Garage Remote intermittently working........

[Janitor Tzap]

I have an old Chamerlain Garage Remote that has been working intermittently.

I replaced the small push button in it, that had failed, with a panel mount push button I had.

Had too remove the circuit board, and placed it in another box to accommodate the larger panel mount push button.

But even when you can see the LED lighting up, powering the circuit.
The Receiver doesn't always respond.

I've replaced the 12V battery with a fresh one, thinking that it wasn't supplying enough current.
Only the Receiver still doesn't always respond.
I've reworked the solder on the circuit a couple of times now.
But that hasn't effected it either.

The Main IC on the circuit board in the Remote is an in house chip.
So I've got nil information about this remote.
The assembly date on the remote shows in was made in June 1998.


Signed: Janitor Tzap

[dacflyer]

just a wild guess, have you tried another remote yet,to isolate if it is the remote or the receiver.

[Janitor Tzap]

just a wild guess, have you tried another remote yet,to isolate if it is the remote or the receiver.

Yup.
I have two other garage remotes.
One that is the same as the one pictured.

And a programmable one.

Both work just fine.


Signed: Janitor Tzap

[dacflyer]

Hmm, ok, so that's a good step in the right direction..
only other thing i can think of is a possible defective part such as the transmitter transistor some other part..
you have any way to trace things out ? such as a SILLY-SCOPE..lol
might just be a simple part failing.. might be able to compare reading with your good remote.

another possibility to try.. hold the button down and flex or twist the board, if you get good results, you may have a hairline crack in a trace somewhere that is not easily seen.

[Lenp]

On a wild shot......

I noticed your replacement switch has a red plunger.
Most often this type of switch, with the red plunger, is a N/C switch.
Did you check that?

[Janitor Tzap]

Hmm, ok, so that's a good step in the right direction..
only other thing i can think of is a possible defective part such as the transmitter transistor some other part..
you have any way to trace things out ? such as a SILLY-SCOPE..lol
might just be a simple part failing.. might be able to compare reading with your good remote.

If I have to get that involved with it.
I'll just replace it with one of those programmable ones.

another possibility to try.. hold the button down and flex or twist the board, if you get good results, you may have a hairline crack in a trace somewhere that is not easily seen.

That sounds more plausible.
Since the old push button got harder to push, and the board was getting flexed.

On a wild shot......

I noticed your replacement switch has a red plunger.
Most often this type of switch, with the red plunger, is a N/C switch.
Did you check that?

Nope, it is a N/O switch.

Well I have pulled it a part once more.
Replaced a 22uF 16Vdc{It was reading more like 34uF}
Reheated the solder joints, looked for cracks, and cleaned the board with isopropyl alcohol.
Letting it dry for a bit before I give it a try again.


Signed: Janitor Tzap

[haklesup]

maybe the receiver forgot that transmitter code, did you try the basic setup to program the receiver for a remote?

Not sure how strong the signal is but maybe you can make an RF probe out of a diode and oscilloscope probe to verify that RF signal is being transmitted

[Janitor Tzap]

UPDATE:

maybe the receiver forgot that transmitter code, did you try the basic setup to program the receiver for a remote?

I went and tried re-setting the code.
I had the remote next to the receiver Ant, and as soon as I pressed the remote button, the door went up,
before I could put the receiver into Learn Mode.

I then moved 10 feet away from the receiver, and it still responded to the remote.
I moved 20 feet away and it stopped responding.
ARGH!

Okay, time too stop messing with this, since it clearly has some kind of signal strength issue.


Signed: Janitor Tzap

[haklesup]

Interesting, at least it's working. I can't come up with a believable theory as to why changing the activation switch would alter the effective range unless the signal went through the switch itself and you have extra resistance, but that would be a poor design, I doubt that's the case.

I agree you are approaching negative ROI on your labor considering the reasonable replacement cost.

They now have a WiFi kit for GD openers. First you replace the switch button assembly then add a WiFi to Ethernet dongle, download the app and now you can open and close your garage from anywhere in the world, how's that for range. On e-bay the price was quite reasonable. I like that it notifies me on the phone whenever it is opened or closed giving me another layer of security for my home.

[sghioto]

Most of those older remotes have an adjustable trimmer cap to center the frequency. If your's does try turning it about 1/16" either left or right to find the center which will give the best range. Other than that check the antenna connection.

Steve G

[dacflyer]

be sure to use a non conductive tool when adjusting the trimmer cap..

[dyarker]

Unless antenna was part of original case (now gone), or new case is metal (shielding the antenna(which may be etched on the PCB and not noticable)) Or a broken capacitor between output transistor and antenna. Lots of things weaken a signal. Don't ignore receive antenna either!

Cheers,

[Janitor Tzap]

Most of those older remotes have an adjustable trimmer cap to center the frequency. If your's does try turning it about 1/16" either left or right to find the center which will give the best range. Other than that check the antenna connection.

Steve G

Yes, it has a trimmer cap.
I normally don't mess with them, when they have been adjusted and set from the factory.
It looks like dirt, and dust has gotten into it thou.
I'll mark the current position the trimmer is in, try cleaning it, and put it back at that set position.
Then give it a try.

Unless antenna was part of original case (now gone), or new case is metal (shielding the antenna(which may be etched on the PCB and not noticable)) Or a broken capacitor between output transistor and antenna. Lots of things weaken a signal. Don't ignore receive antenna either!

Cheers,

The original case, and the new one are just ABS Plastic, with no metal in them.
The new case is an old plastic pen case that I had lying around.
It looks similar to this case:
Only wider because it held two pens.

The receiver is fine.
As I stated, the other two remotes work just fine with it.


Signed: Janitor Tzap

[Lenp]

Those vintage door openers, with the 8 bit code switches were a hacker's dream.
With just a bit of code, a parallel port and some cheap hardware you could open garage doors all over a development!

[Janitor Tzap]

UPDATE:

Sorry for the lateness of replying.
But I've got so many other things going on, that I didn't get time till now to respond.

I sprayed the Trimmer Capacitor with contact cleaner removing the dust.
But the range was still about 10 feet.

So I started tweaking the Trimmer Capacitor 1/16" either left or right.
But this too made little difference in the range, maybe 15Ft maximum before the receiver would no longer activate.

Time to put a fork in it then.
Well,
I can't complain too much about it.
It's 16 years old, and has seen a lot of use.
The battery in it now is the third one.
So it has been dependable, considering all the rough use it gets.


Signed: Janitor Tzap