ST50 instruments - blank faces

[redunculous]

So a while back my instruments would occasionally not switch on - once the boat seemed to be warmed up they would so I put it down to corrosion and figured I would fault find at a later date.

I recently installed a new depth sounder for my garmin and as a result removed the old raymarine transducer and ran the new cable all the way through to the helm.

When I was there I decided to remove the Depth and Speed ST50 displays because I have GPS speed and new depth straight to the garmin so they were no longer needed.

When I was working I found by chance that the connection that was power into the depth was the culprit for my instruments (several disconnects / reconnects tracing the beep coming on) as it was daisy chained through.

I removed the depth and speed instruments and wired the power to the remaining instruments (wind and auto pilot) - nothing came on at all. I tried them individually - nothing.

I checked the cable and have 12v. I plugged the 12v back into speed - nothing, tried depth - nothing.

Is there something I am missing that is the reason nothing would be coming on?

I am totally lost, if there is power I expected the displays to light up - there is definitely power.

 

[Rich Stidger]

Just a thought- did you have the CodeLock function enabled on the original Depth/Speed instrument? Perhaps that is the reason nothing powers up if that instrument is not in the chain.

You can test by putting it back in the chain and if that is the cause, then just disable the CodeLock and all instruments should power up.

 

[redunculous]

Rich

Didn't even know about this codelock! Will take a look when I get back from the land of sand

 

[Rich Stidger]

If you didn't know about it, you probably don't have it setup. Unless a PO had it set.

 

[redunculous]

I've asked the PO about it today as we are good friends - he wasn't aware either as he never changed anything from the PO before.

Surely it would have worked when it was direct connected to the one with the codelock (if it is enabled)

 

[Bill Roosa]

is the ground side good?
you have to have a place for the current to go or it will not work at all. If you have 12 V supply then, assuming they did not go bad all at once the ground wire is your suspect.

 

[Bill Roosa]

Oh yea, to test the ground wire just test between the known 12 volt and the ground wire. should read 12 volts again.

 

[redunculous]

Bill

I didn't think of that whatsoever when I was sat there with my voltmeter in hand scratching my head

I will have to track that down and test it

Thank you

 

[redunculous]

Well

I'm back home in the US finally and now re-thinking this

Surely when I popped my voltmeter onto the pos and neg pics thats the ground covered?

I thought that normally a DC powersupply will have a positive and negative out?

I do remember there being 3 pins though

If there is a pos, neg and a ground - I guess I need to go find the ground

Look forward to some education here.

 

[Rich Stidger]

The 3-pin Seatalk cable has +12V (red), ground or negative or return (shield), and serial data (yellow). Make sure that you measure 12V between the +12V and ground pins.

BTW, in a previous post I suggested that the problem could be that the instrument you removed from the system was the master and that now all of the other instruments are "code-locked". Thinking about this more, I now believe that if the problem was a code-lock issue, that the instruments would not be blank but would display "Codelock set Enter Code". So I think you should concentrate your effort on verifying the power.

 

[redunculous]

Thanks for the response Rich

The pins is where I got my initial 12v readings from so I know the ground is good?

 

[Rich Stidger]

I don't have a drawing of the pin-out handy, but between two pins you will have a solid 12-13 volts. That reading should essentially be the same as the voltage at your power panel distribution.

If you measure between the data line and ground, you will see about 3-5 volts. So if you measure the pins and you find a pair that have a solid 12V, then I think you should be good. The only other issue that you might have is a poor ground where you could measure 12v but when the instrument begins to draw current, the voltage drops due to the poor ground (or +12v connection).

 

[redunculous]

Ok so back to checking my breaker at the panel and the ground bar right?