Hi,
Having recently aquired 4 TU417's and hardly a lamp still working, I thought I would do a bit of research to see if there was a suitable replacement bulb that didn't require modification to the rubber bases (the wedge base replacement option, which also makes it hard to use the original blue tint lamp shrouds), and maintained an OEM look.
This is my solution -
A bit if fiddling, and here is a replacement bulb
And fitted to the rubber holder, no mods needed
And fitted to the Tuner - the bulb diameter is slightly larger (11mm compared to the originals at 10mm), so the shrouds need a slight squeeze to get them on, but is is fairly easy to get them into place over the new bulbs.
Lights on
And a couple of front panel shots
The bulb spec is 7.5V 220ma, 1000 hour and 1 MSCP output. The measured voltage in situ is 7.6VAC, so it is pretty close to the voltage spec of the lamp. The actual measured output of these alternative lamps is around 0.8- 0.9 MSCP
As part of the research I tried the 8V 250ma globes from vintage electronics, but found them to be a tad dim at arounbd 0.5 MSCP output. I also tried an 8V 300ma wedge globe from a local supplier, and it was around 3 MSCP (6 times brighter than the 250ma one). The 417 I have changed the globes in did not have one working original, so I could't measure the output of an original lamp for comparison purposes, but hopefully one of the other 417's I have will have a working lamp.
It helps if you have one of these when doing this sort of work
A Lumasphere for measuring the light output from small light sources (it measures in Lumens - divide by 12.57 to get MSCP)
Now.... where did the bulbs come from......
They are "removed" from a standard G 3 1/2 Lamp (CEC part number 51, and they are also available from CML I think under the same generic number). The "removal" takes a couple of minutes, and then I tack soldered some 30awg wire wrap wire on to the ends of the existing wires to extend them.
I have an enquiry in with CEC to see if they can supply a quantity of the bare bulbs with longer wires, hope to have some more info next week. Also exploring the possibility of getting 8V 300ma bare bulbs made to give a bit more light output. It may also be possible to use 8V 300ma B9a style lamps (think I have found a source of these), these would sit similar in height to the wedge base as they have an elongated bulb. I am going to try this for comparison purposes if the source comes good.
Hope this is of interest to those contemplating lamp replacements in these Tuners.
Cheers
John
Having recently aquired 4 TU417's and hardly a lamp still working, I thought I would do a bit of research to see if there was a suitable replacement bulb that didn't require modification to the rubber bases (the wedge base replacement option, which also makes it hard to use the original blue tint lamp shrouds), and maintained an OEM look.
This is my solution -
A bit if fiddling, and here is a replacement bulb
And fitted to the rubber holder, no mods needed
And fitted to the Tuner - the bulb diameter is slightly larger (11mm compared to the originals at 10mm), so the shrouds need a slight squeeze to get them on, but is is fairly easy to get them into place over the new bulbs.
Lights on
And a couple of front panel shots
The bulb spec is 7.5V 220ma, 1000 hour and 1 MSCP output. The measured voltage in situ is 7.6VAC, so it is pretty close to the voltage spec of the lamp. The actual measured output of these alternative lamps is around 0.8- 0.9 MSCP
As part of the research I tried the 8V 250ma globes from vintage electronics, but found them to be a tad dim at arounbd 0.5 MSCP output. I also tried an 8V 300ma wedge globe from a local supplier, and it was around 3 MSCP (6 times brighter than the 250ma one). The 417 I have changed the globes in did not have one working original, so I could't measure the output of an original lamp for comparison purposes, but hopefully one of the other 417's I have will have a working lamp.
It helps if you have one of these when doing this sort of work
A Lumasphere for measuring the light output from small light sources (it measures in Lumens - divide by 12.57 to get MSCP)
Now.... where did the bulbs come from......
They are "removed" from a standard G 3 1/2 Lamp (CEC part number 51, and they are also available from CML I think under the same generic number). The "removal" takes a couple of minutes, and then I tack soldered some 30awg wire wrap wire on to the ends of the existing wires to extend them.
I have an enquiry in with CEC to see if they can supply a quantity of the bare bulbs with longer wires, hope to have some more info next week. Also exploring the possibility of getting 8V 300ma bare bulbs made to give a bit more light output. It may also be possible to use 8V 300ma B9a style lamps (think I have found a source of these), these would sit similar in height to the wedge base as they have an elongated bulb. I am going to try this for comparison purposes if the source comes good.
Hope this is of interest to those contemplating lamp replacements in these Tuners.
Cheers
John