MJ850 - cheap. Too good to be true?

[ukdave0]

My Mj-850 also failed in the 5% on all the time mode after just the inital swimming pool test.. I think I had the newer version because 1.) I could not get the strobe to work and 2.) I got everything apart except not able to get the head off the body.

I also have the MJ-810. It failed to work on it's very 1st dive. I think maybe a hick-up with the magnetic switch as it worked fine before and after the dive.

 

[micbu]

I also have the MJ-810. It failed to work on it's very 1st dive. I think maybe a hick-up with the magnetic switch as it worked fine before and after the dive.

Do you have the P7 version of the MJ-810? It is a common problem of the MJ-810 P7 that it fails to switch on under water.
Everything will be fine if you switch it on at the surface. I still don't know why this happens, but I am investigating. I know this problem only for the P7 version.

I do not think that you have the new PCB. The 5% shining is yet known for the old PCB only.

Michael

 

[project6]

Michael

How do you remove the PCB from the aluminum housing?

Send me a message if you have any spare PCB for the 850

/Frank

 

[micbu]

You need a special tool to do that correctly.
You can try following: unscrew the black plastic part and remove the battery contact.
Place a suitable screw at the place of the battery contact. screw the black plastic back at its place.
pull at the screw to remove the holder of the PCB. ! I do not know whether the plastic can stand the necessary force!

Michael

 

[ukdave0]

Do you have the P7 version of the MJ-810? It is a common problem of the MJ-810 P7 that it fails to switch on under water.
Everything will be fine if you switch it on at the surface. I still don't know why this happens, but I am investigating. I know this problem only

It's the CREE version. The light wouldn't switch on at the surface before entering the water (so I didn't take it in the water). It worked before the skiff ride to the site, then worked afterwards. And a correction - it did work fine on an earlier 1st dive, a late afternoon dive so I haven't been able to really appreciate the brightness yet.

 

[Maurice]

Quick update on the MJ850 saga:

The lamp has cleared China Customs... it might actually arrive at the factory in Shenzhen.

I'll party when it returns... but this seems to be another BIG step in the whole process of getting something repaired in China.

 

[Maurice]

It took a while. This weeks update is about how it returned...:

I have the lamp in my possession again... The factory repaired and sent the lamp to me quite quickly. Within days it was on the flight back to Europe and after some Customs issues I now have my lamp and tested it to 9.5m and 10+ minutes on highest setting.

Read the blog for more details.

Conclusion so far:

There are 2 types of MJ850 but only one type actually works. The factory shipped the older versions until a few months ago, I heard from the sales / support persons there. There is no real way of knowing if you have a good MJ850 or not... without opening it or testing it to destruction.

 

[Spg01]

Glad to hear that it is working again. I have really liked mine, once I found out that the batteries have a protection circuit on them.

 

[guyharrisonphoto]

I am going through the same problems that others have mentioned with these lights.

Light #1: Worked great for about 10 dives. Then, the light head had a small leak. The battery compartment did not flood. There was no way to drain or dry the hear and corrosion has now rendered it useless. The seller (NOvae, a great company) will replace the light.

Light #2: Worked for 40 minutes and then cut out on its first dive. Tried new batteries and worked for 1 hour in the pool and then quit. Batteries are fine. Now it will not turn on at all. The seller will replace this one, too.

Batteries: Very uneven quality. In Light #2, one of the batteries was bad (showed 0 volts and would not take a charge). Seller replaced it with a new set.

I then purchased two sets of spare batteries (4 total). Two of the 4 were bad and are being returned.

Some of the batteries, when Light #1 was working, gave 3 hours of burn time, with gradual dimming. Others gave about 2 hours and cut out suddenly. There seems to be no way to tell if you have "protected" batteries or not.

I will see if my replacement lights and batteries fare any better. I had been using these as primary lights on night dives. When they work, they are absolutely superior and have, for me, a perfect beam. The center spot is bright and good for signalling my buddy, and the outer perifery is very bright as well and very broad. The best combination of characteristics I have seen.

Personally, I wish MagicShine (or whoever manufactures these) would make them with higher-quality electronics and more bulletproof construction. I would happily pay $300 for these lights if that were the case.

 

[CMAN]

I got my MJ850 back in May. One of the batteries showed zero volts and would not take a charge. I contacted Deal Extreme and they would give me a $10 store cupon or I could mail the entire package back to China for an exchange (I took the $10 option), I then ordered some batteries from someone here in the U.S. for $30 and the light worked except it wouldn't shut completely off. No big deal to me as I figured I would just remove the batteries when not in use. I took the light up to Alpena on its first dive and the head flooded but the light kept working through the entire dive. When I got back to the boat I opened the battery compartment and a little water had gotten in. I disassembled the entire light (with the help of Joe from Thunder Bay Scuba) and dried it out for a couple of days. I reassembled the light and it worked the first few times I tried it but now it has died and I think if I replace the PCB (I have the blue one) I might be able to salvage it.