DKB 1202 Yellow screen

desantii

New member
Banned
Joined
Sep 24, 2009
Posts
68
Country
Chicago
Hi, I have a DKB 1202 ram expansion from the site but I am having problems with the FPU. With no FPU it works fine. When I plug and an FPU an oscillator (I have tried two FPUs and 4 oscillators) I get a yellow sceen and no boot. With no oscillator (FPU only) black screen and no boot

any thoughts

thanks
 

keropi

Active member
VIP
Joined
Dec 5, 2007
Posts
7,143
Country
Greece
Region
Ioannina
obviously there is some damage in the FPU-related circuity... is there any visible damage (like scratches in tracks etc)?
 

Justin

Active member
Joined
Sep 14, 2008
Posts
12,176
Country
United Kingdom
Region
UK
any use bud?

Amiga system will not boot. Screen flashes colors or keyboard lights flash.

You may notice that when you turn on or reset your Amiga a few different colors flash by. These actually mean something. Here you go:
Red Bad ROM
Yellow CPU Exception Before Bootstrap Code is Loaded
Green Bad Chip RAM or Agnus (check seating of Agnus)
Black No CPU
White Expansion passed
Grey CPU Passed

Constant white is failure of CPU.

Or as taken from the Amiga 4000 Service Manual:

Passed Test
Light Gray Initial hardware configuration tests passed.
Initial system software tests passed.
Final initialization test passed.

Failed Test
Red ROM Error - Reseat or replace
Green CHIP RAM error (reset AGNUS and re-test)
Blue Custom Chip(s) Error
Yellow 68000 detected error before software trapped it (GURU)

The system performs the following test sequence:

1.

1. Delays beginning the tests a fraction of a second to allow the hardware to stabilize.
2.

Jumps to ROM code in diagnostic card (if found)
3.

Disables and clears all DMA and interrupts.
4.

Turns on the screen.
5.

Checks the general hardware configuration.

If the screen remains a light gray colors and the tests continue, the hardware is OK.

If an error occurs, the system halts.
6.

Performs checksum test on ROMs.

If the system fails the ROM test, the screen display turns red and the system halts.

Keyboard
One Blink ROM Checksum failure
Two Blinks RAM test failed
Three Blinks Watchdog timer failed
Four Blinks A short exists between two row lines or one of the seven special keys (not implemented)



#related td {font: 8pt verdana,arial;padding-left:10px; text-indent:-10px}#related a,#related a:visited,a:active {color:#306;}
 

desantii

New member
Banned
Joined
Sep 24, 2009
Posts
68
Country
Chicago
I have not checked the keyboard lights, will do so. Board looks ok physically

thanks
 

Zetr0

Ya' Like it Retr0?
Joined
Nov 22, 2007
Posts
9,900
Country
UK
Region
Norfolk
@desantii

Under Kickstart 2.04 and up, most of the error colour codes were scrapped and not implemented on the Amiga A1200 it uses Kickstart 3.0 and up, as such MOST codes mentioned are not a good enough indicator of what the error is.

To be honest, "RED = Hardware Assetion Failure" is the only garantee you have.

I have to admit I love this bit =)
Or as taken from the Amiga 4000 Service Manual:

Failed Test
Red ROM Error - Reseat or replace
Green CHIP RAM error (reset AGNUS and re-test)
Blue Custom Chip(s) Error
Yellow 68000 detected error before software trapped it (GURU)
Now, I have an A4000, and I will be damned if I can find that Agnus or that 68000 cpu.

The above only really applies to A500's and A2000's with Kickstarts under 2.04 otherwise most of the error colour codes you will get are a guestimate at best.


Now it would seem that you are suffering from FPU assertion failure, that is to say, you put it in and the system hangs, the question is - why?

the FPU is quite a transparent circuit to be honest, I am assuming you have the following card

dkb1202.jpg


Two FPU's and 4 Oscilators lends me to believe -

1. theres a fundamental fault with the card,
2. you have either the xtal or FPU inserted incorrectly


Lets take the easy one (number 2) and isolate that first
dkb1202-xtalfpu.JPG



Next is a little more involved, so lets see what we got -

With the FPU installed and no Xtal in the socket the system wont boot:

As the FPU is not reporting, hence the black screen of nothing-ness: this is to be expected - even though there are two chips with different pathways (the FPU and the mobo based CPU) both of these are seen as one entitiy by the system - as such if the FPU doesn't work niether will the onbard CPU.


With any XTal installed the FPU an error screen is shown:

Now this can be a number of issues however we can rule out the following

1. it is not an FPU failure
2. it is not and XTal failure

so what can it be ?

Lets take a look at the mechanical,

1. Inspect the solder points of the Trapdoor connector, do any of them touch each other?

2. Inspect the FPU socket is it cracked or fractured in a corner?

3. Inspect the FPU socket Pins, are any of them crushed/crippled inward

4. Inspect the XTal socket - do all the XTal pins fit nice and snugly?


Thats just to begin with, hit that lot up and see how you get on =)

good luck
 

desantii

New member
Banned
Joined
Sep 24, 2009
Posts
68
Country
Chicago
Thanks Zetro! It is exactly that card

From the testing done its is definitely something with the card, it looks ok but I will have another look. I have tried with 2 FPUs and 3 oscillators so I guess that rules them out. I have also tried in another A1200 and same issue so not an A1200 issue
 

desantii

New member
Banned
Joined
Sep 24, 2009
Posts
68
Country
Chicago
Ok, so I cleaned it up and still nothing, all looks ok but same yellow screen so I am just declaring dead FPU hardware.

Cleaned up, inserted both FPU and Xtal = Yellos screen, constant reboot
Xtal and no FPu = normal boot
FPU and no Xtak = no boot, black screen

Same issues on difefrent FPUS, Xtals and another A1200

thanks everyone for your help
 

Kin Hell

Active member
Banned
Joined
Nov 25, 2007
Posts
6,970
Country
U.K.
Region
Cornwall
@ desantii

Did you buy this board via AmiBay as a fully working board?

If so, raise the matter accordingly. (y)

Kin
 
Top Bottom