First published April 2012.
Edited:25 June 2012 and 28 June 2012
Go to comments on this article.

Replacing the remote and receiver of a garage door opener

This roller door was branded 'ADS Dominator' and is about 17 years old. The radio receiver within had gone a bit deaf. My customer reported that the remote had to be within a metre of the unit in order to for it to work. He had tried new batteries but since the door behaved identically with the second remote, it had to be the receiver. In all other respects, the door behaved normally.

First steps

I initially confirmed with a spectrum analyser that the remotes were transmitting on 315MHz; that they were putting out enough signal, and also checked that there were no interfering signals on the same frequency which could have been an explanation for the remotes needing to be close to the unit. All was well in that department, so I stripped out the control board in an effort to see if anything obvious was wrong.

The following picture is of the control board. The receiver and all the control circuitry is integrated in surface mount technology on the underside of the board.

receiver board pic

I removed the board, inspected for obvious wiring faults, dry joints or smoked components but all actually appeared in relatively good condition. I elected to put it back together at that point, hoping to be able to obtain a schematic in order to try and investigate the fault.

It soon became clear that neither a new control board or a schematic of the control board was available. I could have looked at the receiver problem without a schematic, but the door would have been out of service for more than a couple of weeks and even then, without a guarantee of success.

The better way

Replacement remotes are difficult to find for the 315MHz frequency, so as a solution for this, kits comprising a new receiver plus two remotes are available. These operate on the more modern 433MHz. I realised that this option is the much faster way to deal with either a broken obselete remote, or in our case, a faulty receiver. A new receiver is typically smaller than the size of a cigarette packet, requires a source of dc voltage and simply momentarily operates the 'manual button' input of the system.

Magic Key kit MK701

Kits for new remotes and receivers are available in N.Z but we found an Australian based on-line shop called MagicKey, which offers such products. They had a kit called MK702 which includes 2 remotes plus receiver unit for AU$98 plus $8 postage. In our money that was going to be NZ$135. In the event my client said he needed only one remote because with this retrofit receiver, the old remotes still work, even though in this case, he has to stand right outside his garage door. So, we chose the MK701 kit with one remote and which was only AU$76 including postage, making it just under NZ$100 to us. The kit arrived in 3 days! Below is what comprises the kit.

MK701 kit pic

The unit was simply screwed to the back cover of the existing opener, and in the case of our ADS Dominator, was simply wired to the three terminals already at the back. The terminals can be seen from the inside in the first photo above. One terminal, labelled 'C' provided dc voltage of +12V, the centre terminal labelled 'B' was the common and the 'A' terminal is the operate terminal. Usually, any manual operate button is wired across A and B, and should remain connected. The new receiver momentarily shorts A and B by virtue of a relay contact. The fitting took under 15 minutes and it all worked from at least 10 metres away. The supplier had already pre-coded the receiver to the fob transmitter, but if not, the receiver will learn the transmitter code by holding down the 'learn' button for a few seconds. Magic indeed!

This receiver will operate from 12V to 24V either dc or ac. It takes 24mA when idle and 41mA when the relay is operating. Other than for use as a garage door opener replacement, it could be put into service for almost any application that needs a remote control such as a outdoor light or security alarm or almost anything.


There are no comments yet

Go to comments form