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BarryL Samba Member
Joined: November 01, 2004 Posts: 14255 Location: Casa de Oro, California
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Posted: Sat Dec 19, 2015 6:52 pm Post subject: Turn signal flasher 58-60 how it works |
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Here is a closer look at how the early style turn signal flasher relay is constructed and operates. This version is a 6 volt 2 X 18 watt type.
The nichrome wire type flasher relay is an exquisite example of German engineering and a masterpiece of design using analog materials of the day.
Outside.
Inside.
Components of the nichrome wire turn signal flasher relay.
The trigger or key to this whole mechanism is the long single strand of nichrome wire stretched top to bottom.
Nichrome wire has properties that allow it to lengthen when heated and contract when cool. The designers of the nichrome wire turn signal relay used a finely tuned strand of nichrome wire to achieve the blinking effect for the bus' turn signals.
The nichrome wire is insulated from the metal arms it is connected to.
A. Power enters here.
B. Travels up this coiled section of nichrome wire which creates resistance.
C. Enters the single strand of nichrome wire.
D. Continues down to here.
E. Goes to ground to complete the heating/lengthening circuit.
Here is the sequence of events that make the bulbs flash.
1.
When driving, all these areas are powered but nothing is occuring. The nichrome tension wire is at its tautest and holding the electromagnet/turn bulb arm and contact against the turn signal selector switch electromagnet and bulb power feed but there is no activity until the turn signal lever is activated.
2.
When the turn signal lever is activated it completes a circuit to the 2 X 18 watt bulbs selected by the direction lever left or right, sending power to those areas.This starts a reaction as the bulb's filaments glow bright.
An electromagnetic field occurs in the steel tree as the bulbs complete the circuit. This pulls in the duration power supply arm and speedometer arrow light arm magnetically to make their contacts and complete their respective ciruits.
3.
The moment the duration contact completes its circuit to the nichrome wire, the straight taut tension strand expands from the heat generated as the wire resists electron flow and the top spring is able to pivot the contact away from the electromagnet/turn bulb contact.
4.
The instant the expanded nichrome wire and top spring disconnects the electromagnet/turn bulb power contact, the turn bulbs go off and the electromagnet field collapses simultaneously disconnecting the speedometer arrow bulb and nichrome duration wire feed.
5.
Now the unpowered nichrome tension wire cools rapidly and shrinks back to its original tension which closes the electromaget/turn bulb contact as the top spring is unable to hold it open and repeats the process over and over...
... until the turn signal lever is returned to its central, or off position, which opens the circuit and stops the reaction.
_____________________________________
Built into each unit is the ability to sense a burned out bulb or ungrounded bulb.
The top spring and nichrome duration tension wire are tuned to attract and pull away from a certain amount of magnetic pull vs spring tension.
The turn signal circuit must have 2 X 18 watts load on the electromagnetic coil in order to be strong enough to close the duration circuit arm which will heat the nichrome wire. If one bulb is burned out, most likely, the other bulb will just remain on until the turn signal lever is turned off. Sometimes there is enough electromagnetism to pull on the speedometer arrow bulb but it doesn't blink.
These units are well built and will give long service if kept relatively dry with clean contacts.
Last edited by BarryL on Wed Dec 23, 2015 9:04 am; edited 1 time in total |
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Stocknazi Samba Member
Joined: June 18, 2004 Posts: 5150
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Posted: Sat Dec 19, 2015 7:09 pm Post subject: Re: Turn signal flasher early style how it works |
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Excellent write-up.
It's always fun to open these t/s units up and get them working again.
Usually all that's required is to clean the contact points. _________________ WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).
"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."
Thomas Jefferson |
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easy e Samba Member
Joined: May 28, 2008 Posts: 3931 Location: 1 hr north of Santa Barbara
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j.pickens Samba Member
Joined: December 03, 2002 Posts: 9789 Location: Exit 7, New Jersey
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Posted: Sun Dec 20, 2015 11:20 pm Post subject: Re: Turn signal flasher early style how it works |
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Now I'm feeling guilty for going out and buying a $6 flasher relay at NAPA when an original fails! _________________ Founder and Chairman Emeritus, ECMSAS
BBX BBXII and BBXXI Long Distance Award Winner
BeaterBarndoor wrote: |
i wish more people would actually drive their vws rather than just talking about what they have in the garage. |
Red Fau Veh wrote: |
If you've seen one sunroof swivel seat kombi, you've seen them all! |
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BulliBill Samba Member
Joined: July 09, 2004 Posts: 4572 Location: St Charles, MO
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Posted: Mon Dec 21, 2015 8:35 am Post subject: Re: Turn signal flasher early style how it works |
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Hi Barry and all,
Incredible write up of the process for us non-electrical dumkoffs! Nice explanations and great, clear and well-marked photos too. Thanks for taking the time to illuminate this subject for all of us.
I was lucky enough to have Barry offer to take some time and look inside my flasher unit just like that one and fix it when mine wouldn't work correctly during my build process. It will eventually go back in my '59 Double-Cab with my pride in having a VW buddy work on a piece of my Bus! Thanks again Barry for your help with my unit, and for showing us how these flasher units work and what they look like inside!!!
Bill Bowman _________________ I'm looking for these license plate frames for my fleet:
Coeur D'Alene - Lake Shore Volkswagen
Mission VW - San Fernando
Thornton VW - Stockton
Thanks for any help! |
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Fredrok Samba Member
Joined: July 06, 2014 Posts: 227 Location: Under the evergreens. CO
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Posted: Mon Dec 21, 2015 9:04 am Post subject: Re: Turn signal flasher early style how it works |
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GREAT write up Barry, thanks for taking the time. |
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coolerthanelvis Samba Member
Joined: June 30, 2003 Posts: 924 Location: San Diego, CA
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Posted: Mon Dec 21, 2015 11:35 am Post subject: Re: Turn signal flasher early style how it works |
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BulliBill wrote: |
Thanks for taking the time to illuminate this subject for all of us.
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I see what you did there. Clever!
Great write-up, Barry! _________________ Shawn
SV2s member #420
'68 Westy
"Do or do not, there is no try."
-Silent Bob |
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BarryL Samba Member
Joined: November 01, 2004 Posts: 14255 Location: Casa de Oro, California
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Posted: Mon Dec 21, 2015 1:20 pm Post subject: Re: Turn signal flasher early style how it works |
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BulliBill wrote: |
I was lucky enough to have Barry offer to take some time and look inside my flasher unit just like that one... |
'Sup! That is yours. Here's how it went.
Outside looks good with grounding strap in place going to mounting leg.
Got out the dummy load for the 2 X 18 watt relay.
Doesn't work, hmmmmm.
Sometimes the grounding rivet is funky but this looks good and isn't
loose or corroded.
Sometimes a slight right or left of the tension screw will bring it back to life but only slight, about 2 minutes on a clock face.
Still no dice.
Time to open it up. This rivet has to come off first.
I want to reuse this rivet so micro surgery with a Dremel to unlock the brass.
A little pry job around the soft aluminum edge will get a lip to open on the can. Any scratches under the lip will be hidden later.
I use baby Channel Locks to smooth and open the lip finally.
Make sure the lip is open further than the phenolic wafer it wraps over.
I like to leave a little trace of the key so the can goes back on the same relative way it cam off.
The inside is not NOS but isn't bad except for the little ancient spider web.
The top spring isn't rusty which water damaged ones will show.
Uh oh! This should be closed.
Sometimes the tension has loosened and needs tightened to get it to close.
This adjuster is frozen from time.
Manually holding the turn circuit works.
Manually testing the speedometer turn arrow circuit requires this to close.
The speedometer turn arrow bulb circuit works manually.
So, what's wrong? The nichrome wire has a fracture at the base from who-knows-what: sometimes over voltage, sometimes dropping, sometimes old age. This photo is after I tried a patch with silver solder which never works.
To repair it such that it fits Bill's old can and contacts I'll use parts from an NOS one and parts from the old base.
The replacement NOS style has slightly different leg positions so those have to be connected to the best possible location.
A fresh new nichrome wire.
Now the can is put back on with soft light small hammer taps.
Then roll a smooth plastic screw driver handle to smooth it all. I marked the new contact locations in the phenolic disc.
Bench test good.
I reinstalled the old ground rivet. lightly hammered, then solder for reliability. Real world burn in good.
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BulliBill Samba Member
Joined: July 09, 2004 Posts: 4572 Location: St Charles, MO
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Posted: Mon Dec 21, 2015 5:48 pm Post subject: Re: Turn signal flasher early style how it works |
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Holy Shit! Barry, you're an electronic "God"!
I bet I couldn't have ever done all that, even if I could figure out what was wrong! I didn't realize that was "my" flasher can too. Very cool. I definitely need to get that can back into my '59DC before Spring. Thanks again!
Bill _________________ I'm looking for these license plate frames for my fleet:
Coeur D'Alene - Lake Shore Volkswagen
Mission VW - San Fernando
Thornton VW - Stockton
Thanks for any help! |
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BarryL Samba Member
Joined: November 01, 2004 Posts: 14255 Location: Casa de Oro, California
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Posted: Mon Dec 21, 2015 7:34 pm Post subject: Re: Turn signal flasher early style how it works |
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BulliBill wrote: |
Holy Shit! Barry, you're an electronic "God"! |
I'm not worthy.
Hey, you are one of the Samba Supreme Beings. Like I told you, though, it's guaranteed as long as I live. It might flicker or fail but send it back and I'll make it new again. |
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Suboval Samba Member
Joined: September 15, 2003 Posts: 794
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Posted: Tue Dec 22, 2015 7:59 pm Post subject: Re: Turn signal flasher early style how it works |
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Nice writeup Barry!
Welcome to the relay club.
The canned relays were used from 58-60.
The early 55-57 relays were the bakelite ones.
_________________ It all works on paper.
There's two things we learn from history:
1.) History repeats itself.
2.) We don't learn from history. |
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BarryL Samba Member
Joined: November 01, 2004 Posts: 14255 Location: Casa de Oro, California
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Posted: Wed Dec 23, 2015 9:03 am Post subject: Re: Turn signal flasher early style how it works |
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Suboval wrote: |
The early 55-57 relays were the bakelite ones. |
What do those look like inside? |
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BarryL Samba Member
Joined: November 01, 2004 Posts: 14255 Location: Casa de Oro, California
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Posted: Wed Dec 23, 2015 9:07 am Post subject: Re: Turn signal flasher early style how it works |
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Suboval wrote: |
The canned relays were used from 58-60. |
Re-titled to reflect that, thanks. |
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Suboval Samba Member
Joined: September 15, 2003 Posts: 794
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Posted: Wed Dec 23, 2015 9:24 am Post subject: Re: Turn signal flasher early style how it works |
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BarryL wrote: |
Suboval wrote: |
The early 55-57 relays were the bakelite ones. |
What do those look like inside? |
_________________ It all works on paper.
There's two things we learn from history:
1.) History repeats itself.
2.) We don't learn from history. |
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vwbusman66 Samba Member
Joined: May 17, 2014 Posts: 386 Location: Kingsville, MD
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BarryL Samba Member
Joined: November 01, 2004 Posts: 14255 Location: Casa de Oro, California
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Posted: Thu Dec 24, 2015 1:22 pm Post subject: Re: Turn signal flasher 58-60 how it works |
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vwbusman66 wrote: |
Been there, done that: |
Yes, I saw you in the sticky and didn't what to add my diatribe to your already thread. |
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