I’m hoping someone might point me on the right direction on this one On a William time warp.
The two inner rollover lamps (incandescent) are partially on and flickering at startup as is the playfield credit lamp. As soon as a point is scored anywhere all three are then 3/4 on. All three are the only lamps on the same column lamp circuit. I’m guessing it might be the two driver transistors q62 and 63.
In lamp test these lamps flash on and off correctly.
when the feature activates to light the rollovers they go to full brightness. And back to 3/4 when the feature goes off again. So basicallythey appear to operate correctly but never go fully off - as if there’s a ’leak’ in the circuit somewhere.
Q62 tests the same as the others while in circuit so could be ok. Not tested 63 yet as tricky to access until I take board out (again!).
To try and narrow things down I tried to test the voltage across the base and emitter of q62. I was hoping to see if the output of IC13 to see if it went high when conditions were met to switch the lamps on. However I just get 0.2 v here at all times. I suspect my test logic might be flawed here! I do have a logic probe but wasn’t sure about using it here as I know this is higher voltage at this point.
Can any guide me to confirm the circuit is ok to this point? I’m suspecting the tip42 is probably the culprit but would like to confirm before I swap it if possible.
Thanks
The two inner rollover lamps (incandescent) are partially on and flickering at startup as is the playfield credit lamp. As soon as a point is scored anywhere all three are then 3/4 on. All three are the only lamps on the same column lamp circuit. I’m guessing it might be the two driver transistors q62 and 63.
In lamp test these lamps flash on and off correctly.
when the feature activates to light the rollovers they go to full brightness. And back to 3/4 when the feature goes off again. So basicallythey appear to operate correctly but never go fully off - as if there’s a ’leak’ in the circuit somewhere.
Q62 tests the same as the others while in circuit so could be ok. Not tested 63 yet as tricky to access until I take board out (again!).
To try and narrow things down I tried to test the voltage across the base and emitter of q62. I was hoping to see if the output of IC13 to see if it went high when conditions were met to switch the lamps on. However I just get 0.2 v here at all times. I suspect my test logic might be flawed here! I do have a logic probe but wasn’t sure about using it here as I know this is higher voltage at this point.
Can any guide me to confirm the circuit is ok to this point? I’m suspecting the tip42 is probably the culprit but would like to confirm before I swap it if possible.
Thanks