(ET) E15 card 1 thoughts....

[Christopher Zach <cz alembic crystel com>]

Well, I think this E15 card is working again. Basically I replaced all 
11 diodes, and the transistor on the left side. It passes logic for 
running 1a, and 2a, with the little delay bump. So I think it might work.

I do think I need to replace my replacement transistor: The 2n5309 has a 
50 volt Vce while my replacement is a normal switching transistor with 
only a 15v Vce. So it's going to blow up soon.

That said, it's probable that the transistor is good, I'll do some 
checks on the old one and see. And all the SCRs look good, it seems like 
it's the diodes that just disintegrate.

I'm not sure why the diodes die so badly, maybe they aren't rated for 
40+ years, it seems to be the same case on all three boards I have 
reviewed. The E20 Card 4 diodes are different, and don't seem to take 
the same level of damage (although I have had to replace all six diodes 
on the left of my E20 board because they blew up due to old age as well. 
Go figure)

But overall I'd say if you're having problems with your E15 and you've 
checked all the normal stuff do a check on the diodes. Might find some 
of them opened.

I'll get some molex connectors over the next month and solder together a 
nice harness so I can install and remove this from my E15. Then I'll 
test it in the spring with the 36 volt pack I have currently over in the 
E20's weight box. Anyone have a recommendation for pins to connect to 
the card 1 pads or a particular Molex?

Chris