SOLVED what should I expect from the trigger signal of a scope?

Hi,
I finally decided to try to get the trigger to work on my scope. Telequipment D1010.
I fixed the trigger switch (broken contacts) a while ago but the trigger does not work.
There is an external trigger socket and a switch position for the external trigger.
If I put a 1khz signal into channel 1 at 5v, from an arduino, I get a clean square wave on the trace but it is moving across the trace without a trigger signal.
I assume the broken switch took something out.
The switch is now fixed.
What signal do I need to put on the external trigger input to trigger the trace on the screen?
Can I just put the 1khz signal from the arduino straight to the external input?
I don't know if the circuit before or after the switch is broken and an external input might help decide which it is.
Thanks,
Bob.

I have an old telequipment I use now & again.
Yes you can put the sqaure wave on one of the channels and the trigger i/p at the same time.
I had a problem with mine regarding the trigger, the vertical attenuator switch was grounded to the chassis via the threads & nut, but it had corroded creating an open, taking it all apart was a right pain, so I soldered a wire from the switch to the chassis, trigger now works perfect, the other thing that was messed up was the vertical position control for one channel, it was so sensitive you couldnt get the trace to stay on screen.

Manual is here: http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Telequipment/D1010.pdf

A lot of scopes want you to generally use channel 2 if your doing a single channel. It's natural to try to use channel 1.

Select the operating mode TO CH2. Apply a signal to channel 2.

Set trigger to Normal

With a waveform displayed (A few divisions at least) you should be able to adjust the level and slope controls to get a stable trace.

Thanks for the replies.
I tried the signal on the external i/p and got nothing.
I then took a close look at the trigger level switch, it has 3 tiny brass wipers for selecting tv, norm or auto.
It seemed a bit stiff so I took it to bits and 2 of the 3 wipers had broken off. I am gluing them at this time so I will respond when I get it back together and check it.
I have a manual on pdf thanks, downloaded from somewhere long ago.
I know how to work the scope and neither channel 1 or 2 were allowing me to trigger the signal.

I have now got it partially back together and it works like a dream on both channels.
I even put the signal into the ext socket and switched to ext, the trace is totally steady, if I pull the signal out of the ext socket the signal runs across the screen. Quite chuffed with myself now.
Again thank you for responding.

Excellent well done.
I find the trigger on mine not that great, I need to fiddle with the trigger level to make the trace steady every time I use the 'scope.
But its a D61, cheapo effort made for tv bodgers, your is pronbably a better design.

The little brass 'fingers' were pretty well mashed. I managed to tease them out and the switch does sometimes need just a small touch to make it connect as if it is a dirty contact but it is much better.
Thanks to all for replying. I am pleased to know that the ext input just needs the same signal as the one on the channel and I tried it successfully.
Keep safe everyone.
Bob.