Pilot Lamp Jewels...One Size Fits All?

[nevetslab]

While I was selecting Panel Lights, settling in on a molded RED LED lamp pre-packaged that snap-fits into a 1/4' hole and had 6" tinned lead wires, that was easy. This Blackstar S200 Chassis that I'm using for the KT88 Power Tube Test Fixture has a very nice Pilot Light fitting and a thread-in RED Jewel. While searching for what I thought I'd seen someplace....a molded LED Fitting that had mulitple fingers to press-fit into a large OD housing where a threaded- Jewel Lens cap could screw in, I never did find what I recall seeing someplace. I looked thru all of the wiring and parts I had removed from this Stage Prop Blackstar S200 chassis, and never did find WHAT they used for a pilot light that fit into their nice machined Jewel Cap assy.

The molded Neon Lamp assy I found made by Bulgin looked like it could be easily adapted with some neoprene cable jacket material (I have a small bag of a multitude of sizes from various cables over the years, which come in handy for such tasks), but....Digi-Key didn't have the RED Neon Lamp assy....just the GRN one. So, I bought that, then went to Antique Electronic Supply/CE Dist and bought one of their P-L116 GRN Jewels. Looked like it would thread right in. The only holders they showed were those found in Fender amps, and something else that was a molded package that I've never seen before.

The GRN Jewel arrived a couple weeks ago, and I unthreaded the RED Jewel, and went to thread in the GRN one. Got a turn and a half and it jammed, not threading in any further. Backed it out and looked.





Close inspection revealed two different thread pitches. I fetched my screw thread pitch gauge and found as I surmised, two distinctly different thread patterns. Very similar diameter, but the GRN one wil NOT thread in any further than seen in the third photo. RATS. So much for selecting the GRN Neon Lamp to solve that Pilot light issue. There's a Fender Twin Reverb in the shop at present, and I removed it's RED Jewel, and checked the GRN one. Threaded right in, so those Jewels CE Dist sells DO fit the Fender part. Just not this part Blackstar uses. Sigh...........

Back to what I thought I'd seen....having then looked again at every LED lamp holder, fitting, to try and find what I recall seeing that would snap-fit or friction fit a T-1 3/4 size LED. Never did find what I recall seeing, so no idea who made it. That led me to this Molded White Plastic/GRN Lens Bulgin Neon Lamp.

Has anyone seen such an LED holder that would fir into the insides of a pilot light Jewel like this? I thought about scrapping this nice machined part Blackstar had selected and fitting one of those ugly holders Fender uses. Nope. Don't wanna.

[loudthud]

There are LEDs that have that same bayonet base as the old #47 incandescent lamp with internal current limiting so they run off of 6.3VAC.

[nevetslab]

I'm aware of those, and have them in my inventory. This Jewel Lens mount is NOT the Fender-used part that accepts the Bayonet base.

[nevetslab]

I found my bag of cable jacket sleeving, and found two sizes, one that fit nice and snug within the Panel Mount assy Blackstar used (for whatever lamp assy they have), then a second one that both fit inside that sleeving, as well as the Bulgin LE2950WLG5 125/250V LED Pnl mnt Lamp assy fits snug inside of that. I let it protrude into GRN Jewel lens as far as it would thread in. When I powered this up, it was already glowing fairly bright at 12VAC. At 120VAC, VERY BRIGHT, while only pulling 10mA AC Mains current. I forgot this was NOT a Neon, but a line-level LED assy.





I guess this will work. I'll have to see if I can find an O-Ring to fit into that gap between the Jewel cap and the mounting assy. It does partially thread in...just the wrong thread. Advancing the Variac when this was already bright at 12VAC, I was afraid I'd see fireworks,but not so. No trouble seeing the amp is powered on! I suppose I could always buy the RED lamp in this series when it becomes in stock, but....that's another $8 plus shpg, so I'll just live with this for the time being.

[Greg Robinson]

Steven, not sure if this is exactly what you want, but if you purchase the "Fender-style" pilot lamp assembly, you can discard the rear bayonet holder and fit just the bezel, which is then compatible with the Fender lens caps. You'd still need to figure out a holder to retain the LED in the lens, but in a pinch you could use a dab of hot glue or neutral cure silicone, not like they require frequent replacement like a filament lamp.
https://www.cedist.com/products/dial...pilot-assembly

[nevetslab]

Steven, not sure if this is exactly what you want, but if you purchase the "Fender-style" pilot lamp assembly, you can discard the rear bayonet holder and fit just the bezel, which is then compatible with the Fender lens caps. You'd still need to figure out a holder to retain the LED in the lens, but in a pinch you could use a dab of hot glue or neutral cure silicone, not like they require frequent replacement like a filament lamp.
https://www.cedist.com/products/dial...pilot-assembly

That's actually a good idea. While the threaded body isn't quite as long as the part Blackstar uses, it's ID looks the same, as the Jewel lens does partially fit into it. So, my two cable jacket sleeves would still fit nice and snug into this one. The OD would no doubt fit the chassis, and then I'd have full matching thread to work with. I'll order that in the morning. Thanks!

[nevetslab]

Today the Fender-style pilot lamp assembly arrived. I removed (with some difficulty) the mounting nut from the frame side of the threaded bushing to which both the frame and the Jewel fit. As luck would have it, the OD of the threaded sleeve is larger than that of the nice machined chrome part Blackstar selected. So, their flat dress nut won't fit the shorter and plain-looking threaded sleeve. I'd have to ream out the hole of the chassis to make that work. At that size, all I have is the 7/16-1" tapered Reamer to attempt enlarging the mounting hole. I'll stick with the machined chrome part that I have, and pick up an O-ring to finish the task. Worth trying though.

I wired up the Output side of the power switch, having already routed the existing Mains wiring from the IEC connector over to the power switch, and replaced the 18AWG insulated Fast-on with a 14-16AWG Fast-on, adding the pilot light wires to Load cable of the power switch, so that's now tied in and feeding the 6-position Barrier Strip across the chassis, so now starting to wire up the AC Mains & Fuses for power distribution. The Molded AC Fan cables came in, so that will tie in on the fuse side of the Heater Power Xfmr. Gave a quick look and feel at the air flow of the 120mm size NMB 74CFM Fan that will be mounted on the far end of the cabinet, where it will be pushing air into the insides of the chassis (thru the end-vents) to aid in cooling the heat sink that will be cooking from the heat regulating the Fender Hot Rod Deluxe Power Xfmr to supply the 400VDC Screen/Preamp voltage. The other end of the cabinet will have an opening to exhaust the hot air from inside the chassis to the outside world. Upper side of the fan will aid in pushing air across the power tubes. Preamp tubes are inside shields.

[nevetslab]

Found some BLK O-Rings that fit just right, 0.50" ID, 0.062" thick. With it installed, the GRN Jewel screws in just where the O-Ring begins to compress, so must be just before the mismatched threads would halt it. Looks like it belongs.