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 Autohelm ST-30 display trouble		  New Topic  Topic Locked
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dmreece
Deckhand

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USA
11 Posts
Initially Posted - 01/25/2008 :  10:58:21  Show Profile
I have an Autohelm ST-30 Bi-Data. Autohelm is now owned by Raymarine.

The LCD display is beginning to fail. Several segments won't display unless I push on the casing. Any suggestions on how to fix this. I hope the answer is not replace the unit. I would then have to pull the boat to replace the thru-hulls.

Thx,
-dr
David Reece
78 C25 #454 SR/FK "T-Shirt" Arlington, Tx.
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Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts
Response Posted - 01/25/2008 :  11:12:01  Show Profile  Visit Frank Hopper's Homepage
$
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Voyager
Master Marine Consultant

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USA
5445 Posts
Response Posted - 01/26/2008 :  13:23:26  Show Profile
DR -

Check one thing first: put on a pair of polarized sunglasses and look at the display with it powered up. Turn your head around sideways to adjust polarity. The segments may magically reappear! Sometimes the LCD polarizing filter "burns out" on LCD displays, especially if it's been in the sun forever.

Electrically:
LCDs have a few failure modes, but yours sounds reasonably straightforward:

1. LCDs have driver circuits. They "drive" the LCD elements as you would expect. The drivers typically connect in two ways to the LCD:

A. directly with soldered ribbon cables (flat plastic flexible material with printed circuits right on them). If the solder joints become corroded, you can usually fix them by removing the old solder, and then re-solder them using some new solder.*

Also, sometimes the flexible cable cracks, so inspect the flat cable to see whether the circuit traces are cracked. You may be able to run a jumper wire to replace the bad trace(s).

or

B. Connectorized LCDs. These have a plastic multi-pin connector with a cable that will sometimes corrode or foul. You can clean the contacts with sandpaper or vinegar, but make sure to rinse them clean or they'll corrode worst next time. Buzz out the individual cables to make sure there is end to end connectivity. If there are any dead cables, replace them by splicing in a new wire.

Bad electrical connections from the driver to the display is the most likely cause of the problem, because you can press the case and re-make the connection.

2. Sometimes the driver chip itself will corrode and separate from the printed circuit board. Depending on your skill with sandpaper and a soldering iron, you may be able to resolder these connections.

Newer circuits use fine pitch ICs that you really cannot repair -they're too small - but older circuits use 0.10" pitch ICs that are not too tough to fix.

One caution with any circuits or IC's - random static electricity on your body can destroy circuits in a flash. Make sure to use standard ESD prevention like a grounding strap and conductive foam to prevent zapping your circuit. (Also wait for a rainy day)


* [This assumes that you know how to solder, which many DIYers do.]
<<Watch out for acid core solder - don't use it - rosin core is the right type to use. Be aware that older solders are made of Tin and Lead (which has been found by the state of California.....)>>

Good luck . . . .
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Renzo
Admiral

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USA
621 Posts
Response Posted - 01/27/2008 :  09:22:40  Show Profile
Bruce - Thanks for the trade secrets I'm going to save them for future reference, could be useful for many electronic apparatus.
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Voyager
Master Marine Consultant

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USA
5445 Posts
Response Posted - 01/28/2008 :  18:03:06  Show Profile
My Pleasure
Love the name of your boat, Zingara.
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SCnewbie
Navigator

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166 Posts
Response Posted - 03/30/2008 :  17:19:19  Show Profile
Just wondering if you got it working. The display on mine won't work either.
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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.