2000 - black screen... Chips good... PSU good...

[chiark]

Cheers TC, the board is out of its case and all that's plugged in is the power and the video monitor

[chiark]

OK, changed agnus... Now get a light grey screen, then multicolour garbage on the monitor compressed down to about 10 scanlines!

Time to change/check denise...

[chiark]

stranger and stranger - when J101 is on 1-2, and J500 closed, I get a normal power sequence which then reboots...
Remove 500 and I get the strange video effect
Change 101 to 2 3, and with J500 closed I get a different strange video effect
Remove J500 and I get a normal power sequence then reboot.

Bloody weird.

[TheCorfiot]

@chiark,

I'm in work & dont have my A2000 schems handy to identify the jumpers for you, sorry my friend.

Try BBoAH I think there maybe a summary there.

Are you confident regarding the Agnus making good contact all the way round ???

TC

[chiark]

Yep. And I've replaced the 8372 with an 8375... Same.

As soon as it's about to boot, or seek the drive, or display the workbench disk picture, it reboots. (Plugged a floppy in, and it does the same without seeking. Damn)

[TheCorfiot]

Originally Posted by chiark

Yep. And I've replaced the 8372 with an 8375... Same.

As soon as it's about to boot, or seek the drive, or display the workbench disk picture, it reboots. (Plugged a floppy in, and it does the same without seeking. Damn)

chiark
I don't think the 8375 is pin compatible with the 8372 (someone correct me),

You have replaced Gary too???

TC

[chiark]

Gary?
yup. With known good ones.

8375 - right, i'll swap it back. Mine is an 8372a if that makes a difference?

Every chip on this board worked perfectly in my other 2000... (And that has an 8371 agnus)

[TheCorfiot]

8372a is the PAL 1MB chip agnus.

Don't take my word for the 8375 not being pin compatible, I'm sure this is the case but hopefully Zetro will be along soon to confirm this for us..

Keep fighting you are making progress, Don't give up, but if you do send me the Mobo & I'll have a go for you..

TC

[chiark]

Power LED is giving 6 flashes prior to the reset. Bugger, where's the reference for power LED flashes when you need it!?

EDIT: interesting, suggests the problem might be agnus related. Damn!

[chiark]

Just rereading this, I noticed rkauer's reference to the TTL flipflop...

Any more info, sir?

[rkauer]

Maybe I can send you the TRM...

Amiga Schematics.

Download the 4 A500_2000 TRM's (Technical Reference Manual) and look for "grey screen" - Agnus related-problem.

[rkauer]

Originally Posted by chiark

Power LED is giving 6 flashes prior to the reset. Bugger, where's the reference for power LED flashes when you need it!?

EDIT: interesting, suggests the problem might be agnus related. Damn!

Quoting manual:

One Blink ROM Checksum failure
Two blinks RAM test failed
Three Blinks Watchdog timer failed
Five Blinks Your Amiga has become nuclear. RUN!

[Zetr0]

Hello there my fellow forum chummies,

heres the results from my research on the 83xx Agni chips

8375 [A500+ 390544-01]		8372 [A3000]	8372B		8370

pin#		#desc		#desc		#desc		#desc

01		DRD13		DRD13		DRD13		RD13
02		DRD12		DRD12		DRD12		RD12
03		DRD11		DRD11		DRD11		RD11
04		DRD10		DRD10		DRD10		RD10
05		DRD09		DRD09		DRD09		RD09
06		DRD08		DRD08		DRD08		RD08
07		DRD07		DRD07		DRD07		RD07
08		DRD06		DRD06		DRD06		RD06
09		DRD05		DRD05		DRD05		RD05
10		DRD04		DRD04		DRD04		RD04
11		DRD03		DRD03		DRD03		RD03
12		DRD02		DRD02		DRD02		RD02
13		DRD01		DRD01		DRD01		RD01
14		DRD00		DRD00		DRD00		RD00
15				+5V		VCC		VCC
16		_RESET		_RESET		_RESET		_RESET
17		_INTR		_INTR		_INTR		_INT3
18		DMAL		_DMAL		_DMAL		_DMAL
19		_BLISS		_BLISS		_BLS		_BLS
20		_BLIT		_BLIT		_BLIT		_DBR
21		_WE		_WE		_WE		_RRW
22		_RW		_RW		_RW		_PRW
23		_REGEN		_REGEN		_REGEN		_RGEN
24		_AS		_AS		_AS		_AS
25		_RAMEN		_RAMEN		_RAMEN		_RAMEN
26		RGA8		RGA8		RGA8		RGA8
27		RGA7		RGA7		RGA7		RGA7
28		RGA6		RGA6		RGA6		RGA6
29		RGA5		RGA5		RGA5		RGA5
30		RGA4		RGA4		RGA4		RGA4
31		RGA3		RGA3		RGA3		RGA3
32		RGA2		RGA2		RGA2		RGA2
33		RGA1		RGA1		RGA1		RGA1
34		28MHZ		28MHZ		28MHZ		28MHZ
35		A20		A20		A20		_XCLK (,A20) JP5
36		_CDAC		_XCLKEN		NC		_XCLKEN
37		7MHZ		_CDAC		_CDAC		_CDAC
38		CCKQ		_7MHZ		_7MHZ		_7MHZ
39		CCK		_CCKQ		_CCKQ		_CCKQ
40		14MHZ		CCK		_CCK		_CCK
41				TEST		PAL/NTSC	TEST	
42		CRA0		VSS1		VSS		VSS
43		CRA1		DRA0		DRA0		MA0
44		CRA2		DRA1		DRA1		MA1
45		CRA3		DRA2		DRA2		MA2
46		CRA4		DRA3		DRA3		MA3
47		CRA5		DRA4		DRA4		MA4
48		CRA6		DRA5		DRA5		MA5
49		CRA7		DRA6		DRA6		MA6
50		CRA8		DRA7		DRA7		MA7
51		_LDS		DRA8		DRA8		MA8
52		_UDS		_LDS		_LDS		_LDS
53		_CASL		_UDS		_UDS		_UDS
54		_CASU		_CASL		_CASL		_CASL
55		CRA9		_cASU		_CASU		_CASU
56				DRA9		DRA9		_RAS1
57		_RAS0		_RAS		_RAS		_RAS0
58		_RAS1		VSS2		VSS		VSS
59		A19		A19		A19		A19
60		A01		A01		A01		A01
61		A02		A02		A02		A02
62		A03		A03		A03		A03
63		A04		A04		A04		A04
64		A05		A05		A05		A05
65		A06		A06		A06		A06
66		A07		A07		A07		A07
67		A08		A08		A08		A08
68		A09		A09		A09		A09
69		A10		A10		A10		A10
70		A11		A11		A11		A11
71		A12		A12		A12		A12
72		A13		A13		A13		A13
73		A14		A14		A14		A14
74		A15		A15		A15		A15
75		A16		A16		A16		A16
76		A17		A17		A17		A17
77		A18		A18		A18		A18
78		_LPEN		_LPEN		_LPEN		_LP
79		_VSYNC		_VSYNC		_VSYNC		_VSY
80		_CSYNC		_CSYNC		_CSYNC		_CSY
81		_HSYNC		_HSYNC		_HSYNC		_HSY
82				VSS		VSS		VSS
83		DRD15		DRD15		DRD15		DRD15
84		DRD14		DRD14		DRD14		DRD14


8375  SRC: A500 PLUS MAINTENANCE MANUAL
8372  SRC: "FATAGNUS PRESENT DANS LES AMIGA 300" .GIF
8372B SRC: "8372B-AGNUS_PIN.TXT"
8370  SRC: "8370-AGNUS-PLCC.PNG"

from my research I can say that there is a pin compatible 2MB 8375 Agni for the A2000 / A500, these are those that are used in the A600 and some versions of A3000.

The most common is the A500+ which has a pin shift on pin 40.

my other thoughts that could be a problem.

If the board has suffered a battery leak, then its likely that its changed the chemical property of some of the metal alloy that makes up some of them sockets.

For instance,

I was very VERY fortunate to be given an A2000 from G-H in the AmiBay Recycle Bin, and also very fortunate that my friend r0jaws was able to pick it up. however the battery had caused server damage to not so much the board itself but to the CPU and its connector.

Fortunately the CPU Connector just had a nasty scum of green, alas not so could be said for the CPU, in fact it had reacted so bad on one side that the pins were as weak as paper and as you touched them they collapsed off the chip. (fear not that lovely Motorola cpu has a new home as my keychain )

so I would say double check the IC sockets closest to the battery for any metal fatigue and replace the socket.

with the gray / white screens you are sooooo damn close.

good luck my friend

[chiark]

Cheers Z, that's the thing: it's close. I can almost feel the success already
The 3 track repair to the kickstart chip area is not neat, but works... The weird thing is my other 2000 has an 8372A in it and that works with the 8375. if I put the 8372a in the "new" machine, I get nothing at all.

Agni are bloody weird.

[Zetr0]

Originally Posted by chiark

Cheers Z, that's the thing: it's close. I can almost feel the success already
The 3 track repair to the kickstart chip area is not neat, but works... The weird thing is my other 2000 has an 8372A in it and that works with the 8375. if I put the 8372a in the "new" machine, I get nothing at all.

Agni are bloody weird.

.... >_< !

man thats frustrating, I thought the 8372a was a 2MB NTSC Agni, I could be wrong, back to my studdy

there are some OLD revisions of A2000 motherboards that have thier Ram configured in such a way that the 2MB Agni just wont work, if I remember reading the file from aminet correctly. what revision of board is it?

LOL, I have just asked a question I fear I may fail on, had I of re-read the thread I would of seen it I am sure.

[chiark]

Now there's the strange thing. I *think* they're both 6.3 revision boards: one is brown, has suffered a severe battery leak, was owned by a tinkerer who has soldered switches on a few jumpers and is generally a bit of a mess; the other is green, has the octal latches to the right of the cpu on a daughterboard (upside down) for no real reason, has suffered a slight battery leak, and looks very clean and was owned by a butcher who it appears tried to swap a kickstart by inserting a screwdriver *under* the chip SOCKET and forcing it out, damaging tracks in the process.

The brown one works fine. The green one is in the reset loop... So, so close...

I have pics, but they're not with me: will post later!

[TheCorfiot]

Originally Posted by Zetr0

.... >_< !

man thats frustrating, I thought the 8372a was a 2MB NTSC Agni, I could be wrong, back to my studdy

there are some OLD revisions of A2000 motherboards that have thier Ram configured in such a way that the 2MB Agni just wont work, if I remember reading the file from aminet correctly. what revision of board is it?

LOL, I have just asked a question I fear I may fail on, had I of re-read the thread I would of seen it I am sure.

@chiark / Zetro

That's why I have always hesitated from inserting an 8375 in place of an 8372A in my A500 / A2000

AGNI can confuse the mind and soul

TC

[chiark]

This must be a Thursday. I never could get the hang of Thursdays.

(Oh hang on, it's Tuesday... Damn!)

[TheCorfiot]

Originally Posted by chiark

This must be a Thursday. I never could get the hang of Thursdays.

(Oh hang on, it's Tuesday... Damn!)

B***ocks, don't start me off now, you are depressing me, I thought it was Bloody Friday

[chiark]

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