Romisen RC-F4 Problem

hmm...ive been through two romisen rc-f4s. both suffer from this problem where sometimes the flashlight would go to a very dim mode and sometimes it works perfectly fine. sometimes when i change the orientation of the batteries such as take out one battery and rotate it 180 degrees, it works fine. sometimes i do not need to change the orientation of the batteries, just loosen and tighten tailswitch again and it works fine. sometimes when i loosen and tighten, there is a quick flash at full brightness followed by dim mode, as if my batteries are low. batteries that i am using are trustfire 3.7v protected rcr123a with gray wrapping found on Dealextreme. the batteries work no problem on a romisen rc-n3. just a note, i have clean the threads and ends of flashlight multiple times.

pics:
working fine:
dim light (my fenix e01 is even brighter than this):
weird washer found under switch:


pill:

youtube video showing problem: http://www.youtube.com/watch?v=82f-BPqmO-0

I bought 1/2 dozen of these to give to my kids and a couple friends. None have yet to have a problem. I don't know why they put the washer in the tail cap though. I removed it on a couple and there didn't seem to be any difference.

Anyway, maybe you have some grounding or other connection issue. What happens if you jar the light when the light dims? Also make sure the little round thing that holds the LED is screwed in tight.

I run mine off 17670, but the kids lights are all using primaries.

Curly said:

I bought 1/2 dozen of these to give to my kids and a couple friends. None have yet to have a problem. I don't know why they put the washer in the tail cap though. I removed it on a couple and there didn't seem to be any difference.

Click to expand...

Mine (just shipped, black finish) didn't even have a washer.

Anyway, maybe you have some grounding or other connection issue. What happens if you jar the light when the light dims? Also make sure the little round thing that holds the LED is screwed in tight.

I run mine off 17670, but the kids lights are all using primaries.

Click to expand...

Is this light SUPPOSED to work with 16340s? I received one yesterday, and gray Trustfires like the OP, and I'm getting the same behavior. Sometimes it would run up to 5 seconds, then go dim, other times just flash briefly or not light at all. At first I suspected the light, but on primaries, which are probably about 1/3 run down from use in another light, it operates continuously for as long as I wanted to run it (several minutes).

I wondered if one of my cells was funky, but it sounds like the driver is not happy with the voltage going over 8.0 V. Lacking another RCR123 light, what would be a safe way to run the cells down 5 to 10%, to take the edge off them?

This morning, after I checked for the tail washer and greased the clicky threads with Phil Woods lithium grease (which seems to work, though I don't know if it's a very good choice), it ran for the longest yet on the 16340s, about 30 seconds, before crapping out. Does the voltage of Li cells drop a bit when they cool off from a fresh charge?

How is the output on 17670 compared to primaries? I wanted to order that cell but they were out of stock at DX. Which brand are you using?

I'm no flashlight authority, that's for sure... I do know that all the ones I bought work fine on primaries. I have no intention of using RCR123.

Light output on 17670 is the same as primaries from what I can tell. They don't fit unless you open the tube up a few thousandths of an inch. We put ours on the lathe with small boring bar.

Sounds to me like these don't like the higher voltage of 2 RCR123.

the fact that the voltage may be over 8v may be the problem. unfortunately i dont a multimeter as the battery died ill try to see if i can get my hands on some of the ones in school.

if the issue is the driver cannot handle over 8v well, does anyone know any method to knock off a little on the batteries?

Is this light SUPPOSED to work with 16340s? I received one yesterday, and gray Trustfires like the OP, and I'm getting the same behavior. Sometimes it would run up to 5 seconds, then go dim, other times just flash briefly or not light at all. At first I suspected the light, but on primaries, which are probably about 1/3 run down from use in another light, it operates continuously for as long as I wanted to run it (several minutes).

Click to expand...

i believe that these should work with 16340s. it is even stated on dealextreme's product page and bessiebunny's budget flashlight review that RCR123As work fine.

I suppose if others are using the 16340 with them maybe it's okay. However, the fact remains that you are having issues and I'm not. The difference is I'm using a single lithium. You should try it with primaries to see what happens. If that works then it may be a voltage issue.

Take the switch-cap off completely and use a piece of wire to contact the body tube to the battery negative terminal. Does the problem persist? If it consistently goes away, then it could be a problem internally with the switch, or a contact problem between it and the body tube.

Hope this helps

I just got a grey one and had the same problem.
You have it mostly apart but you don't have the switch apart yet. Take the switch the rest of the way apart, so you can see the PCB with the switch on it. There is a gold-plated ring on the PCB that must make contact with the switch housing. There isn't really a spring for that part, it just relies on the (kind of crappy) threads to clamp down on the PCB and make contact.
On mine, this part was not very tight. After I tightened it down it worked fine.

It'll probably work loose again. If it had some kind of spring washer or something to help keep those PCB traces tight against the body it would work better.

Romisen RC-F4 CREE Q5 Vs. RC-F4 CREE P4






RC-F4 Q5 Vs. RC-F4 P4

kramer5150 said:

Take the switch-cap off completely and use a piece of wire to contact the body tube to the battery negative terminal. Does the problem persist? If it consistently goes away, then it could be a problem internally with the switch, or a contact problem between it and the body tube.

Hope this helps

Click to expand...

i just tried it
the orientation of the batteries does not matter anymore. as long as there is contact, so i guess the problem lies in the switch. i played around with the switch, however i do not see anything loose. if anything, i notice that the threads seem rough and there are some grinding. here are some pics of the switch.

the threads arent reallly dirty, its just silicon grease.

Re: Romisen RC-F4 CREE Q5 Vs. RC-F4 CREE P4

You can get one from here.

http://www.cpfmarketplace.com/mp/showthread.php?t=179034

Re: Romisen RC-F4 CREE Q5 Vs. RC-F4 CREE P4

Threads merged.

after doing kramer5150's wire test, im pretty sure the problem lies within the switch. there is nothing much i can do to the switch as i see nothing really wrong with it. i'm going to try to do an exchange AGAIN to dealextreme :sigh: i hope 3rd time would be a charm.

j2kei said:

after doing kramer5150's wire test, im pretty sure the problem lies within the switch. there is nothing much i can do to the switch as i see nothing really wrong with it. i'm going to try to do an exchange AGAIN to dealextreme :sigh: i hope 3rd time would be a charm.

Click to expand...

+1 on the wire test. I fiddled with my switch and also couldn't get a fix. I'm going to ask for credit toward another model, since it's pretty clear the switch on the F4 is a dud design.

Too bad, since the external parts seem really well made and I like the slim form factor. I was planning to grease all the O-rings really well and try diving with it (NOT calculated to be good for its life expectancy but it's cheap and expendable), and I want the smallest front window possible to minimize force on the glass. The Romisens are worth a shot since all the joints come apart easily and are O-ringed.

I made two more youtube videos. first one shows the problem that a simple loosen and retighten fixes the problem temporarily. the second video shows a switch bypass and that everything works fine when the switch/tailcap is out of the factor.

http://www.youtube.com/watch?v=9XK8t4QTvRs

http://www.youtube.com/watch?v=iWEF1ZWKNVM

as for picking up another light, I honestly do not know which light to get if i was going to exchange. this is my first light that uses 123a, and i bought a charger and batteries because of this light. in addition, dealextreme feels reluctant to do any exchanges with me as i have already done one exchange on this light. they did however offer me an exchange in switch, however I do not have any caliper to measure the diameter and do not know which switch would work for this light.

I have had this same problem with 2 drop-ins. Both times, same thing. I found the problem using wire to directly connect the cell to the LED and it worked perfect every time . Turned out to be a cold solder joint. You can see my brutle ugly solder job. I just had to get past the twisting the tail end was fixing the bad connection up front and hooray!

j2kei said:

I made two more youtube videos. first one shows the problem that a simple loosen and retighten fixes the problem temporarily. the second video shows a switch bypass and that everything works fine when the switch/tailcap is out of the factor.

http://www.youtube.com/watch?v=9XK8t4QTvRs

http://www.youtube.com/watch?v=iWEF1ZWKNVM

as for picking up another light, I honestly do not know which light to get if i was going to exchange. this is my first light that uses 123a, and i bought a charger and batteries because of this light. in addition, dealextreme feels reluctant to do any exchanges with me as i have already done one exchange on this light. they did however offer me an exchange in switch, however I do not have any caliper to measure the diameter and do not know which switch would work for this light.

Click to expand...

interscape said:

I have had this same problem with 2 drop-ins. Both times, same thing. I found the problem using wire to directly connect the cell to the LED and it worked perfect every time . Turned out to be a cold solder joint. You can see my brutle ugly solder job. I just had to get past the twisting the tail end was fixing the bad connection up front and hooray!

Click to expand...

i have never solder before so i dont really understand what are you saying hahahaha. well here are some macro pics of my switch:







btw, DX offered to exchange the switch, does anyone know which switch I should exchange with?

It is not the switch internals that are the problem, it is the aluminum casing that holds it.
Basically in the new F4's protected RCRs are too long so that the switch casing will not make proper contact will the body.
What you need to do is unscrew the pill(where the led is) about one turn then put the head back on. Then take out the internals out of the switch then lightly sand the top layer of aluminum off the top of the switch as in the picture below.

Just ask me if you need me to clarify what I mean.

so basically i need to loosen the led pill by about one turn, then sand the top of the casing (near the spring) a bit?

btw, i know this is out of the thread topic, but i returned the light back to dealextreme as not only did it have this switch problem, but also the threading at the end was so terrible that it took a lot of strength to loosen and would always grind. dealextreme offered me a option to get a replacement rc-f4 or i can choose another flashlight. having been through two, i feel scared as i have been having bad luck with this particular light. so im asking is there any light out there that is recommended for me to exchange the rc-f4 for?