1000 Lumen Duracell Flashlight Teardown

Here, I'll show you how to disassemble a Duracell 1000 lumen flashlight. While it may not be very practical, somehow it's satisfying to tear apart a product with a serious design flaw.

These flashlights were designed to run on alkaline batteries, not rechargeable batteries. Rechargeable batteries are capable of a much higher current output than alkaline batteries. The switch in the end of the flashlight does not limit the current to below the 3 A maximum limit on the Cree XM-L datasheet.

The flashlight I'm about to disassemble was the victim of such careless behavior as to actually use rechargeable batteries in a Duracell branded flashlight. One click of the button and that was it. The LED was burned out. This feature made for some very unsatisfied customers. Now, for the disassembly.

Update 14 April 2018: I checked out the new Duracell 1000 lumen flashlights at Costco and they now say they work with rechargeable batteries. 

First, I'll remove the lens with two strap wrenches.

Next, I'll unscrew the LED module.

Next, I'll pop the plastic off that surrounds the LED. This is the part that secures the LED and heat sink (MCPCB assembly). There is heat sink compound between the MCPCB and the aluminum housing. But this plastic piece doesn't seem to be a very secure or reliable method to make sure the MCPCB doesn't come off the base if the flashlight is dropped.

After un-soldering the two wires, the MCPCB can pop out.

The original MCPCB was part number RB-AL03, made by RAYBEN. It's rated at 0.5 - 0.9 C/W, with maximum operating temperature 110 C.

I looked up a similar LED on mouser.com and found an XML LED for $6.93 each, or $3.24 each for 2000 at a time. I didn't find the same MCPCB available online, but another one for an XML that sells for $1.01 each, or $0.44 each for 10,000 at a time. So it's not surprising that you can find XML MCPCB assemblies on ebay for less than $10 each.

But is it worth it to fix an $18 flashlight? Probably not. Your labor per hour, ordering the parts, and paying for shipping makes it impractical. However, if you could pop in a higher power MCPCB, then maybe it would be worth it to make a custom flashlight. Or, how about a UV LED for spotting fluorescent dye? Or how about a red, green, or blue flashlight?

And, of course, what teardown would be complete without a look at the power button assembly? I used a 17 mm socket and a hammer to push the button out. Then I rotated it counter-clockwise when the ground tabs got up to the threads so that they wouldn't get caught.

Here it is, the power switch board. This is the assembly that cost Duracell so much in product returns. (I have no idea how much.) They must not have realized that you should use a current source to drive LEDs, not a voltage source. Notice that there are no inductors on the board. That means they aren't using a DC-DC converter such as a buck converter. Now, was it worth it to have all those product returns to save a buck, leaving out an inductor? I think not.

Well, there you have it. The power button actually still worked (on my other flashlight) after I re-assembled it.

Diagnosing Insufficient EGR Flow

1999 Mercury Cougar 2.5L V6
OBD-II trouble code P0401

The check engine light came on and gave me code P0401 for insufficient EGR flow. I should have gone straight into diagnostics mode instead of shop-and-swap. I replaced the DPFE sensor because I had one fail on my old 1995 Windstar and figured this one had failed too. I also replaced the EGR valve because that's the first thing back-yard mechanics replace when there's an EGR code. I knew better, but was lazy. Both those parts still had some life left in them. Oh well. With my luck, they probably would have failed eventually. But that didn't take care of the trouble code. So I needed to get to work and properly diagnose the problem.

I connected my OBD-II scanner and set it to capture the DPFE sensor voltage continuously. The flow sensor was reading about 1 volt for no flow. So far, so good.

Next, I needed to apply vacuum to the EGR valve's vacuum port. All you need to fully open the valve is 5 inches Hg. I revved the engine up and the voltage didn't go over 1.5 V. Holding the EGR valve fully open at 2000 RPM, it only read 1.2 V. Fully closed is 1 V; full EGR flow is 5 V. I wasn't getting much flow.

I needed to narrow down where the restriction was. So I removed the EGR valve, plugged it's intake port and ran the engine. Exhaust came out of the tube, as expected. Revving the engine got the DPFE sensor to read up to 5 V at wide open throttle. Bonus! Max EGR flow reads 5 V. The new DPFE sensor was working as it should.

Next, I needed to see if the EGR valve itself was much of a restriction. This step was just to exhaustively diagnose the flow restriction for each part. I attached the old EGR valve to the tube, without bolting it to the intake manifold. Revving the engine with 5 in Hg applied to the EGR vacuum port gave me over 4 V. If I was being scientific about it, I would have recorded the exact results and test conditions.

EGR flow sensor - check.
EGR valve - check.
Intake manifold ports - need to check.

Now it appears that the most likely location for the flow restriction is in the intake manifold. I reassembled everything except the vacuum hose to the EGR valve. While revving the engine with 5 inches vacuum on the EGR valve port, it didn't get over 1.5 V on the DPFE sensor. Bingo. My intake manifold EGR ports were plugged.

I took off the upper intake, which I didn't really have to do. Of course, I didn't know that at the time. The job can be done by removing the throttle assembly. But by taking off the manifold, I could spray it off and blow it out without getting garbage in the intake.

By the way, spraying carb cleaner and mass airflow cleaner in the EGR port didn't work. Blowing compressed air into the EGR port didn't clean it out either. It seemed like there wasn't a restriction because the compressed air could blow through, but if you look at the picture below, one of the three ports was completely blocked off. The other two were mostly blocked. If this was a heart, and the EGR ports were heart arteries, the patient would have been dead.

Gray arrows showing clogged EGR passages

I peeled off the gasket and cleaned out the EGR ports. Unfortunately, I forgot to take a picture of it all cleaned out. A screwdriver was all the technology I needed to remove the carbon build-up.

Carbon build-up in EGR passages

After re-assembling it, I repeated the EGR flow test. I watched the DPFE sensor readout while applying 5 in Hg vacuum to the EGR valve vacuum port and revving the engine. I got over 3 V, so cleaning out the ports definitely made a huge difference. Again, sorry I didn't get the exact measurements and test conditions. It was enough to show me that it was working.

Simply driving for 10 miles didn't turn the light off, so I resorted to resetting the check engine light with my OBD-II scanner. I was hoping the code would go away on its own so I didn't have to wait a day before getting the emissions checked. Amazingly, after driving another 10 miles or so, the readiness monitors were all ready for emissions testing. I was thinking the evaporative emissions system wouldn't be ready for a day. The light didn't come back on, and it passed emissions. Yay! It barely passed safety though. The emissions guy advised me on the left rear caliper. It wasn't braking as much as it should have been. I have a feeling I know what's coming soon on this blog.

Obnoxious Password Rules

We've all seen password rules, and most likely been annoyed by them. They think they're doing us a favor by requiring a highly secure password. But freedom is better. The more password rules they have, the less secure the password is because it's harder to remember, and it has to be written down, in its entirety. It can be so easily forgotten that you have to use the forgot password link and have a temporary one emailed. And email isn't very secure.

Can you imagine having to remember a password like this? &#p>b2"D8%u>w+\{6

On August 14th, I tried to login to my.t-mobile.com and was redirected to a page where I was required to change my password to a more secure one. I tried one of my usual passwords, and all the check marks turned green, so I figured it was good. So I clicked the button. No good. I tried several new passwords that appeared to satisfy the password auditor, but they still didn't pass their new, hidden stringent quality standards auditor, so I made up a stupidly complex password with absolutely no words found in the English dictionary. That appeared to be the problem with my other attempts. They included words found in the dictionary.

This new password had 16 characters, upper and lower case letters, numbers, and symbols. It looked like the gibberish that would appear on the screen when you tried to open an executable file in notepad. Finally, their algorithm appeared to accept my new password. But, since their server was "experiencing problems", I couldn't make it all the way through the password changing process. I didn't know if I should use my new or old password to log in.

I tried logging in with my new password, then my old password, but somehow went over the number of attempted login re-tries and got locked out for 24 hours. They had an option to "click here" and email me a temporary password. I tried, but of course, the server was "experiencing problems". Could it be that the overly stringent password requirements backfired? I was imagining thousands of frustrated T-mobile customers cursing their website, unable to pay their bills.

Replacing the timing chain on my 1999 Cougar 2.5L V6

I count it as a blessing that the engine didn't fail. It was close, and it could have had the timing chain fail at any time. It wasn't making noise (aside from the rattle at start-up), so I figured it was okay to drive the car to the airport and back before changing the timing set. My wife advised against it, but I figured it would be ok. She was right, but thankfully not so right that the car didn't make it.

Since I found the timing chain guide fragments in the oil pan, it was only logical to replace the entire timing set.

1999 Cougar 2.5L V6 DOHC, showing both timing chains

After removing the cover, I rotated the engine counter-clockwise and it made the left side timing chain very loose. The tensioner didn't keep tension on it in this situation. Here, I can lift the chain off the guide and shake it. The left side (front of car side) timing chain had actually skipped a couple teeth. This explains the loss of power. Getting blocked by trucks passing from behind you when you're trying to merge into traffic gets old really fast.

Check out how worn the old guide is compared to the new one. This was all because it was missing the plastic piece. Without that plastic piece, the chain just tore into the aluminum.

Old and new timing chain guide, without the plastic piece attached

Old timing chain guide that lost the plastic piece

Since the chain was so loose, it somehow rubbed on the oil pump. It looks fine still, so I'm not going to replace it this time. (The oil pump is on the bottom half of the picture, with the crankshaft protruding out from the center of it.)

Oil pump housing damage

After doing this job, I can tell you that if the oil pump ever needs to be replaced on this car, it'll be more than the oil pump needing replacing. There's no oil pressure gauge. That means that if the oil pressure light comes on steady while driving, it would probably mean "you need a new car". But it may also be repairable. You could start by taking out the radio, then you have a big pile of used parts that you roll out of the driveway. Drive another assembly of parts (commonly called a car) into the same space, re-install the stereo, and you're good to go.

Not only had one guide completely failed, the remaining three guides all had fragments broken off. They were barely hanging on.

Broken chain guide, barely hanging on

So, to prevent the plastic from coming off the new guides, I glued the plastic pieces on all four new guides with black RTV silicone. I wonder why the engineers didn't implement something like that in the first place.

Glueing the timing chain guides together

I find it puzzling that they warn us to never rotate the engine counter-clockwise, but this can happen a little bit every time you shut off the engine. Also, what happens when you stall the engine when you're trying to start on a steep incline? These things happen, and the manufacturer can't just assume that the engine won't ever rotate backwards during every-day use.

The plastic timing chain guides had a small clip to keep them from sliding off, but they look like a backwards rotation could easily dislodge them and break pieces off as I saw on my engine.

After installing the left side chain, and counting and re-counting links to be absolutely sure it was timed correctly, I noticed that the other chain had black links for aligning with the timing marks. Oh, how easier the first chain would have been if I had seen those. Oh well. The left side chain is either on backwards, or doesn't have marked links.

I got confused on how they counted the links. The literature says that there are ten links between the timing marks on the intake and exhaust cams. I took that a little too literally. There are ten whole links if you put the marked link over the mark, instead of putting the mark between the links. If you line the marks up between the links then it's 11 links between the two cams, and 24 instead of 23 from the cam to crank mark.

If someone ever takes this engine apart, they may wonder how in the world the chain skipped a tooth on all three sprockets, yet remained exactly in time.

So if you have a marked chain, then put the marked links directly over the timing marks, and count the unmarked links between the marked links and you should end up with 10 links between cams, and 23 between cam and crank on the non-tensioned side. That goes for both chains.

One thing I learned on this job was that there's a special way to rotate the cams to neutral. At cylinder 1, TDC of the compression stroke, the left side chain's cams are in the neutral position. Remember, left side chains are on the right if you're facing them. Let me explain. No, there's too much. I'll just summarize. Left is in reference to the left side of the engine as you sit in the driver's seat in a traditional rear-wheel drive vehicle.

If you then rotate the crank clockwise from TDC so that the crankshaft key is in the 3 o'clock position, then the right side cams (your left . . . towards the rear of the car) are in the neutral position. If you try to install the second chain with cylinder 1 at TDC, you may have the cams snap-turn and pinch your thumb. It's okay. My thumb is fine now. Oh, and 3 o'clock is as you're facing the front of the engine. The front of the engine is on the passenger side of the car, in this case.

The car is running better now. Before the repair, it would lose power above about 5200 RPM. I mentioned that to my son after he borrowed the car, and he said "yeah, I noticed."

Of course.

Now it pulls all the way up to 6500 RPMs. I didn't go all the way up to the rev limiter, and it definitely accelerates faster than before.

Update 22 May 2017

The left timing chain tensioner failed. The product was Engine Tech brand and only had a 12 month 12,000 mile warranty. It's been almost two years since I installed it. Here's the link to that blog entry.

What's the biggest part you've ever found in an oil pan?

The 1999 Mercury Cougar 2.5L V6 has been leaking oil since I got it last fall. I tried changing the timing cover seal for the crankshaft. That wasn't leaking much. I rebuilt the power steering pump. That wasn't the biggest leak. It looked like the oil pan gasket was leaking, so I decided to change that. If it's still leaking, then the timing cover gasket better be it.

The engine used to make a bad chattering noise when I started it until it built up oil pressure. I didn't know what it was, but then one day, the noise went away. That should have been a clue that something bad happened. Cars don't just fix themselves. If the noise went away, then something probably fell off, or broke.

When I took the oil pan off, the oil pump pickup screen was cram packed with debris. Again, not good. That was restricting oil flow. In the oil pan, I found some sizeable chunks of what looked like a timing chain guide.

Timing chain guide chunks

So without that plastic piece, the timing chain has been rubbing on metal instead of plastic. That's not good. The oil had a brassy metallic color to it when I drained it.

There's a baffle in the bottom of the oil pan that I removed to get the rest of the chunks out. 

1999 Cougar 2.5L oil pan, inside view

Oil pickup tube and screen, cleaned out

Bottom of engine, oil pan removed

Timing chain, looking from the bottom of the engine

Without the plastic piece on the timing chain guide, it will change the timing of the camshafts on that bank. The OBD-II scanner also showed a long term fuel trim difference between bank 1 and bank 2. That means there's an air flow difference between the two banks. So this was the cause of at least some of the missing horsepower.

H19txt Disassembly

I was moving a cabinet on a hand-truck when it fell off and I tried to catch it. My earpiece was in my pocket when I tried to catch the cabinet, and the earpiece got squashed. It still works, but the microphone no longer picks up sound well enough to hear.

So, for the sake of sharing, I decided to disassemble the H19txt. It was already broken, so any further damage wouldn't matter to me. Obviously, I'm not responsible for any damage caused by following the same procedure I list here.

First I removed the top gray cover. If you use a sharp knife and pry it towards the center, it should release the clips and pop off.

Next, remove the plastic trim by prying away from the body. These two pieces were already damaged from being squashed between my thigh and a falling cabinet.

The flip easily comes off by prying the clips wider. One end fits over a square side that activates a switch on the circuit board. The other end is rounded. It's the same basic style as the H17. I broke the flip on my H17 and ordered a replacement. The replacement was the H19 style. The replacement didn't have the rubber bumper on it that made it close softly. That's one feature from the H17 that I like better than the H19txt.

 The circuit board can be removed by first prying up on the USB connector end. Then carefully slide it towards the USB end of the earpiece.

Underneath the circuit board, we can see the lithium ion cell. It is taped in, and can be removed by prying it out.

For my replacement H19txt, the first thing to do is to hold the call button down when opening the flip to get to the settings menu. I turn off the voice prompts so that it takes less time from turning on to being able to talk when I answer the phone.

So, if you have an H19txt and want to replace the battery or something, I hope this helps.

Fixing buzzing H19txt bluetooth earpiece

After a year or so of using my H19txt, it started buzzing like something was on the speaker. I thought the speaker may have either been torn, or my ear hair was poking into the speaker.

After a little testing, I determined that my ear hair was definitely not poking into the speaker. So I decided to peel off the speaker grille. There wasn't much to lose at this point if I broke it. Luckily, it was attached with foam tape. Here's a picture of the earpiece with the grille removed.

You can see the black double-sided foam tape on the back of the speaker grille. There is a bunch of pocket lint, skin cells, and maybe even some ear wax built up on the screen over the speaker. Since I had a microscope handy, I took a picture of it.

After a little cleaning, the screen looks better.

Amazingly, after pressing the grille back on, the buzzing sound was gone.

I also went through the menu and turned off the voice interface. (To get to the menu, hold the call button down as you open the flip.) So now when I turn it on, it just beeps instead of saying "Phone one connected . . . More than eight hours of talk time." If I get a call and it's in my pocket, I can open the flip and put it on my ear and start talking sooner instead of waiting for it to get done saying "phone one connected".