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Date:         Sun, 23 Sep 2007 01:54:05 +0200
Reply-To:     tinker man <tinkerman007@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         tinker man <tinkerman007@GMAIL.COM>
Subject:      Re: ECU firmware location
Comments: To: Leslie Schwartz <lhs_emf@pacbell.net>
In-Reply-To:  <059701c7fd71$72626010$57272030$@net>
Content-Type: text/plain; charset=ISO-8859-1

Yep, I know those, but usually prefer the solder wick for delicate jobs because that mechanical sucker sometimes sucks also the thin, over-heated tracks... The solder wick actually is safer and doesn't spread the solder particles around like the mechanical ones. Newly induced shorts aren't fun at all (like a grain of solder bridge underneath an IC and shorting two pins, but not visible... But I'll definitely get myself a solder sucker too, for those occasions I need it.

On 9/23/07, Leslie Schwartz <lhs_emf@pacbell.net> wrote: > The mechanical solder suckers - mechanical single trigger action plunger work pretty well. > > -----Original Message----- > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of tinker man > Sent: Saturday, September 22, 2007 6:22 PM > To: vanagon@GERRY.VANAGON.COM > Subject: Re: ECU firmware location > > On 9/17/07, David Kao <dtkao0205@yahoo.com> wrote: > > Hi TM: > > > > What you are doing is very challenging. > > Yup, you can say that again... > > > Another suggestion, if you really want to skip all the headache in > > dealing with those linear IC's. LM2902 and 2903 are very cheap. > > Just buy enough of them and replace them from your board. It is not difficult > > to replace them. > > Nope, not so easy with my board because it's dual sided (as opposed to > the US versions) and it's quite difficult to clean the holes with a > solder sucking wick, even if I cut those parts off. The solder cools > too fast, and the holes seem pretty tight too. I don't have a vacuum > type yet. The board is also covered with lacquer, making soldering and > cleaning pretty difficult, heck, even measuring voltages requires > penetrating the lacquer with the probes!...(on both sides of the > board, even the part pins). > > > It would be extremely difficult if you were dealing with > > surface mount devices. > > Yep, lucky it's not. > > > Just replace them one at a time. There are only > > a few of them. I used to do a lot of that. You will need a deslodering tool, > > a vacuum tool to suck the solder off when it is melt by your solder iron. > > The trick in doing this is you need to do it fast to prevent heat damage > > to other components not being removed. > > Yep, BTDT. Removed the power transistors only to find they were OK... > Actually, I'm pretty experienced in that area too, but I'm afraid that > all the fighting with board might damage it, and it's also hard to see > shorts because all the shiny gunk left after soldering - I don't have > a cleaning agent to clean the board after it. > > > My estimate is it will take about one hour the most to replace all the IC's > > on the board. It will take a minute to solder a replacement chip back in. > > Yes, but with the danger of damages and shorts to my only board... > > > I would go this way than troubleshooting the circuit. It's a dumb blind > > approach but it is faster. > > I can understand this approach and it works sometimes, but I usually > prefer analysis before I use the cutting knife... > > Actually, I've made good progress and have even verified that some of > the IC's and transistors are working without removal, but tomorrow I'm > supposed to get two working units and then comparing signals will make > it much easier. > > Anyway, thanks for the good suggestions! > > cheers, > TM > > > > --- tinker man <tinkerman007@GMAIL.COM> wrote: > > > > > Hi David, seems this post is on the wrong thread (should be on ISCU debug). > > > > > > Anyway, I agree with all your recommendations and have actually > > > followed just that path. > > > Seems that in my ISCU the output transistors are actually OK because I > > > can inject a signal and get an output (and I've removed them for > > > testing too). > > > Also, even with analog circuitry not all signals affect all others, > > > since certain signal paths can stay unaffected until they reach a > > > problematic junction (where they meet a bad signal). Also, analog > > > circuits can be easier to debug with simple tools like a DVM than > > > digital ones that require storage scopes and logic analyzers...less > > > timing issues, clocks, etc. So it's not all so bad. > > > > > > And thanks for your complements, and although this crusade started > > > because I'm struggling to fix my van's multiple FI problems (I got > > > sick of waiting for the dealer to solve them, wasting my time and > > > money...) I hope this is going to be more of a group project (already > > > have gotten some preliminary qualitative results from a few members, > > > and lots of useful info anyway) for the future benefit of all list > > > members. > > > > > > And regarding possible damage on the test bench, I think I warned > > > enough about that... > > > > > > Cheers, > > > TM > > > > > > On 9/17/07, David Kao <dtkao0205@yahoo.com> wrote: > > > > Linear circuit like this without a schematic is very difficult > > > > to troubleshoot. Unlike digital circuit, a bad component that > > > > causes a signal (voltage) to drip off will be propagated to > > > > everywhere. That makes all signals all over the circuit board to > > > > goo wrong. It then becomes extremely difficult to locate the > > > > component that causes everything to go wrong. Digital circuit > > > > on the other hand is extremely easy to isolate the faulty device. > > > > > > > > I would take a dumb approach to troubleshoot such a circuit board. > > > > Check all cable connection first. Check the power transistors > > > > by checking the P-N or N-P junctions to see if any of them becomes > > > > short or open. Check all resistors, especially power resistors, to > > > > see if any of them is burnt out or changed value because of heat > > > > over time. Look for any other components for sign of damage. > > > > This approach usually can be faster and sufficient to locate the > > > > bad component and have it replaced. > > > > > > > > If you want to check out the active components then use an oscilloscope, > > > > preferably a digital scope that can memorize the measured signals. > > > > Sync and hold the signal with traditional scope is almost impossible > > > > for this task. > > > > > > > > LM2902 can be configured as amplifier, filter, analog buffer, etc. Single > > > > supply voltage makes their circuit more complex than those with dual > > > > differential supply. But LM2902 and LM 2903 operating at such low power > > > > level makes them extremely durable. Troubleshooting with live voltage on > > > > can be more damaging than actual use on the Vanagon. > > > > > > > > Your effort in troubleshooting it is admirable. Good luck. > > > > > > > > David > > > > > > > > > > > > --- tinker man <tinkerman007@GMAIL.COM> wrote: > > > > > > > > > On 9/17/07, Bob Donalds <donalds1@verizon.net> wrote: > > > > > > TM > > > > > > I did not mean to exclude the list > > > > > > I'm kind of out of my league with the tech part of this > > > > > > > > > > Maybe, but you have lots of important info backed up by lots of experience... > > > > > And yes, those microprocessors ARE my league...:-) > > > > > (but engines, distributors, dynos and mechanics aren't...). > > > > > If my Garage mechanics (not only VW) were competent at fixing fuel > > > > > injection systems I wouldn't get into it, but it seems when it gets to > > > > > electronics they get a dumb look on their faces and start replacing > > > > > very expensive parts unnecessarily... > > > > > So I've learned to diagnose before I let them get near. They do the > > > > > mechanical stuff, I do the thinking...:-) (With the help of the list > > > > > and Bentley). > > > > > > > > > > > so share anything I write you with the list > > > > > > > > > > Great. This will stir much interest, I'm sure. > > > > > > > > > > > the CPU is again not something I looked at I was getting this looked at with > > > > > > SRS in Walpole MA Dick Shine > > > > > > > > > > What's "SRS in Walpole MA Dick Shine"? > > > > > > > > > > > He was taking out the EPROM's and reading them for me that's a far as I got > > > > > > so that's why I have what's on the EPROM's > > > > > > > > > > Like I said, good for backup and verification. > > > > > > > > > > > and as I said Daryl told me the Euro has no hookup for 02s > > > > > > > > > > That's interesting, because in the US Digijet (I think you told me) do > > > > > support O2 sensors, and someone on this thread reported that US > > > > > Digijets use a completely different CPU (Z80). So maybe US and Euro > > > > > Digijets are completely different animals. I'd like to get an internal > > > > > picture of all those. Currently I have just a 1990 Euro Digijet and > > > > > Jon Kenneke has posted on his website > > > > > (http://kenneke.com/vwfi/fi.html) a US Digifant. > > > > > I need more internal pictures of all models available (1983.5-1991, US > > > > > and EURO) to clarify these issues. > > > > > > > > > > > can you tell me what dist you have is it the 2.1 or the 1.9 with the vac can > > > > > > > > > > Already did in previous thread, it seems it does have a vac can. > > > > > TM > > > > > > > > > > > > > > > > > > > > > > > > > ____________________________________________________________________________________ > > > > Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - > > > Check it out. > > > > http://answers.yahoo.com/dir/?link=list&sid=396545469 > > > > > > > > > > > > > > > > > ____________________________________________________________________________________ > > Yahoo! oneSearch: Finally, mobile search > > that gives answers, not web links. > > http://mobile.yahoo.com/mobileweb/onesearch?refer=1ONXIC > > > > >


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