exxos's Atari, Amiga & retro forum

HigashiJun wrote: 30 Dec 2021 12:06 I will perform other tests, and if there are no results, I guess I will have to give up...

I think I mentioned this before, which is why I developed the MEGA clock buffer board. But I think we had this conversation already.

exxos wrote: 30 Dec 2021 12:09

HigashiJun wrote: 30 Dec 2021 12:06 I will perform other tests, and if there are no results, I guess I will have to give up...

I think I mentioned this before, which is why I developed the MEGA clock buffer board. But I think we had this conversation already.

Yes, but unfortunately your board is not in your online store any more...

HigashiJun wrote: 30 Dec 2021 12:17 Yes, but unfortunately your board is not in your online store any more...

I know, but you only need to add a schmitt buffer to the CPU 8MHz clock really in this case.

In fact, just put your scope on the 8Mhz clock on the CPU on x10 first, see if things get better or worse..

Simply adding 68R in series with the CPU clock may help.. it really depends on what signal is causing the failure though.

HigashiJun wrote: 30 Dec 2021 12:06 My PAK has just 2 spots for GND and VCC. 2 thick wires are connected to GND and 1 thick wire is connected to VCC.

That's what I was referring to. A good ground connection in particular is required to reduce ground bounce.

exxos wrote: 30 Dec 2021 12:41 I know, but you only need to add a schmitt buffer to the CPU 8MHz clock really in this case.

Considering that the 68000 clock line is conveniently located between ground and Vcc pins, it should be relatively easy to "bodge" a SN74LVC1G17 onto the relocator to test if this helps.

HigashiJun wrote: 21 Dec 2021 09:50 Like this one...


Gotek.jpeg

Yes :)

czietz wrote: 30 Dec 2021 09:36 Sorry, I haven't followed this thread. Did you solder multiple additional ground (and possibly also +5 V) connections from the PAK to the mainboard? As short as possible and made from thick wire, as described in the PAK manual? In my experience, the PAK3 is one of the least troublesome accelerators.

Sufficient grounding is actually a big deal. I think I've got 3 grounds coming off my Pak board in total. The manual stresses this as did Holger Zimmerman himself, when I corresponded with him. Clean bus signal, grounding, solid P/S, those seem to be the usual issues that cause
problems.

I totally agree with you Czietz. I've played around with several accelerator boards over the years and the Pak 68/3 and AdSpeed remain at the
top of the list for being the most reliable and having had the least problems with...

PS Would have to check to see exactly how many grounds I have but I know it's multiple...

@exxos @czietz

Thank you both for your advices.

I will check that as soon as I get the Schmitt trigger.

Today's update:

No more weird issues today with the new CPU relocator...

Everything runs smooth as before and even at 40 Mhz:


The FDD is also OK:


The problem was the blitter. After having soldered the 2 blitter spots on the Mega ST motherboard to disable it, I have refitted the chip in its socket. And even with the blitter disabled, the chip was causing issues.

So the main goal now is to make the PAK68 run with the STGA or VOFA adapter, and as for now, it does not want to.


and I have the Mega ST freezing at this screen (no matter if is is at 40 Mhz or at 8 Mhz in the fallback mode):


Seems the journey is not yet over...

;)

Those links for the blitter are not enable disable . They route bus request signals via the blitter, or not.

I was advised that my PAK68/2 wouldn't work with the Blitter, you may want to check if it's the same for your version.

EDIT: Here is the link to that info: https://www.exxosforum.co.uk/forum/viewt ... tory#p5092

PAK68/3 is a no for the Blitter too.