Morris Minor Owners Club

This may be a daft question, but why does a Voltage Stabiliser have a 'Top'?
Mine is fixed upside down and am wondering if this may be contributing towards a weird electrical problem I'm having. I thought these were solid state?

I don’t know, maybe there is something in there that gravity has an effect on, however if it says ‘top’ why not put it that way then you’re covered ! We are lucky to have some knowledgeable electrical people here, who can probably give you a more definitive/better answer.

Unless it's a modern equivalent unit, I don;t believe that there are any "electronics" in there, it's a bi-metallic strip. when cold, the contacts close and pass current, then the strip heats up, bends, and the contacts open, thus stopping the current. The strip cools and then the strip returns to its original shape, closing the contacts and starting the cycle again. This happens very quickly, and the result is that the correct voltage is sent out. There might be a small weight that acts to close the contacts, and this needs gravity, or there might be a heat sink to dissipate heat at the top, but it's so long since I opened one that I just can't recall. However, no electronics, and, as above, if it says top then fit it that way up - you wouldn't ignore the "top" on a head gasket would you?

Ah - I thought it was solid-state, but if it's mechanical I guess that makes sense!

No indeed - I would certainly mount it the right way up, unlike the person that fitted it previously Fixed now!

OK, so now that you have now fitted it in the correct orientation, has this solved your problem?

oliver90owner wrote: ↑Sun May 15, 2022 10:11 am OK, so now that you have now fitted it in the correct orientation, has this solved your problem?

Maybe...

I was having a weird problem when I turned on the indicators, I'd temporarily loose electrics to the indicators, wipers, brake lights, fuel gauge and radio. It wasn't blowing a fuse and after a random amount of time (typically 20mins) - it'd all start working again (or after an ignition off/ignition on).

I could easily replicate the problem.

Like a bit of a wally, I've changed 3 things and now the problem appears to be fixed.

1. I've re-mounted the stabiliser the correct way up.
2. I've re-wired the indicator switch. Couldn't see an obvious problem with it, but had it in bits whilst checking the voltages
3. The indicator flasher unit appeared to have been wired the wrong way round (but must have been like that for years - at least as long as I've owned the car). Fixed that.

Now all seems to be fine.

If I was a betting man I’d put money on that fault being a dirty/loose fuse holder, the one with White wires one end and Green at the other.
It won’t be the ignition switch as you don’t mention the engine stopping, the coil and fuel pump supply is unfused, everything else you mention goes through the ignition switched fuse.

Regards John

Yes. Dirty fusebox is most likely. Also, I have never seen "TOP" on a voltage stabiliser - which only controls the fuel gauge doesn't it? I would suggest that it is an aftermarket one.

StillGotMy1stCar wrote: ↑Mon May 16, 2022 8:15 pm If I was a betting man I’d put money on that fault being a dirty/loose fuse holder, the one with White wires one end and Green at the other.
It won’t be the ignition switch as you don’t mention the engine stopping, the coil and fuel pump supply is unfused, everything else you mention goes through the ignition switched fuse.

Regards John

Ah, that's interesting.. I don't recall for certain now, but I'm reasonably confident the headlights weren't effected which would add some weight to your theory. So potentially only items on the (ignition) switched live were effected. I'll have a look at that.. Not sure why it would only become apparent when the indicators were used, but maybe there was a fault with either the flasher unit or the switch which was causing a high current draw..

ManyMinors wrote: ↑Mon May 16, 2022 8:52 pm Yes. Dirty fusebox is most likely. Also, I have never seen "TOP" on a voltage stabiliser - which only controls the fuel gauge doesn't it? I would suggest that it is an aftermarket one.

Indeed it's aftermarket.. It's actually only used for the temperature gauge but I was wondering if it had a fault, could it have had an impact on the earth somehow potentially?! (gettit? )

So much aftermarket electrical stuff is poor quality that I would suspect the unit itself. The original ones are used in conjunction with the fuel gauge (from 1964) and give very little trouble. Maybe look for a secondhand one of those?
All the items which you say stopped working are supplied by the same single fuse which is why the fuse (or more likely the fusebox) is the obvious culprit