So after opening my bike's igniter unit (since it was opened before and was put back together with hot glue!) and am going to change the output transistors and capacitors soon...then discovered this while cleaning it up



A glass diode with a single green band, no letters or numbers. Does anyone know what diode is it? Or a much more common diode to replace it? There's also another diode that has white powder-ish buildup (round, presumably ceramic, white with one end colored blue) and wonder if that also needs replacing. For now, the broken one is the priority. Hopefully I won't have to scavenge other igniters for parts!

Oh I hate those old Japanese glass diodes, they are a pain to figure out. The green band indicates a Schottky, the one to the right with a black band is a Zener.

I'm assuming you have a multimeter with diode test function? Test the intact one next to it and post the forward voltage, for a Schottky it should be between 0.3v and 0.7v.

As far as replacement goes, finding an identical diode will be difficult. I have fitted 1N5818 (30v/1a) diodes in the past and they have worked. You could get away with a 1N5817 (20v/1a) though, I just had the 1N5818 in stock at the time.

I believe the reason they used glass originally was for heat dissipation but I can't see that part of the circuit pulling anywhere near the 1a rating of the diode, from what I can remember it's well under 100mA.

MadMotoUK

The diode beside the broken one (green band) reads 0.586 volts. This seems to be a regular diode.
For reference, a SB560 (Schottky, 5A, 60v) reads 0.255 volts and an IN5401 (Chinese version of 1N5401, silicon rectifier, 3A, 100v) reads 0.549 volts on my multimeter.

As for why it is glass, it is the hermetic seal. Impractical to do with a metal body, and plastics does not provide it (much more in that era perhaps), meaning moisture over time can seep and result in diode parameters shifting or just be destroyed. Problem is they do shatter and break...and light exposure affects some things.

Might just pull all of them out (please no, there are six of them and it has been tough getting the muck off the ICs by desoldering them) and replace all of them with silicon diodes to even it out.





Then onto the transistors...




Left one suspiciously fake, the writings faded off after some lighter fluid and the bottom of the PCB shows it might have been replaced previously

Bottom one is the transistor on the left. Thoughts?