Glass bead rectifiers

[john dozier]

Anyone used them? How is their quality.? the only manufacture I can find on the web says they are fast response. Any help would be appreciated. Thanks

[Damon Hill]

Got any specific part numbers in mind? Soft recovery types are preferred.

[john dozier]

These are in a Chinese made DAC. Part number is BY56MV, This number produces nothing on Google. Thanks

[john dozier]

I have some Fairchild "stealth" diodes I can use,but the board the glass diodes are mounted on is small it would be a real PITA. I would like to leave them if possible.Thanks

[Conrad Hoffman]

There's a whole series of BY diodes, some of which are ultra fast, not soft by any means. I think mine are Philips. I didn't have any luck with a quick search, but may be able to find you some data later. No idea about the quality of Chinese-made versions.

CH

[Conrad Hoffman]

Searched through my data and didn't find anything for a two letter prefix. Now if it were a three letter prefix like BYM, that might produce more results. I don't know how ambitious you are, but it is possible to test diodes and rectifiers for speed and recovery. I think the circuits are sometimes published by the diode makers, or at least the test conditions are given.

Conrad

[jneutron]

Originally Posted by john dozier

Anyone used them?

Yes. As well as involvement in a manufacturing line for them.

Originally Posted by john dozier

How is their quality.?

That depends on the manufacturer.

Originally Posted by john dozier

the only manufacture I can find on the web says they are fast response.

They can be anything from 2 microseconds to 2 nanoseconds.

Originally Posted by john dozier

Any help would be appreciated. Thanks

Sure. Do you have any particular question?

In general:
1. The axial lead glass bead is a method of passivating the junction to prevent ionic contamination from destroying the diode. It is applied as a slurry to the device, and it is fired. It bonds to the moly or tungston slugs that sandwich the die. The leads are typically nailhead coppers that are brazed to the slugs.
2. Some diodes such as the '914, are glass sleeves slipped over the brazed assembly and fired, it shrinks and seals to the slugs.
3. Super-rectifiers, such as General Instrument (their patent expired in the late 80's), had a glass bead that was overmolded with plastic to facilitate auto-insertion.

In the early days, the glass bead was a symbol of high reliability. As the molding plastics and protection compounds improved, non-glass devices became more and more reliable.

Cheers, John

[john dozier]

Thanks for the information. The part number on them is BY56MV. I would like to know if replacing them with Fairchild "stealth" diodes would improve the sq in a Chinese made DAC. Replacement would be a real PITA due to the size of the circuit board and I would rather not have to do it. If it would SIGNIFICANTLY improve the sq, then I will do the fiddly bits. Thanks

[tomchr]

Hard to tell without having a schematic or knowing what function the diodes perform.

~Tom

[john dozier]

They are all in the power supply forming bridges for rectification of incoming AC. Regards and thanks