MBDZM@ROHVM1.BITNET (11/09/90)
Help! I recently fried the power supply on my Amiga 2000. I did this by shorting a terminal on the serial port to ground. I have replaced the fuse, but it just keeps blowing. So here I am looking for a new power supply. There are several places that have new ones in my area, but they want about $150. Can I hack an IBM a/t supply (about $50) to work? The voltages seem to be ok +5, -5, +12, -12, but there is a line marked "TIC". That is the one I can't figure out. Is it there on the IBM supply? Can I fake it? Thanks, Geoff Mendelson (215) 242-8712 uunet!gsm001!gsm
graham@venus.iucf.indiana.edu (JIM GRAHAM) (11/10/90)
In article <90313.094443MBDZM@ROHVM1.BITNET>, MBDZM@ROHVM1.BITNET writes... >Can I hack an IBM a/t supply (about $50) to work? Yes you can. I've done it. >The voltages seem to >be ok +5, -5, +12, -12, but there is a line marked "TIC". That is the one >I can't figure out. Is it there on the IBM supply? Can I fake it? Darn! Wish I had my notes with me. I can't remember what the TIC line is all about. I do remember that I did not have to worry about it. On my supply, there were several identical connectors (all with 4 pins). Additionally, there was one long connector which normally went to the mother board of the pc. This connector was the one with the "TIC" line. I am presently running an Amiga 500 with A501, external floppy, two (2) Seagate ST238R HD's, Omti controller, and interface between the A500 and the controller off this single supply, and it doesn't even get warm. It is NOT a stock AT supply. It's from some mail-order company. When I was playing around with the hookup, I learned that it has internal "sensing" of the load (which, in my opinion is not exactly efficient... the load should be "sensed" AT THE LOAD). However, it regulates very nicely and I'm quite happy with it. -> ->Disclaimer: I'm not ashamed of what I say. <- <- Sorry if the above disclaimer is too long. __________________________________________________________ | Internet: graham@venus.iucf.indiana.edu | | UUCP: dolmen!graham@iuvax.cs.indiana.edu | | FIDO: Soon! | | BBS: The PORTAL DOLMEN, (812) 334-0418, 24hrs. | |__________________________________________________________|
inuy@vax5.cit.cornell.edu (11/11/90)
In article <7652@cica.cica.indiana.edu>, graham@venus.iucf.indiana.edu (JIM GRAHAM) writes: > In article <90313.094443MBDZM@ROHVM1.BITNET>, MBDZM@ROHVM1.BITNET writes... >>Can I hack an IBM a/t supply (about $50) to work? > > Yes you can. I've done it. > >>The voltages seem to >>be ok +5, -5, +12, -12, but there is a line marked "TIC". That is the one >>I can't figure out. Is it there on the IBM supply? Can I fake it? > > Darn! Wish I had my notes with me. > > I can't remember what the TIC line is all about. I do remember that I > did not have to worry about it. > > On my supply, there were several identical connectors (all with 4 pins). > Additionally, there was one long connector which normally went to the > mother board of the pc. This connector was the one with the "TIC" line. > > I am presently running an Amiga 500 with A501, external floppy, > two (2) Seagate ST238R HD's, Omti controller, and interface between > the A500 and the controller off this single supply, and it doesn't even > get warm. > > It is NOT a stock AT supply. It's from some mail-order company. > > When I was playing around with the hookup, I learned that it has internal > "sensing" of the load (which, in my opinion is not exactly efficient... > the load should be "sensed" AT THE LOAD). However, it regulates very nicely > and I'm quite happy with it. A few notes on PC power supplys. First, I have yet to see one that uses remote sensing. This ensures the voltage is correct at the load by compensating for any voltage drops in the wireing going to the load. While this sounds like a good idea **VERY** nasty things happen if the senseing wires become disconnected while the power supply is connected. The power supply suddenley sees the load has no voltage being applyed to it, and it begins cranking the voltage up trying to compensate for the 'losses' in the connecting wires. WHat winds up happening is the power supply cranks the voltage up full boar, sometimes with very nasty results. Best bet is to jumpre the sense and output terminals right at the supply, and use haevy wire going to your load. Next, most PC style switching power supplys do not like being ran without a load. I have a 'dummey' device that consists of a few 25 watt power resistors that draws about 2 amps off the 12 volt line, and about .75 amps from the 5 volt line. This seems to be a good combination. Last, if you where wondering, the PG line on a PC power supply stands for power good. It goes high once the power supply has stabelized after turning it on. Matthew Kleinmann
daveh@cbmvax.commodore.com (Dave Haynie) (11/13/90)
In article <7652@cica.cica.indiana.edu> graham@venus.iucf.indiana.edu writes: >In article <90313.094443MBDZM@ROHVM1.BITNET>, MBDZM@ROHVM1.BITNET writes... >>Can I hack an IBM a/t supply (about $50) to work? >Yes you can. I've done it. >>The voltages seem to >>be ok +5, -5, +12, -12, but there is a line marked "TIC". That is the one >>I can't figure out. Is it there on the IBM supply? Can I fake it? >Darn! Wish I had my notes with me. The TICK line is a 50/60Hz output clock from the line. Since in most areas, the power line frequency is regulated for use with clocks, the Amiga's run-time clock gets its timebase from this. It is possible to run an A2000 using the VSYNC line (which is a tad under 60Hz on an NTSC system) instead of TICK by changing the J300 jumper, which is between the U300 CIA chip and the Paula chip on the motherboard. The A500 always uses this for its timebase, and it works, its just not as accurate as the line voltage. -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Standing on the shoulders of giants leaves me cold -REM
billsey@agora.uucp (Bill Seymour) (11/13/90)
In article <90313.094443MBDZM@ROHVM1.BITNET> MBDZM@ROHVM1.BITNET writes:
:Help!
:
:I recently fried the power supply on my Amiga 2000. I did this by shorting
:a terminal on the serial port to ground. I have replaced the fuse, but it
:just keeps blowing. So here I am looking for a new power supply.
Are you sure you've fried the power supply itself and not something
on the motherboard? Does the power supply blow fuses when it's *not*
plugged into anything? This sounds more like you would have blow something
on the motherboard than the power supply, since the voltages available at
the serial port just don't very much amperage behind them.
:Thanks, Geoff Mendelson
:(215) 242-8712
:uunet!gsm001!gsm
--
-Bill Seymour billsey@agora
***** American People/Link Amiga Zone Hardware Specialist NES*BILL *****
Bejed, Inc. NES, Inc. Northwest Amiga Group At Home Sometimes
(503) 281-8153 (503) 246-9311 (503) 656-7393 BBS (503) 640-0842billsey@agora.uucp (Bill Seymour) (11/18/90)
In article <15799@cbmvax.commodore.com> daveh@cbmvax.commodore.com (Dave Haynie) writes: :In article <7652@cica.cica.indiana.edu> graham@venus.iucf.indiana.edu writes: ::In article <90313.094443MBDZM@ROHVM1.BITNET>, MBDZM@ROHVM1.BITNET writes... :::The voltages seem to :::be ok +5, -5, +12, -12, but there is a line marked "TIC". That is the one :::I can't figure out. Is it there on the IBM supply? Can I fake it? : ::Darn! Wish I had my notes with me. : :The TICK line is a 50/60Hz output clock from the line. Since in most areas, :the power line frequency is regulated for use with clocks, the Amiga's :run-time clock gets its timebase from this. It is possible to run an A2000 :using the VSYNC line (which is a tad under 60Hz on an NTSC system) instead :of TICK by changing the J300 jumper, which is between the U300 CIA chip and :the Paula chip on the motherboard. The A500 always uses this for its :timebase, and it works, its just not as accurate as the line voltage. The problem with switching the J300 jumper doesn't come into play until you try to hook up a peripheral that uses HSync... Some that come to mind are the Flicker Fixer, SuperGen and the 2320. These will not work right unless you have a real 'TICK' signal. :-( :-- :Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" : {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy : Standing on the shoulders of giants leaves me cold -REM -- -Bill Seymour billsey@agora ***** American People/Link Amiga Zone Hardware Specialist NES*BILL ***** Bejed, Inc. NES, Inc. Northwest Amiga Group At Home Sometimes (503) 281-8153 (503) 246-9311 (503) 656-7393 BBS (503) 640-0842
MBDZM@ROHVM1.BITNET (11/27/90)
Thank you all for your advice. I modified an IBM PC (65 watt) power supply to work with the AMIGA 2000. It worked fine , but I couldn't get both floppy drives to run as they drew too much power. I did have to move the jumper to provide TICK from the sync. So I bought (for $60) an IBM clone 200 watt power supply. My Amiga now runs happily. The configuration is: AMIGA 2000 (old chip set) with 1.3 roms. Commodore 3.5 inch floppy NEC 3.5 inch floppy FLICKER FIXER!! GVP SCSI controller with 0 ram installed. MICRON 2 meg memory board. (going to go as soon as I get simms for above) QUANTUM Pro-drive 105s. If anyone cares, all of the above with the exeception of the NEC floppy will run on an original IBM PC power supply (63.5 watt). Most places with PC's have them in a junk bin as they upgraded them a long time ago. Please note that the IBM supplies have a circuit that SHUTS THEM DOWN instead of burning out when you short any of the leads. Circuit diagrams will be sent upon request. Thanks, Geoff Mendelson. uunet!gsm001!gsm (use this address, not the bitnet one)