Re: (ET) E20 down, only one speed forward

[Ben Griffith <griffithba gmail com>]

Here are the part numbers I used to replace the transistors:  
Q401 was replaced with a 2N222 (from a 15-pack of generic NPN transistors) and Q402 was replaced with a TIP31.
The leads aren't laid out the same as the board calls for, so you have to twist both of them around a bit from the way the originals were mounted.  

It occurred to me that the fact that it worked didn't prove that my replacement transistors were doing everything they are supposed to.  But then the top speeds cut out when the shunt overheated, so I guess they're working.  Cleaned up the shunt and haven't had any problems since.  

If it matters, my E20 is a DA model.  I don't know if the different card 4 models would have different transisitors.

-Ben

On Sun, Nov 22, 2009 at 9:53 AM, Christopher Zach <cz alembic crystel com> wrote:

David Roden wrote:

I stopped having these kind of problems - and headaches with those flaky little connectors GE used on the card edge - when I put a modern (well, late '90s era anyway) transistor controller in my ET.  

True, there is that option, and to be honest it makes the Elec-Trak a lot more survivable than say my US Electricar Prizm. If that controller fails either we fix it or you have a large rock in your driveway.

That said, the thing that is annoying me about the Elec-Trak is the same thing that annoys me about the Prizm: Both controllers do not have proper fuses.

On the E20 there is a "fuse" for the controller circuitry, however it's rating is much too high for the circuits on the control boards. As a result if a component shorts you don't blow the fuse, you blow traces and the like. Very annoying. On the other hand this is a single-layer board, and is as dull as dirt to fix. Assuming I can find out the part numbers for the transistors.

That said, it looks like the smaller diodes are starting to die. The bigger ones for the field control have all been replaced, guess I need to get some smaller ones from Radio shack now.

Chris

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