A4000 gone dead!

[dvvrue95]

Hi there,
my A4000 recently obtained from Ebay has died on me.
I was installing a 2nd (replacement) drive and decided to use Disksalv 'cause of the problems (errors) with HDInstall
so I left the machine on overnight.
On my return the machine power light was on but not much else, I had powered off monitor last night but when I switched it on it was just a bank screen.
I tried a soft reboot but inspit of some hd activity and hd light flashing no joy and then I noticed the powere light was flashing. So I powered off and disconnected both drives and powered on this time I just had the green power light flashing?? Any ideas what it could be. I dont think it is anything to do with hd's.I get a blnk screen no
no WB 3.0 insert disk icon.

thanks, Ian

[dvvrue95]

Hi thanks for ALL feedback,

A.
I unplugged psu from motherboard and
measured :-
-17v on Red (-12v)
+6.8v on Orange (+12v)
+5.04 on Yellow (+5v)

all open cct. i.e. nothing connected to psu
can anybody please check their setup I have shown what I think are the correct voltages in brackets, WOULD A DODGY +12V rail cause these problems? If I'm correct
it looks like psu has gone down.PLEASE ADVISE.

B.
I stripped everything down to motherboard and then re-seated socketed chips, daughterboard, and A3640 board. Reconnected psu and switched on (without hd's or fd connected initially I got a guru meditation (s/w error) message followed by purple screen, so I switched off reconncted fd and switched back on this time just a flashing power led! oh and the fan in the psu runs - since then just a flashing power led and fan running.

C.
IWhen I first got the machine I stripped the battery out since it looked in a bad way, have cleaned up as much as possible and replaced with a NiMh battery but clock settings still does not seem to hold up that was after a couple of days of having machine on charging new battery.

[dvvrue95]

Hi,

OK voltages measured with psu connected to MB, but no hd or fd connected :-

ORG +7.11V
RD  -17V
YL  +4.92V

all measured with reference to GND.

Having done that test again comments about not reconnecting psu to anything noted!

thanks again

Will try to track down a spare AT/ATX psu in the next few days to eliminate psu.

[dvvrue95]

Amiga Ground is Blue not Black.......
OK so I'm an idiot!

It was only when I was trying to match up the A400 psu leads with a "borrowed" ATX psu that I realized my previously silly mistake in measuring the voltages from the A4000 psu.

The A400 uses a power good indicator (logic 1, which I have taken as +5volts) which comes out on the Brown wire, previously I hade been looking at some (duff) info which suggested that was Ground, in fact there are two Blue wires which are Ground.
If I measure using this convention I now read the following :-

Gnd (Blue) Red    (-11.95)
 "     "   Orange (+11.48)
 "     "   Yellow ( +5.02)

also if I measure Gnd (Blue) Brown (+4.95), which I guess is the logic 1, power good indicator from the psu.

All above measured connected to mb without hd's or fd connected.
I have reseated all socketed chips, including removing and refitting the 3.0 roms, if I switch on now I get the flshing green power led which seems to flash quickly for five or six times, pauses and then repeats five or six quick flashes accompanied by a Yellow screen which displays twice and then screen goes blank.

I think (but I'm not too sure after the voltage fiasco)a Yellow screen is supposed to indicate a "68000 detected h/w or s/w error" ---- whatever that means. http://www.amiga.org/uploads/smil402e47bbde2c2.gif
http://www.amiga.org/uploads/smil402e47bbde2c2.gif
I have managed to "borrow" a ATX psu and will be getting a converter cable later in the week so will try to use that to eliminate the A4000 psu.
Sorry for the naff readings at the start of this article, hopefully the ATX psu will do the trick.
Thanks again for all your contributions,
Ian