1967 capacitors(dash)

[rich heimbrod]

please excuse my ignorance on this, but when i took my cluster out, some capacitors came loose, some the wirw pulled out. what is the purpose of these and do i need to replace all of them. i'm upgrading the radio (sorry)maybe static won,t be a factor.

[Jack H.]

Re: 1967 capacitors(dash)

Short of an introductory course in electrical engineering and a circuit topoplogy analysis, a 'quick' answer to what each capacitor was intended to do is way to broad a subject. Essentially, 'caps' are to electrical charge flow as a bucket or catch basin is to the flow of water (temporary storage facility).

The part has MANY applications in electrical circuits (timing component, general storage vehicle, AC/DC 'splitter' and so on). You have to get specific (which cap/where) in order to expect a competent answer. Further, the factory didn't put these parts there for their health, so if you broke one or more of 'em I guess I'd advise you to replace them.

ONE thing a capacitor is used for is a frequency sensitive 'splitter'. In general, capacitors block DC current but pass AC current components. How high the 'pass band' frequency is depends on the native impedance of the surrounding circuit and the capacitor's rated value (uF).

So, from a radio interference perspective, 'tacking' a capacitor to ground at the point where a known 'noisy' circuit component is positioned, is a means of letting the higher frequency AC noise components travel to ground and 'die' versus propagating down the car's power lines and conducting and/or radiating to interfere with radio reception -- DC electrical components 'ignore' the cap while AC electrical components 'see' the cap as a quick path to ground.

You'll find capacitors installed for this reason (RF suppression) tacked here/there throughout the car's electrical system adjacent to various 'known' noise sources. Items like the heater fan, the ignition coil, the alternator or generator, the headlight switch and so on.... Each has it's own job and some may be 'cosmetic' in nature (their effects only show up when you're in a radio reception 'fringe' area, tuned to a weak AM station, Etc.) while others can be more critical in nature.