Thomas Duplex Safelight Repair

[Robin Khlop]

Hi. I am trying to fix an old Thomas Duplex safelight, and can't find the necessary parts. I've already bought a new SOX 35w bulb which didn't solve the issue, so I suspect that the magnetic ballast is at fault. There doesn't seem to be a lot of information on where to get replacements, and most ballasts have a separate capacitor, which mine does not. Any advice?

 

[Rickbb]

I used those at a printing company decades ago, they are a unique specialty product. Parts will be near impossible to find. Maybe some old school printing darkroom supply house may have them.

 

[Robin Khlop]

I found a ballast meant for fluorescent lights on eBay. Will it work for my purposes, or does it have to be for low pressure sodium lamps specifically? If it's the right one, is there anything else I need alongside it? https://www.ebay.com/itm/234811743370

 

[480sparky]

The ballast is for a fluorescent lamp, so it won't work for a LPS lamp. Your images only show the ballast. Is there not a start capacitor?

I can't image HID lamps being used in a darkroom. They get very hot with they are on, and if you turn if off even for a few seconds, it will take 5-10 minutes for it to cool down in order for the lamp to re-strike.

How much would you pay for a new fixture?

 

[Robin Khlop]

I don't see a separate start capacitor, and the only components in the fixture are the ballast shown in the images and the bulb socket. I've used an identical safelight before and the heat has never been an issue, even after running for many hours. I'm not looking to buy another one since I have other safelights and just want to learn more about this one, but I appreciate the offer.

 

[480sparky]

The missing capacitor may be the issue.

The operating heat isn't a problem. The problem is, if you turn it off, it'll be 5-10 minutes before you can turn it back on.