i'm back again, having been busy working on my problem. this is my problem: the magnet is supposed to do this - here you can see it easily catching the ball, then a second time it catches it but only just
[video=youtube;vwzQEW3Oiag]
however, unfortunately it has been mostly doing this instead:
[video=youtube;Xy-mF4ZMqrk]
:confused1::confused1::confused1::confused1::confu sed1::confused1::confused1::confused1::confused1:: confused1::confused1::confused1::confused1::confus ed1::confused1::confused1::confused1::confused1::c onfused1::confused1::confused1::confused1::confuse d1::confused1::confused1::confused1::confused1::co nfused1::confused1:
so first i looked for an electrical problem, but all the transistors tested ok, and the coil itself tested ok, and it's the right coil and they're new, non-magnetisable balls, and the circuit is intact and all switches are functional, and the magnet is flush with the playfield and has been filed flat .... so i was running out of ideas. but not quite out.
1) it was suggested that
the earth to the magnet coil may not be up to scratch, so i doubled it up:
it didn't seem to do anything though :confused1: and yes, i know that wire coiled round the cabinet braid is well cra_ppy. so sue me.
2) i'd noticed that
the coil wiggled about around the magnet itself, was not held tight. so first i tried bending the bracket a few degrees, which did nothing much. so i increased the shim holding the coil tight to the playfield. it comes with this rubbish looking washer thingy. i tried a rubber ring but it was too fat. but a couple of e-rings seemed to do the trick, now the magnet was held snugly in place.
this time i noticed a real difference - instead of catching one or two balls in ten, it was now catching five or six in ten :hippie:
3) in that RGP thread i linked above, someone mentioned that when the ball is delivered across, it first goes up a few inches, before dropping down. he changed
the delivery angle and stopped the upward movement, with good results. so i slightly bent the yellow tab at the bottom of the yellow delivery wireframe ramp thingy -
fantastic. i stopped the upward movement too, and now i had the magnet catching maybe 7 or even 8 out of 10. the youtube videos up ^^ there were recorded at this stage.
4) so finally i took ronsplooter's advice, and
watched what happened to the current at the coil, while the ball was sent across to it. croc clips from the coil and up through a handy hole meant i could keep the playfield down for this. take a look:
[video=youtube;v9Mj9aYq-SQ]
this demonstrated that the coil receives about 0.6A for about a second or two, and that this current doesn't arrive until
just before the ball gets there. so timing does play a major role, and it will be dependent partly on the bend of that yellow tab and how much the ball travels up before descending, and partly on the inherent steepness of the table. i keep my tables on maximum incline as i like them fast (back legs all the way out, front legs all the way in) so i'm not helping myself here, but it seems i have to do some more experimentation with that delivery angle by adjusting the end of that yellow ramp. i want to delay the ball's arrival at the magnet by a half a second or so, but i don't want to allow the ball to rise too far and so gather too much speed on the way back down. i need to find the happy medium.
and that's more or less it. i think it's a bit of a design fault, and that they should have had the magnet turn on slightly sooner, but i've enjoyed the journey.
