Tested a Carley #912 PR Adaptor to Failure?

It seems to be both spec and folklore that the Carley #912 PR base adaptors are rated to 1 amp but will run up to 1.2 amps without incident. Has anyone actually run one of these units to failure? For example, fine with 1.2A, fine with 1.3A, toasty with 1.4A, crispy critter with 1.5A?

I'm interested in the mode of failure and actual upper tolerance limit of operation, intermittent or continuous.

Wilkey

I've had 2 out of 4 of my 912 fail on me. I don't think this was from heat. I believe the potting material started cracking from repeated replacing of the bulbs. The heat from a 12V 20W halogen bulb didn't bother it.

So Soloco,

You're saying the potting material stress cracked? How much effort would you say it takes to plug and unplug a bulb? Did you have to rock it side to side to get it out or could you just pull it straight out?

Thanks for the quick answer,
Wilkey

The potting material is soft and pliant. When I drill a hole in the center for a W/A glass tail I have to keep pins in the holes to keep them from being squished shut or otherwise deformed.

I would think it's a good bet that the cracking was a heat denaturing phenomenom. Have you ever looked at a cracked plastic bulb socket rated for 60W that you ran 100W bulbs in for a long time. Sometimes they crumble when you try to unscrew a light.

I believe the 912 is made for a T2.5 base. I was using halogen bipin bulbs which have a base designation G4. I assumed (maybe my bad) that they were the same because the distance between the pins is the same. I realized that the T2.5 spec has much thinner pins. I had to push pretty hard to get some G4 base bulbs into the socket. After a few bulbs they slid in fine, probably because whatever was in its way earlier had rubbed/cracked off. Now the sockets that I used with the G4 bulbs tend to flicker sometimes, which is really irritating and pretty much unusable. Hope this helps.

I also have noted that the Carley T-2 1/2 and W/A T-2 1/4 bulbs have similarly thin pins compared to some G4 pins.

Actually, the W/A fixed length pin seems a little thicker than the Carley bulbs whose longer untrimmed wire leads are more prone to bends and wiggles.

The first time I put either a Carley or W/A bulb into any 912 I experience a tight interference fit. This spring loading makes for a good contact as long as it lasts. I don't know how many replacement cycles it's good for or how quickly heat reduces available replacement cycles.

Is there anyplace that one can find a unified list of specifications for the T-sizes? The Carley info does not always match the WA info. There's got to be a standard somewhere.

Hmm, the potting material is soft and pliant? Has anyone tried dissolving out the filler with solvent? If it is soft to begin with then gets hard (presumably through heat) then that means there is chemical cross-linking going on. If it is not fully cross-linked prior to the heat exposure, it may be possible to swell the base+filler in solvent and scrape it out, replacing it with J-B Weld. There are a number of solvents that might be worth trying. Acetone, toluene, turpentine, 5F5.

Wilkey

Perhaps it would be helpful to try and minimize the force-fit deformation by sanding down the leads a bit to see if you can take off a few thousandths.

Wilkey

The potting material's not soft. It's like.... clay that has been dried, but not yet fired. Metal rubbing against it can scrape it up pretty bad.

Thanks Soloco.

Wilkey

When I say soft, its a relative term. It's firm to the touch but will migrate and deform without cracking or breaking when I drill a central hole for the WA bulb tails. The texture is plasticene, not crystaline or granular.

I find the texture similar to the white plastic switch / socket assembly in the Energizer DB flashlights. FWIW, The DB plastic gets soft and deforms with heat.