Bright Lights...

Azurden

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Donor 4 years: 2013-2016
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Have a Hyperball that the P row of lights are brighter than all the rest. Game plays, but the P row of lightning bolts seems to also flicker in game when they should not. Traced out the circuit and verified the components i could such as resistors, diodes, and transistors. For better or worse I installed sockets for the known IC's in circuit and since it uses several of the same ones in key areas I flopped them around to see if the problem follows an ic... it does not. It does have a few of the SR type resistors in the circuit not sure out to test those. Do transistors ever test ok but turn on when they should not?

Anyone seen anything like this happen on a driver board before?

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The schematic I have is a bit hard to read but check Q48 or whatever transistor drives 2J1-2
 
Yeah they all check out. Thinking was 47 and 48 in that part. That's why I wondered if a trans can pass a test with a meter and still do something funky like this.
 
What do you have on the base of the transistor? Compare the signal with the others. Could be IC10 or a stuck PIA.
 
I already checked all the other IC's, also installed a socket for the PIA for testing purposes as I had a few extras to test with. Ruled that out as an issue.

Well, pulled Q47 and Q48, both of the transistors tested fine in and out of circuit. I had some extra new ones, so I just installed (what the hell right) Once I replaced them everything now works the way it should. Color me confused.
 
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How did you test for leakage? How did you test their Beta (gain)?
Just because you test a transistor B-C-E to see it is not "short" and it has "diode drops" at the correct polarity etc, does not mean it is still in spec.
 
How did you test for leakage? How did you test their Beta (gain)?
Just because you test a transistor B-C-E to see it is not "short" and it has "diode drops" at the correct polarity etc, does not mean it is still in spec.

I had posted this above...

"Yeah they all check out. Thinking was Q47 and 48 in that part. That's why I wondered if a trans can pass a test with a meter and still do something funky like this."

I was not aware of "leakage" or "Beta" I only know how to test for shorts. So I poorly worded the above question based out of a lack of knowledge seeking guidance on such things.

So how DO you test for leakage on a trans to prove it is in spec?
 
Seems in that circuit you have an NPN Darlington and a PNP.

For leakage, you can build a circuit and test any leakage current and compare to the datasheet (or use a special meter).

For gain (hfe), easiest method is to use a meter that has that test function .. and again, compare to the datasheet. (It tests the relationship between base current applied and resulting collector current as the transistor turns on; with the relationship Ic = Beta * Ib where Ic is collector current, Beta is the gain (hfe) and Ib is the base current; example, if Beta is 50, and you apply 10mA to the base thru a resistor, then resulting collector current is 50x10mA = 500mA; if the test applies 10mA and only measures 250mA, then Beta is 25 and not 50 and thus not in spec ...).

2N6548 Darlington:
https://www.mouser.com/ds/2/68/2n6548-17304.pdf

TIP42 PNP:
http://www.mouser.com/ds/2/149/TIP42-890119.pdf

Hyperball manual / schematic:
http://mirror2.ipdb.org/files/3169/Hyperball.pdf

Example Meters with hfe function:
(examples only; I do not specifically endorse any of these; though the LEADER LTC-906 is cool ... ) :)

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