345EEQX@CMUVM.BITNET (Robert Devantier) (01/23/90)
Since someone posted a notice saying they had problems with the power
supply in a German-made B2000, I thought I should go and test my power
supply. I should say I have had no problems with the computer in the
two years plus that I have owned it, but did have a friend who had one
from the same batch that the power supply was flaky.
My question to the net is: Should I be having a problem when the power
supply is under the following load?
System: German B2000 (4.1 rev upgraded to 4.5 level, including the new
MOS Gary and Fatter Agnus)
ProRam 2000 w/2 meg 100ns RAM
ProDrive DF1, A-1010 (full-height) DF2
A2088 w/ an external 1020 drive and a Tandon 20-meg
hard-card.
Processor Accelerator.
The situation: When I have all three Amiga drives formatting, and doing
a DIR OPT A of the Amiga JH0 partition of the Tandon,
all I get from Drive A or B of the PC side is an
error reading drive x. If any one of the devices stop
their access, the PC drives magically work OK.
Am I experiencing the limit of what my Power Supply can handle? I know
this is the extreme case on power usage, but I have 4 meg of chips
coming, and a 68030 board is down the road somewhere, along with some
sort of A2091 system with an external HD. Should I start saving up now
for the $95 power supply, or just stop lighting my room with drive
activity lights? I would think 200 Watts should handle all of this.
Please respond directly, or the nets. I will post a summary of any
personal mail if there appears to be a need. I would have posted this
to .tech, but Bitnet sort of limits my scope of the world...
Thanks for the help in advance.
-----------------------------------------------------------------
Robert Devantier | 345EEQX@CMUVM.Bitnet | Student Programmer
Central Michigan University | {!Amiga!} | Computer Services
"It doesn't matter what I think, they'll sue me for what I said."dpm@k.gp.cs.cmu.edu (David Maynard) (03/02/90)
A friend of mine has an Amiga 2000 that stopped working a few weeks ago. When he turns it on, the power light comes on for a few seconds and then shuts off. He disconnected the power supply and discovered that it will only deliver a small amount of current before shutting down (using different resistor loads well within rating). He also noticed that the fan appears to be broken (even when run from a different power supply). Our guess is that the fan may have failed causing the power supply to fail. Has anyone else seen such a failure? Is it likely that the board is still okay? So far he hasn't found anywhere that has the power supply in stock. It looks like it will cost ~$180 when places do get them. So the question is, can we hook up a standard (~200W ?) PC power supply? The Commodore supply only lists +5, -5, +12, and -12 voltages which are all standard, so it would seem that a little custom cabling (and a large, ungainly external power supply) would fix things for <$75. Would he need to add a cooling fan to the enclosure (it is currently a 2-floppy system with no expansion boards)? Thanks for any suggestions, David --- David P. Maynard (dpm@cs.cmu.edu) Dept. of Electrical and Computer Engineering Carnegie Mellon University, Pittsburgh, PA 15213 ---
dpm@k.gp.cs.cmu.edu (David Maynard) (03/03/90)
Thanks to Don Perley, who pointed out that the A2000 power supply has a protection circuit that shuts itself down when the fan fails, the A2000 is now working again. Replacing the fan with a new one made everything better. Thanks for everyones help! -David --- David P. Maynard (dpm@cs.cmu.edu) Dept. of Electrical and Computer Engineering Carnegie Mellon University, Pittsburgh, PA 15213 ---
dlleigh@mit-amt.MEDIA.MIT.EDU (Darren Leigh) (03/03/90)
In article <8249@pt.cs.cmu.edu> dpm@k.gp.cs.cmu.edu (David Maynard) writes: > >A friend of mine has an Amiga 2000 that stopped working a few weeks ago. >When he turns it on, the power light comes on for a few seconds and then >shuts off. He disconnected the power supply and discovered that it will... The power supply in my 2000 broke about a year ago. The LED wouldn't even stay on for a few seconds -- it would turn on and then off again almost instantly. I'm not sure what is causing your failure, but you should not try a component level fix of a power supply unless you really know what you are doing. Remember that you have thousands of dollars of equipment relying on this power supply, and one bad glitch could trash it all. >So far he hasn't found anywhere that has the power supply in stock. It Deja vu. >looks like it will cost ~$180 when places do get them. So the question is, >can we hook up a standard (~200W ?) PC power supply? The Commodore supply >only lists +5, -5, +12, and -12 voltages which are all standard, so it would >seem that a little custom cabling (and a large, ungainly external power >supply) would fix things for <$75. Would he need to add a cooling fan to >the enclosure (it is currently a 2-floppy system with no expansion boards)? I'll tell you what I did that fixed mine for about $50. First the disclaimer: DISCLAIMER: The following is provided for informational purposes only. I make no claims that this will work for your system or that it can be done safely. The equipment described contains hazardous voltages and should only be opened and modified by trained personnel. If you don't know what you're doing, take it to the shop and let someone who does fix things. Otherwise you are endangering your equipment and your life. I first got the idea of just replacing the entire internal power supply. I ordered a really small (in physical size) PC clone supply (I think it was 150W), but when I got it, I found that it would not quite fit inside my case. Remembering that most of the clone hardware is made by the same companies and that defacto standards abound, I checked inside the metal cases of both the Amiga and clone power supplies. It turned out that the power supply board inside each was the same size. I put the clone board inside the Amiga power supply case, added a little custom cabling and voila! The one subtelty was that was that I had to change one of the jumpers on the 2000 motherboard. The amiga power supply has a TICK output which is a TTL 60Hz signal derived from the power line. Your new power supply probably won't have one of these so you need to tell your Amiga to use the VSYNC signal instead. I think it's jumper J200, but I don't have the docs with me. Check the schematics in the back of the user manual. The problem with this is that your real-time clock will only run at 59.94/60.00 the proper rate. This is significant over the course of a single day, so you'll need to run "setclock load" at least that often. If you're serious about having a clock run at the right speed, you can generate your own 60 Hz tick signal. If you generate this from the power line, PLEASE be sure to isolate it properly. Just using the entire PC clone supply externally would also work, but it would be ugly and less portable. You'll still have the clock problem too. Putting a fan inside the 2000 (even though the power supply is external) would be a good idea. Please e-mail me if you have questions, problems or success stories. Darren Leigh dlleigh@Wmedia-lab.media.mit.edu (Internet) mit-amt!dlleigh (UUCP)
ridder@elvira.enet.dec.com (Hans Ridder) (03/05/90)
In article <8249@pt.cs.cmu.edu> dpm@k.gp.cs.cmu.edu (David Maynard) writes: >A friend of mine has an Amiga 2000 that stopped working a few weeks >ago. He also noticed that the fan appears to be broken (even when run >from a different power supply). Our guess is that the fan may have >failed causing the power supply to fail. Has anyone else seen such a >failure? Is it likely that the board is still okay? A local service place had an A2000 come in with similar symptoms (no power, fan not working). They wound up replacing the fan, and the power supply started acting normal. I didn't work on it myself, so this information is second hand. You might have your friend try disconnecting or replacing the fan (or try installing a similar load for testing), it's cheaper then a replacement power supply! > David P. Maynard (dpm@cs.cmu.edu) -hans ======================================================================== Hans-Gabriel Ridder Digital Equipment Corporation ridder@elvira.enet.dec.com Customer Support Center ...decwrl!elvira.enet!ridder Colorado Springs, CO