(Topic ID: 307080)

System 7 Driver Board - Resistors R77 - R84

By The_Great_Man

2 years ago



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#1 2 years ago

I have been working on the Driver Board of a Laser Cue System 7 game. I have found that the Resistors R77 - R84 test at 1.0K ohm and appear to be the same Resistors as used on R196 - R203. The Bill of Materials on the Driver Board Assembly Drawing that I am using shows that the Resistors at R77 - R84 should be 4.7K ohm. All of these resistors appear to be the originals. The Resistors at R196 - R203 test at 1.0K ohm. I am in the process of replacing Resistor R199 as it tested bad.
I am preparing to replace the Resistors at R77 - R84 with 4.7K ohm resistors but does anyone know if the resistors that are on my board (1.0K ohm) are correct for this game? Thank you.

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#3 2 years ago

I have often used cut off leads from diodes, resistors and install them.

#4 2 years ago

Thank you but the resistors I am talking about are R77-R84. I understand that resistors R196-R203 have been replaced with 0 ohm on some System 7 boards. But what about R77-R84 - Should these be 1.0K ohm or 4.7K ohm?

#5 2 years ago
Quoted from The_Great_Man:

Thank you but the resistors I am talking about are R77-R84. I understand that resistors R196-R203 have been replaced with 0 ohm on some System 7 boards. But what about R77-R84 - Should these be 1.0K ohm or 4.7K ohm?

Weird board - I've seen System 6 boards with 4.7k for R77-84 and 1k for R196-203.
System 6 driver (resized).jpegSystem 6 driver (resized).jpeg

And I've seen System 7 boards with 4.7k for 77-84 and 1k for R196-203 (but then 0 ohm in the 204-211 spots).
System 7 driver (resized).jpegSystem 7 driver (resized).jpeg

And, as others have pointed out, some System 7 boards have 0 from 196-211.
System 7 alternate driver (resized).jpegSystem 7 alternate driver (resized).jpeg

But I've never seen 1k in R77-84.
I don't think you would go wrong by switching R77-84 to 4.7k.
I would probably also put in jumpers for R196-203 and get rid of the 1k there.

These are just guesses though. I haven't seen a board like yours.

#6 2 years ago

I would leave them as is. Not a critical value.

After all - they have worked perfectly for 40 years.

#7 2 years ago

Thanks. My feeling is to leave them alone. Not sure if they have been working since I am fixing - attempting to fix - the game for a friend. Just seemed strange that they were different from the Assembly Drawing. Does anyone know what these resistors actually do - Switch Row Inputs?

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