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DanHoug
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Joined: December 05, 2016
Posts: 4777
Location: Bemidji, MN
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dabaron
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Joined: June 21, 2018
Posts: 2559
Location: Philly, mang
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 Posted: Thu Apr 11, 2019 12:18 pm Post subject: Re: AFM replacement wiper board |
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| DanHoug wrote: |
well... this arrived today:
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looks like it has been calibrated - notice the soldering between the far right pads. i wonder how these were aligned and if the carbon is logarithmic across the range.
_________________
1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
BiWerks Design, LLC |
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DanHoug
Samba Member
Joined: December 05, 2016
Posts: 4777
Location: Bemidji, MN
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| Posted: Thu Apr 11, 2019 1:12 pm Post subject: Re: AFM replacement wiper board |
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and the resistor pads have been laser cut.
_________________
-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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Ahwahnee
Samba Member
Joined: June 05, 2010
Posts: 9799
Location: Mt Lemmon, AZ
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| Posted: Thu Apr 11, 2019 1:31 pm Post subject: Re: AFM replacement wiper board |
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The ad says:
| Quote: |
Before you place order , please check the part number of your original sensor is :
0280202079
025906301C
025906301
Part number is on the surface of your original sensor |
Did you find one of those p/n on your original sensor? |
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0to60in6min
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Joined: November 27, 2006
Posts: 3416
Location: OR & CA (Oregon/California)
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jlrftype7
Samba Member
Joined: July 24, 2018
Posts: 3577
Location: Chicago
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| Posted: Thu Apr 11, 2019 1:37 pm Post subject: Re: AFM replacement wiper board |
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| Ahwahnee wrote: |
The ad says:
| Quote: |
Before you place order , please check the part number of your original sensor is :
0280202079
025906301C
025906301
Part number is on the surface of your original sensor |
Did you find one of those p/n on your original sensor? |
Good question....
_________________
'68 Westy- my first VW and vehicle/Bus- long gone.- sold it to a traveling Swiss couple....
'67 Type 3 Fastback, my 2nd car- gone
'69 Semi-Auto Stick Shift Beetle-gone
2017 MINI Coopers, our current DDs
‘84 Tin Top - Hilga....Auto |
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DanHoug
Samba Member
Joined: December 05, 2016
Posts: 4777
Location: Bemidji, MN
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| Posted: Thu Apr 11, 2019 2:14 pm Post subject: Re: AFM replacement wiper board |
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in my photo, you can see "Bourns" and ...9006... so there is a PN on it. i COULD go out to the garage and look but we're in the middle of a blizzard.
Bourns is a maker of excellent quality potentiometers. the carbon track on this China one is what i would worry about over the long term... just how resistant it is to wear. it looks to have a more matte finish than the OEM.
_________________
-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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dabaron
Samba Member
Joined: June 21, 2018
Posts: 2559
Location: Philly, mang
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| Posted: Fri Apr 12, 2019 5:26 am Post subject: Re: AFM replacement wiper board |
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| DanHoug wrote: |
in my photo, you can see "Bourns" and ...9006... so there is a PN on it. i COULD go out to the garage and look but we're in the middle of a blizzard.
Bourns is a maker of excellent quality potentiometers. the carbon track on this China one is what i would worry about over the long term... just how resistant it is to wear. it looks to have a more matte finish than the OEM. |
i would be more concerned that the carbon resistance has been calibrated across the full scale. this ain't no Bourns, but it sure mimics the look
your part number begins 288... it's under the wiper
_________________
1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
BiWerks Design, LLC |
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dbeierl
Samba Member
Joined: April 22, 2009
Posts: 164
Location: Providence, Rhode Island, USA
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| Posted: Fri Apr 12, 2019 7:29 am Post subject: Re: AFM replacement wiper board |
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| DanHoug wrote: |
in my photo, you can see "Bourns" and ...9006... so there is a PN on it. i COULD go out to the garage and look but we're in the middle of a blizzard.
Bourns is a maker of excellent quality potentiometers. the carbon track on this China one is what i would worry about over the long term... just how resistant it is to wear. it looks to have a more matte finish than the OEM. |
025 906 301 is the 1.9l AFM
025 906 301 C is the 2.1l AFM
A bit cynical perhaps, or maybe they just misunderstood. The ad says it's for 2.1l.
I suspect that the hand rework on your resistor plate is because the laser trim ran out of range and severed the last resistor completely. |
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dbeierl
Samba Member
Joined: April 22, 2009
Posts: 164
Location: Providence, Rhode Island, USA
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| Posted: Fri Apr 12, 2019 7:36 am Post subject: Re: AFM replacement wiper board |
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| dabaron wrote: |
i would be more concerned that the carbon resistance has been calibrated across the full scale. this ain't no Bourns, but it sure mimics the look
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It has, you can see the laser trimming marks on the individual resistors. Whether it's correct is of course another question. |
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MarkWard
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Joined: February 09, 2005
Posts: 17119
Location: Retired South Florida
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| Posted: Fri Apr 12, 2019 9:19 am Post subject: Re: AFM replacement wiper board |
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What a niche market. Looking forward to hearing how it does. It would be nice to have a condemned meter and bring it back to life with one of these replacement boards.
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Ahwahnee
Samba Member
Joined: June 05, 2010
Posts: 9799
Location: Mt Lemmon, AZ
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| Posted: Fri Apr 12, 2019 9:24 am Post subject: Re: AFM replacement wiper board |
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| dbeierl wrote: |
...025 906 301 is the 1.9l AFM
025 906 301 C is the 2.1l AFM
A bit cynical perhaps, or maybe they just misunderstood. The ad says it's for 2.1l... |
I think those are the p/n for the entire AFM unit - the number the ad referenced appears to be for just the plate/track/circuit board.
On my 1.9 is is there behind the wiper and is 1 288 310 051. |
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DanHoug
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Joined: December 05, 2016
Posts: 4777
Location: Bemidji, MN
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| Posted: Fri Apr 19, 2019 12:49 pm Post subject: Re: AFM replacement wiper board |
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a bit more work on the replacement board...
loosening the AFM board screws. these are bonded with both a heat sensitive locking compound and a 'squaring' of the screw threads to prevent loosening. so heat the screw head with a 200watt solder iron with a fine tip and put some valve grinding compound on a good fitting screwdriver and they come right out with strong downward pressure while turning
here's the two boards when out:
prior to and after replacing the board, i set up a test jig supplying 5vdc to pin 3, pin 4 ground, and voltage signal of wiper off pin 2. my OEM board did NOT have drops when swept using an analog meter but i'd previously cleaned the track, wiper contacts, and pivot contact. the below chart shows voltage comparative readings between the OEM and the China board using the intersection points formed by the resistance pads. it wasn't a perfect reference but fairly close.
so far, without a test drive, the China board looks to be a good copy, with a slight voltage boost at pre WOT. the durability of the conductive pad remains unknown.
_________________
-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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Butcher
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Joined: December 05, 2015
Posts: 1285
Location: Right Here
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| Posted: Sat Apr 20, 2019 8:18 am Post subject: Re: AFM replacement wiper board |
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| If I recall, the screws are Pozidriv not Phillips. Using the right bit will allow a better result. I had to heat the bolts up to release the locking compound. You really do not want to break/strip those bolt heads. |
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dbeierl
Samba Member
Joined: April 22, 2009
Posts: 164
Location: Providence, Rhode Island, USA
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| Posted: Sat Apr 20, 2019 9:10 am Post subject: Re: AFM replacement wiper board |
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| Quote: |
| but i'd previously cleaned the track, wiper contacts, and pivot contact. |
The pivot contact apparently gave trouble (as did similar ones in hard drives of the same period) as by at least '84 they added the wire visible in your AFM to bypass that contact completely. |
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Ahwahnee
Samba Member
Joined: June 05, 2010
Posts: 9799
Location: Mt Lemmon, AZ
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| Posted: Sat Apr 20, 2019 11:03 am Post subject: Re: AFM replacement wiper board |
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[quote="dbeierl"]
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| ...The pivot contact apparently gave trouble (as did similar ones in hard drives of the same period) as by at least '84 they added the wire visible in your AFM to bypass that contact completely. |
I think that change was later than '84 (OP has a 2.1) but it is worthwhile adding the wire to the earlier AFM:
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DanHoug
Samba Member
Joined: December 05, 2016
Posts: 4777
Location: Bemidji, MN
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| Posted: Sat Apr 20, 2019 12:36 pm Post subject: Re: AFM replacement wiper board |
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| Butcher wrote: |
| If I recall, the screws are Pozidriv not Phillips. Using the right bit will allow a better result. I had to heat the bolts up to release the locking compound. You really do not want to break/strip those bolt heads. |
i think you're right. after that photo i put in M3 x 8 - 0.50 pitch 12.9 Allens. the screw length that comes out is 8mm but the hole is not threaded the entire way, more locking i suppose so you have to use either 8mm with washers or 6mm without washers for length. either way, hardened Allen head screws are the way to go when it goes back together.
_________________
-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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colorfull
Samba Member
Joined: January 01, 2018
Posts: 14
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| Posted: Tue Apr 23, 2019 7:33 am Post subject: Re: AFM replacement wiper board |
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DanHoug,
Did you get a chance to test your refurbished AFM?
Very curious about the results...
Cheers! |
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DanHoug
Samba Member
Joined: December 05, 2016
Posts: 4777
Location: Bemidji, MN
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| Posted: Tue Apr 23, 2019 7:37 am Post subject: Re: AFM replacement wiper board |
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no, not yet. i'm waiting for a spring scale to arrive so i can set the arm tension to the exact value of my current AFM. i've been tweaking my spring tension yet again and am really happy with the drivability and mpg so i've very close... waiting on eBay for the spring scale.
_________________
-dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
|
| Back to top |
|
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dbeierl
Samba Member
Joined: April 22, 2009
Posts: 164
Location: Providence, Rhode Island, USA
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| Posted: Tue Apr 23, 2019 8:32 am Post subject: Re: AFM replacement wiper board |
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| DanHoug wrote: |
| no, not yet. i'm waiting for a spring scale to arrive so i can set the arm tension to the exact value of my current AFM. i've been tweaking my spring tension yet again and am really happy with the drivability and mpg so i've very close... waiting on eBay for the spring scale. |
You might find this arrangement useful... |
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