MSD Garage door tango??

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boilermaker

boilermaker

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NO, I have not been drinking! So it goes this way. I have a MSD 6al on my slant. Yesterday as i was backing out of the garage, the door started on its way down ( no button pushed, old opener no door laser ). Took the antenna out, on the car.
Anyway, it seems that the car running at 750-800 rpm will trigger the door. Any one heard of this? Or, maybe I should speed up on my way out.

Thanks,
John
 
I work with some rf stuff for a living, it's not hard to believe your car is making rf, but powerful enough to trigger the door? That's really surprising. Maybe you can shield your sensor to test it
 
Peyote said:
I work with some rf stuff for a living, it's not hard to believe your car is making rf, but powerful enough to trigger the door? That's really surprising. Maybe you can shield your sensor to test it
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Just reading about MSD and pacemakers. There is talk about RF (MSD) problems with them as well. Maybe this is a good lesson for others? It sucks for my antenna.....
 
Try this:
Find a Radio shack still in business or any place to buy some .1 mfd, 50 volt or higher disc shaped capacitors.
Connect the two wires of the capacitor to the same terminals that the two wires to the garage door button go.
Your remote control will still work, but if the
wiring to the button is being triggered by rf from the ignition, it will be fixed.

But if the rf noise is triggering the actual remote control receiver, you'll see no change.
You don't have a fiberglass hood, do you?
Another possibility is that your hood is electrically isolated from the body by paint or oxidation.
I added a heavy ground wire from a new bolt into the hood to the firewall to greatly decrease ignition static on AM reception.
Make sure you still have a factory ground strap from a bolt near the back of the block to the firewall on the passenger side.
Your car is "transmitting" wideband noise and triggering the receiver somehow.

Does your AM radio reception have ignition noise static? I would expect it to.
 
Try temporarily disconnecting the wires to the manual button, and see if it still does it.

Another possible fix: if the wires to the button are two side-by-side wires molded together parallel, disconnect them and twist them so they run in a spiral twist, maybe
4 to 5 twists per inch.
Then reconnect.
No foolin'.
This is how old 1930s "noise-free" radio antenna lead-in wires were made.
The reversals cause the noise pickup to be cancelled.
You were not in the EE school at Purdue, I gather.
 
I have 2 4ft shop lights in my garage. when I start the charger with the hood open underneath the lights , they blink off and on . it's crazy .that's with a revonator ECU and otherwise stock ignition
 
I had a friend who was into CB radios. He had a 454 in a Chevy truck with two alternators, two D8 bulldozer batteries in the bed and a 1500 watt amp on his mobile. We used to sit out in front of the local neighborhood grocery store WAY out in the parking lot. I noticed one day while he was talking that everytime he keyed the mic, the automatic doors on the front of the store opened. lol Those were some fun times. Lyle dies from heart disease several years ago. His doctor told his wife that he believed the extreme RF from high power CB equipment through the years contributed. It can be nasty stuff.
 
It is unlikely that the problem is at the manual switch, because it typically engages the relay coil, and that takes more current than would get there remotely by RF. If the wires to the switch are acting as antenna, for remote receiver, then the fix of capacitor by Darthomas may not work, because the signal is likely getting there common mode. The capacitor would be a differential mode fix, and at switch end is pointless. A more suitable fix could be to apply a snap-on common mode choke at garage opener, on manual switch wires.

But with that said, a fix at the garage door will not fix the problem source, the MSD, so who know what other interference and problems it may create when driven about.

MSD CDI is multi-strike at lower RPM, and the re-strike interval may get by the simple decoder strategy of the RF receiver. You could try reprogramming, the receiver and transmitter with new codes. That was done using selector switches on most older models. Again no fix at problem source.

A better fix is to perhaps use an Ohm meter to measure plug wire resistance to insure a plug wire or two has not opened up. Also check for spark leaks on a humid day at night, carefully looking at all HV boots and cap terminals. Check distributor cap, rotor, coil to cap cable .....
 
RustyRatRod said:
I had a friend who was into CB radios. He had a 454 in a Chevy truck with two alternators, two D8 bulldozer batteries in the bed and a 1500 watt amp on his mobile. We used to sit out in front of the local neighborhood grocery store WAY out in the parking lot. I noticed one day while he was talking that everytime he keyed the mic, the automatic doors on the front of the store opened. lol Those were some fun times. Lyle dies from heart disease several years ago. His doctor told his wife that he believed the extreme RF from high power CB equipment through the years contributed. It can be nasty stuff.
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I had a sloppy tuned Linear Amp on my CB, man that thing would bleed over onto anything, used to drive down the street in front of a Sonic and place orders LOL.
 
I guess your gonna have leave the garage on the rev limiter? lol. That is a new one on me, I've never heard of that!
 
Kitcarlson is right , if you try a capacitor, it MUST be right at the terminals on the opener, not at the switch,
and there's no guarantee that will solve it, either.
It could still be common mode, and then you'd need to try another capacitor from one or the other wiring terminal for the switch to some metal frame point of the opener.
Still no guarantee.
Absolutely try changing the code!
If you don't mind having less sensitivity, consider wadding up the wire for the antenna into a ball, or lengthen it or shorten it.
Could help, many possibilities here, rf bugaboos are fun to iron out.
 
There are also snap-on ferrite beads, where you loop wires a few times, and snap them shut. They suppress rf in wiring, and could be tried on the button wiring.
I have no idea what frequency your remote uses or if a physical wire droops out of the opener like older ones had, but running an antenna wire through such a bead would desensitize it some.
If there's enough RF, it can be picked up directly by the circuit board in the opener anyway.
I'd like to know if disconnecting the button wires from the opener changes anything.
 
the67fish said:
I had a sloppy tuned Linear Amp on my CB, man that thing would bleed over onto anything, used to drive down the street in front of a Sonic and place orders LOL.
Click to expand...
I used to put a Galaxy CB and hunnert watt linear into rental cars when I was on the road for work.
One time I had just left home and was on I-94 near downtown Chicago, and a truck right behind me keyed up what must have been a kilowatt rig into phased antennas.
It walked through my linear backwards, and the rectified RF keyed up the pull-in relay on MY linear! That gave me a few seconds of consternation, for sure!
 
Darthomas said:
I used to put a Galaxy CB and hunnert watt linear into rental cars when I was on the road for work.
One time I had just left home and was on I-94 near downtown Chicago, and a truck right behind me keyed up what must have been a kilowatt rig into phased antennas.
It walked through my linear backwards, and the rectified RF keyed up the pull-in relay on MY linear! That gave me a few seconds of consternation, for sure!
Click to expand...
The guy building these "illegal" amps we used was a trip, kinda dangerous too lol, he built a big base unit for home, 1500 watts or some crap, had a big triple beam directional antenna outside and one time he had it aimed just right that when he keyed it up his neighbor got electrocuted when leaning on his chain link fence in back yard.... true story LOL
 
the67fish said:
The guy building these "illegal" amps we used was a trip, kinda dangerous too lol, he built a big base unit for home, 1500 watts or some crap, had a big triple beam directional antenna outside and one time he had it aimed just right that when he keyed it up his neighbor got electrocuted when leaning on his chain link fence in back yard.... true story LOL
Click to expand...
Electrocuted as in, like, dead?
 
the67fish said:
I had a sloppy tuned Linear Amp on my CB, man that thing would bleed over onto anything, used to drive down the street in front of a Sonic and place orders LOL.
Click to expand...
Years ago a buddy was on call for the plumbing shop he worked for. The radio in his work Truck would bleed thru several different drive thrus...
 
There are all kinds of RF interference issues. Years ago, when I worked HVAC/R service, my boss built a brand new shop, a few hundred feet from an electrical contractor. One Monday he practically accused me of leaving the shop "wide open." I told him I hadn't been anywhere near the shop all weekend. Turns out the two-way radio system next door was arbitrarily opening the shop door. We fixed that QUICK. Unplugged the receiver, and just used the indoor wired button.

As a former RADAR tech in the Navy, and having been a radio amateur for a large chunk of my life, as well as having worked a few years for a Motorola service shop, the "stuff" that can cause issues is truly amazing. One thing, EG, that is a BIG gotcha is known as an "external mixer." Think crystal radio. ANYTHING that causes what is known as a "non linear device" can mix RF signals and cause undesired outputs. Have you heard of the underground / spy / "foxhole" radios in WWII? Back then razor blades were not stainless, they were STEEL, which RUSTS. Take a safety pin, and a rusty blade, and if you are "lucky" you have an RF detector. A mixer.

A rendition of a "foxhole radio:"

foxhole.JPG


Now what this translates to in some of what I've been involved with is this: Looks galvanized fence parts, gutters and even roofing that is two pieces can form an external detector, IE "foxhole radio."

A great example of this is that if you go up to a radio site with lots of transmitters online, all you need do to see this in action is to tune in a "weaker" station on your scanner. Now take two screwdrivers, cross the blades so they touch, and rub them together. You will HEAR the scratching in the radio!!!! This is because 2 or more transmitters are "mixing" in the screwdrivers, your "foxhole radio detector" and are producing RF noise, "mixing products"

This same thing can happen in a miriad of ways. LED diodes!!!! HEY!!! They are DIODES. "Crystal radio!!!!". If you are say, a CB'er or amateur, and troubled with TV interference, look no further than a mast mounted amplifier for the TV, FULL of components which can be mixers......detectors.

I guess the point is....this ain't easy, sometimes.


The bane of my existence nowadays is modern digital "stuff" and "switching" (switch mode) power supplies, and I JUST RECENTLY discovered that AC powered LED lamps (some) generate RF noise and hash.
 
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To illustrate how easily two-way radio interference can "happen........."

Here's a photo off Google of a Pullman WA city water site on Skyline drive, also used for a "few" radios. Yup. I "been" up that little tower, 60? ft

4gn52b.jpg


At the time, (mid 90's) we had added a radio in the building. There was only 3 or 4 radios total, and IMMEDIATELY one of them started having problems. Turns out that on that simple little site, with just a few radios........

When two certain transmitters would be on the air, the third harmonic of one would mix with the other, creating a frequency that was DEAD NUTS on the receiver frequency of the victim radio. The two were mixing in one of the radios that was NOT transmitting, right in the RF power amplifier. This then was acting as your "crystal radio." I believe, later that one of the other techs went down there and put an "RF circulator" on the offending radios
 
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If you want to soup up that radio, strip the wood off the lead and use fine copper strand to tie to safety pin. It reduces the resistive loss. Also add a tuning cap in parallel with coil to get a better balance of LC. Instead if hooking antenna directly, couple with turns as transformer. It was a crystal radio that started it all for me.
 
I have to unplug the power wires to the winch on my race car trailer, when I park it in my yard. Seems the neibors kids remote cars operate on the same frequency as the remote for the winch. Took a little while to figure out why the cable would wind up either slack or tight as hell.
 
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