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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: gary2000 on June 14, 2019, 02:48:11 PM

Title: A4000 motherboard-getting there
Post by: gary2000 on June 14, 2019, 02:48:11 PM
It's coming along...
Title: Re: A4000 motherboard-getting there
Post by: Acill on June 14, 2019, 09:53:37 PM
If you have any issues let me know! Also here is some good resource to help you. Its a part placement guide that John Hertell had another user help us put together. It makes builds a lot easier.

http://www.hertell.nu/locator/locator.php?project=A4000
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on June 16, 2019, 09:09:19 PM
Thank you. I'm sure I will have questions.

Yes, that placement tool works well!
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on June 29, 2019, 07:55:29 PM
Would anybody know what the part number is for the 6 pin power connector? I bought amp 350711-1, which looks to be correct, but has male contacts instead of female.
Title: Re: A4000 motherboard-getting there
Post by: Acill on June 30, 2019, 08:34:16 PM
I'll see if I can find it for you here in a bit. I am in Australia currently and need to search Mouser carts for my past orders.
Title: Re: A4000 motherboard-getting there
Post by: Acill on June 30, 2019, 08:55:40 PM
Here it is: https://www.mouser.com/ProductDetail/TE-Connectivity-AMP/350827-1?qs=%2Fha2pyFaduhO9K6hFWyj%252B9di953Oe11BRMqF7eT3GVg8f210t5DoTg%3D%3D

Mouser Part: 571-350827-1
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on June 30, 2019, 10:31:50 PM
Thanks !
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on September 07, 2019, 06:43:53 PM
First test result is a black screen , with video sync and no serial output to diagrom . Clocks look okay and voltages are fine , except -12 measures -11.13

Should sclk on Lisa be 3.571 MHz?

Should ECLK on U300 CIA be 714 KHz?

kbrst is always held low .  Should this go high on reboot?

 Seems to be no activity on Paula, Gary , Alice address lines

 This seems to be a global issue keeping the system down .

 Any other basic items I should check ? I'm trying to be methodical, but find myself stabbing in the dark .




Title: Re: A4000 motherboard-getting there
Post by: gary2000 on September 15, 2019, 04:50:28 PM
It's working!

 Fail pin was pulled low by power supply PG brown/ gray cable, so Gary would not reset . In Skynet power supply , IC7 I suspect is bad . I got impatient, and just cut the wire and ran to five volts.

 Diagrom checksum test okay, CPU and chip ram is seen .

 Hangs on fast ram check . But, that's progress .
Title: Re: A4000 motherboard-getting there
Post by: matt3k on September 17, 2019, 02:51:58 AM
Thanks Acill!  You and Chucky have saved the Amiga hardware community.
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on September 17, 2019, 01:40:18 PM
Thanks Acill!  You and Chucky have saved the Amiga hardware community.

 Absolutely !
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on October 07, 2019, 01:35:01 AM
Well, moving along smoothly until I inserted the Zorro daughterboard. The computer will boot one out of 10 times with errors if the daughterboard is in place . It works flawlessly without it , so far with diagrom. Will not boot with original ROMs , though.

 Anybody have a similar issue ? So far, checking u701/U714 pals , buster  and the CPU are involved as well.

 Will not be very expandable at this point , weird .
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on January 11, 2020, 01:00:21 AM
Just to update:
Replaced PAL U714 which corrected zorro II problem.
With diagrom, CPU okay, chip RAM tested okay, fast RAM ok, all video and audio tests okay, IRQ/CIA okay, zorro II detected ram card, IDE detected correctly, floppy drive seen.
With 3.0 roms will not boot, resets, and then stops after screen turns on. 
OVL = L with diagrom and H with 3.0 rom, is that normal?

Anyone have any other suggestions to check for?

Are 3.1 roms available for download to burn for me to purchase? I do not want 3.1.4 at this time.
Title: Re: A4000 motherboard-getting there
Post by: Rotzloeffel on January 13, 2020, 01:14:36 PM
I do not want 3.1.4 at this time.

Why not ? They are much more better than 3.1..... using big harddrives for example….
Title: Re: A4000 motherboard-getting there
Post by: paul1981 on January 13, 2020, 07:06:28 PM
I do not want 3.1.4 at this time.

Why not ? They are much more better than 3.1..... using big harddrives for example….

I read this a lot here and there (mostly YouTube). I and many others use large hard drives under 2.0, never mind 3.1.4. ;)
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on January 16, 2020, 09:32:04 PM
I have nothing against 3.1.4, I only wanted 3.1 to test with. (Have enough unknown variables to deal with).
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on February 03, 2020, 12:01:04 AM
The only issue I had with running diagrom was a vertical hold problem rolling screen.

Could someone tell me the in-circuit value of R514, which shows 10K? Mine is 3K or 4.5K without resistor, and this does not seem normal.
Title: Re: A4000 motherboard-getting there
Post by: gary2000 on February 16, 2020, 01:07:35 AM
Well, it finally booted to Kick start screen!

The Commodore roms went bad, which was surprising.

One issue other than the occasional yellow screen, is when you put in a disk OVL is held high. You must turn off and turn on again for the high to low to happen. Has anyone seen this happen?

Most games will not fully load and there is graphical corruption when trying, but work bench will load fine.