a500 black screen troubleshooting

[powrslave]

A500 rev 6a
only power led lights up
only thing connected is keyboard (with/without) and 520 rf
system board on the bench
no caps lock LED

Aside from caps, could it be a bad 68000 or a bad 1.3 ROM?
I'm considering changing the ROM out but was wondering if a bad ROM would cause this.

Power up, screen changes to a darkish gray and then goes black.

I will be testing all caps with esr as soon as it arrives.
In the meantime I've already changed:

R406
c401
c402

[Thomas]

If the power LED lights up, (really lit, not half-bright), then the CPU, the ROM and one of the CIAs are ok. The LED is driven by an I/O line of the CIA which is controlled by the CPU but only if the ROM contains instructions to do so. If you remove the CPU or the ROM, the LED will stay dark (or half-bright on later Amiga models).

[jdupuis]

Hi,
 
 This may help as it has helped me over the years: From my Amiga World Magazine. Issue Oct. 1994 page 4 "Denny on DOS"

The screen flash at first power up is actually a series of colors. Fist color is Dark Gray. If it stops here you need to open up and press all chips down firmly in place. Second color is Light Gray. If re-seating chips does not help you have serious problems. Third color is Red. Indicates problem with Kickstart ROM, faulty expansion cards and loose Agnus chips. Try pressing down Agnus. If still no good, try removing expansion cards. Replace one card at a time until you find the problem. Fourth color is Green. Chip RAM problem. Bad memory chip. Fifth color is Blue. Indicates problem with Custom Chips. Again, re-seat or there is a faulty Custom Chip.
 
 If you do get past where your boot process stops now, this will help if your 500 boot up stops at another color.
 
 Cheers!!