Installing the PAK68/3

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Installing the PAK68/3

Postby TheNameOfTheGame » Sun Oct 06, 2019 1:30 pm

I am going to try to get my PAK68/3 running. I bought it a couple of years ago, but it has never even been plugged in :lol: Well that has to change.

Here is the board I am going to work with. Hopefully it is functional. I bought it as working, but you never know.

pak_resized.png

It looks to be in pretty good condition. A little closer examination is needed so I can tell what I'm dealing with. Here's some of the major features.

pak_chips_resized.png

From the image above I can see the oscillator is 25Mhz which is fine. I'd rather bring the unit online with the slowest configuration and then work on increasing the speed. I'd like to get to 50Mhz eventually. Also, I know the TOS is the German version since that is where I bought it from. I have the modified USA version of the PAK-TOS so I will need to change to that. And finally, I see from the GALs that I will need to change a couple of them. Specifically U4 and U5 need to be updated. Also, U6 is ok since there is no FRAK/2 board. If I add a FRAK later it would be to be changed.

One thing to mention is the EPROMs used (27C1001-15) are 150ns parts. The manual states to use 120ns components. So I will be using the faster access chips when I change the ROMs out.

There are a lot of jumpers on the board. Twelve to be exact. I guess it would be good to know what they are set to in case I need to change them.

pak_jumpers_resized.png

From looking at the jumper settings above, it appears that nothing has to be changed; they are set just right. That's good!
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Last edited by TheNameOfTheGame on Sun Oct 06, 2019 5:28 pm, edited 2 times in total.

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Re: Installing the PAK68/3

Postby Arne » Sun Oct 06, 2019 1:39 pm

TheNameOfTheGame wrote:I'll probably need to solder a component in??

4K7 x8 according to the BOM.
Image

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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sun Oct 06, 2019 2:44 pm

I will be using an original ST for this upgrade. There a few things to do to prepare the motherboard for the PAK. These are recommended steps from the PAK manual, mainly if higher speeds are desired. Since I am going to shoot for 50MHz eventually, it probably would be best to get the motherboard in shape up front.

st_mainboard_resized.png

This old ST had 10k pullups for the bus terminators. As per the manual, I changed the data bus terminations to 4.7k and the address bus terminations to 3.3k. Additionally, the line drivers were changed to 'F' types. Next, the SIMMs in the Marpet 4mb extension were changed to 60ns types. I physically removed the original motherboard RAM chips which can save some of the power budget. Finally, the power supply was changed. Adding extensions such as the PAK can be too demanding for the stock power supply. For this board, I installed a 90W picoPSU.

st_mainboard_changes_resized.png

The new SIMMs were tested with YAART to ensure they were sound. This completes the motherboard prep.
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sun Oct 06, 2019 2:47 pm

Arne wrote:
TheNameOfTheGame wrote:I'll probably need to solder a component in??

4K7 x8 according to the BOM.


Yes, thanks I saw that also. I was curious as to why nothing had every been soldered there. The pads are clean. But, I think I will solder it in just to be safe.

*Edit* - The information on RN1 this reply pertains to has been moved 2 posts below.
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sun Oct 06, 2019 2:58 pm

Forgot one point on the motherboard prep. The line drivers/buffers on the Marpet extension are 74HC244E type. Being CMOS, I think they should be fast enough.

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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sun Oct 06, 2019 4:37 pm

Moved a bit of information from the first post to this one since I found a couple of issues with the visual inspection.

One thing I noticed is that the resistor network RN1 is not populated. The solder pads are clean and nothing has ever been soldered there. I'll probably need to solder a component in.

Also, under the GALs U1 and U2 are two missing parts, R48 and C43. They are not on the Parts List in the manual, but the manual states they are needed if clock buffering is used. So I will need to equip these later.

Lastly, the through-holes for the 74F00 used when buffering the clock are empty, but that is to be expected since again this board isn't set up for clock buffering yet.

Here is a diagram of the missing parts.
pak_missing_resized.png
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sun Oct 06, 2019 7:57 pm

Looking at the RAM on the board. Seems the Tag-RAM U18 and U19 are 25ns parts. The Parts List calls for 20ns chips. Might not make too much of a difference until I get to higher speeds, but it's something to note.

Also the Cache-RAM chips U14-U17 are under the ROM chips. These look like they are 15ns so they should be good.

pak_ram_resized.png
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Mon Oct 07, 2019 2:32 pm

Thinking about power requirements and how I'm going to hook up to the power connections.

The strange thing is I took a look under the microscope and neither power hookup has ever been used. Pads are brand new.

pak_power.png
pak_power_b.png

So can the PAK be operated under mainboard power only? It seems this board was.
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Re: Installing the PAK68/3

Postby Bikerbob » Mon Oct 07, 2019 2:58 pm

Thanks so much for this thread TheNameOfTheGame as I hope to be dealing with this myself very soon. I am putting mine in a mega ST/4 and I do have some issues with some of the soldered on RAM -10ns but I was not aware of some of the other things to look for, so this really made me aware I have to go through the board before thinking about the PAK68 et al.

James

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Re: Installing the PAK68/3

Postby DarkLord » Mon Oct 07, 2019 8:45 pm

Don't forget about grounding! The manual stresses this point and I agree.

I've got something like 3 different grounds coming off the Pak board in
my STacy.

Lots of fun watching this - keep us posted and updated with pictures! :)
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Mon Oct 07, 2019 9:53 pm

Oh yeah for sure I'll definitely hook up good grounds! As with the 5V, the GND pads are also pristine. So there are two options:

1) The PAK was never installed.
or
2) The previous owner never hooked up the PAK's VCC and GND and just used the CPU socket connection for them.

Either way I'm going to use the pads :lol:

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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sat Oct 12, 2019 5:34 pm

Continuing on...

So the power and ground pads being pristine might not mean the board was never used...using the power connection is recommended in the manual, but not required. Just something to note.

manual_markup.png
manual_b_markup.png

I needed to update a couple of the GALs (U4 and U5). Looking closer at them, I realized all the GALs in that area had been inserted upside-down. You can clearly see the notches in the chips are not aligned with the stenciled notches. This is a very bad thing and if the board was ever under power, then those GALs are almost certainly blown. Removing the GALs showed that the sockets themselves had been soldered in reversed.

pak_gals_reversed_resized.png

To avoid uncertainties I decided to replace all 4 GALs. In addition I needed to solder RN1 which for some reason was never populated. Finally, I burned the English PAK-TOS to replace the German version the board arrived with.

pak_new_chips_resized.png

Before the PAK can be finally powered-up, I had to add the power connections. I made a small cable and soldered it to several points on the board from underneath. I left 5V2 and GND2 unconnected. I'm not sure what they are needed for.

pak_power_resized.png

That's it. The PAK is ready to try out.

pak_power_installed_resized.png
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Re: Installing the PAK68/3

Postby DoG » Sat Oct 12, 2019 6:23 pm

5V2 and GND2 is just another place to power the board from. U3 is only needed if you got a 68000 in the socket and want to boot up that instead of the PAK.

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Re: Installing the PAK68/3

Postby DarkLord » Sat Oct 12, 2019 7:11 pm

Don't know how much it will help but here are 2 pictures of the Pak board in my STacy I'm
fairly certain that I used at least 2-3 grounds.

P7070002_FINAL.JPG


P7070009_FINAL.JPG
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sat Oct 12, 2019 8:19 pm

After double-checking all connections I turned on the power to the ST. There was no smoke or loud pops so that was good :D but the screen just stayed white. It never made it to the desktop and there was no PAK logo. I felt the chips on the PAK and nothing was hot, but I turned off the computer after 10 or 15 seconds. I did try a couple more times, but always a white screen.

So the first thing I did was remove the PAK and put the old 68000 cpu back in the motherboard to make sure the ST still worked. Sure enough it booted fine no problem. The issue was with the PAK it seemed. My first thought was to put the 68000 cpu in the PAK and set the board to run in alternate operating mode. But GAL U3 under the cpu socket was itself socketed which made it too high and there was not enough clearance to put the 68000 in.

pak_68000_clearance_resized.png

This just required some 32pin SILs added to raise the 68000 up, but for the future, I would like to directly solder GAL U3 and the F86 to reduce the overall profile of the PAK. Also, jumper J5 was removed for alternate operating mode.

pak_68000_sils_resized.png

Unfortunately, the white screen remained. Looking at the manual, I saw that in addition to J5 being removed, jumper J6 also needs to be open.

pak_alt_op_mode.png

Removing J6 and retesting resulted in disappointment as the screen stayed white. I removed and verified the PAK-TOS roms (and printed new labels with their board locations which I thought was better) and they were correct. So at this point I wondered if the previous owner had damaged the board since he had shipped me the board with the GALs reversed. Since I had intended to try 32MHz speed after the PAK had been set up I had the 68030RC33 and the oscillator at hand. I removed the old cpu and oscillator and fitted the replacements.

pak_new_cpu_resized.png

Placing the PAK back in the ST and powering on I was greeted with a nice PAK logo. Progress! Unfortunately, that was it...it never would move past the logo to the memory test or desktop.

pak_logo_only.png

I then tested it in alternate operating mode with the 68000 and it still was stuck at the logo. Making progress, but still not there. I removed the 68882 fpu and FPU-Enable jumper J3 and tried again. Still only the logo.

Since I was using Petari's improved TOS 1.04 on the mainboard, I considered maybe the PAK's boot patch was overwriting something and causing the hang. So I burned a straight vanilla TOS 1.04 and tried again. Still stuck. :lol:

Thinking about the problem, it seemed the switchover GAL was important for both the 68000 and 68030 cpu so I decided to change it. I was surprised to see a capacitor in the socket under the GAL. Not sure if that is in the manual, but I will need to read it again and see if it is mentioned.

pak_new_U3_resized.png

After connecting the PAK back up and switching on the power I was happy to see the memory test and then the desktop!

pak_memory_test.png

pak_desktop.png

This was a very encouraging development! However, all is not quite well as I will explain in the next post.
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sat Oct 12, 2019 8:27 pm

DoG wrote:5V2 and GND2 is just another place to power the board from...


Thanks, yes, I figured that but it wasn't mentioned in the manual so I didn't hook anything to them.

DarkLord wrote:Don't know how much it will help but here are 2 pictures of the Pak board in my STacy I'm
fairly certain that I used at least 2-3 grounds.


Yeah, I went with 2 grounds. I think it will be enough. Thanks for the pictures! :cheers:

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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sat Oct 12, 2019 8:35 pm

Well, the PAK was apparently damaged by the previous owner as I've had to replace quite a number of components. But it is booting now and stable, but there is still a problem.

The floppy drive will not read. It displays an error message when trying to open the A: drive. The error is the same with the 68030 or 68000 in alternate mode.

pak_drive_error.png

This is where I have stopped for the moment. I did remove the PAK and try the drive again with just the 68000 plugged in. The drive worked normally as expected.

At this point I need to just replace the remaining parts one at a time I guess unless someone has another suggestion. Might end up replacing every part on the board by the time I'm finished. :lol:
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Re: Installing the PAK68/3

Postby DoG » Sat Oct 12, 2019 8:41 pm

I have a 10k bus resistor array on the data lines on the 1772. But I had that installed before i got my PAK installed so never thought about that.Maybe try that?

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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sat Oct 12, 2019 8:51 pm

DoG wrote:I have a 10k bus resistor array on the data lines on the 1772. But I had that installed before i got my PAK installed so never thought about that.Maybe try that?


Interesting idea. The manual mentions possible problems with the floppy, but says the patched PAK-TOS has corrected the error. But that is something I will definitely keep in mind. Thanks! :cheers:

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Re: Installing the PAK68/3

Postby DarkLord » Sun Oct 13, 2019 6:53 am

Hang in there, you're definitely making progress. If you've ever read the (very)
chaotic thread where I discussed putting my Pak board in, you'd see that I had
a problem where my STacy would crash with x amount of bombs on the screen
but only after it had been left turned on so many minutes. Darn near drove me
crazy. :)

So you'll get it sorted out, I'm sure.
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sun Oct 13, 2019 4:31 pm

Uh oh, I think I killed something.

I replaced all the remaining chips on the PAK except the Cache RAM and the floppy still wouldn't read. So then I decided to do the pull-up fix for the floppy data lines.

I used a 4.7k resistor network because it's what I had handy. But I made a mistake. See the picture below. I soldered to R14 instead of C14. Unfortunately I powered it on a couple times like this. Once I realized my mistake and moved the wire to C14 to catch the 5V it was too late it seems. Now I get no drive light on the external floppy although I can hear the motor run. But worst of all I have no floppy icons on the desktop anymore. I tried with the PAK and without the PAK just the 68000. No floppy icons either way. I probably damaged the DMA controller or the WD1772 controller. :(

pak_wd1772_resized.png

*Edit* forgot the schematic I used:

wd1772_schematic.png
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Sun Oct 13, 2019 6:45 pm

Ok, changed out the DMA controller and the drives are back on the desktop. :angel:

The good news is the drive works when the PAK is used in alternate operating mode with the 68000. The bad news is it still doesn't work in 68030 mode. It makes a grinding sound trying to access the drive before throwing the error dialog.

I have changed about every IC on the PAK now. The last one I changed was U6 GAL P6-ST. I thought I didn't have any more GALs to use but I found one that could be erased so I burned a new one. The only ICs I haven't changed are the Cache-RAM chips under the PAK-TOS ROMs because they are soldered in. But I did disable the cache via the jumper and it didn't change anything. At this point I think the PAK is in pretty good shape. Now I have to look at the possibility of a motherboard timing or data issue.

So what is different when the PAK is operating in 68030 mode that could make the drive not accessible? I probably need to get my scope out now. Not sure what to really look at though so any pointers would be appreciated!

P.S. I tried using a PuPla/2 buffer board under the PAK, but it didn't change anything. The error was still there.

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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Mon Oct 14, 2019 2:53 pm

Ok, I was thinking about my floppy drive issue. Since it only happens in 68030 mode I started considering timing issues and the faster clock. The manual talks about clock buffering being able to fix some dma problems. Also mentions clock buffering as required when an fpu is equipped which I have.

clock_buffering_resized.png

So I decided to install the buffering and got the parts together. Looks pretty simple. :wink:

clock_buffering_parts_resized.png

However, looking at where the 74F00 has to be placed reveals some complications. The oscillator socket covers two solder points. And on the solder side, the 74F00 will cover two solder points for the oscillator.

clock_buffering_obstruction_resized.png

So the plan was to remove the oscillator socket to allow access to the solder points for the 74F00 and also remove R47 since it had to be changed. Also, the solder bridge must be cleared.

clock_buffering_socket_remove_resized.png

Instead of a socket, I elected to place four single SIL pins to hold the oscillator. This would allow access to the solder points needed for the 74F00. I used the old oscillator socket to align the four SIL pins and soldered the upper two pins. These two pins are the ones that the 74F00 will cover when it is placed so they had to be soldered in now.

clock_buffering_socket_pins_resized.png

However, now I saw that the jumper headers above the oscillator were in the way. There is no way I can get in there to solder the upper row of pins for the 74F00. So I had to remove the jumpers.

clock_buffering_remove_jumpers_resized.png

With that out of the way, the parts can now be soldered in. I first soldered the 74F00 from above and then soldered the jumper headers back in and replaced R47 with the 10ohm resistor.

clock_buffering_solder_74F00_resized.png

All that was left was the clock termination between U1 and U5. They are easy to place. Just had to remove GALs U4 an U5 first.

clock_buffering_clock_termination_resized.png

So I put the GALs U4 and U5 back in and also the oscillator and jumper J9 and that's it! Clock buffering is installed.

While it was fun to do and needed to be done for down the road when I try for 50MHz, unfortunately it did not correct my floppy drive access problem. :(
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Re: Installing the PAK68/3

Postby Gaiyan » Mon Oct 14, 2019 4:02 pm

Great guide, I know i will reference this when I find the time to install mine. Does the PAK work in every other respect than the floppy though?
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Re: Installing the PAK68/3

Postby TheNameOfTheGame » Mon Oct 14, 2019 4:57 pm

Well, the PAK boots to the desktop, the memory test passes and everything functions at the desktop like windows, menus, icons. But without the drive working, I can't run benchmarks or sysinfo and I can't do any burn-in to test stability under load so to speak. So really can't progress with the project until I get the floppy problems worked out. I'm hoping pakman has some advice.


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