Mr. & Mrs. Pac-Man Pac-Maze #4 Red lamp always on...

keithsarcade

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Mr. & Mrs. Pac-Man Pac-Maze #4 Red lamp always on...

Just started doing this today. Took a look at the aux. lamp driver and it looks like a resistor and SCR control this lamp. Resistor is 2k 5% and reading around 1914. SCR is reading around 730 on a diode test, surrounding SCR's are reading between 600 to 680. I think the answer is obvious but just want a second opinion, should I replace these components?
 
Just started doing this today. Took a look at the aux. lamp driver and it looks like a resistor and SCR control this lamp. Resistor is 2k 5% and reading around 1914. SCR is reading around 730 on a diode test, surrounding SCR's are reading between 600 to 680. I think the answer is obvious but just want a second opinion, should I replace these components?

Honestly, both of those readings look fine. I can add this.....I've never seen one of those resistors go bad.....but over the years, I've replaced 100s of those SCR's that have gone bad.

Edward
 
Just started doing this today. Took a look at the aux. lamp driver and it looks like a resistor and SCR control this lamp. Resistor is 2k 5% and reading around 1914. SCR is reading around 730 on a diode test, surrounding SCR's are reading between 600 to 680. I think the answer is obvious but just want a second opinion, should I replace these components?

I would check the output pin of the MC14028B (BCD-to-Decimal Decoder) associated with the suspect SCR with a logic probe and the game in attract mode before replacing anything. The output pin should not be stuck high. If the decoder pin is low or strobing then I would replace the SCR. If it's stuck high then the decoder is likely bad.

Most likely the problem is a shorted SCR but that's something else to check before replacing it.
 
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