ballast trouble in home built uv light box
Friday night I built a uv light source with the plans here: http://www.eepjon.com/ubldit.htm . I bought the same ballasts that are listed in the parts list. I bought them locally at Grainger: http://www.grainger.com/Grainger/searchresults.jsp .
All of the lights don't come on every time. They've all come on a couple of times, then when I plug it in a few minutes later only a few will come on. The rest are glowing dimly on the ends, but do not fully come on. There are 8 bulbs/4 ballasts. Wrong ballasts??
My darkroom is fairly cold (basement, winter, Iowa). It's about 58-62 in my darkroom right now.
Have you tried juggling or twisting each paired tube that doesn't come on? I gather its a pair of tubes at a time that doesn't light up 100%? I found that for me and fluorescent fixtures, this does the trick, due to lack of 100% clean contacts with the socket.
I have jiggled & adjusted the tubes a couple of times. I have also checked the wires to the lampholders. I plugged it in a while ago & all of the lights came on. I let it run for about a minute and then unplugged it. I waited about a minute & plugged it back it. Just two lights on the end came on. I unplugged it & plugged it back in. None of the lights came on, but all were glowing dim on the ends. You're right about the lights in pairs. 2 per ballast.
Hmm, just a few thoughts, just in case you haven't tried it yet, but I have a feeling you have . Please bear with my questions, just thinking out loud .
Do the ones that light up (or not light up for that matter), light up all the time on a consistent basis? If so, can you just swap them with the ones that do not light up. If they light up there, could mean the tubes are the culprits. If they don't kight up, could be the ballast being wrong for the app. May not have enough oomph to get them started.
When I suggested you try unplugging the tubes, did you try it while things are plugged into the power? Sometimes that does the trick and then for some magically reason, all it nice in the universe again ... for awhile ..
Matt, sure you have done this, but I had some problems when I did my first unit as well (only a 4 bulb unit) so let me ask the following - there are two red wires going to one socket, then a pair of blue wires going to the 2nd socket of the pair -right? Then you have two yellow wires going to the first socket - opposite end, then two jumpers that go the the 2nd socket - does this sound right? If not that may be the problem, with the diagram like it is it can be hard to find the correct placement..
Just looked at the ballast you used..if it was the #3X964 from Grainger and you are using the 24 inch BL or BLB bulbs I think that is the problem. The bulbs are F20T12's and the ballast is for F15T8's which are like 15 or 18 inch bulbs..so my guess is that the ballast does not have enough ump! (sorry don't know the correct term) to light the bulbs up and keep them there.
Good luck..and let us see something once you have it working.
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I don't see a grounded metal reflector in the url plans. I didn't use one in my first 'box' and had problems with the tubes coming on - once I added it the bulbs all came on without problems.
Matt, I had this problem when the Gra-Lab my box was plugged into was plugged into a powerstrip, but once I plugged the Gra-Lab into the wall it worked better.
Re-reading the above sentence it is kind of confusing so here is what I am trying to say:
Box--->Gra-Lab Timer--->Powerstrip--->Wall = bulbs not coming on
Box--->Gra-Lab Timer--->Wall = bulbs coming on no problem
Let's see what I've got in the magic trash can for Mateo!
Hmm, I think a quick check of the grounds on the unit is in order ...
Three possible problems (I think they were all mentioned aove).
1. Ballast - Lamp mismatch. Look on the ballast and see what the ballast is designed for. A T-8 ballast will drive a T-12 lanp most of the time, but it won't be an optimal situation. This could cause a problem starting in a cold environment. They also won't be 'driven' at the appropriate level, which will cause premature lamp failure, and possibly premature ballast failure.
2. Lack of grounding behind lamps. It is important to have a piece of metal behind the lamps that is tied into the system ground. This is an integral part of starting a lamp with many ballasts. I use a piece of aluminum flashing that was painted white behind the lamps on my home-built unit. I've never had any starting problems to speak of.
3. Carefully check the wiring diagrams. They will be on the ballast label. Not all ballasts are wired the same way, so read the diagram carefully and make sure that you actually have them wired properly.
I doubt the temperature is the primary problem, because most ballasts are designed for 50 degree starting. However, if you have another problem, like the lack of grounding, the temperature will make the problem worse.
You're right, the Grainger site does call these ballasts out for F15T8. These are the ballasts I used, but on the ballast itself the first item listed is "(2)F20T12" so I though it would work for these bulbs. I'm using the 24" F20T12BL. Maybe I should take these back & get something different?
Originally Posted by photomc
I don't have a metal reflector. The lampholders I used are Grainger 4YA99. I mounted them in galvanized angle on each end. I grounded this angle, as well as the ballasts.
Originally Posted by rogein
I had the unit plugged directly into the outlet, but will remember what you said when I hook it up to a timer. In fact, maybe I should be testing it with the timer.
Originally Posted by Jeremy Moore
I don't have metal flashing, but I do have the lampholders mounted to galvanized angle, and the angle is grounded at both ends.
Originally Posted by Michael Mutmansky
All of the lights come on sometimes & then the next time only 2 will come on. I will recheck everything tomorrow. If I still have no luck, I'll replace the ballasts with a different type. Does anyone have a suggestion?
Thanks for all of the help, I really appreciate it.