rchadd
New member
Hi have a Galaxian board that seems to be playing fine except there are no stars displayed.
I have done some research on various repair logs and found the following chips seem to be most responsible for the stars:
1A & 1B (74LS164 - 8bit shifter)
2A (74LS30 - 8bit nand)
2B (74LS366 - hex bus driver inverting)
1D (74LS107 - dual JK flip flop)
9N (74LS259 - 8bit addressable latch)
In particular it was suggested that should check pin 15 of 2B and also pin 9 or 9N which seems to enable the stars to appear.
My question is how should I check these pins?
Can I do it with a regular multimeter or do i need to get myself a logic probe?
I am wondering...could i build myself a simple logic probe with a led and resister? That would help verify presence of 0V or +5V right?
Would appreciate advice as I didn't want to first start playing with the board in case i end up causing even more issues!
thanks in advance
I have done some research on various repair logs and found the following chips seem to be most responsible for the stars:
1A & 1B (74LS164 - 8bit shifter)
2A (74LS30 - 8bit nand)
2B (74LS366 - hex bus driver inverting)
1D (74LS107 - dual JK flip flop)
9N (74LS259 - 8bit addressable latch)
In particular it was suggested that should check pin 15 of 2B and also pin 9 or 9N which seems to enable the stars to appear.
My question is how should I check these pins?
Can I do it with a regular multimeter or do i need to get myself a logic probe?
I am wondering...could i build myself a simple logic probe with a led and resister? That would help verify presence of 0V or +5V right?
Would appreciate advice as I didn't want to first start playing with the board in case i end up causing even more issues!
thanks in advance