Hey guys. Got an interesting one so thought I would share to see if anyone has come across this before I dig deeper. All leds locked on. Leon chip or roms.

. No boot on a system 7 board. Has good PIA good cpu chip , clock,reset and power all good. Good sockets [no scanbe and all meter out] Only leon chip installed, burned to 3 different chips at u17 to make sure chip will work in the board, All roms and rams removed and still no boot.

Both 2114 rams at pin 8 are held low and should be high at 5 volts and no action on data lines between ic1 cpu and ic9 data tranciever chip.

All read high at 5 v after replacing u9.

Before replacing ic9 there was no power at all between ic19 and ic1 cpu. Thoughts?
Cheers

lol whoops I meant u17l I posted before morning coffee. Note to self...must have coffee before doing anything. edited above.

i corrected the number above I meant u9 . Yes I meant clock signal at ic1. Shows good signal at pin 37 and correct voltage at pins 38,39.
Activity at all address lines and as for data lines when the ic9 is pulled there is no activity at all across the data lines on either side of the ic9 socket or on the cpu.

When ic9 is installed the socket legs that go to cpu and cpu data lines are always high and legs that go to the 2114 rams are all active and good.

aha. Thanks for getting me to check that again!!!! I had signal there yesterday and now its gone at ic9 pin 1. CPU is fine.

Replaced the 1c7 yet again and now its fine again and there is action on data lines now yea!!! except pin32 of cpu is low and should be pulsing.

Thats the third 7404 in that socket besides the old one. Goes to show buy more than 1 when you get spares. Still no action on pin 32 da1 i think
still no leon run But we are closer. Thanks bud.

ok update.
got data signals at all d0-d9 on cpu and ic9 and r/w is high on pin 34 of cpu and low on pin 1 of ic9. Still no leon run and pin 8 on both 2114's are low and should be high or the chip will never run.
Thoughts?

no boot when no 2114's installed and actually the lines go dead on the cpu and ic9 data lines when they [2114's] are not installed as well.
Should not need the rams or roms to run. Something fishy here....

Also checked back through the path from pin 8 on 2114's back through the three chips and they and all read low too. Socketed ic32 but not the other 2 yet.

ok update. Got the 2114's pin 8 to stay high now. 2 bad chips at ic32 and ic12 caused that. Thats 4 bad chips on this board so far to get it this far along. Its almost there. All data lines and address lines active but leds do not flash.

The segment led and 2 extra leds come on now and go out and thats it. They stay off no matter what unless I cycle power then come on and go off.
digging deeper...

I do not think the pulgs were ever incorrectly installed as the sound board is still good and cpu chip and PIA are both good. But something serious happened here. Game is new to me and just pulled it out of storage. Got it last year but been busy.

Ok. Finally got some time to finish looking at this and after I realized that the third 7404 I replaced was bad in a row I got consistant signals everywhere and found a bad leg on an address buffer. Problem solved.

Leon chip runs fine now. Lesson....even though you replaced the chip your 'new' one may be bad even the third time out. They all acted differently when installed too but all were bad.. Bad batch I guess.
At least I had 5 on hand. 3 of which were bad from the supplier.

Posted solution for others in case they have similar trouble.

Metered the traces as I had the same thought. Checked over everything carefully with magnifying glass even. Everything is good. Its a nice clean board with no acid damage or hacks.

I have had some other chips in the same batch bad out the box from same reputable supplier so maybe the mailman was having a bad day that day. Stuff happens.