Assembled TF536 - help needed

[sampedenawa]

Well we can tell you exactly which pins are bridged if you do a complete memory detection and try editing the memory and see which byte lanes arent happy.

This is the 4th or 5th thread with exactly the same symptoms. all 4 were resolved using memory editor, complete memory detection and some magnification.

Ok, I will do a complete reflow (just in case) and follow this hints if the behavior does not change. Thx

[sampedenawa]

Well we can tell you exactly which pins are bridged if you do a complete memory detection and try editing the memory and see which byte lanes arent happy.

This is the 4th or 5th thread with exactly the same symptoms. all 4 were resolved using memory editor, complete memory detection and some magnification.

Reflown & performed memory edit test.
Same behavior.

Editing memory results:

Writing all 0x00:
$40000000 00 00 80 00 00 00 80 00 00 00 80 00 00 00 80 00
$40000010 00 00 80 00 00 00 80 00 00 00 80 00 00 00 80 00
$40000020 00 00 80 00 00 00 80 00 00 00 80 00 00 00 80 00

etc.

So bad lines at address $40000002 $40000006 $4000000A $4000000E $40000012 and so on--- any hint on where to look for bridges ?

[terriblefire]

And what happens when you try to write 1's ?

Try the following patterns, 0s As 5s and Fs.

It looks like a bad data bit D15 (lower half of the 32 bit data bus) so far

[sampedenawa]

And what happens when you try to write 1's ?

Try the following patterns, 0s As 5s and Fs.

It looks like a bad data bit D15 (lower half of the 32 bit data bus) so far

FFs -> all correctly written
AAs -> all correctly written
55s -> read back D5 at same positions where reads 80 if writing 00 (as I would expect)

Can you point me to the location of pins related to D15 (I obviously don't have any schematics or layout :)
Thanks

[terriblefire]

My bet is that D15 on the ram is shorted to power. But here is everywhere that bit gets routed.

debug1.PNG

debug2.PNG

[sampedenawa]

My bet is that D15 on the ram is shorted to power. But here is everywhere that bit gets routed.

Mighty Stephen !!!!!!
Correctly spotted: there was a bridge under IC7, indeed.
Not visible with the uscope, hidden enough.

I focused my troubleshoot on the cpld and did not consider the "Easy-to-solder" ram chips....

Board working 100% now, thank you very much for your support and for your spectacular project.

Cheers,

[terriblefire]

Excellent. Enjoy

[terriblefire]

@sampedenawa I also noticed this...

Screenshot 2020-11-02 at 18.59.31.png

This will cause you to get 32mb repeated twice...

Enter some data at 40000000 and check if its repeated at 42000000

Then run Amiga Test Kit for further shorts.

[sampedenawa]

I spotted this last one and It was "fixed" after my previous reflow.

Just finished to pass all memory tests, everything 100% works as it should.

If only we have had such an accelerator board at good old Amiga times .. ;)