Bennet V351 Trim Tab switches

[60F]

Hi,

I have a 435 princess fitted with the Bennet V351 Trim Tab switches c. 1990. Whilst going through the usual system checks we have discovered that the trim tabs are fully descended and will not move.

The switches (four round 1 cm buttons covered in rubber seals on a chromed plate about 3.5cm square) could probably do with changing anyway and may well be the source of the problem, however things have moved on from the 1990's and I am not sure where to get replacements (obviously a direct replacement would be ideal as the holes are the same and the wires connectors could just be cleaned up and replaced directly to aid simplicity).

I have a feeling that the fault may be the switches. None of the trim tab buttons work on the flying bridge but the two forward buttons down below make the cabin lights dim very slightly (a little puzzling as I would have expected all the mechanicals to run off the engine start batteries which are new) and you can just about hear a hum from the motor in the aft cabin below the seat. In theory pressing these switches would make the trim tabs descend and as they are already fully descended they cannot do any more. Pressing the rear most buttons creates no pump noise and there is no dimming of the lights.

I have checked the hydraulic fluid, which seems OK.

Any thoughts on the problem or sourcing of new switches would be gratefully received.

Thanks.

 

[JaySTee]

Can you hear the pump run when you press the switches? You could test the switches with a multi meter with a continuity setting to make sure they are functioning but it is more likely to be the pump or rams at fault. I would be tempted to replace the whole system with something more modern from Bennett or Lenco Lenco Link Bennett Link depending on your preference for electric or hydraulic rams...

 

[omega2]

Ours have been in commision far longer than yours, if you can hear the pump when going for full down, and the tabs are already down then you are just overloading the motor and that's why your interior lighting goes dim, if you have a fuse in the tab system it should have blown. Do you get any pump noise when "lifting" the tabs? if not then go through the wiring check for corrosion, and the solenoid connections which will be found in the vicinity of the pump. When you get them working use them or lose them, by lifting and depressing now and again.

 

[60F]

There is no noise when trying to lift the tabs. I think the best option is to remove the unit from the helm and short across one of the up switches to see if that will get the pump (and associated tab) going. If it doesn't, I probably need to find a marine electrician.

 

[Bassplayer]

There is no noise when trying to lift the tabs. I think the best option is to remove the unit from the helm and short across one of the up switches to see if that will get the pump (and associated tab) going. If it doesn't, I probably need to find a marine electrician.

I replaced my switches like yours with the latest switch with indicators and autoretract. A really big improvement. Quite a big job as you have to run a new cable through and add a new control unit.
Where are you ? If you are anywhere near Kent/Medway you are welcome to come and see mine in operation.

 

[omega2]

Just switch the wiring from one solenoid to the other, you should get UP instead of DOWN.

 

[Cheekybrat]

if you have a look through this http://www.bennetttrimtabs.com/pdf/owners_manual.pdf
it should give you some ideas, I noticed if the trim tabs go down but not up its usually low voltage of the batteries. I have the older system similar to yours and to be honest they are quite easy to fathom out. Don't waste your money on a sparky

 

[60F]

Thanks, the owners manual is very useful. I am hoping that you are right about the batteries, it did make me wonder when the lights dimmed. When I go down over the weekend I will check whether the tabs are on the engine start (which I mioght have expected of all of the mechanicals) or service batteries. The former are new so that shouldn't be the problem, but the latter, although connected to the charger via the shorepower, are older and may be weak. Hopefully some quick checks with a meter will sort it out as you and Omega2 have suggested.

I got in touch with David Cain at www.marinecomponents.co.uk via the link from JaySTee and have bought two of the standard new switches. So thanks for that JaySTee.

Thanks also for the offer Bassplayer, I was tempted by the indicators and autoretract, but decided to go for the simple fix in the end.