Problem with Mag85

[buickid]

I bought a (ab)used 3D Mag85 off of a member in CPFMP. (I trust him entirely, I'm not accusing him of hiding anything ) It probably got a little tweaked during shipping or something.
Anyway, when I turn the head, the light turns on and off. The reflector does have a focusing cam installed. I took apart the switch and cleaned all the contacts and stretched the spring out a little, as well as put a little more curve in the leaf spring that rubs against the bulb holder. It still exhibits the odd behavior. The on-off thing also occurs when I hold the light upside down or right side up and gently tap it on the desk. I'm guessing something doesn't have enough tension, but I can't figure out what...

 

[buickid]

Anyone? I think it has *something* to do with the switch assembly, though I have no idea what it could be...

 

[Linger]

If it occurs when you're turning the head issue is with lamp contacts.
I experienced the same intermittent contact when I received my first 2DMag (last week actually). I'd dropped the bi-pin straight in the socket, fine on ceiling bounce but when i leveled the light it'd go out, or was intermittent as I adjusted focus. Took me a min to take it apart and realise I hadn't used the retaining ring. Fix is to unscrew retaining ring, it holds pr flange or bi-pin adapter firmly in socket while you move the light around.
If thats not you, i'm still sure it's a lamp contact issue

 

[buickid]

The retaining ring is securely fastened around the bi-pin holder. This bi-pin holder is a pretty old one from FM, I wonder if its possible that its faulty. When I nudge the bulb gently with the reflector edge, it turns off, and when I let go, it turns back on.

 

[LuxLuthor]

There are so many places where the problem can originate, it is hard to answer. Obviously, if a light touch that moves the bulb is having it turn on/off, then it is likely that the bipins are not making adequate contact in the bipin holder. That can be because there is corrosion/oxidation on either the bipin(s) and/or holder tubes, or inadequate bipin tension against holder tubes.

Wearing eye protection (since these are high pressure halogen bulbs)....you can try to gently sand surfaces of bipin legs. Try to put a little bend/kink on lower end of one of the legs, holding with needlenose pliers close to the glass so you don't put any stress on the glass and break it.

You can also lightly abrade the side of the socket the bipin holder goes into, as well as the sides of bipin holder, and bottom center contact pin, before replacing retaining ring.

If that doesn't fix it, then you have to move on to the switch, taking that apart with 5/64 Allen hex wrench and looking for electric carbon arc damage on switch contact points.

You can also make sure positive and negative contact springs are clean & free of oxidation, as well as tailcap contact edges.

That should keep you busy for a while. :candle:

 

[Databyter]

I'm also thinking bi pin holes. If a thicker pin bulb was ever used in it then the smaller thickness mag85 bulb will not have as tight of a grab

I have thought in the past that carefully tinning the bulb legs with solder to make them slightly thicker and more grabby might work for this problem ( I did this accidently testing LED's on my AA mag).
On the other hand this is a high heat area, It occurs to me that you may just end up soldering the bulb permanantly to the holder, so not a great idea after all.

You can use some de-oxit/progold in the suspected areas, this will definitly remove any age/wear oxidation /dendrite corrosion and can't hurt.

Just remember that this is a high heat area, when I recently sprayed pro gold all over my switch and tower assy my mag85 smoked alot when I first used it. I had to clean the lens and reflector.

Word to the wise, if you use pro gold in this area let it smoke without the head for a while. Pro gold seems to leave a residue that burns, or possibly it was resin from my solder job that smoked on mine because I did the pro gold and solder job in the tower spring at the same time. A very clean soldering job though.

Good luck. This is a small problem and I'm confident it will not trouble you for long.