exxos's Atari, Amiga & retro forum

frank.lukas wrote: 09 Sep 2024 15:18 ... why don't you just remake all GAL chips new using Lattice 16V8-15ns GAL chips ?

@frank.lukas

Can you please confirm with me if these are the correct parts?

Lattice Semiconductor Corporation GAL16V8D-15LP Programmable Logic PALs and GALs - U62 U63 U67 U68

https://www.jameco.com/z/GAL16V8D-15LP- ... ?CID=MERCH

Lattice Semiconductor Corporation GAL20V8B-25QP Programmable Logic PALs and GALs - U44

https://www.jameco.com/z/GAL20V8B-25LP- ... ?CID=MERCH

Thank you.

Badwolf wrote: 10 Sep 2024 09:44

sdisla wrote: 09 Sep 2024 15:27 I replaced only four U63 U62 U67 U68, still waiting for U44 the one near the DSP side of the board.

! will keep looking, keep you posted, thank you for your support.

No worries. Keep looking. Check pins around the affected GAL for intermediate voltages or drift, etc. Check removing the GAL still resolves the problem.

Try to keep a written record. It will help as you'll have hundreds of things to check.

Good luck & keep going. You're getting closer, I'm sure.

BW

@Badwolf

I did the measurements with the new ICs and for my surprise these GAL chips behave as blank ICs.

In order to sort this out I check with the scope the following combinations getting the same readings:
- AS A1 with new U62 U63 U67 U68 installed.
- AS A1 with new U63 U67 U68 installed no U62
Our current finding with the originals GALs
- AS A1 with no CHIP installed.

I reinserted the originals U63 U67 U68 no U62 and check for AS A1 and I get the correct reading 0101.

Let me see how I can get them back to the vendor to check if they are blank.

In the meanwhile, I will get the Lattice ICs as per @frank.lukas suggested and program them myself.

We still have the chance that it could be a bad U62 or perhaps U44.

Keep you posted.

Is everything ok under that clock patch mod board? It's not shorting anything or has caused any broken traces?

If it's only tapping 5V and GND you could power that from flyleads and get it out of the way during investigation.

BW

Badwolf wrote: 11 Sep 2024 09:31 Is everything ok under that clock patch mod board? It's not shorting anything or has caused any broken traces?

If it's only tapping 5V and GND you could power that from flyleads and get it out of the way during investigation.

BW

@Badwolf

No shorts under the clock patch mod board.
I sent back the GALs I purchased to the vendor for analysis.
I ordered the Lattice GAL16V8D-15LP and I will try to program them.

Keep you posted.

Thank you for your support.

Badwolf wrote: 11 Sep 2024 09:31 Is everything ok under that clock patch mod board? It's not shorting anything or has caused any broken traces?

If it's only tapping 5V and GND you could power that from flyleads and get it out of the way during investigation.

BW

@Badwolf

“A picture is worth a thousand words”

All 4 GALs replaced...

No words to express my gratitude for all your help as well as @exxos and @frank.lukas

Thank You.

... a very long run to the finish. Great that the computer is now working again. Congratulations ...

Glad to see the machine operational again!

stephen_usher wrote: 17 Sep 2024 10:45 Glad to see the machine operational again!

@stephen_usher

Thank you!

frank.lukas wrote: 17 Sep 2024 07:17 ... a very long run to the finish. Great that the computer is now working again. Congratulations ...

@frank.lukas

Thank you!

sdisla wrote: 17 Sep 2024 06:34

@Badwolf

“A picture is worth a thousand words”
[/quote]

Sensational news!

Sometimes you get lucky and 'well you may as well take the GALs out as they're socketed' has hit the jackpot. Very well done!

You've also learned some new tricks with debugging hardware, so hopefully the Falcon's in good hands from now on.

Bravo zulu.

BW