Servicing an Autohelm ah800 analogue

[Dellquay13]

Has anybody any positive experience of successfully servicing one of these archaic tiller pilots?
I have gotten past the security screw issue, and have realised the body clam shells are glued and sealed as well.
Before I get the multi tool out and make a right pigs ear of opening it up, I was wondering if anyone has managed anything useful once inside?
My unit has started running in 2-3mm increments, but very occasionally moving smoothly, just to show it still can...
TIA
Chris

 

[earlybird]

The gluing is not as sent out from the factory. Once inside make sure that you can reinstall the drive strings correctly, photograph or sketch.
When the movement of mine became very intermittent ( 30+ years ago) the commutator and brushes of the motor proved to be completely shot. A replacement motor cost a bomb IIRC so I didn't bother.

 

[V1701]

What's the issue with it? Or if it's caput you might as well have a go as nothing to lose...

 

[Dellquay13]

The gluing is not as sent out from the factory. Once inside make sure that you can reinstall the drive strings correctly, photograph or sketch.
When the movement of mine became very intermittent ( 30+ years ago) the commutator and brushes of the motor proved to be completely shot. A replacement motor cost a bomb IIRC so I didn't bother.

The none standard glue is dismaying.
I learnt an old saying from a long gone gaffer "if we can't fix it, we fix it so no other f@cker can fix it" and if the previous owner hasn't already done that with the glue, I can see it looming on the horizon when I start hacking at it.
It's working to an extent, albeit stuttering, and until £500 falls out of the sky to replace it, that is probably how it will stay...

 

[Dipper]

I assume you have undone the screw under the compass rose and the one under the central plug in the switch. If so, maybe a hair drier might soften any glue up enough to allow you to prise the cover off.

As to the stuttering, the arm runs up and down steel tubes/bars so they might just need some fresh grease. If you get it open, as has been said already, take photos of the string arrangement with the arm extended and withdrawn. Then if the string breaks, you will know how to replace it. I've done that with whipping twine.

Check the condition of the rubber stops either end. They can become perished.

Also, cut a slot into the heads of the security screws so that they can be fitted and removed with a standard flat head screwdriver.

 

[Dellquay13]

I

I assume you have undone the screw under the compass rose and the one under the central plug in the switch. If so, maybe a hair drier might soften any glue up enough to allow you to prise the cover off.

As to the stuttering, the arm runs up and down steel tubes/bars so they might just need some fresh grease. If you get it open, as has been said already, take photos of the string arrangement with the arm extended and withdrawn. Then if the string breaks, you will know how to replace it. I've done that with whipping twine.

Check the condition of the rubber stops either end. They can become perished.

Also, cut a slot into the heads of the security screws so that they can be fitted and removed with a standard flat head screwdriver.

I didn't know about the screws under the compass and switch, thanks for that. I got the security screws out quite easily, but I stopped when i saw the glue around the seam.

 

[Dipper]

I
I didn't know about the screws under the compass and switch, thanks for that. I got the security screws out quite easily, but I stopped when i saw the glue around the seam.

The compass rose metal plate is stuck on with a soft glue. You can lever it off gently - maybe a bit of heat would help there. The screw in the switch is a cylinder around the thread.

 

[andsarkit]

The switch has a collet fixing like this:

If you unscrew the round 'nut' it will slide off. If you try to force it off you will break the switch (how do I know!)
Before you remove the compass label make a notch on the plastic base at North so you can replace it in the same position.

 

[Dipper]

The switch has a collet fixing like this:
View attachment 126955
If you unscrew the round 'nut' it will slide off. If you try to force it off you will break the switch (how do I know!)
Before you remove the compass label make a notch on the plastic base at North so you can replace it in the same position.

Collet - that's the word that I was looking for (and failed to find).

 

[Dellquay13]

When opened, does the mechanism rest in the top or bottom shell? If it is in the bottom I will definitely have to uncouple the switch and rose from the lid before opening

 

[andsarkit]

Everything is mounted on the base. This is the AH1000. I think the 800 might be similar

 

[andsarkit]

Here is a link to the source of the pictures:
Autohelm 1000 – Jouet Sheriff
You can select English language for a translation.

 

[Dipper]

Andsarkit beat me to it but just undo the two screws and pull off the switch and compass disc.

 

[Dellquay13]

Here is a link to the source of the pictures:
Autohelm 1000 – Jouet Sheriff
You can select English language for a translation.

That link is so useful, best quality pdf of the handbook I've seen too. ????