Wanted Type 100 or 300 autopilot computer - working or non working
- Thread starter Tim Owen
- Start date
- Boat name
- JOY TO THE WORLD
- Berth
- Gosport
- Boat type
- Moody 44 (90s)
- Cruising area
- Solent
Hi Tim I sold my old 300 to a chap called Daniel Hawkes in 2021, he was repairing these as a side hobby. He may be able to help? daniel@positivemarine.com
John
John
- Boat name
- STOLEN MOMENTS
- Berth
- Birdham Pool, Chichester
- Boat type
- Moody 346
- Cruising area
- Solent
Service manual here:
Tim Owen
Member
- Boat name
- DULCINEA
- Berth
- Kerrera Marina, Oban
- Boat type
- Moody 40 (90s)
- Cruising area
- West Coast of Scotland
Thanks David, i have that manual, but it leaves the actual circuit diagrams blank and just gives block diagrams - so fault finding is going to be tedius as ill have to trace the surface mount boards..... I do have some clues to what is going wrong - probably the gate voltage driver VDBL for the output bridge to the helm motor. The +/- 12V motor drive drops to +/- 2V after a couple of hours use and causes the autopilot to alarm etc,
I currently have a replacement stuck somewhere in the UPS system.
I currently have a replacement stuck somewhere in the UPS system.
- Boat name
- STOLEN MOMENTS
- Berth
- Birdham Pool, Chichester
- Boat type
- Moody 346
- Cruising area
- Solent
Tim
I recently repaired one of these for a colleague - in his case the clutch drive output was dropping/intermittent. I replaced the power FET in the clutch drive and 'reflowed' the surface mount components which form the drive to the FET. After that it started working OK. The power FET's in the clutch and motor drive are relatively easy to replace (you just need a soldering iron and solder 'sucker' ). The FETS were obsolete but it was easy to source modern ( and better) equivalents.
To reflow the surface mount components I used a hot air solder gun. But there is little else you can do internally as replacing surface mount components is very tricky. To make matters worse the drive components were under a blob of 'potting' (see picture below) to support the FET . I had to carefully remove this by heating with a solder gun and picking it off with a dental pick.
The processor is plug in and pre programmed - but the getting a replacement for it given its age would be nearly impossible unless you had a donor unit.
I agree the service manual is a little frustrating as it has some circuit diagrams and a mix of block diagrams - it leaves you to work out how the drive for the clutch and motor is implemented. My guess is that Raymarine do not intend folks to be able to repair these units.
Kindest
David
I recently repaired one of these for a colleague - in his case the clutch drive output was dropping/intermittent. I replaced the power FET in the clutch drive and 'reflowed' the surface mount components which form the drive to the FET. After that it started working OK. The power FET's in the clutch and motor drive are relatively easy to replace (you just need a soldering iron and solder 'sucker' ). The FETS were obsolete but it was easy to source modern ( and better) equivalents.
To reflow the surface mount components I used a hot air solder gun. But there is little else you can do internally as replacing surface mount components is very tricky. To make matters worse the drive components were under a blob of 'potting' (see picture below) to support the FET . I had to carefully remove this by heating with a solder gun and picking it off with a dental pick.
The processor is plug in and pre programmed - but the getting a replacement for it given its age would be nearly impossible unless you had a donor unit.
I agree the service manual is a little frustrating as it has some circuit diagrams and a mix of block diagrams - it leaves you to work out how the drive for the clutch and motor is implemented. My guess is that Raymarine do not intend folks to be able to repair these units.
Kindest
David
Tim Owen
Member
- Boat name
- DULCINEA
- Berth
- Kerrera Marina, Oban
- Boat type
- Moody 40 (90s)
- Cruising area
- West Coast of Scotland
Hi David,
I have my unit on the bench at home, trying to fault find it without anything plugged in, so a little tricky! You might have some ideas, so here are the symptoms/observations from on board;
1. It works normally for about 2 1/2 hrs after turn on.
2. It fails because the motor isn't getting enough volts to move it and the autopilot then falls over as soon as the coarse error is outside its limits with a motor fault.
3. The time to failure doesn't seem to depend on whether the autopilot is engaged for all the time or how hard it is working, just how long its been switched on
4. It takes a few hours of power off to recover and then is OK for another period. If you try again sooner it falls over pretty quickly.
5.Observing the outputs when its failed in the boat, the clutch o/p is OK but the motor output is reduced to around +/- 2 volts when I flip a coarse alteration that would normally move the motor. The output motor voltage is quite accurately the same magnitude in both directions.
My initial diagnosis was that it was a thermal issue, and that as the power switching in the motor drive bridge still did something and was symmetrical left and right it was unlikely to be a part of the bridge circuitry itself. I thought the most likely problem was in the doubled voltage VDBL that is needed to switch the N channel enhancement FETS fully. However, on the bench the Doubled supply voltage appears to be stable and a hot air gun gently played around doesn't cause it to fail. I can't see any other part of the circuit that is common to both left and right motor corrections, and its hard to believe two separate parts of the circuit would develop the same fault. I don't have the circuits for the FET drivers but they should be symmetric so unlikely to be the problem.
I'll continue to poke around and see what else I can find!
Any thoughts would be appreciated!
Post Script - This morning the VDBL fell to 12V from 24V on heating, so somewhere that is the fault. Now I need to find the faulty component - not too easy without the full diagram as the surface mount is difficult to trace!
Tim
I have my unit on the bench at home, trying to fault find it without anything plugged in, so a little tricky! You might have some ideas, so here are the symptoms/observations from on board;
1. It works normally for about 2 1/2 hrs after turn on.
2. It fails because the motor isn't getting enough volts to move it and the autopilot then falls over as soon as the coarse error is outside its limits with a motor fault.
3. The time to failure doesn't seem to depend on whether the autopilot is engaged for all the time or how hard it is working, just how long its been switched on
4. It takes a few hours of power off to recover and then is OK for another period. If you try again sooner it falls over pretty quickly.
5.Observing the outputs when its failed in the boat, the clutch o/p is OK but the motor output is reduced to around +/- 2 volts when I flip a coarse alteration that would normally move the motor. The output motor voltage is quite accurately the same magnitude in both directions.
My initial diagnosis was that it was a thermal issue, and that as the power switching in the motor drive bridge still did something and was symmetrical left and right it was unlikely to be a part of the bridge circuitry itself. I thought the most likely problem was in the doubled voltage VDBL that is needed to switch the N channel enhancement FETS fully. However, on the bench the Doubled supply voltage appears to be stable and a hot air gun gently played around doesn't cause it to fail. I can't see any other part of the circuit that is common to both left and right motor corrections, and its hard to believe two separate parts of the circuit would develop the same fault. I don't have the circuits for the FET drivers but they should be symmetric so unlikely to be the problem.
I'll continue to poke around and see what else I can find!
Any thoughts would be appreciated!
Post Script - This morning the VDBL fell to 12V from 24V on heating, so somewhere that is the fault. Now I need to find the faulty component - not too easy without the full diagram as the surface mount is difficult to trace!
Tim
Last edited:
- Boat name
- STOLEN MOMENTS
- Berth
- Birdham Pool, Chichester
- Boat type
- Moody 346
- Cruising area
- Solent
Hi Tim
I think it would be quite difficult to diagnose the fault without some form of test rig. The unit I repaired was given to me came with no other parts, so I made up a test rig using a spare autohelm compass, a C70 plotter (connected by seatalk to the course computer), a high current 12V power supply and some 'loads' (in my case 20ohm resistors) and test meters connected to the clutch and drive motor outputs. Car sidelight bulbs would also do as loads. The C70 has the provision to drive the course computer in lieu of the more normal ST4000.
Looking at your symptoms it very much says that something is overheating. The primary candidates would be the four drive motor power FET's, but from you description of the symptoms it may be the drive to them. The lack of full circuit diagrams is a bit of a hinderance but it may be possible to 'backwards engineer' the circuits from the information given. This is what I had to do with the clutch drive. I found that the drawings showing the component placement and the parts list helpful in that respect. In the case of the power FET drivers, you are looking for transistors TR22-31. However as the negative and positive output of the motor drive circuit is symmetrical but low, it may be in the 'common' parts of the circuit, TR18 to 21. It may be worthwhile checking the outputs from the microcontroller P1.4 and P1.6 to see if they have changed. If Vdouble is stable, try taking a look at Vreg/ ZD1 to see if that is changing.
To help decode the outputs of the microcontroller, I have attached its specification below.
I would look around for anything that is getting hot - to do this I use a infra red non contact thermometer (you can get them from ebay for less than £10) With the unit not powered I use a component tester to try and find failing components. ( see: New Component Tester Colorful Display Electronic Tester Convenient For Diode Tri | eBay UK (https://www.ebay.co.uk/itm/157795441476?_skw=Electrical+component+tester&itmmeta=01KQ9RFMN79XX4SD875600JBAJ&hash=item24bd575b44:g:ndoAAeSwwhFpcYGi&itmprp=enc%3AAQALAAABAGfYFPkwiKCW4ZNSs2u11xCAl5bs21KOL3Exs4hEKSUQ9z0%2BYBfqEplurVobTrrPRaFWihfNF8yPcfR2kuX2fDxwCnYtfDtQYH1En3ss%2FOgnfDxX%2FfcfbjlOR603Sms%2BUdKwcMRdFiVI9KloiY%2BbqSp59xJrG4s9hdjD4nwx9dTSXb5VDEOFNx84xzC0sGrdeWVsRByH3kl4HfYCe8TANrk4wRS7Nea2lb1h5vo%2BuXF%2FcNuCRHtS%2FY3%2Bf0PiMNUxSBst%2FSdr8yL3Oukamn4iwtdctdpRKZrIJivqTwIW3xphYPmjHweXcGagH6p70WJHt0bmnpejQutThFsYaaU40ck%3D%7Ctkp%3ABk9SR_LKvri6Zw) )
Ideally you need to remove the component to test it, but I find this device can give a good indication of whether the component has failed (or not) by testing in circuit,
If I were repairing this unit I would probably start by changing the 4 power FET's ( The clutch one I changed cost just 90p + £3 postage!) as its quite easy to change them and this will make certain whether (or not) they are the problem, then start by checking around the drive circuits.
Hope the above helpful
Good luck
David
I think it would be quite difficult to diagnose the fault without some form of test rig. The unit I repaired was given to me came with no other parts, so I made up a test rig using a spare autohelm compass, a C70 plotter (connected by seatalk to the course computer), a high current 12V power supply and some 'loads' (in my case 20ohm resistors) and test meters connected to the clutch and drive motor outputs. Car sidelight bulbs would also do as loads. The C70 has the provision to drive the course computer in lieu of the more normal ST4000.
Looking at your symptoms it very much says that something is overheating. The primary candidates would be the four drive motor power FET's, but from you description of the symptoms it may be the drive to them. The lack of full circuit diagrams is a bit of a hinderance but it may be possible to 'backwards engineer' the circuits from the information given. This is what I had to do with the clutch drive. I found that the drawings showing the component placement and the parts list helpful in that respect. In the case of the power FET drivers, you are looking for transistors TR22-31. However as the negative and positive output of the motor drive circuit is symmetrical but low, it may be in the 'common' parts of the circuit, TR18 to 21. It may be worthwhile checking the outputs from the microcontroller P1.4 and P1.6 to see if they have changed. If Vdouble is stable, try taking a look at Vreg/ ZD1 to see if that is changing.
To help decode the outputs of the microcontroller, I have attached its specification below.
I would look around for anything that is getting hot - to do this I use a infra red non contact thermometer (you can get them from ebay for less than £10) With the unit not powered I use a component tester to try and find failing components. ( see: New Component Tester Colorful Display Electronic Tester Convenient For Diode Tri | eBay UK (https://www.ebay.co.uk/itm/157795441476?_skw=Electrical+component+tester&itmmeta=01KQ9RFMN79XX4SD875600JBAJ&hash=item24bd575b44:g:ndoAAeSwwhFpcYGi&itmprp=enc%3AAQALAAABAGfYFPkwiKCW4ZNSs2u11xCAl5bs21KOL3Exs4hEKSUQ9z0%2BYBfqEplurVobTrrPRaFWihfNF8yPcfR2kuX2fDxwCnYtfDtQYH1En3ss%2FOgnfDxX%2FfcfbjlOR603Sms%2BUdKwcMRdFiVI9KloiY%2BbqSp59xJrG4s9hdjD4nwx9dTSXb5VDEOFNx84xzC0sGrdeWVsRByH3kl4HfYCe8TANrk4wRS7Nea2lb1h5vo%2BuXF%2FcNuCRHtS%2FY3%2Bf0PiMNUxSBst%2FSdr8yL3Oukamn4iwtdctdpRKZrIJivqTwIW3xphYPmjHweXcGagH6p70WJHt0bmnpejQutThFsYaaU40ck%3D%7Ctkp%3ABk9SR_LKvri6Zw) )
Ideally you need to remove the component to test it, but I find this device can give a good indication of whether the component has failed (or not) by testing in circuit,
If I were repairing this unit I would probably start by changing the 4 power FET's ( The clutch one I changed cost just 90p + £3 postage!) as its quite easy to change them and this will make certain whether (or not) they are the problem, then start by checking around the drive circuits.
Hope the above helpful
Good luck
David
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