Date: Tue, 4 Sep 2007 20:13:07 -0400
Reply-To: "T.M." <tinkerman007@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "T.M." <tinkerman007@YAHOO.COM>
Subject: Re: It's time to hit that idle Stabilizer on the head!!!
Wow, I'm honored!
While searching the list for BD438, I came across some very interesting
posts by the two Jo(h)ns responding to this/my thread, and see that you
and others have made great progress already. Your website (KENNEKE.COM) is
awsome! Why didn't you hint you have such a nice website?...
Looking at your ISCU page I see that our units are quite different (I have
a 251 907 393C, while you have a 'B' model). My unit has two BD438
transistors connected to each other, while yours has only one as far as I
could see. Otherwise, the design looks quite similar with three LM2902 and
one LM2903. You mentioned analog V->F converters, I said integrator
circuits, basically they're the same thing, right?
And I saw your posts planning to reverse engineer the ISCU...
Well, I've done part of it by now, mostly the power supply circuits and
the output driver, but it's not complete yet. And I see there's no point
comparing voltages between two different designs (B & C).
I think it would be best that we post our pictures (with annotations and
test points marked) on the web somewhere, so people could add their
measurements too. I don't think we even need to reverse engineer the thing
completely - several crucial test points could provide most of the info we
need.
And now to your post -
On Tue, 4 Sep 2007 15:58:38 -0700, jon <jon@KENNEKE.COM> wrote:
>Very interesting. I've never seen an ISCU with any other failure than the
>high current transistors. I have seen a rare case where the diode check
>came out good...on a bad transistor.
Yup, I was thinking of that possibility...I probably hurried a bit in
soldering them back in because I didn't have a spare and hoped to find the
problem elsewere, but no problem taking them out again with my superquick
technique...
>Also, with electronic items of that age, check out the electrolytic
>capacitors (or, simply replace them all...sometimes that is just as easy).
Not so easy with mine, because it was completely dipped in/covered with
laquer before being put in it's box, to seal it against the elements.
Heck, it's tough touching the PCB and getting a connection at all!...:-)
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