Author Topic: strange ballast  (Read 2424 times)
marcopete87
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strange ballast « on: October 14, 2012, 04:06:55 AM » Author: marcopete87
Hi all!
yesterday, during volountering at the scrapeyard, i managed to recover an 2x40w ballast (i suppose, because length of the lamp).
the problem is that this ballast is very strange and rusted, so i can't get any information about it.

the ballast have 3 connections, 2 of them are widely separated from the tirdth.
two lampholder appeared as being parallelized.

i suppose that the schematic was:
Code: [Select]
L--Ballast--Tube--+
          --Tube--+--N

the fixture didn't have any starter.
can it be an instant start?
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Medved
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Re: strange ballast « Reply #1 on: October 14, 2012, 05:26:52 AM » Author: Medved
Wasn't there a capacitor connected between the 3'rd ballast terminal and Neutral?

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Ash
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Re: strange ballast « Reply #2 on: October 14, 2012, 11:59:21 AM » Author: Ash
If it would eb like this, it would not do anything before the lamps strike (as a lamps that did not strike is open circuit, so it won't have neutral, no voltage input, unable to make the output to strike the lamps.....)

If it is 3 wire, its either 2 chokes in a common enclosure - then there must be starters or other starting devices in the fixture, or is Instant Start - in this case it must be connected directly to the AC by 2 of the wires, and the 2 lamps connected in series from the 3rd wire to the neutral

Either that, or there is a 4th wire that is cut short or snapped
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marcopete87
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Re: strange ballast « Reply #3 on: October 15, 2012, 05:38:13 AM » Author: marcopete87
thank for the answers.
unfortunately i recovered this ballast from scrap, with an very messed-up wiring, but no capacitor.
it have 3 connectors.
today i'm planning to measure the impedance between poles (and post an photo).
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marcopete87
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Re: strange ballast « Reply #4 on: October 15, 2012, 07:32:45 AM » Author: marcopete87
here is the photo, with all data i know.
http://www.lighting-gallery.net/gallery/displayimage.php?album=lastup&cat=0&pos=0&pid=71168

i'm thinking about this: http://www.repairfaq.org/REPAIR/F_flamp.html#wd (see tirdth example)
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Medved
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Re: strange ballast « Reply #5 on: October 15, 2012, 11:43:18 AM » Author: Medved
I don't think, the 3'rd circuit is for >70V lamps (F40T12,...) operated at 120V mains.
Your ballast look more like designed for SOX (see my comment at http://www.lighting-gallery.net/gallery/displayimage.php?album=lastup&cat=0&pos=0&pid=71168).
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marcopete87
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Re: strange ballast « Reply #6 on: October 15, 2012, 04:34:52 PM » Author: marcopete87
thank to all!
Medved, i removed this ballast from 2x40w fixture, so it can't be sox (i also have an na90 ballast, and is totally different).
tomorrow i'll try to setup 2x40w preheat t12s.

i recovered an t12 40w osram color 20, tomorrow i'll post pictures.
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Ash
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Re: strange ballast « Reply #7 on: October 15, 2012, 04:48:31 PM » Author: Ash
There are some more tests to run to determine what it is, so dont risk blowing up lamps and starters for now

Determine whether the windings share the same core or are on separate cores (how - see in the gallery image)

Test each winding separately in series with incandescent lamp
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Medved
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Re: strange ballast « Reply #8 on: October 15, 2012, 05:11:11 PM » Author: Medved
Medved, i removed this ballast from 2x40w fixture

And how that was wired?
You mentioned both lamps parallel with no starters. That would suggest a redundant circuit with one lamp working and the second as "stand-by" in an instant start concept. For such system the SOX ballast would be just the required ballast to provide reasonable run current (0.35A; for 0.43A lamp it is still OK), as well as high enough OCV (~600..700Vpeak with the ~3uF) for cold cathode ignition (that would not be a lifetime problem, if the lamps are supposed to run long time for each start).

The redundant circuit (the one with lower striking voltage would ignite, leaving the second one OFF; When the first one fail and so does not ignite, the second lamp take over, so the fixture get more than double the lamp life and way greater reliability) could reasonably work only with 2 terminal discharge lamps connected plain parallel (so cold started). Managing the heating current would make the gear way complex (it would require an active switching element, like relay or so): Connecting them to low voltage heating source would mean the lamp, what is OFF, would be heated, so the cathodes would evaporate, so degrade, so compromise the overall reliability. Filaments connected in series would mean the current path would be lost, when one of the filaments break, so compromise the reliability as well. Connecting complete lamp+starter combos parallel mean the starter's would interfere with each other, causing starting difficulties of the overall system. Moreover if one starter close sooner than the other one, it's lamp would most likely run and after it wear out, that starter would cause the complete setup to flash, giving no chance to the second one to take over, so simply not working as redundant system either.
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marcopete87
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Re: strange ballast « Reply #9 on: October 15, 2012, 05:18:07 PM » Author: marcopete87
i don't know much about wiring: it was in an commercial refrigerator that i found dismantled (i supposed series, because i didn't see any starter, but i couldn't recover full fixture).
i think it wasn't for redudancy.
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marcopete87
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Re: strange ballast « Reply #10 on: October 16, 2012, 04:19:17 AM » Author: marcopete87
i've tested  ;D
it works very well, silent and cold  :D

edit: see my new album to see this odd ballast operating  :a_fluor: :a_fluor:
« Last Edit: October 16, 2012, 09:15:37 AM by marcopete87 » Logged
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