Date: Sun, 16 Jan 2005 15:27:49 GMT From: Retro-Bob <uctraingSPAM-ME-NEVERnospamanet.com> Subject: Re: Opened DI Casette - For those interested
On Sat, 15 Jan 2005 04:24:53 GMT, "James Sweet" <jamessweetnospamail.com> wrote: >Well that epoxy pretty much precludes any reasonable chance of repair. I'd >love to know what's under the potting though and what actually fails, >wouldn't surprise me if it's something as simple as a cracked solder joint. >Just for the hell of it you could try tearing out that lytic and replacing >it, though they usually fail gradually. Mylar capacitors (the blue boxes) >occasionally short, I suspect there's semiconductors burried in the potting >epoxy though, know anyone with an xray machine? I pulled my NG900 DI apart too and found the same thing... everything epoxied into place. I have had two other cars (Nissans) with DI systems and they had individual coils so I was thinking of just swapping out the Saab individual units from new to old as the old ones went bad. However, the epoxy prevents any such plans. FWIW: On the other engines where there are individual DI coils they often have a separate ignition module which I think Saab has embedded in the epoxy. There is a little electronic stuff on top of the each coil, usually similarly sealed in tight. These cars also have coils go bad at 60K miles likes Saabs - pretty much all of them have the same problems. The ignition modules rarely go. That leads me to believe that it's the coil itself going bad... or something else in that direct area. I think the overall issue is that you can't put electronic components into the top of a cyl head, heat them up to a couple hundred degrees day after day, bounce them around on the road, and don't provide any cooling via fans, fins, or heat sinks - and expect them to last. You've built a system with parts that *will* knowingly degrade and fail. Of course, you may not care when you sell them at $75-$100 each.
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