IMG_2523.JPG Hello Guys, The saga continues!

My logic probe has arrived. After watching a few youtube videos on how to use it, i set out to check if the system has a clock.

i go check the clock on the affected socket UC7, B-Phi2 on pin 25. it should be "oscillating". I get both LED's lighting ...

Yeah i have been reading his blog quite a bit looking for a post with a similar issue. Its an interesting read for sure.

Also public holiday here so the Postal service has not delivered my logic probe.

I a bit lost at what i should be doing right now.. Wait for the Logic porbe and then check B-Phi ...

Alright, the guy who sells it is on vacation till June 7th and is not taking orders, but i signed up for the mailing list to get reminded when he returns. I will then order it.

Emmanuel

https://www.tindie.com/products/tynemouthsw/pet-diagnostics-module/
This is the diagnostic board i was shown earlier.

when im ordering something from the guy, i was wondering if this is a "Good to have" because many people on youtube who have these machines, have one of these too:
https://www ...

No it does not, but my logic probe should finally arrive on monday.

Emmanuel

So i think something some where went terribly wrong. Im now gonna go through every step of this thread and note down my results. I just have the feeling ive done some things wrong, and maybe reported some wrong information.

1: I have measured Voltages on the board to see if I have the necessary ...

So could it be that im looking at the wrong 74LS10 Chip? Instead of in socket UG7, theres a 74LS10 Chip in socket UA5? And to that 74LS10 chip, i do have continuity to 7417. I found it by tracing any path from 7417 to where ever it goes.
If the one in UG7 is the one that has to be connected, i can ...

It's possible the previous owner of this board cut some of the traces as part of a troubleshooting effort. If they thought one of the circuit paths had a short to Gnd or Vcc perhaps then it might make sense to divide the path into shorter segments and then see which segments become clear and which ...

small update:

probe each and every track/via/component (where you have a bare conductor) that has a track that leads away from (or to) the area where you loose visual on the track you are trying to trace. Do this on both sides of the board. And include other pins of the same chip.


Thank you for ...

In 0002.PNG, pin 1 of all the visible chips is at bottom left. Several have a big notch showing the end of the chip featuring both pin 1 and the highest-numbered pin. Two have a much less noticeable dimple next to pin 1 itself.

I have gathered as much with the notch. The two that have less ...

Hi again, man this board worries me. I tried again to find out why i dont have continuity to 74LS10 and i cant figure it out. I dont know how to work my way towards the issue, and i dont really know how to work my way backwards because i cannot find the trace that leaves pin 1 from 74LS10. The ...

Sorry the work week has started again.

So im struggling a bit, I think i have traced B-phi2 from the 7417 to everywhere except that Pin 1 on the 74LS10 chip in UG7. So i try to find where it physically runs but fail because when i check where pin 1 is connected to on the back of the board, it ...

Ok, im testing continuity with the beeper now, im using the picture attached as a reference.

Ive found the the Phi2 going from from the UC7 socket to pin 25 on the 6522 chip. and the beeper does go off.
The Line leaving the schematic is labled BΦ2.

BΦ2 reappears on the "Display Logic" schematics ...

The affected Socket is UC7.

All these tests are with the chip removed from UC7

1: I have tested the RESET and when turning it on, it goes to 0.20V for a short second before going to 5.12V
I measured 5V on Pin 11 of the UC7 socket so i assume this is 5V on that socket. When turning the machine on ...

IMO the risk of that is very small. I would swap the chips and see what that reveals. Good luck! :)

-- Jeff

So i have put the second 6520 in the first slot and it resulted in the same 0.12 V in IRQ of the 6502 as the first 6520 did. I put it back into its original position, leaving the first ...