armanmik at earthlink.net
Wed Jul 27 14:29:37 EDT 2005
>From: "rob hod" <rob3 at hod3.fsnet.co.uk>
>Subject: Re: Electronic gremlins
> Very interesting mike, - For a while now on my '88 100 my digital clock
>backlighting has been intermittant with the lights on. (it should just dim
>when you turn the headlights on, but as often as not it just goes out).
> it would take out the
>cruise control with it... Doh!
>Funny thing was that using the left indicator brought the speedo back to
>life temporarily (until I turned it off)! Anyway I suspected ingress of
>moisture and/or earthing issues. Certainly it seemed to be behaving itself
>OK again today.
> However is it the case that this link in the cluster could be the problem?
>or part of the problem?
> Cheers, Rob.
I'm not familiar enough with the instrument cluster on the '88 100 to know
how similar it is. If it is the "new style" dashboard (padded eyebrow over
instruments), there is a good possibility that this is the problem. If it
is the "old style" more angular dashboard - (84,85, 86, 87?), probably not.
The problem is the various connectors are flow soldered all at once on
assembly (with a "wave soldering machine")- if you get the machine hot
enough to solder the big pins correctly, all the itty bitty diodes and
resistors melt. If you keep the machine cool enough not to toast the little
parts, the big parts won't heat up enough and you wind up with cold solder
joints. This problem is not confined to car parts - I've seen it on plenty
of other electronic devices, power supplies, etc.
Solution is to remove the PC boards from the cluster, examine all the
larger, heavier parts with a jeweler's loupe (5x or so), and prepare to be
amazed at how crappy some of the solder joints are. Using a 35 watt
soldering pencil and some new, fresh rosin core electronic solder, just
resolder the entire row - and anything else that looks suspicious. Add
contact enhancer, reassemble and away you go!
90 V8, not just a car, an ADVENTURE!
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