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Bally & Stern Early Solid State Schematics Question


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Question

I have been working on repairing a couple of issues on a Lamp Driver Board of an Early Solid State Stern machine for the first time and have been going over the schematics (Link to Manual with full schematics)

 

112901420_ScreenShot2019-03-11at6_44_05pm.png.2f18c51dc2c229929b26f08468e28f29.png

 

From the screenshot above :

1) What do the numbers I have highlighted in Blue represent?

2) It looks like the numbers highlighted in Red represent the pin on the U3 chip which connects to the respective SRC/Transistor... is that correct?

3) How accurate are theses schematics ? .... because if 2 is correct the resistors (highlighted in purple) don't match what is on the board.

 

 

Thanks

 

Jason

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1) What do the numbers I have highlighted in Blue represent?

 

This 4514 logic chip is a 1 of 16 decoder. Those numbers boxed in blue are the 16 logical outputs. Only one output can be selected and made active high at any time. The selected output is based on binary representation of four inputs marked D1, D2, D3 and D4

 

2) It looks like the numbers highlighted in Red represent the pin on the U3 chip which connects to the respective SRC/Transistor... is that correct?

 

Correct, the numbers boxed in red are the pin numbers of the 4514 logic chip.

 

3) How accurate are theses schematics ? .... because if 2 is correct the resistors (highlighted in purple) don't match what is on the board.

 

Unfortunately the first version lamp board with the 4050 buffer chips at U5 to U8 have those resistors boxed in purple marked incorrectly. The next version of lamp boards where the 4050 chips at U5 to U8 were discarded have the correct resistor numbering (the resistor numbers match the respective SCR number they're attached to as you see on your schematics).

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