A500 rev5 stuck in white screen. HELP!

[amigaosx]

Hi guys,
I'm struggling with this A500 rev5 board.
It does the boot sequence but gets stuck in the white screen just before the workbench floppy image.

I'm testing the machine without anything attached, no keyboard, no floppy, no expansions.

Things I've tried:

- Tested all the socketed chips in a working A500 rev6, they tested ok.
- Full recap
- Reseated and cleaned all socketed chips

-Following a troubleshooting guide I've desoldered U37 (74LS32), it tested ok and placed a socket.
Measured EMI301 (in the troubleshooting guide it says EMI1301, I guess this is a typo), it should be 1 ohm, tested 1.4 ohm.

-Inspected the board for broken traces, couldn't find any.

-Removed the original kick ROM and placed DIAGROM with a special adapter for rev5 boards.
It just shows garbage on screen, so I built a serial cable and connected to a windows machine with Putty.
I can see and control DIAGROM via Putty.
All tests seems ok, except for audio test, it sounds choppy (see attached video), and graphic tests crashes the machine, or shows garbage graphics, except for raster test, it looks ok.
Mouse works, Joystick works.
RAM, CIA, IRQ, PORTS test all passes fine.
I've attached the keyboard to test it under DIAGROM and all keys works, except it doesn't reset (CTRL +A +A).

Somebody suggested to test the IPL and INT signals, I'm not sure what are those for, but I check the schematics and followed the traces that carries those signals and they seem fine (just did a continuity test)

PAULA pin 15--- > IPL2 ----> pin 23 68000 ok
PAULA pin 14 ---> IPL1 ---> pin 24 68000 ok
PAULA pin 13 ---> IPL0 ---> pin 25 68000 ok
AGNUS pin 17 ---> INT3 ---> pin 17 PAULA ok
PAULA pin 18 ---> INT6 ---->pin 21 CIA EVEN ok
PAULA pin 16 ---> INT2 ---->pin 21 CIA ODD ok

I've attached some pics of DIAGROM and the video that shows the choppy sound.
As a side note I've tested the board for shorts and I get 48 ohms between +5v and GND, is this ok?

Sorry for the long post!!
Any help will be very much appreciated!

[ Show youtube player ]

[ Show youtube player ]

[solarmon]

Check the memory traces going to the CIAs

[amigaosx]

Originally Posted by solarmon

Check the memory traces going to the CIAs

Ok, will check and report. thanks!