Diplomat electric aerial won't go down

[mycav]

Although the SC303 works fine I hadn't noticed the aerial was always fully up.
The motor works, the aerial tube's not distorted and the plastic drive cable's fine too.
By taking it to bits I can wind it down manually but when the radio's on, up it goes again. It won't go down under its own steam
Inside the base of the aerial unit there's a round plate, with a small insulated area and 3 sprung contacts. It's turned by a cog which is driven by the plastic drive cable's assembly, but its securing screw was loose and it may be mispositioned.
It looks like that plate determines how long power's applied to the motor but does it also control up and down or is that done by the obsolete relay that's also in the unit?
Does anyone have a circuit for the aerial innards please, or can describe how it should work?

[Robsey]

I have an aerial ready for stripping and servicing. I can have a look on Sunday if you like.

Otherwise, you can pick up an aftermarket aerial for less than £40.
I fitted one recently, just so that I could strip my GM aerial.
It was struggling and clunking with the aerial rarely fully up or down, although I do suspect that my mast is distorted or damaged too.

[HAIRIBO]

My old one had similar problem. Ended up taking it all apart, degreasing all the plastic gears. Cleaning them, then regreasing. Worked after that.

[Robsey]

does it also control up and down or is that done by the obsolete relay that's also in the unit?

I am presuming that the relay is not actually obsolete, but probably reverses the polarity of the wires to the motor when voltage is applied to it or removed from it via the red/white head-unit controlled feed.

I suspect that there is a minimum of a relay controlled via a timer circuit (Capacitor and/or transistor / timer IC) that applies voltage in either direction for say ten seconds,
or there is a a surge detector, that detects a current increase across the motor because the aerial has reached the end of it's travel.

[mycav]

Any help will be gratefully received!
This is the car's original aerial so it's had a good run over a quarter century.
However, I'd like to know how it works (and fix it), particularly as I can't see that anything's damaged.
It was really quiet in operation and that's why I didn't notice it'd stopped working.
Inside the unit there's little space to do electrical tests or to determine the relay's pinout as the wires are so short. Otherwise I could possibly work out how it was designed to function.
As the relay's obsolete there's no info on it online and, as it's very difficult to see through the relay case, I can't tell for sure where the contacts and coil connections come out.
My final act will be to completely dismantle the electrical section and find a replacement relay, if necessary, to satisfy my curiosity!
The relay seems to be a good bet unfortunately!
Changing direction would be a good reason for it to exist so all I have to do is find out what the trigger is to change direction.
The disk I mentioned always rotates to the same point when the upward drives stops and that's where I know it cuts off the drive voltage.
It looks like I'll have to do a demolition job to find out how the aerial changes direction when the drive voltage is removed by turning the radio off.

[Robsey]

I presume the disc you are on about is this one.



I have just stripped and cleaned my aerial, but the electronics bit is a bugger to get out.
The disc is easy to remove and clean, but the circuit board is quite tight in there.
I presume it is being held down by the internal wires.

Mine was amazingly dry and full of sticky black dust.
No visible remnants of grease anywhere.

I have reached the conclusion that it is my mast that is jamming up.
The rest works fine.

[Robsey]

I checked out the disc - it does spin quite freely, if the two fingers on the underside of the main drive disc aren't engaged in the drive cogs.

But it's actual orientation will not matter as it does not appear to have any alignment marks or notches.
I presume, with use, it will return to it's normal resting place by itself.

As for your issues, of no downward drive, it is my opinion that: -
The relay is faulty
Or
You have a dodgy / dry solder joint where the relay is soldered to the circuit board.
Or
One of the wires soldered to the circuit board is damaged.

I have looked up a "321 D012-K" relay, however I am unable to find a proper data sheet or a suitable / matching relay.

[mycav]

There was the correct relay available on French Ebay yesterday. Other than that it seems really hard to come by and the pin orientation seems different from all the other relays that have the same switching arrangement. That's two pins for a 220 ohm coil and two sets of changeover contacts.
I guess that since it's not working I could strip it out without making things worse...so I will.
The contact plate always returns anticlockwise to the top right where the fixed 12V is disconnected from whatever it was doing.
I find it hard to envisage what sort of method allows the polarity to the motor to be reversed when the radio's switched off, except a CR timing circuit as you suggested.
Still, it'll all become clear when I've dismantled it and if it's an electronics/electrics problem then it's fixable.
It'd probably be OK too if a relay contact's a bit burned too but, here's hoping.

[Robsey]

You could always try a scrap yard for an MX5, old Jaguar or similar car with an electric aerial.

They are all constructed in a similar manner, so plenty of potential for spares and repairs.

[ilovedmymantas]

I guess that since it's not working I could strip it out without making things worse...so I will...
…Still, it'll all become clear when I've dismantled it and if it's an electronics/electrics problem then it's fixable.
It'd probably be OK too if a relay contact's a bit burned too but, here's hoping.

The newer things are the less they last, electronics shrink and they become more fragile

That relay looks like 1970's tech to me?
I fixed a blown-air heating system in a 70's built house by cleaning the contacts (and a little bending) on a similar looking relay. It lasted until the heating was replaced 14 months late so I'm sure a refurb will work for you.
All I used was a folded 1/4" strip of fine wet & dry, about 2" overall length.


My mate's got a bit of a rarity, a Nissan cube.
It's been off the road for 8 months because of a keyless-start ignition problem so I'm glad my car is older, more chance of fixing things rather than replacing them.

[Robsey]

Oh eck, Nissan Cube?..
Only one step up from a Kia Soul...

A bit like crimped hair on a woman...
Looks rediculous, and serves no real purpose.

And keyless entry / starting... another huge step back for security.

I agree, proper electro-mechanical parts are so much easier to fix.

[mycav]

The car failed its MOT due to rust that I can't fix and to repair professionally would cost thousands.
I won't be trying to get it fixed and it can't be stripped for spares in the drive here. So it'll sit outside until a scrap company arrives to drive it off to its fate.
At least I can now strip the aerial down with impunity...

[Robsey]

That is massively sad news.

Time to look for a replacement Cavalier?

[mycav]

Having driven this car for 22 years I got quite used to it, with aircon, electric sunroof, central locking, heated leather seats, excellent handling, 38mpg, no nasty electronics and a very good radio.
For me it had it all but now I've just had it.
Maybe an advanced welding course is called for...now there's a thought!

[Robsey]

It is a pity you are not near to Manchester.

The lad who rebuilt my car did a fantastic job of building a solid car from a rust bucket. My car was VERY bad.
Any lesser person would have scrapped it.

All in, the welding was a little over £2,500, which is nothing considering he spent several evenings a week doing his magic for just over 12 months.

All proper shaped panels, not pathetic plates.

Dependent upon your situation,
Troy is highly recommended for cost-effectiveness and a keen eye for detail.

[ilovedmymantas]

Having driven this car for 22 years I got quite used to it, with aircon, electric sunroof, central locking, heated leather seats, excellent handling, 38mpg, no nasty electronics and a very good radio.
For me it had it all but now I've just had it.
Maybe an advanced welding course is called for...now there's a thought!

I sense a flicker of hope here
you obviously like the car, you've had it a long time and you know what's been done to it mechanically. Metal's replaceable.
The alternative is another car with unknown history

My advice would be buy yourself a gas & gasless mig welder. (gas is better but a bit more expensive, flux-cored gasless is ok if the metal/atmosphere's not too damp)
-Don't buy a 'stick' welder, they blow through old metal! (I apprenticed as a welder).

Practice on some old metal first.
I'm sure there are plenty of tutorial vids online for mig welding that can walk you through it.

It may be old school but older washing machines are an excellent source of replacement metal, especially the back covers, which are clearly galvanised & of a good thickness

[mycav]

Even if I'd done the MIG (gasless) welding myself and bought the parts needed I'd be looking at the thick end of £600+. Having looked at the other rusty areas, I'd run the risk of an annual MOT failure as the rules continue to tighten. I didn't want that stress.
So, I'm now £100 richer but I have no Cavalier.
What hurt most in the transaction was that the guy who collected it originally said it would be stripped for parts. When he'd actually seen it he said he'd probably do it up for himself, so I may catch a glance of it from time to time to put salt in the wound!

[Robsey]

It is a shame to see a Cav go,

But on the upside, at least this one may live to see another day.