What is this

[AirScooter]

Can anyone tell me what this is please. It is marked E505 and has a single red dot on its top.

[retiredfeline]

I wish your second picture was sharper and zoomed in on the item. It looks like a transistor, if has 3 terminals. Or maybe a LED if 2 terminals and the top is red.

Those are some seriously old ceramic DIPs.

[SeanB]

Normally hat package was a diode or transistor, led's in this generation did not use the ceramic and epoxy fill package, but used a modified TO18 package with a glass top to allow light out. Very likely a transistor that has had the absolute snot blown out of it, but the case did not shatter. But a better image is needed, especially of where it goes on the board.

Looking at the board and the front that screams old Fluke, it probably is a reference diode, likely 6V8, either a simple temperature compensated zener, thus the looking like a capacitor, because there are 2 compensation diodes in the package, or a speciial Fluke zener, which is pretty much the same.

[xavier60]

It gets a mention here, https://www.eevblog.com/forum/metrology/the-ltflu-(aka-sza263)-reference-zener-diode-circuit/msg1285938/#msg1285938

[retiredfeline]

led's in this generation did not use the ceramic and epoxy fill package

I was remarking on the DIPs in the sockets.

[Jwillis]

I can't really see it well but I keep getting a reference of the E505 as a 1ma JFET current regulator .

[Gyro]

I can't really see it well but I keep getting a reference of the E505 as a 1ma JFET current regulator .

Agreed. I just pulled out my 1979 Siliconix Plastic FET databook - The TO92 equivalent, the J505, is a 1mA current regulator diode (JFET type).  Replacement is available from Linear Systems...

https://shop.micross.com/pdf/LSM_J505_TO-92.pdf


P.S. It probably wouldn't be recognised correctly on a cheap transistor tester.

[tszaboo]

I think that is two blurry images.

[Shock]

It's a... have you checked the Fluke 8000A schematic and parts list?

[Psi]

Can anyone tell me what this is please. It is marked E505 and has a single red dot on its top.

That's not a component, that's a spider.

[cheater]

This could well be a reference diode used as a voltage reference for the DMM to compare other voltages against (and essentially all other measurements). If you replace it you'll have to recalibrate your meter.