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TAF , knocker not working keeps blowing fuse ,

Lee ellison

Lee ellison

Lee9168
Joined
Dec 16, 2013
Messages
572
Location
Billingham, North East England
Can any one help , my knocker , which was not fitted when I got the game , is now fitted , it worked for a bit then it blew the fuse ,now as soon as I put a fuse in and test it blows the fuse again , how do I check if the coil is ok , or is there any thing else I can check , cheers lee
 
Does your coil have any component installed between the tabs.
Have you disconnected one of the wires and re-measured?
 
Snip one end if the diode off and re measure. If you connected the coil in reverse the diode will be short but the coil will be good. For a reading of 0.4 ohms the coil would probably be obviously overheated, so I suspect the diode is short.
 
You can reconnect the coil WITHOUT the diode. BUT it's possible that the driving transistor is short, and coil may lock on and blow fuse again. So be ready to switch off. If this happens then driver board needs repair.
 
pinballmania said:
You can reconnect the coil WITHOUT the diode. BUT it's possible that the driving transistor is short, and coil may lock on and blow fuse again. So be ready to switch off. If this happens then driver board needs repair.
Click to expand...
Thanks . Is their any way of checking the driving transistor , ? Also if the board needs repair , can you do that ?
If it works without the diode , what is the diode there for ? Just trying to learn a few things ;)
 
Yes. With a meter but too complicated to explain here effectively.

The diode suppresses damaging currents when the coil turns off. But on this era of machines a diode is installed on the circuit board so the coil diode is superfluous.


Yes
 
Thanks , I,ll try it back on in the morning . .
There is no plug connector on this coil so how do I know which wire goes to which end , cos as I said this was not connected when I got it ?
 
Replacement diodes are cheap as chips if u need any lee just bought 100 on cpc for about £2. Also the schematic should tell you what wire should be connected to why side
 
RudeDogg1 said:
Replacement diodes are cheap as chips if u need any lee just bought 100 on cpc for about £2. Also the schematic should tell you what wire should be connected to why side
Click to expand...
Are all diodes the same rating ?
The schematic does not show individual solenoids it just shows high power wiring diagram , and this does not show which side of the solenoid/ diode the power or drive go to !
 
Where diodes are fitted, connect the thicker live wire to the banded end of the diode. Diode have various ratings but the standard part is 1N4004.
 
pinballmania said:
Does your coil have any component installed between the tabs.
Have you disconnected one of the wires and re-measured?
Click to expand...
Andy I know off this topic here but did you see my thread on the WH2O audio board. I am after a schematic can you help ?

Cheers kev
 
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