Author Topic: EEVblog #1091 - LED Studio Light Repair  (Read 13057 times)

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Offline EEVblogTopic starter

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EEVblog #1091 - LED Studio Light Repair
« on: June 03, 2018, 01:06:26 am »
Dave discovers a potential systemic manufacturing issue with Lifud LED light drivers.
A repair of two of Dave's failed Lifud LED studio panel light drivers.

 

Offline IanB

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #1 on: June 03, 2018, 01:34:58 am »
A triumph of legislation over science.

People spent years figuring out the best solder formulation and by experimentation they discovered that it was a tin/lead alloy. Then legislators came along and said "Nope. Science is wrong. You can't use what works best."

Manufacturers, of course, were overjoyed. They had spent ages figuring out how to make things fail just outside the warranty period and now the lawmakers had required them to make things that fail early by law. More things get thrown away, more replacements get purchased, manufacturers benefit, and lawmakers get to feel all pious about saving the planet  ::)
 

Offline VK3DRB

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #2 on: June 03, 2018, 03:41:27 am »
Good video Dave - I enjoyed it. In the old colour TV days, dry joints were perhaps the most common failures, especially where intermittent faults occurred. Tapping with the back of a screw driver could usually help narrow down there the dry joint was. Another trick was using heat and freeze to exacerbate an intermittent problem from a cracked joint. In this case, using cardboard shields could quite often narrow it down to a few joints.

One thing I noticed was these LED drivers had no RCM mark. This means they cannot be imported and sold in Australia.
 

Offline chickenHeadKnob

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #3 on: June 03, 2018, 05:26:55 am »
Good video Dave - I enjoyed it. In the old colour TV days, dry joints were perhaps the most common failures, especially where intermittent faults occurred. Tapping with the back of a screw driver could usually help narrow down there the dry joint was. Another trick was using heat and freeze to exacerbate an intermittent problem from a cracked joint. In this case, using cardboard shields could quite often narrow it down to a few joints.


This. Not just in the olden days of through hole though. Maybe I have been lucky with respect to electrolytic caps and unlucky with inductors, but the number of repairs of consumer goods involving either one has been roughly 60/40 with cold joints on pc mount transformers dominating. Two different brands of microwave oven went intermittent crapski after 10+ years in service with power supply inductor joints for example.  Dave missed an opportunity to show how judicious and delicate board flexing under bias can quickly isolate the problem.
 

Offline BravoV

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #4 on: June 03, 2018, 06:40:03 am »
Moral story, when it comes to dead end when trouble shooting a problematic ROHS soldered circuit, last resort, try re-solder all joints.  ::)

Offline G7PSK

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #5 on: June 03, 2018, 09:07:01 am »
When it is just a small board like that the easiest thing to do is just re do all the through hole joints, it's quicker than looking for them in many cases.
 

Offline Brumby

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #6 on: June 03, 2018, 01:35:29 pm »
When it is just a small board like that the easiest thing to do is just re do all the through hole joints, it's quicker than looking for them in many cases.

I've done that before.

Sometimes it even works.
 

Offline EEVblogTopic starter

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #7 on: June 03, 2018, 02:23:20 pm »
Dave missed an opportunity to show how judicious and delicate board flexing under bias can quickly isolate the problem.

Err, I'm not going to go show people how to flex a live mains PCB.
I've also use that technique where it doesn't isolate the problem.
 
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Offline EEVblogTopic starter

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #8 on: June 03, 2018, 02:26:03 pm »
Good video Dave - I enjoyed it. In the old colour TV days, dry joints were perhaps the most common failures, especially where intermittent faults occurred. Tapping with the back of a screw driver could usually help narrow down there the dry joint was. Another trick was using heat and freeze to exacerbate an intermittent problem from a cracked joint. In this case, using cardboard shields could quite often narrow it down to a few joints.

Yes, I'm sure I've done that before in a video or two.
 

Offline SilverSolder

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #9 on: June 04, 2018, 01:15:33 am »
A triumph of legislation over science.

Lead free solder... yuk.  This stuff is definitely not as good as "proper" solder.
 

Offline Fungus

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #10 on: June 04, 2018, 06:27:45 am »
A triumph of legislation over science.

Nope. We simply can't dump lead into the environment in the quantities used by consumer electronics.

It's bad, mmmmkay?
 

Offline james_s

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #11 on: June 04, 2018, 07:12:04 am »
A triumph of legislation over science.

Nope. We simply can't dump lead into the environment in the quantities used by consumer electronics.

It's bad, mmmmkay?

So don't dump it into the environment, recycle it. And with longer lasting gear, there is less of it being junked in the first place.
 

Offline Kjelt

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #12 on: June 04, 2018, 07:48:03 am »
that, educate people no longer to buy the <$1 products and make the manufacturer/seller responsible for environmentally safe disposure.
They make the profit, they should clean it up.
 
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Online ejeffrey

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #13 on: June 05, 2018, 05:24:18 am »
Sure.  The manufacturers would hate that, consumers would hate that, and even in the best possible implementation a large fraction of electronics waste won't get recycled properly. Oh, and if you are actually serious about it (rather than using it as a fig leaf for "I want to keep using leaded solder and not worry about it) it is absolutely the most hobbyist / small shop / kickstarter unfriendly practice you could imagine, since basically all of those things would have to be heavily restricted until you showed you had the ability to guarantee recycling and safe disposal of your products for decades to come.

I don't mind people complaining about lead free solder.  It is definitely harder to use and more prone to problems than leaded solder.  That is established fact.  But it also comes with real, documented scientific downsides.   To say it is "legislation winning over science"  is completely missing the point, and is actually anti-science since it ignores science which is inconvenient.  Engineering (and law) are almost never about "A is good, B is bad", but the trade-offs between them.
 
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Offline IanB

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #14 on: June 05, 2018, 06:13:00 am »
I don't mind people complaining about lead free solder.  It is definitely harder to use and more prone to problems than leaded solder.  That is established fact.  But it also comes with real, documented scientific downsides.

I assume you are saying that leaded solder has scientific downsides, rather than lead free as your words seem to indicate? (Because undoubtedly, lead free solder has scientific downsides.)

However, I would like to see some evidence that lead in solder is an environmental hazard. That evidence is absent from anything I have managed to find and read. Firstly, the amount of lead is small, and it is chemically inactive. In a chemistry class, have you tried dissolving lead? It is one of the most chemically resistant metals around. Secondly, electronic waste is rarely mixed in with general waste. It normally goes to special collections for recycling. Thirdly, when general waste goes to landfills it is carefully sealed due to the large variety of potential toxins it may contain. So it's not likely that water leaching from landfills is going to get into the drinking water supply or food chain.
 

Offline Fungus

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #15 on: June 05, 2018, 11:26:06 am »
So it's not likely that water leaching from landfills is going to get into the drinking water supply or food chain.
Would you like an electronics dump near your drinking supply?

At an industrial level: Lead-free works well enough (leaded solder goods used to have dry joints, too!)

At a hobby level: Nobody's forcing you to use it so where's the problem?
 

Offline orion242

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #16 on: June 05, 2018, 12:24:00 pm »
Would you like an electronics dump near your drinking supply?

Near it, hell there are still a lot of lead pipes delivering said water.
« Last Edit: June 05, 2018, 12:26:09 pm by orion242 »
 

Offline Fungus

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #17 on: June 05, 2018, 12:51:00 pm »
Would you like an electronics dump near your drinking supply?

Near it, hell there are still a lot of lead pipes delivering said water.

Sure, but they'll have a nice protective patina on the inside now so there's not much point in replacing them.

Would you be happy if they ripped out all those old lead pipes and replaced them with some fresh ones?

Maybe we should follow the example of ancient Rome: https://www.google.com/search?q=roman+empire+lead+poisoning
 

Offline orion242

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #18 on: June 05, 2018, 01:25:21 pm »
Sure, but they'll have a nice protective patina on the inside now so there's not much point in replacing them.

So that lead buried in the ground is safe enough, but electronics buried in the ground in specially designed areas isn't.  Would think there are more problematic chemicals than the lead to worry about.
 

Offline Scottjd

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #19 on: June 07, 2018, 02:45:50 pm »
And so is the problem with lead free solder on boards that heat up, expand and contract over time. Lead solder has more of a flex with it. Lead free just breaks, so technically it could be a engineering issue with thermal, if they keep it a little cooler then maybe the PCB wouldn’t expand as much? I see more of these breaking in the future.

I know their is different types of lead free solder and maybe another one has more ability to have that expansion give based on the other metals mixed. This solder on these units could be more of a tin based that cracks easier? I just fixed a LCD TV that had an intermittent on or off LCD issue. I was expecting the common failed electrolytic cap on the PSU or the inverter board. Nope, it was a cracked solder joint on thenlne TV, thenlther TV was cheap caps next to somempower resistors, so it didn’t fail from the cap leaking but the cal couldn’t take the heat.

I see more and more things failing these days from lead free solder cracked joints, might be worth another video explaining the different types of lead free solder and how the different metal mixes might be better for one use VS another use?
Just a thought.
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Offline analogo

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #20 on: June 07, 2018, 03:35:16 pm »
A triumph of legislation over science.

People spent years figuring out the best solder formulation and by experimentation they discovered that it was a tin/lead alloy. Then legislators came along and said "Nope. Science is wrong. You can't use what works best."

It is a triumph of one science over another. Chemical engineering found the best formulation for a particular business; environmental studies found that it is a pollutant. Environment >> Business.

Take for instance CFCs. With CFCs you can produce superb and cheap refrigerant fluids. That hasn't stop us from outlawing them for good reasons (the ozone hole).

This is not that different from the various wireless scams out there. Technically they may work, but there are serious health considerations that will limit their power and, in the end, will prevent them from being deployed.
 

Offline apis

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #21 on: June 07, 2018, 05:05:12 pm »
All that solder ends up in landfills and then it leaks out into the environment. There was lead, cadmium and other heavy metals in everything from paint to toys for a while so it was a good thing they began regulating it.

And so is the problem with lead free solder on boards that heat up, expand and contract over time. Lead solder has more of a flex with it. Lead free just breaks, so technically it could be a engineering issue with thermal, if they keep it a little cooler then maybe the PCB wouldn’t expand as much? I see more of these breaking in the future.
There are millions of lead free power supplies that work just fine.
« Last Edit: June 07, 2018, 05:08:13 pm by apis »
 

Offline Fungus

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #22 on: June 07, 2018, 05:10:09 pm »
... electronics buried in the ground in specially designed areas...

You know how I can tell you've never googled "electronics dump"...?
 

Offline orion242

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #23 on: June 07, 2018, 05:45:05 pm »
... electronics buried in the ground in specially designed areas...

You know how I can tell you've never googled "electronics dump"...?

Plenty of areas still dump sewage in the street.  If the locals don't give a toss, its of little concern to me.  How many of these exist in the US/EU etc?
 

Offline apis

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Re: EEVblog #1091 - LED Studio Light Repair
« Reply #24 on: June 07, 2018, 05:52:35 pm »
Plenty of areas still dump sewage in the street.  If the locals don't give a toss, its of little concern to me.  How many of these exist in the US/EU etc?
I bet those places allow led in their solder as well.
 


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