(Topic ID: 161781)

Big Guns: Upper Center flashers over volting and constantly on

By smitherssp

5 years ago



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  • Latest reply 5 years ago by smitherssp
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#1 5 years ago

Greetings,
I recently picked up a BG and have been having a great bit of fun refurbishing it. I've done all the usual maintenance and set about replacing all the blown 89 bulbs last night. When I replaced the pair of top/center flash bulbs (behind the clear globe on the trans) they blew instantly. I measured their voltage and instead of the expected 12-13V it is measuring 31.5V. I thought that maybe the sockets had been mislabeled somehow so I tossing in some 1251 bulbs and boy did they light up! Turns out the sockets are constantly hot (see attached pic). I referenced the manual to determine what is inline between these lights and the incoming power but without a schematic I'm a bit lost. I did determine that D13 on the Aux power board is bad but it doesn't appear to be in circuit with the bulbs in question. All the resistors on the lower resistor board appear okay visually but I need to ohm them out.

My question is: Which components are inline with these particular bulbs? What type of failure would result in a higher/constant voltage? What checks do I need to run? Am I crazy and these are in fact 1251's that are constantly lit?

Thanks so much!
Smithers

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#2 5 years ago

Figured it out. Bad TIP122 transistor in the circuit. Big thanks to WindDrake over on KLOV!
http://forums.arcade-museum.com/showpost.php?p=3376192&postcount=4

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