apollo 13 moon magnet problem

[pokermachine]

Hey all,
Have a apollo 13 problem... the moon fuse keeps blowing, before the fuse blows the magnet will constantly be on and will get really hot!
Have checked what i think is all the wires from the moon all the way back to the main board and i can't see anything that looks odd.
I have also disabled the shaker motor with no change.
Any ideas?

Thanks, Adam.

[goodolddays]

Sounds like the magnet could have a short ? or the driver transistor for the magnet is cactus ?

[Caveoftreasures]

seen this before on apollo 13.  replace the magnet.  not an expensive item.

(have u fired the magnet in the test menu with a ball in hand ?)  The only problem now is, that if u left the magnet on far too long and it got really hot, u may have buggered the board as well.)

use test menu to test magnet which will fire a short pulse, then go from there.  it is likely the magnet would have been stuffed well before the board.

[pokermachine]

Thanks for the reply!!! just changed the transistor on the driver board... the shop didn't have the exact one but sold me an equivalent... soldered it in place and now no magnet at all..... hmm maybe a faulty new part or not really a equivalent....... but must be on the right track for the magnet to not be on..... any thoughts??

originally it had a P20NI0... i was sold P19N820FP... can't find any info on either.

For some reason when i push run on the moon test and other tests for that matter nothing happens but i am getting a reading of just under 5 ohms on the magnet which is what it should be... still magnet???

[Caveoftreasures]

sounds like it could also be a screwd I.C.     OR it wasnt a equiv replacement board part.

NEXT MOVE - phone the best pinball tech in Australia who is a member here - Andrew(Beaky) on 0755 29 8886.  Andy will look after u with a multi-meter in hand.  (Note - I have spoken to Andy this morn and he said give him a quick call etc - he is happy to help u out).
 
Andy looks after all my 3 dozen dmd machines and can help u out over the phone I am sure.

Cavey ! 

[pokermachine]

wow thanks for the help!!! just went and got a different transistor.... try that one out... if thats a no go will phone the pro's 

[beaky]

you may have a crook pre driver transistor Q6
as far as the replacement transistor goes you should use a IRL540 for the P20N10

[pokermachine]

you may have a crook pre driver transistor Q6
as far as the replacement transistor goes you should use a IRL540 for the P20N10

Hmm... if the q6 transistor is on the I/O power driver board then Q6 does not have a transistor... just 3 empty holes.... moon used to work fine tho.

Would using a p19nb20 insted of a IRL540 or P20N10 make the magnet not work now?

[MartyJ]

Do you have a copy of the manual or schematics?

I'd hold off just shotgunning replacements in - especially if you have been given wrong advice and an incorrect transistor is installed it can damage lots of other components.

[MartyJ]

you may have a crook pre driver transistor Q6
as far as the replacement transistor goes you should use a IRL540 for the P20N10

you may have a crook pre driver transistor Q6
as far as the replacement transistor goes you should use a IRL540 for the P20N10

Hmm... if the q6 transistor is on the I/O power driver board then Q6 does not have a transistor... just 3 empty holes.... moon used to work fine tho.

Would using a p19nb20 insted of a IRL540 or P20N10 make the magnet not work now?

According to the manual Q6 is NOT installed.

I'm guessing that beaky was referring to the magnet driver board under the playfield.

The transistor you replaced - this was on the magnet board yeah?

[pokermachine]

Yes i do have the manual, trying to read thru it... have followed through with sight the line it states runs the magnet but no big burn marks.
Yes the transistor was on the little board underneath the playfield... moon wires connect to this board so my guess it is the magnet board... must be it as when game was on magnet ran constantly but now with new transistor just no magnet...

[MartyJ]

 Ok we will try to get you back on track.

If you can upload a pic of the magnet board schematics we can sort it.

First with game off / unplugged unplug magnet and check ohm.

Next there might be a fuse under playfield for magnet. Remove and check with DMM.

Finally check all other fuses in back board

[beaky]

you may have a crook pre driver transistor Q6
as far as the replacement transistor goes you should use a IRL540 for the P20N10

you may have a crook pre driver transistor Q6
as far as the replacement transistor goes you should use a IRL540 for the P20N10

Hmm... if the q6 transistor is on the I/O power driver board then Q6 does not have a transistor... just 3 empty holes.... moon used to work fine tho.

Would using a p19nb20 insted of a IRL540 or P20N10 make the magnet not work now?

According to the manual Q6 is NOT installed.

I'm guessing that beaky was referring to the magnet driver board under the playfield.

The transistor you replaced - this was on the magnet board yeah?

yep Q6 on the playfield magnet interface board.
An IRL540 has a higher current rating and only needs 5 volts on the gate to be turned on properly and is recommended in the Clay repair guides as a replacement and i have used them myself on magnet driver boards

[pokermachine]

Ok, i purchased the IRL540 transistor and the magnet worked... problem was it did not drop the ball when at the full half turn... it held the ball until back at the start position then it let it go... tried to use moon magnet again but fuse has blown... not sure if the ball was released by the moon magnet or the fuse blowing... installed a new fuse and it blew straight away.... its like the IRL540 was working fine but when told to power the moon has stuck on so maybe a part before the magnet driver board is bad.... any ideas???

is this the diagram for this circuit?

[beaky]

yep that's it

if it has locked on then there are problems else where in the circuit also. you will need to find out if the IRL540 has gone short.

you would need to test if any of the diodes or transistors have failed.

I can see a design fault on the aux driver, if the wire from the display board in the schematic has a bad connection or becomes loose there is no pull down resistor on the gate of the Q3 and it will end up killing the transistor.