Autohelm Type 300 Course Computer - "LOW BATTERY"

[Richard10002]

Covering some old ground here, but some fresh ideas may be available.

When I press "AUTO" on the ST7000 control panel, it shows "LOW BATTERY", and wont work.

I have measured the voltage into the computer, and it's over 12v, (usually over 13v). I've also attached a spare ST7000 controller to the computer, and get the same display. The ST60 multi function display panel also shows 13V or more.... the multi function panel seems to get it's power from the computer.

The above suggests that it isnt a problem with the control panel, (which is the usual problem from reading other posts on this), and the fact that the computer is getting over 12V makes me guess that there is something wrong inside the computer.

The following is Raymarines' answer to a similar question:

"I suspect that your problem is related to a local voltage drop at the course computer. This could be caused by either low battery bus voltage, insufficient wire size to the course computer power supply, too small of a circuit breaker, or corrosion on the power supply cabling.

The corrosion problem is most common if the pilot has been installed for any length of time. Undersized power cabling can also be a big player. The wire becomes less efficient as carrying electricity as it heats or becomes corroded. This would explain the pilot working for the first 10 to 20 minutes of operation.

Make sure that the manual's specification for wire guage and length of wire runs was followed on the installation. Also, make sure that the correct breaker size was used for the course computer."

from here:

http://raymarine.custhelp.com/cgi-b...nNlYXJjaF9ubCZwX3BhZ2U9Mg**&p_li=&p_topview=1

Any ideas as to what the problem could be?

Could the computer be getting less than 12V, even though a meter at its' input shows over 12V?

Is it still possible to get these computers refurbished by Raymarine?

Any ideas where I might get a replacement computer? (I'm searching ebay on a regular basis and also doing a regular google search).

Replacing the computer with the latest models would mean replacing the controller aswell.... probably about £2k or more, and the latest ones wont fit in the existing space, so a major job which I could do without

Many Thanks

Richard

 

[wotayottie]

If you are drawing no current throough a circuit you will get a voltage reading much like the battery voltage. Its when you draw current that the voltage drops because of bad connections / corrosion etc.

Is the course computer giving the low voltage signal all the time or only when you ask it to operate the steering ram? My guess would be the latter because thats when the system will be drawing 5 to 10 amps. Then a duff connection / dry joint/ furred up relay contacts etc will cause a voltage drop.

It is a bit of a puzzle that the problem comes up after 10 mins or so, because normally a duff connection stays duff, but wiring is still the most likely issue. One way of checking this is to jury rig alternative power wiring dircet from the battery to the computer and ram.

However, the ten minute bit does make me wonder if you have some sort of failing power transistors or other bit of electronics. In your case I think I would try jury rigging first of all to exclude the wiring system as the cause of the problem and if the problem still persisted I think I would try one of the electronics service centres such as 01929 554 558. I have never used this outfit for repairs myself but a pal who has done so was happy with the result and I have been happy with the help they have given me over the phone.

 

[Richard10002]

It is a bit of a puzzle that the problem comes up after 10 mins or so, because normally a duff connection stays duff, but wiring is still the most likely issue.

Sorry!! The ten minute thing is part of Raymarines answer to a specific question about "low battery" occuring after 10 or 20 minutes. Including the Raymarine answer was probably more confusing than helpful:

To clarify - In my case, the problem is there from the moment I press Auto.

I'm reasonably sure that my wires and connections are OK, (they may not be), which is why I am guessing it could be a duff connection inside the computer.

I'll need 2 people to test whether the voltage drops at the compute input when I press the Auto button, (one to press the button at the helm, and one to view the tester at the computer), so I'll try that test next time I come up to the boat with a mate of mine.

Thanks for the help

Richard

 

[Richard10002]

Just called Raymarine who say I can send it to them for testing and they will repair it if they have the parts. £27.60 plus postage for them to have a look. I guess they will be able to at least tell me if it's a problem with the computer, or that it is working fine.

I'll test the input voltage for a drop next time I'm here and, if it seems OK, I'll send it off to Raymarine.

 

[wotayottie]

If it does it right from the start them I would bet that it is the wiring. Dont forget you can easily have a break mid wire. There is a second possibility however, mand that lies with the motor that powers the ram.

So I suggest.:

1/ Disconnect the ram and power up the puter. Does it still indicate low voltage? Bet is no.
2/ Jury rig alternative wiring. Have someone else there to measure the voltages.

Don't make the mistake we all do of assuming the most difficult / expensive cause.

 

[Heckler]

If it does it right from the start them I would bet that it is the wiring. Dont forget you can easily have a break mid wire. There is a second possibility however, mand that lies with the motor that powers the ram.

So I suggest.:

1/ Disconnect the ram and power up the puter. Does it still indicate low voltage? Bet is no.
2/ Jury rig alternative wiring. Have someone else there to measure the voltages.

Don't make the mistake we all do of assuming the most difficult / expensive cause.

WY
got it in one, Richard do as your told! You know you want to do it!
Stu
PS What was the trip like?