Norman_E
Active member
I have two head units, one being a spare bought because the original one looked very worn. The autopilot setup is a good one with an electric linear drive, J3000X Junction unit (course computer), and fluxgate compass. The whole setup would be very expensive to replace. The problem with the AP11 and some other Simrad autopilot head units is that the push button switches become intermittent, and whilst having to press a button multiple times to get it to respond is a nuisance the real killer is that the tack function requires a simultaneous press on both the starboard and mode buttons and that can become almost impossible to achieve. The problem is caused by the nature of the switches which consist of a small and thin stainless "popper" less than 1cm diameter which sits over a contact ring and central contact on the printed circuit board, held in place by sellotape. Any dirt or corrosion makes for intermittent working.
The received wisdom from the internet is that the switch contacts can be cleaned with denatured alcohol, but in the UK you cannot easily buy it except as methylated spirit, not very pure and adulterated with dye. I bought lab grade isopropyl alcohol and used that. It made some improvement but not enough. I now think I have found a better way to clean them. Having removed all four poppers and used the alcohol to remove residue left by the sellotape I cleaned all of the contacts, both ring and centre on the circuit board, and the poppers, by lightly bunishing them with a fibreglass abrasive pen. On test all switches worked faultlessly. Time will tell how long this cure will last, but it certainly seems much better than cleaning with alcohol alone
The photo shows the switches with one "popper" peeled back, before cleaning.
The received wisdom from the internet is that the switch contacts can be cleaned with denatured alcohol, but in the UK you cannot easily buy it except as methylated spirit, not very pure and adulterated with dye. I bought lab grade isopropyl alcohol and used that. It made some improvement but not enough. I now think I have found a better way to clean them. Having removed all four poppers and used the alcohol to remove residue left by the sellotape I cleaned all of the contacts, both ring and centre on the circuit board, and the poppers, by lightly bunishing them with a fibreglass abrasive pen. On test all switches worked faultlessly. Time will tell how long this cure will last, but it certainly seems much better than cleaning with alcohol alone
The photo shows the switches with one "popper" peeled back, before cleaning.
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