Removing Battery Corrosion and Straightening Bent Lights
Stuck Batteries
Stuck End Caps
Stuck Retaining Rings
Switch Removal and Stuck Switches
Disclaimer: I'll start out by saying that these repairs are tedious and challenging. It is very rewarding to make an old Maglite light again though. If you have a special light and don't feel up to the challenge I do restorations and custom work on most vintage flashlights. My contact info is at the right side of the page.
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When a Maglite fails to light some of the problems are fairly obvious. Dead batteries and bulbs are fairly obvious solutions and those are easily diagnosed by changing the battery or bulb. Maglite even has it's own factory service manual which can be found here. But what should you do whenever everything appears normal but the light will still not light?
This is a fairly common problem I've encountered on restorations and I've run into it on a 5D light I'm restoring for someone currently. As you can see there is no visible corrosion or damage but still it won't light.
The common sources of this problem are internal corrosion of the switch or corrosion of the tail spring. If you have an extra working switch and tail spring they can be easily swapped to diagnosed the problem and most users opt to purchase a new switch at a cost of around $12 rather than try to diagnose the non-working switch. This is an easy, inexpensive fix but I'll still go into how the switch mechanism works and how it looks as well as some simple fixes. I prefer to leave the light as stock as can be and always try to fix parts over replacing them.
To understand how the switch works we must first understand how the light works. In order for the light to work current must flow from the negative side of the battery to the positive side.
1 - The positive side of the battery sits up against the switch and the current flows up to the plunger.
2 - The plunger opens and closes the circuit.
3 - On the opposite side of the plunger the circuit picks up again. This connects to the positive terminal of the bulb. If you look closely you can see that this terminal is wrapped in a plastic insulator. This insulates it from the housing of the bulb which acts as the negative terminal.
4 - The housing of the bulb then connects to the negative contacts that slides along it when focusing.
5 - This is connected to the body of the light through the set screw.
6 - The body of the light is connected to the tail spring and back to the negative side of the battery and the circuit is complete.
You'll notice that this switch is specifically for a non-letter serial light. However, all flashlights work in the same manner. Most aluminum and steel lights flow current through the body. The voltage of the batteries is relatively low so you won't feel a shock as the current is drawn back to the negative terminal of the battery rather than to ground. Because the batteries generally have a low voltage any internal corrosion of the switch or tail spring will usually generate enough resistance to stop the flow of current. That is the case with this 5D I'm working on.
So let's take a look at a working Maglite to see what kind of resistance we're talking about. Shown below is an multi meter set to ohms (a measure of resistance) hooked to the positive and negative side of a new switch. As you can see it reads about 11 ohms. It should be noted that the switch must have a good bulb in it and the switch must be in the on position otherwise the ohms will not register.
The body and tail spring will provide negligible resistance. Checking the resistance between the edge of the end cap that is not anodized that sits up against the very end of the barrel and the end of tail spring confirm this as shown below. Typical resistance is around 1 to 5 ohms depending on the amount of corrosion on the spring.
Now we have a good baseline. We know that ideally the circuit operates with a nominal resistance of 11 ohms. So let's take a look at the light I'm working on and see what kind of resistance it has and I'll see if I can get it's resistance down to the resistance of a good assembly. Shown below is my switch removed from the light and hooked to my multi meter. This removal process can be found here and elsewhere on Youtube.
You can see that the switch has infinite resistance which means there is a part that is not making a connection somewhere or is missing and is inhibiting the flow of current. Next I'll open up the switch and test the individual parts to see if I can find the culprit. This process will be detailed below. All of the values obtained should add to be the total resistance of the switch. If you have a resistance of 60 ohms and you find one part that is 45 ohms you can stop testing because that part is the problem.
As can be seen below the positive battery contact to the positive bulb contact across the plunger has an infinite resistance when engaged. This is most likely the culprit. However, I'll clean all of the electrical contacts as shown below to ensure the circuit operates properly. I'll soak these parts in vinegar and then wire brush them. DO NOT soak steel parts in vinegar because they will corrode. Make sure you only soak the parts shown below as they are copper and aluminum.
Pay extra attention to parts that have visible corrosion as the corrosion is the likely cause of the higher resistance. The set screw and negative bulb housing contact as shown below are a likely culprit as well. This contact rubs the bulb housing and the wear causes it to corrode or the set screw itself corrodes because of the dis-similar metals contacting each. See below for an example from this light with a lot of corrosion.
Shown below are the cleaned up parts. The copper parts should shine like a new penny and you'll notice the resistance is remarkably lower.
Shown below is the resistance test of the switch after I put it all back together. You'll notice it is only 0.8 ohms which is basically the resistance of the bulb. Why the difference vs. the "new" switch above at 11 ohms. Well mainly because the copper parts will naturally oxidize (corrode) over time due to even the most minuscule amounts of moisture in the light which ups their resistance. Right now the light is clean as a whistle but with normal use and exposure to the atmosphere the copper parts won't keep this shine. That's ok though. The corrosion stops after a natural layer has formed and the switch will average out at around 11 ohms.
Maybe you've found the switch has the same resistance as a new switch or that the light still won't work. The next item to check is the end cap and spring. A lot of times if there is a lot of resistance you'll notice that the spring is corroded, the spring seat is corroded, or the non-anodized edge is not making contact with the end of the barrel. All of these items must be completely free of corrosion so that their surfaces all make contact.
With all of the parts now free of corrosion did this light shine again? Judge for yourself in the pic below. So, why did I save this light? Well, another collector I deal with asked me to. Also, it is stamped "Paten Pending" opposite the serial number and lacks the features of a 1979 light so it is a 1980 light. It's from only the second year of Maglite production and is serial number 49,126 so it is relatively low. Please see my Quick Dating Guide if you're interested in these details. The light is nearly 40 years old and in excellent condition other than the non-operable switch so I figured it is a worthwhile restoration especially because someone valued it all these years to keep it going. Here are some pics of the light after it was all repaired.
This light came from a fellow collector who picked it up at an estate sale with the above accessories as well. The estate was from the owner of a large Tennessee construction company and this was likely a personal light of his. A personalized 1980 3D also came with it. The 5D bulb is an old "Safari-Star", a knock off of the Magnum Star Maglite brand produced by police equipment company Safariland. The Maglite belt suspender carriers the old Maglite logo embossed into the leather and on the package so it is from 1980 to 1984. This will certainly make a nice addition to his collection now that it's all back in working order.
As always I'm looking to buy Vari-Beams and Vintage/Rare Mags. Please let me know if you have any, top dollar paid.
I'm really glad that I found your blog. Truthfully, my three D cell Maglites have been living in semi-retirement for the past bunch of years, having been unceremoniously replaced by two Streamlights (Survivor LED and SL-20LP). I've always felt guilty about abandoning them, as they've served me well for over two decades as a Firefighter/EMT.
ReplyDeleteI purchased my very first brand new 3D around 1992 when I started working in EMS. I still have my name engraved on it right above the serial #D38871414. At some point around 1998, I purchased a 4D which is still in mint condition, serial #D4007959366. Somewhere along the line I also acquired a second hand 2D serial #21326272, which is in rough shape cosmetically, but functions perfectly. It'll take a lot more than 30 years of hard use to stop a Maglite from working properly!
Your blog has renewed my nostalgia for these old reliables, so I now plan on cleaning and refurbishing them all. Thankfully there is no corrosion to be found inside any of them, and all of the metal parts and switches are in very good to mint shape. The 2D definitely needs a new reflector, as it's all hazy and I'm unable to polish it to a shine. All three could use new lenses, so I may splurge for the glass over the plastic. I plan on replacing the rubber in all three, new o-rings and switch covers never hurts.
The bulbs in all three still work, and I have spares in the tailcaps of the 3D and 4D, but I think it's time to replace them with the new style bulbs instead. The light output of these incandescents as compared to LEDs is paltry, so anything I can do to max them out is acceptable. It's cost prohibitive to install an LED module when I've already got two LED Streamlights that would blow them away. Frankly, I'd just as soon purchase a brand new LED Maglite than bother converting these three.
Anyway, just wanted to say thanks for giving me a reason to pull these out of the box in the closet for a little TLC. Heck, I just may give them away to friends or family after I refurb them, but they'll surely go to good use no matter what.
Hey, thanks for the kind words!! Those Streamlights are excellent lights as well. The SL-20LP comes from a long line of one of the first rechargables, the SL-20. I did a big post about it on my other light blog too.
DeleteThe reflectors have a chrome spray over plastic so they don't polish real well but you can usually pick up a new one for $4 or 5$ shipped if you check out fleabay every now and again.
I actually still use a lot of my incan lights. Give one a shot after you get them back up and running. I don't use them for work because they're not bright enough but I use them a ton around the house. If I'm going out to get firewood I'll bring my trusty old 2D incan Mag, it fits perfectly under my arm while I'm grabbing pieces and the nice warm light from the incan is so much more pleasing that the cool white light from the LEDs.
I agree with you, it isn't worth it $$$ wise to covert a light to LED with how cheap the new LED lights are. However, I have a 3D Mag and some old that I was just soooo attached to and had so much history with I couldn't bear to replace them. Instead I bit the bullet and threw a Malkoff LED in them and keep running them. Compared to what my buddies spend on guns and trucks an extra $30 didn't sound so frivolous to have a nice light.
Hello,
ReplyDeleteI am wondering how I can remove the switch assembly for my 4 D cell maglite with no d on the serial number. Do you have a blog for the steps to remove it?
Thanks.
I have a short guide here:
Deletehttps://maglitehistory.blogspot.com/2017/07/switch-removal-and-stuck-switches.html
Pretty much you want to take off the switch cover, back out the small hex head screw that holds the switch in place and then remove the retaining ring on the top, bulb side of the light. You can do that with pliers if you don't have the Maglite tool. There are a few videos on youtube showing this.
My 3d cell maglite about 15-20 years old will not light with new batteries and bulb unless the end cap is loosened until it's only about 1/2 turn from falling off. Any ideas?
ReplyDeleteIt sounds like one of the connections in the switch is loose or corroded. New switches run about $12 so unless you feel like tinkering with the switch it's likely easier just to buy a new switch and swap it in. Best of luck!
DeleteHello I'm looking for a head for my 6 d cell maglite no D in the sn# if you could help me out finding one. Thank you jeff
ReplyDeleteHey, I do have an extra one. Please e-mail me at liftd2001@gmail.com Thanks!!
DeleteI love the feel of the pre "D" lights. They are just a bit fatter and fit my hand nicely.
ReplyDeleteQUESTION: What is a good coating for the inside of the barrel and the threads on both ends?
There are lots of recommendations, but I don't want to risk making a mess of my lights.
I like them better too! I usually coat the outside of the switch with a light coat of waterproof grease or Vaseline so it is easy to remove later and adds a little additional water proofing. Same for the threads. I especially like Lubri Film Plus. I don't usually coat the inside of the barrel though because it can make the batteries a bit messy and attract dust.
DeleteIs there any trick to removing the old switch assemblies? I loosen the bolt inside the assembly until it's spinning freely, but the assembly never starts moving around or can be removed.
ReplyDeleteIf this is a pre 1992 Maglite you'll also have to remove the retaining ring from the front of the light. If it's 1992 and after you can slide the switch assembly out of the rear of the light although if there is a dirt or corrosion this can be tricky to do.
Delete