A4000 040 Dead jim?

[MadLensman]

Hi all
 
As most of you know from my intro thread, I am currently having a few challenges with my A4000. She's a 040 model with 2m Chip, 8m fast and no HD so to speak. here's the breakdown so far....
 
Originally had her running, would boot from WB Install disk (WB3) and would access the HD tools but never saw ANY hd (Inc. her original disk)
 
Now:
 
1) No boot screen - Just a dead black screen
2) On investigation, discovered that some clever soul has broken a couple of the SIMM retainer clips - The RAM still sits in the slots fine, and retains ok, but not perfect! - Been like that since I acquired the A4000 so don't suspect this as the problem
3) Checked for ACID damage at battery and caps, none apparent, so assume this is not one of the usual faults!
 
So.......
 
Any pointers? (please!) :biglaugh:

[spirantho]

Disconnect everything except the Chip RAM SIMM and the power and display. Then turn it on. You should see the screen turn black, and then a momentary sync on the TV while it resets the AGA chipset. The screen will eventually turn purple (hopefully). If it doesn't - wait some more. Wait a few minutes. Perhaps an hour. There's reset circuitry that waits for a stable voltage, and this can take a long time if the caps are bad.

Next: Turn it off and put the keyboard in. Start up the Miggy, and when it's been on for a while, press the CAPS lock key. It should light. Press it again, it should extinguish. Then press it repeatedly many times. If it stops lighting/extinguishing, then the CPU is not doing anything. If it keeps doing it, the CPU is working.

If you get any colour on the screen other than black, tell us what it is.

I had this problem with my beloved A4000 - the screen just stayed black.
After recapping it entirely, and rewiring the power supply, I eventually tracked the problem down to something more simple - it was just the Alice chip that had come a little loose from its solder points. 30 seconds with the Aoyue rework station, and it's worked 100% ever since.

[MadLensman]

I shall follow those instructions an await a purple screen of happiness - Many thanks chap!

[spirantho]

Incidentally, looking at your signature... capacitor failure in an A600 also manifests itself as a black screen, usually with the Caps Lock light stuck on. So if this the problem with your A600, now you know why.

[MadLensman]

The A600 overheated and expired - Wasn't a simple cap problem, it just turned it's toes up and shuffled off this mortal coil..... :python:

[paul1981]

The A600 overheated and expired - Wasn't a simple cap problem, it just turned it's toes up and shuffled off this mortal coil..... :python:

I have an A600 where the chips run fairly cool (all of them), then I have another A600 where the chips run very warm indeed, and 3 of them are too hot to touch for more than a couple of seconds (couple of custom chips and the 68000 CPU). That's bad isn't it? Or is it normal? Anyone?

Hope you get your 4000 working BTW.

[MadLensman]

Mine just fried one sunny afternoon whilst reinstalling her HD - I'm in the process of thinking maybe its time to rejuvenate the old girl! (Perhaps - Maybe just rape the FD for the 1200 I've got with a DF0 problem)....

[spirantho]

If I understand your psychological profile correctly (i.e. similar to mine!), there's no point pinching the FD from the 600 for your 1200, because you will want to come back and repair the 600 at some point.

[MadLensman]

You are most correct my friend..... I fail to accept that she is dead, and will no doubt return to repairing the A600 - Simply because she's the only Amiga I have with a decent Wing Commander install on..... Sad but very true!
 
I am in need of a piece of technical critical info though..... Jumpers on the A4000 board... what are the settings usually for the following Jumpers:
 
J501
J502
J500
 
J852
 
J213
J214
 
I can see the legends alongside the jumpers simply enough, J213,214 seem to be ram settings - Although I'm fairly sure that there was never a 4000 with 8mb Chip ram so 213 should be at 2m setting - and J212 must be set for PAL not NTSC so that ones fairly obvious - But the others I'm just ? :huh: don't fancy frying the old girl just because of user error! :crazy:

[spirantho]

Schematics are your friend.

J213: ChipRAM size. Should be jumpered to ground (2MB). No, 8MB won't work.
J214: 8MB Alice. Should be set to pins 2/3 (2MB Alice)
J500/501/502: Sync on Green. Just leave them as is. Not sure what they should be, I don't think you want SoG as it has a sync signal anyway.
J852: RAM size. Set to 4MB for 4MB SIMMs (unsurprisingly). Doesn't matter for now as you should only have your Chip RAM SIMM inserted. You have tried another Chip RAM SIMM, yes?

[MadLensman]

Figured that was the case with the RAM jumpers.
 
My worry is that some other "tech" has been inside the case prior to my acquisition of the 4000 and may have changed settings. A set of full schematics is downloading as we speak so I can check them.
 
Currently on my fourth 4mb SIMM, and have just had the bright idea of pre-testing this particular stick in the accelerator of my working 1200 prior to using in the 4000 so I know it's a known good stick.
 
I do have another worry mind, the keylock switch looks bu66ered - could this be having an effect? Is it supposed to be open or closed circuit for normal ops? - Clutching at straws, but simple things etc etc etc..... :laughing:

[spirantho]

Open circuit is default, don't worry. My A4000 hasn't had a keylock since about 1999 when it was towered!

[MadLensman]

(Mine no longer has one now!!!! - But don't tell anyone!)
 
Still getting just black screen I'm afraid - It appears to be finished!
 
Tried 4 x 4mb RAM SIMMS - All known good units
Processor is now getting warm(ish) where it wasn't before
Get the black screen right after power up - it doesn't appear to reset the AGA set as mentioned
It does appear to be doing something as the "AVI" Message on the TV disappears after power on and the screen goes deathly black.
 
This has to be a simple component failure or voltage issue - Just before the black screen of doom I did notice that she lost all her fast RAM - then wouldn't boot again..... (If that helps!)
 
STRESS - The force generated when the mind over-rides the body's desire to get out a hammer...... :furious:

[spirantho]

First thing I would do is change the caps if you've not done so already.

You can also try powering the machine on while pressing gently on the chips (i.e. try turning on pressing on Alice, then turn off and try turning on with Paula etc. etc.).
Could be a CPU failure. Do you want to borrow my CPU board? I have a spare '030 board lying on a desk at home if you want to try it (but I want it back )

[MadLensman]

Caps all changed, although to be fair, the originals looked A-ok and there were no signs of leakage except around the barrel battery - (Which I also have changed just in case) - After cap replacement she still booted fine and dandy so no worries
 
What actually occured was a sudden loss of all Fast Ram - just 16m to nothing in milliseconds then when I rebooted to check the RAM she refused to boot up at all!
 
So - now got the board out of the case and bread boarded - Getting heat at Alice and CPU so assuming they're running but no output. Buster is colder than a cold thing in a freezer, and paula, she's a mean b1tch - hot one second cold the next boot so thinking I'm flogging the proverbial dead horse maybe?
 
It's a REV B board and I've got a A1200 accelerator with a removable 040 in it that looks compatible with the same slot on the A4000 CPU card - Presumably it's a simple(ish) matter of change the chip and as long as I'm not too heavy handed this'll tell me if the cpu is fubar? (A1200 should boot using the chip from the A4000 if no boot then dead cpu?)
 
Ta for the offer of the cpu board Spirantho - If I could be sure it wasn't something likely to fry someone else's gear I may have been happier to accept.... lol! :hat: