Igniter electronic part identify

[Jaguarjoe]

With a Vcbo of 450V, just about any high voltage zener diode will work there as long as it is somewhat below that 450V.

With an Hfe of only 300, I do not think a 2SD977 is a darlington transistor.

[Thomas Kenny]

Ok Matchless, I will run you picture and diagram past my neighbor and let you know if I can be of any help. Tom

[Matchless]

Ok Matchless, I will run you picture and diagram past my neighbor and let you know if I can be of any help. Tom

Thanks Tom,
Any information will be usefull, even as far as suggesting equivalents. Unfortunately I do not have a faulty igniter to experiment with and do functional tests on, just the one in my bike.

[Harry P.]

I have an old repair manual that shows the schematic symbol of a Zener as the triangle with a straight line with the ends turned out.1 up 1 down..similar to your diagram that has only 1 end turned down....my 2 cents

[Matchless]

I have an old repair manual that shows the schematic symbol of a Zener as the triangle with a straight line with the ends turned out.1 up 1 down..similar to your diagram that has only 1 end turned down....my 2 cents

Thanks, that zener symbol is what I used to draw the schematic from the board in my bike. It is not an "official" scematic. I just guessed it to be a Zener, but thanks for the reply

[Jaguarjoe]

Here's a diode that will work:

http://www.rectron.com/data_sheets/z90-z330.pdf

Mouser sells them but they're not stock items.

[rustybronco]

could the -350 marking be for the peak inverse voltage?

I don't believe it is a zener diode.
I believe it's purpose is transient voltage suppression when the ignition coil field collapses.

[Matchless]

could the -350 marking be for the peak inverse voltage?

I don't believe it is a zener diode.
I believe it's purpose is transient voltage suppression when the ignition coil field collapses.

I am playing with that idea as well, but I am not sure how the Japanese marked their diodes 30 years ago. I think your theory is correct, as exceptionally high back EMF, but very low current is generated when this happens. Normally a standard diode is put across a relay coil for exactly that purpose. A 1N350 has a reverse voltage of 70, so it did not look like the same to me, but...

[rustybronco]

A 1N350 has a reverse voltage of 70, so it did not look like the same to me, but...

I looked at that also, but the only 1n350 i could find illustrated was not a typical diode package. http://www.eca.de/html/1N3/1N350-1.html
what is the breakdown voltage of a ignition capacitor rated at? (?30-40 volts?)
you could measure the primary side P-P voltage of a spare coil with an osilloscope when the field collapses.

http://modecideas.com/faq94.html?newitems

[Matchless]

I looked at that also, but the only 1n350 i could find illustrated was not a typical diode package. http://www.eca.de/html/1N3/1N350-1.html
what is the breakdown voltage of a ignition capacitor rated at? (?30-40 volts?)
you could measure the primary side P-P voltage of a spare coil with an osilloscope when the field collapses.

http://modecideas.com/faq94.html?newitems

On the same site I found a 1S350 which is the Japanese format of the time. The case configuration and size seems to be exactly the same with the rounded ends. Now if we can just find the specs on it and an equivalent..?
Unfortunately no oscilloscope available.

[Thomas Kenny]

Matchless, my neighbor has looked at you diagrams and our picture and wants to talk with you. His name is Joe and you can reach him at 503 738 8677 pacific time U.S. or email him at oda@inlet.com He thinks he can help you. Tom

[Thomas Kenny]

Igniter part identity

Matchless, I gave you the wrong email for Joe, the correct email is oda313@iinet.com

[Matchless]

Matchless, I gave you the wrong email for Joe, the correct email is oda313@iinet.com

Tom,
Thanks I have just resent to the new address. It is very good of him to help. I have had a lot of feedback, but nothing conclusive. It is definitely a protection circuit for the back emf. Some peple are advocating using a 1N4007, others a IDT04560C Scottky diode, another says it must be a fast 400 V diode, others a 24V Zener and even a higher Zener.
I also cannot find the possible original type 1S350, but there is a site (http://www.eca.de/html/1S3/1S350-1.html) that has the data for such a diode, case type S3 which seems similar, but you need to be subscribed and the mention it as modulator ... something, 30 V and it is a single germanium diode.
I am fairly confident that someone will come up with something soon. Thanks for your trouble.

[Matchless]

Here's a diode that will work:

http://www.rectron.com/data_sheets/z90-z330.pdf

Mouser sells them but they're not stock items.

Thanks for the info. Which one of these do you suggest?

[Jaguarjoe]

Thanks for the info. Which one of these do you suggest?

The 330 volt jobbie will work fine.