#Power Supply Problems?
10 messages in this thread
Hello fellow Amigans!
I am having some severe problems with my (usually) trusty A2000HD, and the
problems seem to be the kind that have probably been there for a while, but
have grown considerably worse over a long period.
I currently have a GVP 25 MHz '030 board (1 MB RAM) along with 2 A2091's. One
2091 has 2 MB on it, the other 512K. I have three HD's, one being the original
40MB Quantum, a 52 MB Quantum and a 210MB Conner. Currently, the two small
Quantums are on one SCSI chain on the GVP, while the Conner is on the 2091 with
2MB. The second 2091 with 512KB is by itself. I have a 2MB Agnus installed
using the TMAP board. The mother board is a rev 4.x board (I don't remember
exactly which one) while the 2091's are rev 4.3 and 4.4 (I believe) and the
2091 ROMs are a rev4.x and 6.x. I have the 2.05 system ROM and the 2.1 OS.
My problem is this: prior to installing the GVP board, I was getting some
strange system crashes with guru numbers 0f 81xx xxxx and always in the task
address range of 002xxxxx. It progressed to the point where on rebooting, the
machine came up with the dreaded blood-red board diagnostics screen showing me
that the memory portion of the 2091 with the 2MB was bad (of course, I no
longer had that 2MB available after that). Subsequent reboots without powering
down would always result in that message. Powering down would "reset" the
machine, apparently, and the board would be available again. Again, this was
prior to installation of the GVP board.
Now, with the GVP board installed, the same guru's occur, but now they may also
appear in the 01xxxxxx address range, but I have yet to have them result in the
board diagnostics screen on restart. What has happened, at least once, is that
it apparently loses track of the boot drive, because it suddenly popped up a
black screen with the animated disk insertion into the disk drive routine. The
machine will now "hard-lock" – even no mouse response – if very much memory is
used, i.e. unpacking the AmigaUser.CAT file to RAM (although I can unpack it to
disk just fine). Another example is trying to pull up the catalog in AutoPilot
– AP works fine until I try to pull up the download catalog ( which is ~760KB)
at which time everything just stops. Another example – VLT works fine,
including ZModem downloads, but Term crashes miserably, especially if I try to
do a ZModem download (it uses an external xpr library that must be loaded in is
my guess).
I'm sorry if this is a little long-winded, but this problem has got to stop!
My question: is it possible that the power supply is weak, and as more memory
and disk drive usage occurs, it is not capable of maintaining voltage on the
bus? Or, is this possibly a problem with the motherboard revision? Does
anybody have any similar experiences, or engineering insight as to what the
problem is and how it can be corrected?
Thanking all in advance (especially for the patience to read this <g>),
Duane.
Duane,
I think some consolidation is in order. It will require some investment, but I
think you will be able to avoid some problems you are experiencing.
Regarding the memory situation. I would add more 32-bit memory (8 MB) and get
rid of A2091s. I'm sure you can sell them here in the Classifieds forum for
about $50 ea. Possibly more if you include the memory.
Purchase an inexpensive external tower case or multi-drive bay enclosure (with
power supply) to house all of your hard drives. Connect all of the drives to
the Accelerator's SCSI. You will have to get a 50-pin ribbon cable, with
multiple headers, custom made for connection to all of your hard drives. Of
course, you will have to unterminate all your drives with the exception of the
last drive in the SCSI chain.
You did not mention if you have the original Denise chip on your system. If
so, I would check to see if you can obtain the ECS Denise to insure you are up
to date. For example, our software, Scala MultiMedia MM300, requires that you
have both the ECS Agnus and ECS Denise installed for proper operation.
After all is said and done, you will have a better performing system, with
minimal taxation on your power supply. Indeed, it has been reported that some
rev 4.x A2000 motherboards could not handle extreme electrical loads. This may
contribute to some the problems you have been experiencing.
Regards,
John Chang
Technical Support Manager
Scala, Inc.
Thanks for the quick reply, John! My error on the chipset omission, I do have
the ECS Denise. I am a little concerned about this, due to the potential need
to replace the MB or the PS. I've seen the 300 W power supplies in the
magazines (I believe they're from Micro R&D), but if the motherboard is not
capable of handling the electrical load, the extra power won't help.
Do you know of anyone who sells the external drive towers? With 3 HD's in the
case, it is pretty full, so an external case may be a good answer. How does
the inability to handle electrical loads effect the installation of other
boards, i.e. Bridgeboards and Mac emulators (I've been thinking about an
Emplant lately, with the advent of 486 emulation as well). Would you recommend
a motherboard replacement to a rev 6.2 board?
Thanks for the tech help,
Duane.
Duane,
I've built a few external SCSI towers out of clone minitower cases. If
you're willing to do some work, you can save a lot of cash.
-Jim
MOS via Autopilot & Amiga
Jim;
Thanks for the tip. I have a local friend who has added HD expansion to his
A500 using an old XT case. It seems to work for him – he runs his BBS off of
it. I had never thought of doing it myself, though. Thanks again,
Duane.
Duane,
It's fairly easy to do. I've even seen the complete inside cabling
already made up at the hotel computer shows that spring up everywhere.
That saves some aggrivation if you don't have the right tools to crimp on
those IDC connectors. The Centronics end is a real pain… The connectors
we had would crack in the vice. But we used a piece cut from a popsicle
stick to spread the pressure.. (If you end up with those you'll see what I
mean, otherwise it's too hard to explain without a picture. 😉 ) The other
potential gotcha I've seen is with the power supplies. One of the cases I
built wouldn't spin up properly. Seems the power supply didn't wan't to
regulate with only a drive attached. I added a dummy load resistor on the
5v line. These days, I'd put in a dead pc motherboard as a load. That way
I could use the peripheral slots for video cards that only need power like
TBCs…
-Jim
MOS via Autopilot & Amiga
Duane,
Its the combination of peripherals and cards that makes your system unstable.
For example, it never occured to me to use multiple SCSI cards for RAM
expansion and as hard drive controllers. Goes to show you how well – sort of –
the Amiga can handle such diverse expansion products. Try that with a PC, hah!
But I digress.
If you were powering the hard drives from the bus as oppose to connections to
the power supply, that could be one of instabilities. Adding Emplant et al
should not be a problem since power requirements will be fairly low. I really
don't see the need to replace the motherboard.
Look for peripheral enclosures and tower cases in a copy of "Computer Shopper".
As to a SCSI ribbon cable with multiple headers, give my friend, Julie Howard,
at Redmond Cable a call. Tell her I said "Hi" and that I referred you to her.
She'll either give you a great deal or hang up on you. Just kidding. ;-}
Contact and address is below:
Redmond Cable
P.O. Box 865
Cleveland, TN 37364-0865
Tel: 615-478-5760
Fax: 615-472-3647
Good luck!
Regards,
John Chang
Technical Support Manager
Scala, Inc.
Duane,
I have a 4.1 MB with mods to 4.5 compliance. For a time I had similar
problems (not exactly the same, but that was under 1.3) I took out the GVP
HC-8 card (16 bit mem and SCSI) and moved all the HD and external devices
to run off the GFOrce '040 card. I also upgraded to the lates GVP ROMS
and added a Micro R&D 250 Watt PS. That seemed to clear up all the
"random" problems that were not clearly software related.
wmc – via Autopilot!
Wayne;
Sorry to hear that you have experienced similar problems – makes me feel a
little better in my self-diagnosis, though. Everyone who has replied has
basically pointed to this as at least potentially the problem. I think a
little re-configuring might be in order. Thanks,
Duane.
Duane,
Check with Micro R&D about beefed up Amiga power supplies.
wmc – via Autopilot!