(Topic ID: 235562)

Whitestar Driver Board Repair Question

By statictrance

11 months ago

Topic Stats

  • 9 posts
  • 5 Pinsiders participating
  • Latest reply 11 months ago by pinballplusMN
  • Topic is favorited by 1 Pinsider


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#1 11 months ago

So - I have what I think is a pretty basic question, but I haven't been able to find a definitive answer. Looking at the manual in the below - I need to what all in in circuit for the transistor (the highlighted box). Looking at the board - I believe it's just the transistor itself, resistor, and the little capacitor next to it, but wanted to confirm.

TL/DR - I have a customer who had replaced the coil incorrectly and blew the transistor (significant soot and smoke in the backbox). I replaced the transistor - but am still not getting the coil to fire. Resistor tests good and all other tests I can think to run (confirm coil, Confirm wiring to coil, check diode on coil, etc) all seem to check out, so my issue has to be the board.) I unfortunately don't have a Whitestar machine at my home to test this in while I troubleshoot and the customer lives about 1/2 an hour away, so I'm trying to get it right the second time. If the above all holds true, it has to be the little capacitor next to the transistor, correct?

Thanks ahead of time!

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#2 11 months ago

Not likely going to be the capacitor. If the transitor blew that hard, you've likely got issues into the logic now. Damage into the data lines isn't uncommon in such cases on this board.

You'd be best off to send to a board repair person for proper repair.

Rob Anthony
Pinball Classics
Quality Board Work - In Home Service
borygard at gmail dot com

#3 11 months ago

I'm comfortable with board repair and have worked on a number of them, but largely older ones (sys 11, classic Bally, etc) and haven't had to on this board in the past.

If the data line is damaged, I could run a repair trace from the chip leg to the resistor - but again would need the detail that the diagram (ie - Logic chip --> Resistor --> Transistor) is lacking. I haven't run a logic probe on it - but likely need to do that to confirm the data line/I/C. I had expected the I/C was fine as all other transistors on the 8-16 bank continued to work as expected, save the Q14 Super VUK that blew. In my prior work, if the logic chip was damaged, multiple coils functioned oddly/not at all tied to the I/C.

#4 11 months ago
Quoted from Borygard:

Not likely going to be the capacitor.

I agree.

Quoted from statictrance:

I need to what all in in circuit for the transistor (the highlighted box).

This information should be in Section 5 of your manual, but just in case you dont have one ...
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#5 11 months ago

Make sure the trace from the transistor to the connector on the driver board didn't burn up. I've seen that way more often (and burnt resistors) than blown ttl chips on the whitestar drivers.

#6 11 months ago

Pinguy and Kbliz - Thank you so much. I was looking through the manual from IPDB and when it went from wiring diagram to the self test flow chart, I thought the diagrams were done! I see it now in the manual (though honestly you just copied out everything I need).

Looking forward to getting this back on the bench and traces tested tonight. Thank you both again!

1 week later
#7 11 months ago

Ok - I finally got time to look at the board and still don't think I have a solution...

1 - I buzzed out all continuities and they all check out - I have connection between the right transistor leg and both the little capacitor and the Resistor (and the resistor to the U2 chip), the middle/tab and the connector pin, and the left leg to the little capacitior only. (confirmed this is the same continuity other transistors on the board show, and they all work)

2 - confirmed resistor value (21.6K)

At this point - Could it really be the baby capacitor (C249) ? I don't think there's anything else here board wise that could be incorrect. All connections are made and verified - resistor never blew and logic line buzzes. I can't imagine the short hit just one pin on the chip, but if I take it over to my client's house I can run the logic probe on it to verify

Appreciate all the insight - thank you.

#8 11 months ago

You can always check it to see if its shorted, or just replace it if you are concerned about it. If I was a betting man, and you know for a fact that Q14 is good, I would put my money on U2; this is nothing more than than eight D-Type Flip-Flops tied to a common clock in a single package, its very possible that a high enough spike on the output of one of these flip-flops could destroy it without effecting the other seven.

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#9 11 months ago

I ve seen the ic be the culprit in your situation.

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