Date:         Tue, 31 Dec 1996 12:40:12 -0500
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Dave T. Richards" <us014471@pop3.interramp.com>
Subject:      Re: Air Flow Meters <sigh>

Rocko Flamefart wrote:
> 
> here's a copy of a private post to Herb... edited for artistic sake.
> 
> don't be too quick to condemn an AFM...  i've got several posts on
> these in the archives but i'll relate a little to you now.
> 
> it is my experience that one *cannot* use an ohmmeter to check the
> afm, despite what Bentley says.  there are surface mount capacitors
> in there that charge and discharge as the wiper arm moves and the
> resistance jumps all over the place.  even on a brand spanking new
> one, which i did buy :(
> 
> use an oscilliscope or a fast acting DVM and measure the key-on
> voltage on the wiped output.  look for voltage dropouts or non linear
> response.  each afm that i have tested with resistance alone, has tested 'bad'!
> 
> also, it is very typical for the carbon track to be worn down so one
> sees the fiberglass board.  one can squeeze down the wiper arm to
> have it ride on a new area, but even this doesn't seem totally
> essential.  what DOES make a difference, it cleaning the carbon track
> with a clean pencil eraser and then running a heavy weight cotton bond
> cardstock, eg a 'rough surfaced' business card, under the wiper and
> burninshing the wiper contact.
> 
> let me know if you need clarification on anything.
> 
> -danAlso!
	you rub over the carbon track with the lead of a soft pencil (at 
least 2b) and this will restore the carbon on the track (for a while 
anyway)
	Dave WR3I

-- 
-------------------------------------
Name: Dave (WR3I)
E-mail: us014471@pop3.interramp.com (David Trevor Richards)
Date: 09/12/95
Time: 21:47:25

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