#2000 Repair
15 messages in this thread
I've been trying to revive my dead 2000. One day the screen went black and
the power supply fan stopped.
I replaced the power supply which did not help. I then replaced the CIA
chips, Denise, Paula, and upgraded Agnus to 1 Meg with a kit from Grapvine.
Any suggestion would be appreciated.
Did the fan on the new power supply work? That fan runs off the +12v
and there's logic in the supply that will shut everything down if the
fan isn't turning. It sounds like you have a short that is drawing
too much current & shutting off the supply. Use an ohmmeter to check
between the voltage pins on the motherboard connector and ground.
Then check between the voltages. I've seen at least one 2000 where a
'cabling accident' at the serial port blew the line drivers and
shorted the +12 to the -12. Also, try (first) disconnecting the
cables to the floppies and any HD's.
Thanks for your help. I posted message already, but I didn't
correctly reply. I didn't try the power supply before I put it in
the Amiga. Now the fan does not operate whether it is in the 2000
or not. Voltages are +5V is +6.27, +12is +6.77, -12 is -8.9, -5 is
-5, TICK is +3.22. The power on LED turns on breifly when the 2000
is powered on. I do not see any obvious short on the mother power
connector pins. I have removed all the floppiesand the HD, and
tried to power up with nothing connected and get the same result.
Thanks again for your help.
Jim,
There are a couple of different vendors for the 2000 ps, but I don't think
any of them will power up correctly without a load. The LED comming on
briefly probably does mean something is shorted somewhere. You'll have a
job of finding it, if it's not something socketed. I didn't mean to
suggest that the short was at the motherboard connector, just that it was
a convenient place to check with the ohmmeter. It's also worth a shot to
pull out any expansion boards….
-jim
Jim
I need an A2000 power supply. Who are the vendors you mentioned in your msg to
Jim.A ??
gn
Gordon,
I don't know if you could buy the A2000 power supply direct from
either of those vendors. Commodore had the supplies built by a couple
different companies. But, Micro R&D makes a heavy duty power supply
for the 2000 as an aftermarket product. It should be available from
them, or through your dealer. I think Grapevine Group sells the stock
power supply.
If you mean that the fan will not work when connected to the A2000 power
supply or another power supply then the fan is probably faulty. If
everything I've read about the A2000 power supply logic in this thread is
true, then you must install a known operating fan in the power supply to
test the power supply…. Also, I agree with Jim Steele about
disconnecting all drives and expansion boards and checking with a
multimeter at the motherboard connections…just be SURE the power supply
cord is disconnected from the 115vac source before taking any resistance
readings or you may(will) toast your meter (or it's fuse if so equipped)
also.
// daniel on autopilot in paradise
\X/ with intel and motorola inside
Hmmm. I'm a bit out of my element here. I make my living with PC's, Mac's,
and LAN's, but my Amiga is the the only computer I really enjoy any more.
According to my son this is a case of the cobblers kids going without shoes.
I'll be darned if I'm going to pay anyone to fix my computer.
I think the fans and both power supplies I now own are both ok. I think the
problem(s) is on the system board.
Grapevine suggests the X1 crystal may cause a power up problem. Does any know
what the TICK signal coming off the power supply might be (pin 14)?
Thank you for your help.
Jim;
The TICK signal is a 60Hz clock signal. Some of the machines don't have
the option but for the A2000/2500 type machines there is a jumper (J300 on
any that I have seen). A real easy check is to change the jumper from
TICK to _VSYNC.
Sometimes, there will be a "local" noise source that gets through the
power supply and prevents the machine from comming up. _VSYNC looses you
a small amount of clock accuracy but the machine will work fine.
-bill
I am not sure about pin 14 but the TICK signal should be the signal
provided to jumper J300. From the list of 2000 motherboard jumpers in my
copy of the Amiga 2000 Manual Update:
J300 This jumper determines the time base used for the 50/60 Hz CIA
1 2 3 timer chip. In the normal position, the 50/60 Hz TICK clock,
X-X X based on AC line frequency, is used as a time base. In the
alternate position, the vertical sync pulse from the video
section is used. The system will not operate properly without one of
these clocks.
// daniel on autopilot in paradise
\X/ with intel and motorola inside
Thanks for the information. i'm not sure what to try next. Perhaps upgrading
to a new machine is the most expiditous options.
Thanks again.
Have you thought about how much you'd sell the A2000 and ancillaries for?
// daniel on autopilot in paradise
\X/ with intel and motorola inside
No, I haven't. I have my back to the wall keeping my Mac and PC Novell LAN
runningthat my Amiga has always taken second place.
There is the 2000, the PS, new chips, 52M SCSI w/4M, and 4M RAM card. What it
is worth I do not know.
What I woul like is that given my career, Commodore cut me a deal at their lost
so they can make it up in volume.
Seriously, if I can afford a 1200 and a 50M IDE with a sale my needs would be
met. I apolize for being less than serious. I had a bad packet day.
Jim,
PMJI (newly understood acronym for me, I guess I'll use it here).
I've seen your name on previous postings and have refrained from asking
this question but, I just can't stand it. How many Amdahls can there be?
Are you any relation to the guy who used to be an engineer at IBM and then
quit to start 'Amdahl' that makes IBM mainframe clones?
Robb
The more I rub shoulders with the mainframe people the more this
question seems to come. It is probably not in my best interest to
honest on this one, but I suspect if I asked Mr. Amdahl for an Amiga
600 he would say no.
The Amdahl's I am closest to would be the Garrison Keillor, Lake
Wobegonites – if you are familar with his writings or radio stuff.
I knpw a lot of TLA's but FLA's are new to me. I do not know what a
PMJI is.