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Stern Star Trek problem - where to start

Judderman

Judderman

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5Years
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Hi

Got round to setting ST up back from Pinfest & I have no coils or flashers (apart for the last 3 for some reason). This is the first time I've had to look at anything so modern, so looking in the back I can see LEDs near the fuses - I'm assuming lit means the fuse is OK (& indeed, F10 by the unlit LED was indeed blown). I replaced that & the replacement blew too. Also on the power driver board is a set of LEDs with voltages by them - I assume they should all be lit; the 20V one isn't.

I'm assuming the 20V LED is out due to the blown fuse, and that I have a short making the fuse blow. When something's up the bucket on LW3, I start with this http://techniek.flipperwinkel.nl/desega/ - is there a similar resource for ST?

Is the next step a visual check for loose wires/things touching things they shouldn't be touching, or is there a way to narrow the search?

Regards & TIA, Stew
 
as you said go check for obvious shorts however I've seen when this its been a BR on the board.

you should be able to disconnect all the coils either from the board or by opening the coin door and ensuring high power is off.

turn the game off, keep coin door open swap fuse, power up with coin door open if it blows then I think you have a bridge rectifier issue. If it doesn't pull the coin door switch and step through the coils one by one in test mode to see what blows it.
 
Cheers Neil - will give your suggestion a blast during the week - not sure whether I had the door open or closed when the second fuse blew.
 
Well - gave it a go - with door open the red LED wasn't lit, but when I pulled the interlock button out the LED came on, the fuse glowed a lovely red & blew again before I had chance to go into the coil tests. Not sure where that leaves me diagnostics-wise, but I'll do some judicious printing of the diagrams from the online manual when I'm in the office on Wed. Had a quick shufty & couldn't see anything obviously out of place.
 
No - I suspect there's going to be a lot of checking with the meter, once I can see where things should go
 
Fuse F10 serves all these:

1662407370423.png
So maybe a problem on one of the above.
Also, some of these flashers are linked to the speaker lights so try disconnecting the speaker lights to see if they are causing the issue.
 
I can take a picture of my backbox boards when the pin is on if that helps, let me know
 
Cheers @Itch - don't think that's needed (yet) - in the backbox, everything looks neat & easy to see, it's when it gets under the playfield that it gets tricky.
 
Judderman said:
Cheers @Itch - don't think that's needed (yet) - in the backbox, everything looks neat & easy to see, it's when it gets under the playfield that it gets tricky.
Click to expand...
Just let me know if I can help, btw my one had burnt out the coil which operates the gate that you hold left flipper to open on super skill shot, not sure if it’s a common fault on them or not,

Itch
 
Judderman said:
Cheers Neil - will give your suggestion a blast during the week - not sure whether I had the door open or closed when the second fuse blew.
Click to expand...
well I think the good news is that your board is ok.

Look for coils with diodes on them first, assuming there is no obvious wire damage/short that would be my next area to check. not sure if Star Trek has connectors for the coils into the main power.
 
Pull connectors J6 and J7 from the Driver board. Replace the blown fuse and power on. Check that the fuse remains intact / fuse LED remains lit (this checks the driver board for the cause). Power off and reconnect J7 then power on. Check that the fuse remains intact / fuse LED remains lit, if it doesn't then the problem is with those Group 1 coil flashers. If it does remain lit then power off and reconnect J6 then power on, just to confirm that the problem is with J6 and Group 2 coil flashers. Flashers can blow causing a short so just replacing the flasher bulbs may resolve the issue. It is possible to inspect them with a magnifier to check for broken elements.
 
If fuse 10 is blowing then you most likely have a short in Bridge 2. Take the board out and test it with a multimeter on diode setting. You are looking for a zero reading between any two adjacent pins.

The door interlock cuts the FEED to the bridge, not just the coils.

If there was a short in a coil then the voltage output fuse would most likely blow rather than f10.
 
pinballmania said:
If fuse 10 is blowing then you most likely have a short in Bridge 2. Take the board out and test it with a multimeter on diode setting. You are looking for a zero reading between any two adjacent pins.

The door interlock cuts the FEED to the bridge, not just the coils.

If there was a short in a coil then the voltage output fuse would most likely blow rather than f10.
Click to expand...

sadly that's what I thought it would be also. I thought the fuse would still blow with the interlock, useful to know Andy thanks.

Neil
 
Well, that's been fun - followed @Moonraker's advice :-

J6 & J7 disconnected - fuse OK :thumbs:
Just J7 reconnected - fuse OK :thumbs:
Just J6 reconnected - fuse OK :confused:
J6 & J7 reconnected - fuse OK :confused:
Plays fine :D

Looks like lifting the playfield, checking stuff & moving hanks of wire to look behind them looks to have cured the short (I suspect it'll return in future to bite me on the bum, though)

Thanks for all the input peeps

Stew
 
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