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I have the later model vacuum actuator:

(http://i711.photobucket.com/albums/ww112/jhoff/temporary-4.jpg)

I wanted to bench test the actuator using the method Koan outlines here:

http://forum.w116.org/mechanicals/ok-all-sorted-thank-for-the-replies-please-ignore-this-thread!!/msg39658/#msg39658

Can I apply vacuum to the actuator using a pump and still apply voltage to the pins to test it?  Do the electrics control a vacuum valve inside the actuator?

If the car cooperates I think this'll be my next project  ;)

Quote from: 1980sdga on 28 November 2011, 09:08 PM
Can I apply vacuum to the actuator using a pump and still apply voltage to the pins to test it?  Do the electrics control a vacuum valve inside the actuator?

That should work but ideally you need a reservoir of vacuum and a variable power supply to vary the current through the actuator. With a setup like that the movement of the cable would be in direct proportion to the current. Max current is about 300 mA from memory.

There's a clever little see-saw arrangement inside where the current tilts the see-saw one way and the diaphragm tilts it the other way through a spring.

When the current wins and the see-saw tilts it opens a port to admit vacuum to the diaphragm chamber which compresses the spring and brings the see-saw back to level and closes the vacuum port.

If the current drops the see-saw tilts to the spring side and opens a vent allowing air into the diaphragm chamber releasing the spring allowing the see-saw to return to level closing the vent.

I know all about this, I pulled a perfectly good unit apart rather than testing it on my car first. Stupid!

What do you suspect is wrong with your unit?

koan

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Quote from: Major Tom 6.9 on 29 November 2011, 04:16 AM
Did you take any photos ?

No but I've still got it, I'll do some pics on the weekend.

koan

I'm pretty sure it's OK. I just wanted to test it.

My cruise was working but it exhibited the symptoms of a bad amp. I'm going to have to relocate the actuator because my AC accumulator is in it's spot  ???

I have a vacuum pump/reservoir rig that I used when sorting my ACC and door locks without having to run the engine. I figured I could use it to bench test this accumulator before going to the trouble of installing.

I have a 12v power supply but no way to vary the current. Any input on this?

Thanks!  I'm looking forward to seeing some pics of the inside of this thing!

Quote from: 1980sdga on 29 November 2011, 01:32 PM
My cruise was working but it exhibited the symptoms of a bad amp.

I get aggressive over and undershoots of speed control which I think is the actuator. I tested it on the car and couldn't get smooth operation.

Quote
I have a vacuum pump/reservoir rig that I used when sorting my ACC and door locks without having to run the engine. I figured I could use it to bench test this accumulator before going to the trouble of installing.

I have a 12v power supply but no way to vary the current. Any input on this?

The actuator resistance spec is to 10 to 22 ohms.

An instrument cluster dimmer rheostat in series with the supply should be able to handle the current I think. At minimum resistance the current might be too much to a 10 Ohm actuator but it should reach maximum travel well before that with good vacuum.

Quote
Thanks!  I'm looking forward to seeing some pics of the inside of this thing!

I'll do it (after I finish painting a cornice in 4 colours, hanging a few pictures and helping with curtains, the list will probably grow before the weekend - if I'm really really lucky...).

koan

Quote from: koan on 29 November 2011, 03:09 AM

There's a clever little see-saw arrangement inside where the current tilts the see-saw one way and the diaphragm tilts it the other way through a spring.

koan

It's called a Wheatstone Bridge, and there endeth my useful input to this thread. I also am interested to see any photos or further information to be found.

Edit: Apologies for wrong information, as has been correctly pointed out to me a Wheatstone Bridge in fact is a device to control voltage, impedance etc in an electrical circuit whereas the cruise actuator is more of a negative feedback loop type arrangement.

Cheers,

Quote from: koan on 29 November 2011, 02:50 PM
I'll do it (after I finish painting a cornice in 4 colours, hanging a few pictures and helping with curtains, the list will probably grow before the weekend - if I'm really really lucky...).

Pictures and description posted in gallery, W116.org Gallery » Garage » koan's bits » VDO Vacuum Cruise Control Actuator



And guess what!   Dale is away for the weekend so painting, picture hanging and curtains have taken on an exceedingly  low priority :)

koan

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Quote from: Major Tom 6.9 on 03 December 2011, 07:59 AM
Its always quite interesting to see how things "got done" in the days prior to the dirt cheap electronics that now rule our world.

Like the old ways.

Dale is my partner of 32 years...

koan

Quote from: koan on 02 December 2011, 11:57 PM


And guess what!   Dale is away for the weekend so painting, picture hanging and curtains have taken on an exceedingly  low priority :)

koan

Pick the low hanging fruit. Maybe hang a picture.  BE A HERO!

Quote from: 1980sdga on 03 December 2011, 10:14 AM
Pick the low hanging fruit. Maybe hang a picture.  BE A HERO!

Great idea, good thinking!

koan

Thanks for the pics Koan, very informative. I found a link to a company in California that rebuilds cruise control and climate control systems, might be of use to somebody.

http://gdl-online.com/differences.html  Other info on their site could be useful too.

Cheers,

Thanks guys! Armed with just enough information to be dangerous, I'm off on another adventure  ;D

I installed the actuator this morning.

The small vacuum line on the actuator was plugged and it was still holding vacuum after 8 hours when I pulled the cap. It continued "hissing" while I fumbled around and placed it on the actuator nipple so I imagine my vacuum reservoir system is good to go.  I had some pretty serious vacuum problems when I began sorting the car so I'm a little spooked any time I bring another system online  :P

I'm going to take it on a test drive after checking the door locks again.  I figure if my door locks still work after a few hours then the actuator isn't giving me any problems on that front.

Any advise on adjusting the cable where it connects to the throttle?  For now I have it adjusted so the pad on the cable is just touching the throttle linkage.

I believe it had trouble "locking" onto the speed before but I can't really remember  :-\  I was sorting a bunch of stuff at once and decided to just plug the cruise stuff to rule out vacuum leaks at the actuator.

Since the threaded "vacuum" line is just a vent that leads into the cabin why go to all the trouble to put threads on it?  Maybe a failsafe of some sort to be sure the vent isn't plugged?

Quote from: 1980sdga on 04 December 2011, 12:22 PM
Any advise on adjusting the cable where it connects to the throttle?  For now I have it adjusted so the pad on the cable is just touching the throttle linkage.

The book says the cable should be adjusted to be just clear of the throttle linkage.

Since the threaded "vacuum" line is just a vent that leads into the cabin why go to all the trouble to put threads on it?  Maybe a failsafe of some sort to be sure the vent isn't plugged?
[/quote]

Yes, it's an odd one that.

koan

I went for a test drive and all I seem to have is accelerate. It doesn't lock onto the speed, nor does it do anything else but at least it's sort-of alive...

It seems like my amp is dead.

(http://i711.photobucket.com/albums/ww112/jhoff/temporary-6.jpg)
(http://i711.photobucket.com/albums/ww112/jhoff/temporary-5.jpg)

I'm going in...

(http://i711.photobucket.com/albums/ww112/jhoff/temporary-9.jpg)

(http://i711.photobucket.com/albums/ww112/jhoff/temporary-8.jpg)

(http://i711.photobucket.com/albums/ww112/jhoff/temporary-7.jpg)

It looks to be in great shape. My ACC amp had some pretty obvious cold joints and such but the cruise amp looks pristine. It is covered in some sort of lacquer or something and it smells like a transistor radio from years ago.   I cleaned the contacts and put some dielectric grease on the plugs and tried another test drive.

I went on the highway where I could cruise "the double-nickle".  Nothing... It would accelerate but wouldn't lock.  As I returned home I tried it again at 25mph and it worked  :o  I managed to keep it engaged by using the stalk to accelerate back to speed and it held speed for about 5 minutes and dropped out on a slight downhill. Now nothing except for accelerate. 

I removed the amp after returning home and it was cool. I couldn't find any hot spots.

Maybe check the connection at the speedometer, fuse, ground, etc. and see how it goes.

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Quote from: Major Tom 6.9 on 06 December 2011, 04:54 PM
re-cap and blanket resolder required - theres no avoiding it  8)

theres a thread on here somewhere that lists all the values and where they go.

Wonderful!  I've searched and searched... Still searching.

The silver box is called a Cruise Control Amplifier and here is MT's original thread giving all the values of the capacitators.

http://forum.w116.org/mechanicals/i-pulled-out-my-cruise-control-module/ (http://forum.w116.org/mechanicals/i-pulled-out-my-cruise-control-module/)

It is difficult to get caps that are exact and you may end up with an amplifier that is not as accurate as the original but it should work.

Bill

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