help: RC-F4 (resolved)

[hunter3]

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update: RESOLVED
The problem were protected CR123A's that were too long for the body of the flashlight; this is apparently due to both batteries longer than spec and a flashlight shorter than spec. This disabled contact between the inner spanner of the switch and the end of the body tube. Two possible fixes are either using shorter batteries or adding some contact between the body and the switch. Special thanks to probedude and gohase
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Hey guys,

I just picked up a Romisen RC-F4, but I cannot for the life of me figure out what's wrong with it. It won't turn on.

What IS working:
batteries: two protected CR123As, works fine with battery charger
LED and body: with tailcap removed, LED lights up when I connect a wire from the bottom of the last battery to the body
tailcap: by using it on another flashlight, confirms that it turns on and off properly

What I've tried:
cleaning all connections: FAIL
removing button and plate in tailcap to reduce pressure: FAIL, although it works partially when I do this and barely touch the tailcap to the body... any twisting will kill the light

What MAY be wrong:
batteries too long (though plenty of people have used protected CR123As on this flashlight)
tailcap assembly (doesn't work when pressure is applied to spring?)

Thanks in advance... especially if there's a simple answer for this

 

[gOhAsE]

Re: help: RC-F4

I read about 2 versions of the protected Ultrafire RCR123A batteries. One version was noticeable longer.
Perhaps this is the issue.

Pic:
http://takebeat.asablo.jp/blog/img/2008/02/28/565f9.jpg

Taken from here:
http://takebeat.asablo.jp/blog/2008/02/28/2670790

 

[PlayboyJoeShmoe]

Re: help: RC-F4

Two gray Ultrafire would not work in my light.

I don't use the heck out of 123 lights so I just keep two 123s in mine.

 

[Probedude]

Re: help: RC-F4

It's all in your tail cap switch if you can get the light to turn on when bypassing that.

The end of the body tube, is the edge of it anodized? Try scuffing off the anodization so that when the tailcap is fully tightened it makes contact with the inside spanner nut.

Your batts may be too long but I'd be surprised. I've bought 6 of these RC-F4's and haven't had a problem with many different batteries.

Post a picture of the end of the light with the tailcap removed that shows the depth of the battery relative to the body opening.

 

[hunter3]

Re: help: RC-F4

Thanks Probedude, gOhAsE, and PlayboyJoeShmoe for your replies.

The batteries were 36 mm when I first got them, after being in the flashlight they got squished to 35.5 mm. I don't have a camera on me, but they are aligned with the end of the body... almost protruding even...

The end of the body tube isn't the problem. I have tried connecting a wire from the battery to any point on that circle and it works fine. I am in fact seeing spots now because it was pointed at the ground.

The inner spanner nut is the potential problem though. Because the batteries are so long, I never could get the tailcap to fully screw in, at most only 80% of the way. So the inner spanner nut was never contacted, although in my other flashlights many could turn on while only being halfway screwed in.

I will attempt to remove the protection circuitry from the batteries. This will give me a few more mm.

 

[hunter3]

Re: help: RC-F4

Well I have fixed it without removing the protection circuitry. The problem was indeed the inner spanner not contacting the body of the flashlight, due to batteries that were too long. The temporary fix involved wrapping aluminum foil around the inner spanner to extend its length.

A more permanent fix will involve finding a flat washer with the exact dimensions I need. Though a split lock washer will more likely have those dimensions. I'll post pics when I get home.

 

[Probedude]

Re: help: RC-F4

Glad you figured it out. If I remember correctly, on my RC-F4 the batteries (primary CR123A's) are inside the body by about 0.10".

Come to think of it, I'll have to compare all my RC-F4's. I know one of them I thought was DOA but after snugging the tailcap a bit it works fine. I wonder if I too had a battery stackup problem.

I was using the same brand CR123A's (panasonic) so that didn't change. I wonder if body tube lengths are changing.

Dave

 

[PlayboyJoeShmoe]

Re: help: RC-F4

Well I'll be a Monkey's uncle!

I was going to say how far it was from the back of two 123 to the end of the tube.

The distance is about 2MM but the batteries are actually Gray Ultrafires!

Not sure why I didn't know that....

EDIT: Thought I had unscrewed the light module some to make it happen but just checked and that ain't it.

I must be thinking TK10 when typing RC-F4...

 

[Probedude]

Re: help: RC-F4

Okay, I looked at 2 of my RC-F4's tonight and both have about an 1/8" of distance from the base of the last battery to the end of the body tube. This is with Sanyo CR123A's (not panasonic like I thought).

So if your last battery is flush with the body tube, that's definitely wrong!
What does the height of a single one of your protected cells measure?

 

[hunter3]

Thanks for the replies. The problem has already been fixed, but if you're interested...
Battery sizes: CR123A, unprotected - 34 mm
Ultrafire RCR123A, PCB (long version) - 36 mm
Ultrafire RCR123A, PCB (short version) - 34 mm
Trustfire RCR123A, PCB (my batteries) - 36 mm
Trustfire RCR123A, PCB (short version) - 35 mm

The diagnostic: I've decided that my RC-F4 is slightly shorter than spec. It's 123 mm not including the GITD switch. Combined with my batteries that are longer than spec, this caused my problem.

The solution: The fix was a 2 mm thick ring of aluminum foil around the base of the spring. Solder or a washer would work better, I'll probably do one of those this weekend.

As a side note, it's possible to tail stand your RC-F4 if you have enough room in the tube. You'll need about 3 or 4 mm between the battery and the end of the tube. Simply twist out the switch assembly, remove the washer, and twist the switch assembly back in 2/3 of the way.