A4000TX ATX Amiga motherboard

I bought MC68030FE33C

I see from the pictures of the completed boards that 25Mhz 68030 have been used. If using a 33Mhz cpu, is it simply replacing the 50Mhz oscillator with a 66Mhz oscillator? Would you also need to replace the delay line (U102) to get nearer to the 8nS delay for the CLK90?

Thanks in advance
 
looking at the Mouser BOM it’s about $250 USD

Hmm, you've got me worried. How much did the stuff from Mouser cost?

I'm also interested in this.. anyone?

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I tried it with a 66MHz oscillator and the board runs fine, however some of the zorro cards would not work correctly as the zorro bus is being over clocked.


I bought MC68030FE33C

I see from the pictures of the completed boards that 25Mhz 68030 have been used. If using a 33Mhz cpu, is it simply replacing the 50Mhz oscillator with a 66Mhz oscillator? Would you also need to replace the delay line (U102) to get nearer to the 8nS delay for the CLK90?

Thanks in advance
 
The Chips itself almost work without any issue because 33MHz was planned for later, but Fastram must have significantly faster timings that at 25MHz. Roughly calculated about 80ns / 33MHz * 25MHz i.e. 60ns for default settings and 80ns / 33MHz * 16MHz i.e. 40ns to be able to use Speedramsey
The Delayline may or may not work without modding, the intended 25ns delayline has 5ns, 10ns, 15ns and 20ns taps (10ns i.e. 1/4 Clockcycle is used at 25MHz) but at 33MHz 7,5ns would be the right value...
Also some ZIII cards have issues because they rely on the 25MHz ZIII timing even though the Bus works asynchronously without a fixed clock.
In contrast ZII work flawless, because the timing is determined by the AA custom chip Clock.
 
A4000TX ATX PSUs

A4000TX ATX PSUs

Short follow-up to the earlier discussion in this thread about *new* ATX PSUs for Amiga A4000TX use.

I went ahead and bough the smallest/cheapest model in the Corsair RMx (2018) series, as those are widely available at least here in Finland, and I could find proper looking reviews of those PSUs with measurements looking good. More importantly these PSUs seem to match the required minimum specs for A4000TX use (minimum required ratings: +5V @ 25A, +12V @ 10A, -12V @ 0,6A). There are other matching PSUs available aswell, but I couldn't find many which had proper reviews around with actual measurements included to verify the vendor claims.

So anyway I bought the RM550x (2018) model (PN: CP-9020177-EU), which has ratings: +5V @ 25A, +12V @ 45A, -12V @ 0,8A. So far it has worked OK in my setup, which currently is A4000TX rev 1.1 with the onboard 030 CPU @ 25 MHz + FPU, and a ZZ9000 graphics card. I don't have a 060 turbo card yet.

If someone else buys these PSUs there's one thing to note though: the specs say the ATX power cable is 20+4 pin, but it's actually 24-pin, so you might want to buy a separate ATX 24-pin to 20-pin adapter cable if you want the PSU connector to fit/lock nicely to the A4000TX motherboard (the default 24-pin connector works [with some force applied], but it's not "proper fit" because it's 24-pin / too big).

Links to some reviews: https://www.tomshardware.com/reviews/corsair-rm550x-power-supply,4484.html (earlier 2016 series, 550W), https://www.tomshardware.com/reviews/corsair-rm850x-v2-psu,5568.html (2018 series, 850W) and https://www.kitguru.net/components/power-supplies/aris-bitziopoulos/corsair-rm850x-2018-psu-review/ (2018 series, 850W).
 
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@Hese: on the subject of the IO Shield - any good idea where to get this 3d printed, or even better getting an actual cut metal plate ?

Edit: duh - just figured out you just select metal on one of them 3d print sites :roll:

Do you have a link to a site I could use to print this? Would these I/O shield be printed or cnc cut?
 
On the BOM there are Qty 7 of ATF16V8B-10JU and Qty 1 of ATF16V8C-5JX.

I'm happy that the ATF16V8B-10JU are for both the 4 x GAL16V8-10 and 3 x GAL16V8-15, but I cannot work out what the ATF16V8C-5JX is for.

Any ideas?

Thanks
 
Hi

Could you PM the cost of a fully populated board

Many thanks

Rich
 
A4000TX rev 1.1 PC Floppy Drive Fix
There is a flaw in the rev 1.1 motherboard design when using a PC floppy drive (J300 jumper set to "PC" position). Thanks dorken for reporting the issue.

When the J300 jumper is set to "PC" position, U356 pin 1 receives an incorrect voltage which may cause the chip not to function correctly. U356 is responsible for transmitting Amiga/PC specific floppy drive signals between the Amiga/PC floppy drive and the motherboard.

The issue may occur only when the J300 is set to "PC". When using Amiga floppy drives (J300 set to "AMI"), the chip receives a correct voltage and this fix is not needed. I have used my motherboard with a PC floppy drive without the fix and haven't noticed a problem but your mileage may vary and it's recommended to do the fix if you are using the motherboard with a PC floppy drive.

The issue can be fixed either by replacing one component on the motherboard (Method #1) or by rerouting the U356 pin 1 to another trace (Method #2).

Method #1: Replacing a component
The issue can be fixed by replacing the Q301 (2N3904) with a mosfet such as FDN357N. Mouser stocks FDN357N here. No other modification is needed.



Method #2: Rerouting a trace
The issue can be fixed by cutting the trace that goes to U356 pin 1 and connecting the U356 pin 1 to another trace with a jumper wire. No other modification is needed.

This can done either on the top side (Method #2A) or on the bottom side (Method #2B). Do only one of these modifications.

Method #2A: Doing the fix on the top side


Cut the trace that goes to U356 pin 1 (marked with X in the picture). Solder a jumper wire between U356 pin 1 and R365 upper pad as show in the picture.

Method #2B: Doing the fix on the bottom side


Cut the trace (marked with X in the picture). Solder a jumper wire between the cut trace and J300 middle pin as shown in the pictures.


Sorry for the inconvenience.
 
Hey Hese,

If I apply fix 2A, does that affect the use of the jumper? Ie are locked in PC floppy only or can you still switch between Amiga or PC floppy drives.
 
Dont know if this is the place for general A4000TX questions but hopefully it is. I just bought a A4000TX here on Amibay and want to know if there is a IO-shield available somewhere that fits this board. If not would there be interesting maybe to make a group order for some custom made?

Thanks,

Bjorn
 
Hey Hese, If I apply fix 2A, does that affect the use of the jumper? Ie are locked in PC floppy only or can you still switch between Amiga or PC floppy drives.
With each of the possible fixes the Jumper works as intended, but without a fix it depends on the component tolerances of U356 and Q301 whether the switchover works or not.

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Dont know if this is the place for general A4000TX questions but hopefully it is. I just bought a A4000TX here on Amibay and want to know if there is a IO-shield available somewhere that fits this board. If not would there be interesting maybe to make a group order for some custom made?
Hese already posted a matching IO Shield: https://www.amibay.com/showthread.php?101477-A4000TX-ATX-Amiga-motherboard&p=992934&viewfull=1#post992934 For small series that is quite expensive but many 3d print provider can build a real metal shield with the the stl file. Also a selfmade is possible, preferably use some ESD Filament or print in cheap PLA and use some conductive painting on the inner side and the fold...
 
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Dont know if this is the place for general A4000TX questions but hopefully it is. I just bought a A4000TX here on Amibay and want to know if there is a IO-shield available somewhere that fits this board. If not would there be interesting maybe to make a group order for some custom made?
Hese already posted a matching IO Shield: https://www.amibay.com/showthread.p...ga-motherboard&p=992934&viewfull=1#post992934 For small series that is quite expensive but many 3d print provider can build a real metal shield with the the stl file. Also a selfmade is possible, preferably use some ESD Filament or print in cheap PLA and use some conductive painting on the inner side and the fold...


OK thanks for the link!

I'll take it to one of my customers that have NC-machines capable of creating the patterns in real metal blanks. Don't know if they can read the stl format but I guess I'll find out. Have been looking online for a source that can produce metal IO shields but so far no luck.

Bjorn
 
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Dont know if this is the place for general A4000TX questions but hopefully it is. I just bought a A4000TX here on Amibay and want to know if there is a IO-shield available somewhere that fits this board. If not would there be interesting maybe to make a group order for some custom made?
Hese already posted a matching IO Shield: https://www.amibay.com/showthread.p...ga-motherboard&p=992934&viewfull=1#post992934 For small series that is quite expensive but many 3d print provider can build a real metal shield with the the stl file. Also a selfmade is possible, preferably use some ESD Filament or print in cheap PLA and use some conductive painting on the inner side and the fold...


OK thanks for the link!

I'll take it to one of my customers that have NC-machines capable of creating the patterns in real metal blanks. Don't know if they can read the stl format but I guess I'll find out. Have been looking online for a source that can produce metal IO shields but so far no luck.

Bjorn

I think most newer 3D production System can read an stl, as it is almost standard.
If not just download FreeCAD (as the name says free of charge) create a new Document, and import the .stl then export in the desired File type. E.g. .step should be something everyone should be able to process.
 
Just thought I'd show off some photos of this board in a case I picked.
IMG_4114.jpg
As you can see everything works great. I'm using a PS/2 Keyboard and Mouse with no issues. Running OS 3.1.4 and ROMs.
IMG_4117.jpg
A 64gb Compact Flash Card for the hard drive, and have installed an A3660 Rev 1.1 with a Rev 1 060 CPU clocked at 60mhz.
IMG_4115.jpg IMG_4116.jpg IMG_4119.jpg

Now I am just waiting on my zz9000 (RTG!) and my Fast ATA 4000 MK VII Zorro III card (will hook up my CD Drive when that comes). Almost there guys, but wanted to really say that Hese has put together something special with this board, and allowed me to retire my A1200, as this has become my main Amiga for use now.

Thanks Hese!

PS. I'd like to see some other cases, would anyone mind posting photos of theirs? I did have to modify the one in the photos just a little (using a dremmel) to fit the longer Zorro slots towards to bottom.

*Update:
Just got my customized keyboard from WASD keyboards. This is version 2.
https://drive.google.com/file/d/1zZ28nu1B_DlxydMhdCxFgSR35gPIPuun/view?usp=sharing
 
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Hi there Hese, I'm not sure what the current status of the project is, but I would like to declare interest in a 4000tx board please.

PM on its way shortly!

Thanks,

AndyC
 
A4000TX enthusiasts,

I cannot program the ATMega88. I get the ‘target doesn’t answer. 1’ error message.

I tested my USBASP on an ATMega in one of my other projects and it works fine, so I suspect its either my clumsy soldering or the ATMega was faulty to start with.

I have visually inspected for solder bridges and checked for continuity and shorts and all seems good. However, without a circuit diagram for reference I am now stuck. Its very difficult to reverse engineer a populated multilayer PCB!

Can anyone help, please?
1. Is the keyboard circuit based on a community project or are there any diagrams available to aid with fault finding?
2. Any suggestions on what to check on the PCB?
3. Any tips or tricks to try with avrdude?

I would like to exhaust all avenues before replacing the ATMega. I’m not sure I could desolder a TQFP without damage and its sitting tight between two capacitors.

Thanks in advance

PS - the PIC programmed just fine :)
 
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