Please help me determine some electronics.

[Blanka]

I'm trying to draw a schematic of a vintage game, but I'm puzzled about this piece:


What is the thing with the screw-hole on top?
The chip is a Nec D552 microcontroller.
I drew the connections on the other side in orange.
What is the burgundy colored thing? Capacitor?
It has a marking saying: 0047K 50/100
C6 says 681 so it is probably 680pF
Is it a circuit for an oscillator or so?

[ed12]

hi
tunning coil
used to :tweak: the freq

ed

[Blanka]

Do you know what symbol I need to draw for it?
And any idea what the capacitor is? I can read 3 number caps, but not this one.

[ed12]

hi
a tunning coil is  a coil with an arrow through it
so it represent's an adjustable coil
 the cap's will be in picofard's
norm is 47pf but could be 67pf

ed

[Blanka]

http://www.mikroe.com/old/books/keu/03.htm
If I look here, you see a symbol of the thing (figure 3.3b).
Now the symbol has an internal capacitor, but if I connect this symbol to the surrounding components in my example, there is an external capacitor in parallel to the internal one. Do you think the one used here does not have an internal cap?

[ed12]

hi
3b has a internal cap
3/a have external caps

ed

[Blanka]

Yes, I can see that on the schematics. But has the one on my photo an internal cap, when there is a separate capacitor parallel to it at C6.

[ed12]

hi
yes that happen's all the time in :timming-circuit's:
for your know that's called a >tank-circuit<

ed

[Blanka]

Is the schematic correct like this:


Or should I remove the cap inside the dotted box?

[ed12]

hi
nope it is fine
that is called :tank-tuned-circuit:,some time's there is a cap some time's not

ed