GOTTLIEB SYSTEM 80

[Strangeways]

Don't regret taking the job on Daniel. If the CPU is dead, then you can either continue your troubleshooting or replace the MPU. You already have the new ROM, so there is no real loss here.

I've never replaced the reset section as per Clay's guide.

[ddstoys]

Using clays guide as a guide the reset section tests out ok im going to get stuck back into it hopefully tonight.  Wouldnt have a working system 80B board lying round nino?

[Strangeways]

No - I don't think I have any of those CPU boards at this time. What exactly did you want to know ?

[ddstoys]

Just wanted to buy a working one so i can get it out of my shed and start work on star trek lol. But ill keep plugging away i always do

[ddstoys]

Well ive spent the last few hours testing the CPU as per clays guide.   First fault says its a Game rom issue as the game rom is brand new so i decided to pull the adapter off the board and replace all the chip sockets and test every trace on the adapter and cpu. The eyes are getting sore so im taking a breakfingers crossed all this pays off

[Strangeways]

Persistence is the key to this repair, Daniel - keep it up !

sorry I can't help - but Clay's guide should guide you through.

[ddstoys]

Well ive got the romboard and rom back in which fixed the previous problem now im stuck on the Address lines im supposed to test A0 - A12 or something like that anyone know about this as i cant make sense of it? 

[ajlaird]

Here's a pinout of the 6502 CPU - http://en.wikipedia.org/wiki/File:MOS6502.svg - address lines are labelled A0 through A15 and data line are labelled D0 through D7.

Hopefully you have some sort of logic probe so that you can check signals on these lines and other locations as per Clay's guide.

[ddstoys]

Thanks Andrew.
   And yes i have a logic probe and an osiloscope

[ddstoys]

Well ive pulled the pin for the night but thanks Andrew for the link to that site i used it to find the pinouts for the Riot chips aswell so now i know what pins to test and the ones ive tested are working fine.  So im taking a step back and seeing how i go tomorrow

[ajlaird]

What would be ace is to have a known working one so that you can compare readings with the non-working one. That would be ideal!

[ddstoys]

Sure would andrew but ill just have to keep plodding along

[ajlaird]

Yes, persistence will win out in the end. At least you will know what to look for next time!

[ddstoys]

Yeah thats for sure ill look for another machine lol ill never do another system 80 unless its for myself

[ddstoys]

This things doing my head in....   All the address and data lines are pulsing as per clays  so onto the next test and now its telling me that the riot chips are bad but they are all brand new ive replaced nearly half the chips on the board. GRRRRRRRR