm-meter and test for cracked tracts 🤔thanks
2:00 is 1070 "1080 but good enough for straya" ?
I've never mistaking said that before, no idea why that popped in there.
"...but unfortunately, it hasn't failed."
I recently thought that I was making a lot of dry/cold solder joints, but it turns out that I was just dulling the shine on them when I used a toothbrush to clean off the flux residue.
Some of the joints if you don't see the component lead but a little hill on the solder side, it is possible the lead is sitting on top of the board in the pit but not really soldered. One time I fixed a stand one scale because a resistor for some reason had an actually broken resistor lead I bridged.
No doubt it WAS loose in the previous video.
I wonder if the poor connection has caused the joint to heat up enough to melt the solder just enough to reconnect.
I greatly doubt it, it can't go from loose to rock solid. It moving was just me poking hard (it's not feel-o-vision) and it looked like it was loose.
When in doubt, reheat. In my 50+ years experience, bad joints don't always move.
It is a long shot but maybe the edge connector to the unit to the supply card had a dodgy connection that you overcame by reinserting it. A broken signal may have called the switching controller to shut down?
I always knew that Fluke can't solder properly! :)))
The joint may be a bit dodgy, but the NTC still seems galvanically connected to the pcb.
I've put this reaction already in the comments section of the previous video, but no harm in doing it here again.
With CRT's nine out of ten times it's the line transistor that shows this kind of behaviour when failing. It's the part that also comes the most under stress. In the past when dealing with CRT's with this kind of behaviour this was the part I always checked first, useally with some cold spray. In this case it's transistor VL1109. BUV28 was notorious, but don't get fooled when you take it out and measure it. You probably won't find anything wrong with it then. It useally only fails under load.
If it was a semi then why did it magically fix itself after I soldered the power joints?
@@EEVblog2 Did you also solder the joints of that particular semi? I have no explanation, however I have observed some really strange behaviour of linetransistors in the past. Perhaps your re-soldering actually did the trick.
@@edwinschuddemat8280 If it was on heatsink then I likely did.
...and another thing to check on my version. Thanks.
@@mcconkeyb Best of luck to you. I hope you'll find the problem.
I've just checked the PSU of my PM3394B which has the exact same issue as yours. I found two cracked joints in sector B11: two resistors next to a coil.
Edit: never mind, didn't fix it.
no. you had a leaky cap that reformed its dielectric layer as you were powering the unit repeatedly - issue was exposed by sitting idle for (likely) years. you can wait for it to fail again/completely (which can take years considering they are quality caps with lots of spare electrolyte) or desolder each one and individually measure esr/leakage (tho most likely cap in question will now show as within spec, for the same reason)
Nice theory but it was repeatable a dozen times and then I solder all the power joints and it now it's good?
Maybe try running a stress test on it for a few hours to see if it stops working?
I'll put some more solder on just to take it off.
"I pick things up then put them down!"
i've had joints look like that before. some alcohol will clean it up. its a product of the flux. if you look the rest of the joint around the edges has flux coating on it too.
So it something was sort of off on off on, why does the supply shut down and not come back up? Is there something that keeps it off then that occurs in the circuitry? Would you say the problem is from the switching signal?
Thanks for the video.
In the last video you said that you sprayed the board and frosted over the board, is there a part that when cooled down, could it repair the part. ex PTC before cooling would shut down because it is weak from to many over heats, and the cooling of the part some how give it some extra life. Do not know how these this really works just wondering if there is some part that can be reset or given a new life by cooling.
In theory that's possible, yes.
What happened to the Eakins autofocus microscope? Just curious. 🙂
I have come across a high resistant glassy boundary develop between the component leg and the solder on the pad. This is a problem with lead free solder, particularly the early stuff, where the manufactures were experimenting with the temperature profiles. The joints were better when vapour phase soldering was used, as the temperature was more even. Unfortunately, vapour phase soldering was outlawed because it used a boiling fluorocarbon liquid to melt the solder. Vapour phase was replaced by infrared heating, and this proved difficult to get the right temperature profile, as the components reflected the IR differently between black and silver packages. At the time of the introduction of lead free flow soldering, not all components were really rated for the higher melting point of lead free solder, so the over temperature margins were small, resulting in the solder on dome joints not reaching its melting point.
The horrible lead free solder really does not flow very well, and sometimes fails to wet the joint.
Lead-free solder, a solution in search of a non-problem. What a blow to technology in general.
@@gblargg I am not sure I can agree with that. It is a problem putting the toxic metal lead into the environment, even if it was used for decades as water pipe and in car batteries.
A better solution might have been to introduce better methods of recycling electronic waste, for while the lead was contained on the circuit boards, it was not harming anybody, its the disposal that is the problem.
Lead free solder is horrible to use in comparison with the old tin/lead solder. The new stuff melts at a much higher temperature, it does not flow or wet the metal joints it is trying to connect, it forms joints that look dry and glassy even when they are not. It is far more brittle and much harder to desolder. The alloys used include more expensive and exotic metals such as silver and antimony.
The much higher melting point puts additional stress on the component being soldered, but obviously the early production problems have been solved, as lead solder has been outlawed, and has almost disappeared from mass produced electronics. That still does not make up for its limitations when hand soldering. I still use lead solder for my home built projects, and have a stock of the 60/40 reels.
@@nigeljohnson9820 Don't forget tin whiskers.
@@gblargg they are a problem to both types of solder. I suspect the high resistance layer found on some lead free joints are the result of trapped flux. In general the old lead/tin mix has better electrical and mechanical properties than any of the newer lead free alloys.
When desoldering, it is much harder to keep the whole lead free joints molten st the same time. It is much harder to solder to solder surface mount devices, particularly those where the component pads are on the underside of the device. Needless to say, I do not believe that BGA components are suitable for home projects or even prototypes built by small companies.. The equipment needed to successfully place these devices on a prototype PCB is just too expensive. I spent some time tracking down soldering issues involving an FPGA, BGA component, in the end this required taking X rays of the board, to locate which BGA connection was failing. Something that would be extremely difficult, and expensive, for a home constructor to solve.
It’s not a puny single diode rectifier. It’s a **FULL BRIDGE RECTIFIAH**
is the brightness being driven as high as it was before? have you tried turning it back to 11 and seeing if it fails? it seemed to be less bright after you resoldered it...dunno if that was just the pot dial/rotary encoder being moved, or if the resolder did it...
I thought that might have an effect and tried that but ti didn't make a difference.
@@EEVblog2 bugga
Hi Dave, if you check your other video, you will see how the ntc moves by a couple of mm and stays there just by slightly touching it. This was no normal thing. I don't know if it had anything to do with the issue but it definitely looked like a loose component.
This is not feel-o-vision, you can't see that I poked it hard and moved it which made it look like it was loose.
It would not have been the inrush limiter as you could hear the PSU squealing, so it was getting power.
Does the fan run?
You were making me wince resting you hand on that board. Isn’t there 2kV running around there? 😬 Maybe even 14kV if you try hard enough?
I also commented about this joint on the previous video, mainly because in comparison to the nearby joints it looked dry. Lead free is evil !
I'd definitely reflow that joint after that much wiggling.
Solder joint inspection is a red herring when you don't follow through with instrument based troubleshooting. Prove the failure first before you start flailing around with a solder iron.
These fatigue cracks are evil. They are really visible only with some exact light and view angle, otherwise they look as very clean joint.
There is definitely a crack forming, but did not penetrate through yet, so it will show as perfectly good at any electrical or mechanical (wiggle,...) test. But once it starts, it tends to propagate and it becomes a matter of not that long time till it propagates through the material and becomes a real dry joint fault.
So indeed, technically there is no fault yet on that joint, but the fault is definitely forming there.
Usually not that big deal on double sided boards when it is properly wetted through the whole hole (it has very long way to go before it really fails), but it becomes quite severe on a single side board. Of course being it a fatigue crack, it becomes more severe when exposed to higher forces. Does not have to be a heavy component, could be just thermal cycling...
looks like the joint was OK , BUT , I had the issue with the tin plating of the legs of components lifting of ... and bad contact to the pad , good scrub to get to bare copper retining and problem solved... but I could wigle the component and not seeing any movement on the pad side !! but could feel the component slightly moving... this was on a 7812 and a 7815 from same source manufacture on same amplifier board of the mid 80's ...so do check quality of legs tinning /plating...
good video micro viewing
I've recently had a situation where I felt that something like this was the only remaining possibility... unfortunately, I've had no confirmation; because I probably threw the entire apparatus absolutely as far as possible into the bushes. logic and rational thought and retrospective thinking can be a complicated path... possibly even... a path (if we're lucky) through the bushes.
Perhaps I'm living a metaphor. or perhaps not.
peace.
Hello, I have the 3380B, and I have no CRT screen.
All seems working fine, the knobs, buttons, all the feedbacks, the behaviour when power on and so on, but the only thing that is not working is the Screen, (Completely dead).
I checked all the capacitors, Voltages , inductances and seem fine. So i figure out that the problem is probably at the HV side.
I don't know how to check the voltage at the HV capacitors ( I can't spend 300$ for x1000 oscilloscope probe if this is the way) , but I checked and they have still their capacity.
In my little experience seems like that the flyback transformer is dead, because I can't even discharge the anode when it's turned off. (No sparks there) So I presume that I may have the input voltage at 5kV and no output voltage. ( But the flyback transformer BG2000 it's out of production and I can't find it).
Maybe someone can help me, what do you think? it'd be much appreciated some advices.
I wonder was it maybe just a reseating issue!
Hopefully the scope still worked after being reassembled... sometimes electronics just quit for spite after being second-guessed like that! :-)
Yep, works fine just like before.
@@EEVblog2 I'm still bothered by the way it did show that failure this last time... when you turned it on... This last round- when it started working... know what I mean? have we figured out what occurred there, and I missed it?
and hey- Thanks for that bit on the NTC / PTC thing... I've always considered myself a little confused there, but never really had time to sit down and figure out which was what. of course, now that you have explained it so clearly and concisely, it seems simple and obvious. this is why I watch your videos: Your hard-earned knowledge and expertise are of the highest level... that being the level "trustworthy"- Indeed part of that title consists of: I trust that if you don't know something, you yourself, will be the first to state that fact... not that this situation comes up very often.
That's what I was thinking... but I can tell nobody takes me seriously when I talk about it...usually they just commence to citing various, nebulous subjects, such as emotions and feelings as they relate to inanimate objects and stuff... and then usually stuff about how perhaps I should "see a mental health professional" blah blah blah...
I thank you for the validation.
peace be upon you, sir.
@EEVblog2: could you maybe make a video where you discuss the following: The cheapest "No name" digital oscilloscopes vs. 30 years Old High End scopes. Both are in the same price range, so for somebody who might want to begin with the hobby maybe interesting to elaborate what would be advantages and disadvantages of one vs. the other. Main question is: is an old High End scope worth investing a couple of hundred dollar? The same question for the New Bottom Range Digital scopes. Personally, I do not know. Maybe, probably none of he both, unless you get an analogue one for almost free, broken to repair or similar, or very cheap for a 30-50 bucks..
The same for Spectrum- and VN-Analyzers and such..
Yeah man, proper lighting makes all the difference... it needs to come from a variety of directions, as does ones' viewing, at ones' directive. and be bloody bright, when appropriate.
In some situations varying the color can make a difference... not as much with circuit boards but more with minerals (rocks) and pond water and stuff... my optics suck compared to yours but I still couldn't live without them...
So did we figure out why it exhibited the symptom one last time before it then started working normally? Cuz that part is still bugging me.
I would not expect a dry joint on a plated through hole, Also, if it was a dry joint I would expect some evidence of arcing through the crack in the joint.
why would you call it dry? is that just an electronic term for broken contact?
I think "dry" refers to the opposite of solder "wetting", or "sweating". The "lead" (or the pad) sometimes does not getting hot enough during the manufacturing process. Thus the solder doesn't penetrate (desolve into) the metal of the lead (or pad). Therefore the joint the solder forms isn't as strong and may fail prematurely due to mechanical or thermal stress.
In case of anything, just blanket reflow them all :)
Dave, I think your problem was just a Fluke. ;-)
Which would be a first, because it is never a fluke.
1070 ah well I am hyperactive too. Do NOT just inspect joints! Use quality flux and a good heat recovery iron and time the resolder.
Thermal camera inspection for kicks?
I greatly doubt it would show anything. It wasn't a part heating up when it shouldn't.
Just a thought… in welding there is a crack color test ( for instance look at ruclips.net/video/SVLuKfZwJYo/видео.html for a general idea ), I wonder if this is also available for pcb’s….
@ 3:55 WRONG! Using a PTC thermistor to protect downstream overcurrent will result in the thermistor overheating to destruction and possibly burning a hole in the PCB. You would want a self resetting fuse element there instead. The NTC in the Fluke is a surge limiter. It quickly reduces it's resistance to prevent overheating after it did its job of limiting the turn on surge cause by charging the off line power supply caps.
Just resolder already instead of wasting time with optics, cameras, exposures.
Goodness.
I do appreciate Dave going to great lengths explaining things.
@@kajyakuzonik9130 Nein! Not efficient.
@@johanea wahrscheinlich- but It would have been if the optics had instantly detected a problem that was quickly fixed... but I take your point: I should probably just reflow everything... more. Unfortunately, I don't really know what I'm doing, so I'm always wondering if I'm just wasting my time following the lead that I'm on, or not. Things are complicated. and stuff.
peace.
Just solder it up. Spent more time looking at it than just soldering.
Put that microscope/macro thing away, just grab a damn soldering iron and heat the hell out of it!
FLIR it.
In the other video I did notice that component move when you touched it. Maybe i got "pressed" more into to the board and got better connection: ruclips.net/video/3qhg2NdY5Cg/видео.html
don't wiggle - resolder !!!
1070 resolution?!
@ 9:10 It looks like the component lead is oxidized a bit. Solder coated the tip of the lead but not much of the sides of the lead. However the lead is in a plated through hole in a double sided board and no doubt is sufficiently fused to the copper tracks so no problem there, just kind of ugly looking.
I am a bit turned on by all those Nippon Chemi-con caps... A friend of mine just gave me some big fat ones of the same brand... Did I say big fat? The things are downright menacing looking: 22 cm tall and 7.6 cm wide... 350v, max surge 400v, 12000 mf. I'm trying to figure out what a worthy project for these things would be... I've got six of them.
Just staring at them is great enjoyment, but I want to see what they can do... other than failing when I ask them to do something that they're grumpy about... which given my knowledge on the subject is a distinct possibility. I've heard they don't like to be discharged too quickly- though I don't know why that would be. I imagine somebody out there does though...
Peace and love to all.
I've been tricked by that many times. Lead free is the worst ; can't tell if it's crook or not.
Get out your IR camera.
First! 😋
So that's what they're talking about when they say that... Just call me stupid, would you? Of course now, that makes you last on the list- to someone reading the comments the "latest" will be the "first". Sometimes the simplest things break down when you (me) try and think about them... and "you" become confused... sometimes I feel like there's not enough oxygen in the room... other times I feel like everyone but myself is a moron. I'm probably suffering from some kind of "syndrome" or "complex"; Perhaps there's a pill I could take. at least I live in a country where everyone... uh, can't afford any medical treatment without going into massive debt...
oh, crap:
I live in the U.S.A.* ...which could be embarrassing but for the fact that I was born here... The theory of this country sounds good... then you see what actually is going on... and you are disappointed.
Peace be upon you, sir.
*the "good ol' U.S. of "Sorry World: We didn't all vote for him" A.".