James Sweet wrote:
> don b. wrote:
>> In article <gkmkne$er9$(E-Mail Removed)>, James Sweet says...
>>> Kim Slyns wrote:
>>>> My speedometer/odometer was intermittent for quite a while but has
>>>> now stopped working altogether. Repair is estimated at A$350 so I
>>>> would like to see if I can fix it myself.
>>>> Any ideas anyone?
>>>>
>>>
>>> It's almost always solder joints on the circuit board in the
>>> speedometer.
>>
>> I wish I had better news for you but, I've been dealing with the exact
>> same
>> issue for a year. What repair business said they could fix it for 350? Be
>> cautious of there claims. There are a couple of things that go bad on
>> the 1992
>> 940 speedometer boards. Soldier is one but, this comes from the
>> biggest issue. A
>> capacitor. It goes bad and leaks on to the board. Once that happens
>> the chances
>> of repair drop. Still worth letting them try but get a guarantee! I've
>> sent mine
>> back three times. Each time they SWEAR it works on the "bench".
>> However, after
>> putting it back in the car it was the same. They have had it for
>> months now
>> "trying" to get a replacement from a savage yard and put something
>> together that
>> I can use. Good luck!
>>
>
>
> Should have thought to mention that too, I haven't had the capacitor
> problem on 700s, but I have had it with the analog clocks in 240s.
>
> It's worth replacing all the electrolytic capacitors in things like
> that, they're cheap and most of them fail eventually. Tantalum is an
> option, under most circumstances they last a very long time and do not
> degrade over time or become temperature sensitive, but they are not
> immune to failure either, and when they do, it tends to be spectacular.
> The usual failure mode for a tantalum capacitor is they short circuit,
> and if there's enough current capacity behind them (car electrical
> system for example), they will usually catch fire.
Tantalums are high density high performance caps with good electrical
characteristics. At the end of the day capacitors are hard to make and
they are many many choices which trade off different characteristics. I
doubt these need to have any special characteristics so the thing to go
for is life time (Aluminium electrolitic). It can he hard to find this
in the cataglogue but you want the highest temperature rating with the
longest life. eg 125C at 5000hrs (105C at 2000hrs is also not bad but
much more common). Also go for the large parts variants. I have also
seen solid polymer Electrolitics recently, but are much more expensive.
Also of course go for a high quality brand (usually Japanese).
These circuits are not espeically high density and should be repairable
even it looks a bit messey with extra wire and glue.
--
Tony
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