Date: Sat, 22 Sep 2007 22:34:03 -0700
Reply-To: David Kao <dtkao0205@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Kao <dtkao0205@YAHOO.COM>
Subject: Re: ECU firmware location
In-Reply-To: <1b0df96d0709221758g642e4800u35f4bd204d131948@mail.gmail.com>
Content-Type: text/plain; charset=iso-8859-1
I agree. It's hard without a schematic and the PCB is covered with
a protective paint makes it even harder. For low value (resistance)
resistors you can measure them without pulling their leads off. If the
values are high you can compare your measurement with the spare.
This usually is good enough to find bad resistors. For capacitors
you can use the ohm measurement of an analog VOM to check them.
Capacitors will show charging and discharging behavior. By looking
at how the needle swings you can tell if the capacitor is at least
doing what it should do. Can't tell if the value is correct though.
Catalytic capacitors are the most likely ones to go bad. There should
be only a few of them on your ISCU.
If you have a spare you will feel less risky to turn on your solder
iron. I have seen people who are trained to repair surface mount
PCBs. They are very good in removing and installing parts on very
high density PCBs. If you have similar skill like theirs it is probably
safe to repair your ISCU. But of course you will need to isolate the
defective component. That is the hardest part.
Now that your ISCU is an European breed. I can see why you want to get
it fixed instead of replaced. If you can identify the defective part
It will probably take less then 15 minutes to repair it.
Not trying to tell you how good I am. Just some experience I had. Leslie
is pretty good. He will have some more ideas I believe. Yes, a good
magnifier is a must. Good lighting is definitely needed. A small piece
of damp sponge for cleaning the tip of the solder iron is a must too.
Good luck.
David
--- tinker man <tinkerman007@GMAIL.COM> wrote:
> On 9/23/07, David Kao <dtkao0205@yahoo.com> wrote:
>
> > Try to measure each resistor on the PCB. They tend to change value because of
> > aging and heat.
>
> Pretty hard in my case, with close to 200 parts on the PCB, all
> affecting each other's measurements...
> I was also checking the capacitors, which are more problematic.
> The good news is that I might get a spare unit for comparison and
> testing. I'll keep my fingers crossed till I get it...
>
> Cheers,
> TM
>
____________________________________________________________________________________
Boardwalk for $500? In 2007? Ha! Play Monopoly Here and Now (it's updated for today's economy) at Yahoo! Games.
http://get.games.yahoo.com/proddesc?gamekey=monopolyherenow
