A2000 repairs

[spaceman88]

Hi,
I've never used an A2000 before and now I have 3 of them!!! Unfortunately they all have the same problem. When I turn them on the power light comes on but all I get is a black screen, the floppy drives don't do anything (there are no hard drives). So I took 2 of them apart to remove the batteries, one has missing traces, severe corrosion and I don't think will live again :-(. The other one cleaned up fairly well, but still no picture. I checked the power supply for +/- 12v & +/-5v seems OK. Two of these are A2500's with 68030 cards, will they boot without these boards without changing some jumpers? Is there something common besides the batteries?
Thanks, Len

[Tenacious]

Nice find!  

Have you confirmed a working monitor, which one do you have?

Do you have other working Amiga systems with compatible monitors?  

Do you have a simple video monitor that you can connect the B&W composite output to?

[murple]

Try removing the '030 cards, should boot with the on board CPU without changing anything. In fact, remove any Zorro cards in there too. Try other outputs (composite). If you have a voltmeter and know how to use it, check the voltage coming out of the power supply.

If you get no drive activity and no display at all, that sounds like it could be a bad power supply or else something critical on the motherboard is dead. Maybe it's something easy to fix like replacing a socketed chip. It could be you have a dead motherboard that will be cheaper to replace than fix.

[da9000]

@spaceman88:

AFAIK removing the 030 cards and not touching any jumpers should still cause the machine to boot up fine.

Also, swap the CIAs and/or replace CIAs from one to the other. They can be responsible for non-booting (black screen).

Also, turn up the brightness a bit so that the black screen becomes a dark gray screen. Now, power off and power on the machine and look at the screen all the while to see if the level of black/gray changes. If it becomes lighter black/gray (than when the machine is powered off, then the CPU is probably OK and something else is the problem.

[actung_bab]

make sure the floppy cable is connected to the mb and on the side connector closer to the power connector
you should hear the floppy clicking
l working on one 2000 at moment l lost the rom chip so have to track that down and have one 030 working there nice machines and have broken one (battery) l say forget about the one you have with damaged mb once the damage done that about it am affraid l tryed to get one that died on my 30 mins after l started never gone since.
l found the green power power light blinks after and just before the get terminal damage happned on 4000 also.
keep me in mind as l about to buy another 2000 and u can have mb out of this one if you cant get yours to go
as l dont need more than 2 working 2000s
you should have rom disk image if all its connected to 1084 monitor or tv screen there are also 2 buttons at back of 1084 screen make sure these both set fully out if you connected to amiga monitor
hope this helps

[orange]

do a double check on traces coming from CPU and going right above battery toward the ROM.

[spaceman88]

Hi.
To answer a few of the questions...

I have a 1084s monitor & a Sony TV with video inputs, when I turn it on connected to the TV "NTSC" pops up onscreen so something is going on ( with the "good looking" board, I haven't tried the badly damaged one because it looks beyond repair)

I have removed all boards (Toaster, TBC's & Commodore 68030) and floppy cable

I had the +/-12 & +/-5 on the connector, but I noticed on the last pin (13 or 14) I had 2.5V, not sure if that is normal or not.

I had removed the 68000 to clean under it, used contact cleaner on the socket.

I will try swapping the CIA's & others, I don't have a chip puller for Agnus.

I still have one A2500 (with another toaster GVP 68030) that I have not taken apart yet, hopefully I can get at least one going!

Thanks for any hints, Len

[orb85750]

Is the floppy drive clicking once you remove all the cards?  If so, did you try inserting a workbench floppy?  (But it seems that you would see the request for the workbench floppy on screen if SCSI HDD controller card was removed and if everything were really OK.) -Dave

[Tenacious]

You wrote "I have removed all boards and floppy cable".  IIRC, an Amiga won't boot without DF0: connected, right? It also seems that if you have 2 floppy drives, the ribbon cable must be routed to the correct drives in sequence.  I could be wrong about this stuff, but, its worth a try to connect the drives (if you have two) both ways.  

[nishtek]

Pretty sure it will boot, only takes like 30-60 seconds longer from power on.  Easier with drive plugged in.

I recommend stripping all the boards off all cards.  
First check should be a powersupply. (check at least that the fan spins, although not an indicator that ps is not bad)
Then plug rgb cable and look for color messages.
Check for bend pins, for signs of battery leak.

[murple]

Tenacious wrote:
IIRC, an Amiga won't boot without DF0: connected, right?

It will boot with a hard drive OR floppy OR both. So, no need for DF0: if there's another boot device.

Even with no drives it will power up and show the kickstart screen prompting you to instert a bootable disk of some kind, which is enough to let you know if it works enough to display SOMETHING on screen.

[orb85750]

murple wrote:

Tenacious wrote:
IIRC, an Amiga won't boot without DF0: connected, right?

It will boot with a hard drive OR floppy OR both. So, no need for DF0: if there's another boot device.

Even with no drives it will power up and show the kickstart screen prompting you to instert a bootable disk of some kind, which is enough to let you know if it works enough to display SOMETHING on screen.

If something is a bit wrong with the hard drive or controller card, it may get stuck in the boot-up and simply show a blank screen -- never getting to the floppy drive (that's what happened to me in the past with an A2000).  So make sure you remove all hard drive controllers if it does not boot up with them attached.  -Dave

[orange]

yes, I think it won't boot even if scsi termination isn't set properly.
always look at the diode.. if it lightens up, IIRC its a good sign, checks have passed.

[spaceman88]

Hi,
Just a quick update. I've checked all three boards, 2 are badly damaged from battery leakage the third one has several pins in the 68000 socket that don't make contact, so I'm going to order a new socket. I got a new Ebay motherboard with no leakage (for $34), it's Version 4.4 kickstart 1.2.
I tried two different kick 2.04s from the written off boards (version 6) and neither worked (a kick 1.3 did work). Is there a problem putting 2.04s in a ver. 4.4 board or did I get very unlucky and have two bad chips? Also can I just plug the Megachip from one of the ver. 6 boards into the 4.4 and have it work?
Thanks.