jon928se

OK I've had it to bits cleaned the copper of the "no contact" segment on the back of the gear that causes it to stop. But with the cover off the gearbox/motor (hence no load on the motor) it coasts past the "no contact" segment and continues running. With the motor stopped I can reinstall the gear and it stays stopped so I definitely don't have copper where it shouldn't be.

Will the additional load of pulling the release arm slow it down enough to stop it ? Anybody done this and observed the same?

TIA

jon928se

No one ?

Bueller?

Put it all back together and the only way to stop the motor is to adjust it beyond the travel of the the roller in the lock mechanism.

So what will cause the whole mechanism to be free running enough that the motor can spin fast enough to spin unpowered past where it was designed to stop?

And yes it does unlatch the hatch - so long as you grab it at the right moment .

Glen McCartney

Jon, I had the same issue, finally I just widened the gap maybe 1/16 inch to get it to work. Just have to pull the switch up a little longer. Never could determine why.

Mrmerlin

I would check the 1 amp fuse if its blown then the motor will continue to run for as long as the pull **** is held.
Also if pulling one of the ***** makes the fuse blow the pin inside of the pull **** is grounded,
there is a small phenolic washer that can crack and thus let the contacts touch the pin,
this grounds the contact plate thus blowing the fuse , the fix, wrap some carpet thread around the pin a few times, a drop of super will hold it

WallyP

Filling the gearbox with grease helps, as does widening the cut.

I do seem to remember that there is a thread for an electronic fix for this - perhaps a determined search will find it. Replacing a diode in the system somewhere?

borland

take a look at this thread...

https://rennlist.com/forums/928-foru...ase-motor.html

WallyP

Bingo! You are pretty quick with the search function...

Alan

Stan - it always runs for as long as the **** is pulled (as long as the door is open and the interior lights work). The 1A fuse only controls the parking operation (running when the **** is not pulled). In this instance pulling the 1A fuse will stop the motor continuing to run...

Alan

Mrmerlin

Thanks Alan,
after more info from others it looks like Borland has a good course of action with the CB repair.
Might you have any idea why the diode or resistor fails on the CB?? Bad ground??
Overloaded circuit??

borland

If the transistor's base has a bad ground, it sees +12V and causes the transistor to self-destruct.

With the transistor no longer functioning, the motor will continue to run, as electronic braking effect is no longer performed.

Mrmerlin

Thanks Borland for putting the smoke back in the bottle!
One more, any idea why the ground fails??
Could this be due to the part getting wet ,
or just bad/old soldering

borland

Not sure. Probably all of the reasons you mentioned.

Since these hatch actuators are similar to the door lock actuators, they may be suitable for substitution. I've seen used door actuators going on eBay for about $15 plus shipping. If they are in fact cheap substitutes, for some, the motors may not be worth the effort of repairing.

jon928se

Well I managed to pick up some BC337 transistors today with a current rating of 800ma - also got a couple of BC 697 (?memory) with a higher current rating but otherwise similar characteristics.

See Borlands earlier thread
https://rennlist.com/forums/928-foru...ase-motor.html

I think desoldering and resoldering the new one in may have to wait 'til tommorow - 2nd glass of Shiraz prevents soldering on small stuff.

jon928se

Success

Finally got around to it - got distracted yesterday at Hiltons brazing up his exhaust gas sniffer, putting new MMs and Rack Bushes in his Red89.

Carefully desoldered the old transistor - hiding under the black gear wheel here



Even more carefully soldered the new one in



I need new glasses - had to resort to taking Macro photos to see what was going on - made the soldering interesting when you can't see.

For anyone trying this it's important to make sure the new transistor does sit so high that it fouls the u/s of the black gear - this means bending the legs of the trans a lot closer to the body than I would normally do (risks physically breaking the internal connections) And if you can use normally closed tweezers on the legs as a heatsink when you are soldering.


Just need to re-install the motor and adjust now.

jon928se

Complete Success.

Having got the motor working experimented with motor position but due to the worn rubber hatch receiver there was too much play in the mechanism fro the lock to un latch.

I have got a new insert (one of Jerry's) but I'm saving that for the SE so I decided to shim this one. I wanted something more permanent than the side of an oil can so I used 0.8mm thick alu sheet cut into this shape



This is the trial piece so the 22mm dimension at the top is not in proportion - I made it 22mm on the installed piece so it was long enough to wrap over then under the edge of the receiver so it is clamped when the reciever is bolted down. The 18mm wide tab at the bottom pokes out of the tab slot for the rubber insert and then folds back on itself. Install this end first , and you need to depress the white plastic plunger to get it in.



I also followed Alans advice in an earlier thread and wrapped the actuating cam with nylon cable ties (Zip ties) to take up wear in the lock actuating cam in the male upper part of the hatch lock.