Autohelm ST1000 electronics/logic genius required

Praxinoscope

Praxinoscope

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The service manual is useless as far as the P.C. is concerned, it just says replace if it doesn’t go through the various tests, but at over £170 a time I would like to try and rectify this unit by replacing components (if possible).
The motor is fine, all the information comes up in the display when switched on, including the change in course when the unit is rotated, but when the +10 or -10 course buttons are pressed the motor only moves in 1 degree movements. I thought maybe one of the FET transistors (Tr 15,18,19,21) may have gone so have replaced all four ( no difference) so tried replacing the Regulator (IC1) still the same problem. (This item seems to be obsolete so a bit like finding hens teeth to find replacement).
I’m beginning to think that maybe it is a fault in one of the more complex IC’s. No’s 6, 7 and 8 in which case repair is way beyond my PC repair skills, but if anyone has any suggestions on what the fault might be I would appreciate their ideas.
 
Are those small movements i.e. one degree relating to how much the boat course has changed? Or are you trying this whilst it's resting on the bench?
 
Martin_J said:
Are those small movements i.e. one degree relating to how much the boat course has changed? Or are you trying this whilst it's resting on the bench?
Click to expand...

Bench testing, the rotation of the motor is roughly that of a one degree alteration. I resembles a stepping motor, will turn a small amount in either direction when either the + - ten or +- 1 are pressed.
 
Ah.. If you leave it, does it then step another degree or so and then another.

Just that they turn the boat by applying small movements of the tiller and then waiting for the boat to turn thru perhaps 5 degrees before slowing the turn slightly by reducing the tiller offset to zero.

It's difficult to see what they're up to whilst they are just sitting on a bench.

Also, with a smooth sea the tillerpilot will move less than it will with a rough sea. They take in the order of minutes to correct for changes in sea state.

Sitting on a bench it probably thinks the sea state is flat calm, not much movement is needed and it's waiting until the boat turns before moving tiller back to straight.

This might not be the case with yours but worth considering in the testing.
 
Hi Martin

No if left it just sits there, no movement, motor only moves when +- buttons pressed.
The ‘ram’ is in the fully retracted position, at the current rotation speed it will take a month of Sundays to even reach halfway out.
 
To be honest, I've not had one for a while. But I'm sure that with the onboard autopilot I have now (with wheel steering), if sitting at the dock and pressing +10 a few times, the wheel only moves a number of small increments and then effectively waits for the boat to start turning.

I do seem to think that when testing a tillerpilot out on the bench a few years back that I mounted it on a turntable and then turned it to try and represent the movement of the boat in relation to the angle it was effectively turning the tiller.

Hopefully we might get other suggestions from someone else later!

The fact that it does something shows the buttons are working. In the absence of other suggestions I'll save the service manual for an evening read when I get the chance.
 
Martin_J said:
The fact that it does something shows the buttons are working. In the absence of other suggestions I'll save the service manual for an evening read when I get the chance.
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If you really have a service manual I would like a copy please.

My recollection from bench testing, is if you hit say "+10" the actuator will move a bit, then when you physically rotate the unit 10 degrees it will sense the turn as complete and move the tiller back.
 
I have its big brother, the ST2000. On that, hitting +10 or -10 results in an immediate, large movement of the ram, followed by adjustment to achieve the required heading. The large movement happens even if the pilot is not coupled to the tiller.
 
On my ST1000 when I hit the 10 buttons I get a immediate 10 degree shift. Same for the 1 degree ones.
To move 5 degrees I press the 1 degree 5 times really fast and the ram will move immediately and smoothly though 5 degrees.
Don‘t know if this helps but thought I’d point it out ?
 
Not sure if this is relevant but my ST2000 is exactly the same, loads of movement in 1 degree or 10 degrees button presses, but this is when it is in Standby mode.
When in Auto the amount of movement is determined by the differing compass boat course headings and the chosen auto course.
 
Thanks for the replies to date, my ST2000 works perfectly, the problem is with a ST1000 I am rebuilding, the motor is fine, runs both directions when connected to a DC power supply, the ram unit is in excellent condition, and the flux gate compass is brand new, it’s something on the P.C. board which is not doing what it should
Standby and auto mode can be selected, the buzzer sounds when buttons are depressed, and the display is working correctly, but the the +- keys only activate the motor for what I would calculate is approximately a one degree turn, in either standby or auto mode.
Turning the unit to simulate course change has no effect apart from the change showing on the display.
As said in my OP I really don’t want to paver Raymarine over £170 for a replacement PC when it may just be a cheap component that is failing.
 
Praxinoscope said:
Thanks for the replies to date, my ST2000 works perfectly, the problem is with a ST1000 I am rebuilding, the motor is fine, runs both directions when connected to a DC power supply, the ram unit is in excellent condition, and the flux gate compass is brand new, it’s something on the P.C. board which is not doing what it should
Standby and auto mode can be selected, the buzzer sounds when buttons are depressed, and the display is working correctly, but the the +- keys only activate the motor for what I would calculate is approximately a one degree turn, in either standby or auto mode.
Turning the unit to simulate course change has no effect apart from the change showing on the display.
As said in my OP I really don’t want to paver Raymarine over £170 for a replacement PC when it may just be a cheap component that is failing.
Click to expand...
Given the answers here, I think I would be looking at the logic between the course change input buttons and the motor, if that can be discerned. It looks as if a button that should generate ten pulses actually only generates 1! The logic of the ST1000 and ST2000 are pretty much the same; I think the differences are in the motor and gearing rather than the controller.

What happens if you press +10 or -10 when in "Auto" mode? The display of compass heading should change by + or - 10 degrees; when in Auto mode it displays the desired heading, not the actual heading. If it doesn't, that probably pins it down to the logic of the input buttons.
 
Antarctic Pilot, you may have a point about the logic of the buttons, not sure how I am going to check this, the workshop manual is not very helpful as far as the PC board where the buttons are mounted, for any fault it just says ’replace board’
In fact the ST1000 and ST2000 are identical, apart from the thread form on the ram, the ST2000 uses a coarser thread, the motor, gearing etc. are identical, you just go into the set up of the printed circuit board and set it to either 1000 or 2000 whichever is relevant.
Oh the casing is a different colour but otherwise identical.
Thanks for you thoughts on this.
 
I have in my archives pdf files called "1000 2000 cct" and "st 1 & 2000 service manual". They were shared by Nigel Mercier some time ago. No guarantee but they might be real Raymarine documents. Send me a PM if you're interested.
 
cpedw said:
I have in my archives pdf files called "1000 2000 cct" and "st 1 & 2000 service manual". They were shared by Nigel Mercier some time ago. No guarantee but they might be real Raymarine documents. Send me a PM if you're interested.
Click to expand...

Thanks for the offer, I have the service manual,St1000 ST2000 (83130-1), it’s fine except when you get to thecPC and for every likely PC fault it simply says ‘replace’. It does have the full circuit diagrams and component lists, but no indication on testing the fnction of the board.
 
Have you measured the power transistors after you replaced the vreg? If the vreg is outputting the wrong voltage, it can break the power transistors, at least the AH 1000 easily breaks this way.

Does your lab bench power supply give enough 12v power, so the voltage dip when the motor is starting doesn't cause a reset?
 
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