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Old 27 February 2020, 17:26   #1
Tandrews-ny
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Amiga 2000 Repair - Please help :)

Hey all, I've been working on an Amiga 2000. I got it booting DiagROM (YES!) but KS does not boot. This board worked before I cleaned the battery damage and I've confirmed the chips work in an A500.

Here is what I've checked:
Connections DRA and DRD between paula, agnus, denise.
Connections to CPU.
Connections from DRD to RAM

I am getting something on the screen (PAL), which is fine, but it never gets to the menu it fails before that. Whats even odder, is that I'm getting a single block on my serial terminal, but there is a random "f" that occurs but only one.

I could use some guidance on where to look next.
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Old 28 February 2020, 00:07   #2
r.cade
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Post good pictures of the battery damaged area. Usually the gunk takes out the CPU socket and traces around it and under it.
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Old 28 February 2020, 12:23   #3
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Are you saying DiagROM produces output on the screen but not on the serial terminal?

Checked your terminal settings are 9600,8,N,1?

Does a memory test in DiagROM pass? If you hold down the right mousebutton on start, diagrom will use the start of chipram instead of the end - maybe this would then fail for you.

But yeah, as r.cade said probably still some battery damage remaining under/in the sockets.
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Old 28 February 2020, 15:40   #4
Tandrews-ny
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It produces something but it's single character.
Putty uses those settings by default.

As far as the socket, I've repaired multiple vias and tested continuity...but if you think the pictures will help.
I can't see what's on the screen, it's pal on ntsc and spacebar does nothing
As I mentioned, the board worked before cleanup. But I've pretty thoroughly checked everything.
Quote:
Originally Posted by dalek View Post
Are you saying DiagROM produces output on the screen but not on the serial terminal?

Checked your terminal settings are 9600,8,N,1?

Does a memory test in DiagROM pass? If you hold down the right mousebutton on start, diagrom will use the start of chipram instead of the end - maybe this would then fail for you.

But yeah, as r.cade said probably still some battery damage remaining under/in the sockets.

Last edited by Tandrews-ny; 28 February 2020 at 15:45.
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Old 28 February 2020, 16:42   #5
Vypr
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Have you checked the CIA's? I was fixing an A500 with a similar issue that turned out to be me stupidly putting in one of the CIA's upside down while doing the "Swap the chips to see if it helps the issue" step.
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Old 28 February 2020, 17:30   #6
Tandrews-ny
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Have you checked the CIA's? I was fixing an A500 with a similar issue that turned out to be me stupidly putting in one of the CIA's upside down while doing the "Swap the chips to see if it helps the issue" step.
I can try my a500 cias. But I had tested the chips in my a500 but not with diag ROM. Doesn't Paula handle serial?
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Old 28 February 2020, 18:37   #7
Tandrews-ny
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Post good pictures of the battery damaged area. Usually the gunk takes out the CPU socket and traces around it and under it.
Fixed a lot of that, I did continuity tests between all chips.
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Old 28 February 2020, 20:08   #8
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Quote:
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I can try my a500 cias. But I had tested the chips in my a500 but not with diag ROM. Doesn't Paula handle serial?
The CIA's handle most of the interface ports as well as the system timers so if they are bad (or in my case, upside down) They will cause problems.
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Old 28 February 2020, 20:14   #9
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The CIA's handle most of the interface ports as well as the system timers so if they are bad (or in my case, upside down) They will cause problems.
Okay, I need to test that, but since the system was working, I imagine they should be okay but I understand shit happens.
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Old 29 February 2020, 04:41   #10
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Quote:
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The CIA's handle most of the interface ports as well as the system timers so if they are bad (or in my case, upside down) They will cause problems.
The cias themselves are fine however I found the reset line was extremely messed up. Not the normal reset but the bus. Looks almost like a 60hz sinwave.
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Old 29 February 2020, 18:07   #11
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Progress! Found c909 missing with the schematic. Replaced it and now have video and proper debug. When I use just the cpu I get unimplemented errors. However with my accelerator I get memory test with one bad bit...so much progress

Testing if serial loopbackadapter is installed: <> NOT DETECTED
- Parallel Code $ff - Start of ROM, CPU Seems somewhat alive
Checking status of mousebuttons for different startups:

Set all Interrupt enablebits (INTENA $dff09a) to Disabled: Done
Set all Interrupt requestbits (INTREQ $dff09c) to Disabled: Done
Set all DMA enablebits (DMACON $dff096) to Disabled: Done

Testing if OVL is working: OK
- Parallel Code $fe - Test UDS/LDS line
- Test of writing word $FFFF to $400 FAILED
- Test of writing word $00FF to $400 FAILED
- Test of writing word $FF00 to $400 OK
- Test of writing word $0000 to $400 OK
- Test of writing byte (even) $ff to $400 FAILED
- Test of writing byte (odd) $ff to $401 FAILED
- Parallel Code $fd - Start of chipmemdetection

Addr $00000400
Write: $AAAAAAAA 10101010101010101010101010101010
Read: $AAA2AAAA 10101010101000101010101010101010 FAILED
Addr $00010400 OK Number of 32K blocks found: $01
Startaddr: $00008400 Endaddr: $0000FFFF
- Parallel Code $fc - Trying to find some fastmem (as no chipmem found)
- Parallel Code $fb - Memorydetection done
- Parallel Code $80 - NO Chipmem detected
- NO MEMORY FOUND - HALTING SYSTEM

Last edited by Tandrews-ny; 29 February 2020 at 18:53.
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Old 05 March 2020, 01:46   #12
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Okay, trying to solve why the CPU boots but fails with unimplemented instruction errors. What is the general cause of this? Google was fruitless on this.
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Old 06 March 2020, 00:34   #13
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you need verify if all connection from kickstart to cpu are ok
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Old 07 March 2020, 01:07   #14
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you need verify if all connection from kickstart to cpu are ok
How would it boot if the connections weren't okay?
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Old 07 March 2020, 11:01   #15
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black screen or red
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Old 07 March 2020, 15:32   #16
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Quote:
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How would it boot if the connections weren't okay?
It wouldn't. It looks like you're either missing a bit between the CPU and chip ram, or the chip ram is bad.
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Old 07 March 2020, 17:27   #17
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Quote:
Originally Posted by cpiac64 View Post
black screen or red
White.
Diagrom has to be booting if im getting anything on terminal.
This board did boot at one time, so doubtful its bad ram?
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Old 07 March 2020, 17:40   #18
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white is lost communication with socket chips

change gary, denise, paula e cia with a working amiga 500
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Old 07 March 2020, 17:54   #19
Tandrews-ny
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white is lost communication with socket chips

change gary, denise, paula e cia with a working amiga 500
i have, they work fine. i've tested all chips (outside buster of course) already in my 500 with diagrom. works fine. Im sure its a wire somewhere...just not sure which yet
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Old 07 March 2020, 19:04   #20
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omg i did it...i f-ing did it. I decided to go back through the 68000 lines and see if anything stood out. Found LDS was not making contact to gary (im sure other places too)...Fixed it and BAM! booted fully. No memory errors, no nothing just straight to diagroms memu as it should. Put my accelerator card...also worked!

So damn excited!
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