Arri 650 bulb hum/crackle.

traviswears

traviswears

Well-known member
Picked up a used Arri 650 on eBay this week. Seller had 100% positive feedback and shipped quickly.

However, the light was shipped with the bulb still in the unit and didn't strike the first time (lamp had been jostled loose). I reset it, and struck the light which now works but when I adjusted it from spot to flood, the bulb began humming and crackling loudly and won't stop. It seems to get a bit better if I spot it out, but on flood it's very loud.

The spare globe that was shipped with the package doesn't strike at all, so I don't know if this is a bulb issue or a light issue. I rent Arris all the time and have never found them to be noisy.

Any help/suggestions from the pros?
 
I would say the connections at the back of the unit (inside back) from socket to plug (should be a terminal block) could be loose--that would be my first choice. After that perhaps an issue with a bulb. Buy new bulbs and see is about all you can do if the terminal block shows all good and solid connections.
 
I have seen this often with 650's The connection at the socket and pin is bad. Try a new bulb or clean contacts on lamp and socket. If all of this fails you will have to replace the socket.
 
Paul Hudson said:
I have seen this often with 650's The connection at the socket and pin is bad. Try a new bulb or clean contacts on lamp and socket. If all of this fails you will have to replace the socket.
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Thanks. I'll try a new bulb tonight. If that doesn't work, do I need to ship it off or can I just send for the part? I have a friend who's an electrician so he might be able to install it for me. I don't trust myself to do it.

Also, any idea on how much this might cost? I might try and get the seller to shoulder the cost since this issue wasn't disclosed in the eBay listing.
 
If the one bulb lights and not the other than it is a bulb issue. The bulb is easy enough to check for continuity with an ohm meter. As for the hum it can be a poor connection in either the cable to the lamp socket, the socket itself (check for burn marks in the socket or on the lamp pins) or even the lamp filaments themselves can develop a hum as the bulbs age.
 
Brought it to set today and tried a brand new bulb. Bulb struck but made the same noise. Also, if left on for a period of time, the light would flicker off for 10-20 seconds before coming back on. Must be a connection somewhere as mentioned before. Maybe my local rental house will take a look at it for me this next week.

Thanks for the feedback everyone.
 
because of the design of these mounts they are prone to arcing if the bulb is not seated properly.
this causes pitting and degradation of the contacts and intermittent loss of current and some arcing noise .

unplug the lamp and try cleaning the contacts with emery paper or small file until shiny.
if arcing occurs you should see some sign of it on the bulb, the contact ends will appear black and pitted.
if this doesnt help check the connections on the block in the lamp, these can get damaged or work
loose with spot and flood use.
this will involve some dismantling of the housing.

cheers
 
Paul Hudson said:
Bad socket. I have replaced many of them.
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You were 100% right. Thanks. My local rental house replaced the socket and now I'm good as gold. Only problem is it cost me $100 to fix and now the "deal" I got on eBay isn't much of a deal :/

Tried to ask seller to cover some of the cost with no success. Sigh. Taking the case to eBay Resolution Center now.
 
$100 to replace the socket may seem steep, but besides the cost of the socket there can be quite a bit of labor involved is taking the unit apart and putting it back together. FWIW you might want to learn how to do it yourself as sockets do burn out frequently. Doing a search online I see the sockets go for around $40-50 each.
 
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It is known problem with the Arri 650 sockets. I am not sure why it has not been addressed after many years. When I replace them I use other manufactures sockets. I will not buy Arri 650's for this very reason...unless they are very cheap.
 
Paul Hudson said:
It is known problem with the Arri 650 sockets. I am not sure why it has not been addressed after many years. When I replace them I use other manufactures sockets. I will not buy Arri 650's for this very reason...unless they are very cheap.
Click to expand...

That's really interesting. I'm a newbie and in a small market, so I haven't heard of this before. I mostly use 650s for background lights, to paint a little color somewhere or streak a light in the background. I love them because they still have some punch after a full CTB is applied. What would you recommend as a good substitute?
 
Mole Richardson's are work horses Desisti makes a better socket the LTM sockets are better but the build on the Desisti and the LTM is not as robust as Mole. Buy Mole once and own it for life.
 
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