ST536 in a Mega ST4

[HomeLate]

I made a ST536 a few weeks ago and so far it hasn't been running great. It manages to boot to TOS 2.06 (with rev 5 fixes) but it freezes soon after either during disk access or running a program or demo.

I tested it first in a 1040ST where it exhibits the same behaviour. The 1040ST had all fixes done, including a recap of the psu with Exxos's kit.

Now it's in a Mega ST4 and I experience exactly the same behaviour. Cold boot: it starts up in TOS 2.06 (with rev 5 fixes) but freezes during disk access or when running a program or demo. Warm boot: it freezes during the boot process right after HDDriver has been loaded (I'm running the latest version of HDDriver btw).

I'm using an IDE2CF adapter with a Sandisk CF-card but the same problem occurs when I use an IDE2SD adapter with a Sandisk SD-card.

The Mega ST4 has the busfixes done but the PSU has not been recapped yet. On bank 1 of the rom is Emutos and it has exactly the same problem on both the ST as the Mega ST.

I flashed the Xilinx with the firmware in REV5_ST526_SLOW_ROM V2.zip

Any suggestions are welcome.

[stephen_usher]

Make sure:

• The cache is turned off.
• HDDriver isn't set to load into/use TTRAM.

[HomeLate]

Make sure:

• The cache is turned off.
• HDDriver isn't set to load into/use TTRAM.

Both in HDDriver? Both are turned off. I managed to copy GB 6 on the CF-card from a floppy and even GB 6 freezes after running some tests.

[stephen_usher]

Make sure:

• The cache is turned off.
• HDDriver isn't set to load into/use TTRAM.

Both in HDDriver? Both are turned off. I managed to copy GB 6 on the CF-card from a floppy and even GB 6 freezes after running some tests.

And GB is running from ST RAM?

[HomeLate]

Both in HDDriver? Both are turned off. I managed to copy GB 6 on the CF-card from a floppy and even GB 6 freezes after running some tests.

And GB is running from ST RAM?

Yes, it usually freezes after ROM access.

TOS now freezes after a few minutes when running idle.

[stephen_usher]

OK, so this suggests either a bus timing error or possibly a problem at the MMU.

I had something similar with one of my STFMs and it turned out to be a poor connection between the MMU and its socket. I would reseat that and use contact cleaner on the pins as a first step.

[olivier.jan]

As it happens on two different STs (the 1040 and the Mega 4), I would suspect an issue with the ST536.
I have two ST536 and they both had a similar issue at first. I reflowed some suspicious joints on one of the ST536 and the issue disappeared on this card. So I would recommend double checking all solder joints.

[HomeLate]

As it happens on two different STs (the 1040 and the Mega 4), I would suspect an issue with the ST536.
I have two ST536 and they both had a similar issue at first. I reflowed some suspicious joints on one of the ST536 and the issue disappeared on this card. So I would recommend double checking all solder joints.

Yes, I'm going to check the solder joints again. It runs great the first 15 minutes, GB6 works and I even could run a demo. But then it starts acting up and it freezing within seconds.
So, it must be a heat related issue and a bad solder joint.

I tried Stephen's suggestion but that didn't solve the issue.

[Badwolf]

Yes, I'm going to check the solder joints again. It runs great the first 15 minutes, GB6 works and I even could run a demo. But then it starts acting up and it freezing within seconds.
So, it must be a heat related issue

Let it cool down properly, then fire it up and run a hairdryer (or low setting heat gun) over it. See if you can foment an earlier crash.

If so, there's the smoking gun. Just make sure the heat is low enough that it's all that's smoking...

BW

[HomeLate]

Okay, progress:

I noticed in GB6 caches are turned on while in TOS caches is turned off and I can't turn cache on in the menu:

20240308_183524.jpg (343.22 KiB) Viewed 4338 times

Next, and I think this is the issue, when I remove the IDE adapter the Mega runs rock solid. It's now running a GB6 loop from floppy for at least 45 minutes and it hasn't crashed yet.

So I figure it's an IDE issue with either the ST536 or the IDE adapter. I run into the same issue with the SD-card adapter. I haven't got any other IDE adapters to test with.