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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: djkoelkast on June 27, 2013, 07:38:42 PM
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Hi all,
I've got a bunch of A500s, but there's one odd one between them.
All others have the small square Commodore logo beneath the power/disk LEDs, but this one had a larger badge, the one that is used on the 500 plus as well, but it just says: Commodore A-500.
Is this a later version? Is there any difference between this version and the normal small logo ones?
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Maybe a rev. 6A board inside? What color are the power lights? Usually red is an older 5 board, green is a newer 6 board, but with Commodore who the he#$ knows, really? Best to open it up & check! :D
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I haven't tested the machine yet, I was busy with making one working A2000 out of 2 half working ones, so I'll test that.
I know the A500 with an original 1.2 kickstart has a red power LED, the 1.3 ones usually have a green one. Maybe I'll just open in up then ;)
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I have an "A-500" as well. Green and amber LEDs. There's a rev 6A board in it, but I don't know if it's factory original - the machine was serviced many times under warranty. It had 1.3 originally.
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I believe there were some rev 8a boards in the "A-500" towards then end. Same as the 500+ but without the extra memory or battery.
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Hi all,
I've got a bunch of A500s, but there's one odd one between them.
All others have the small square Commodore logo beneath the power/disk LEDs, but this one had a larger badge, the one that is used on the 500 plus as well, but it just says: Commodore A-500.
Is this a later version? Is there any difference between this version and the normal small logo ones?
Have the same model. Rev 6a inside.
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Ok, just opened it:
It has an 8A mainboard inside, it says A500+ but the + is crossed out.
It has 512K ram and no battery. I haven't booted it up yet, so my best guess is it has KS 1.3.
Also the connections on the back vary slightly, the MONO port is yellow, not red. The L/R audio ports are white/black, not red.
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Last picture
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Commodore A-500.
Sounds like the one I got. The bdge also have a raised silver C= logo on the badge. Green and yellow LEDs. It's a Rev6A inside.
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I've managed to hook it on, it is indeed a normal 1.3 version.
This one is made in Hong Kong, all others either in W. Germany (old version with C= key) or Germany (all others).
Only thing is: it doesn't read a single disk. I've swapped diskdrives (had a spare A2000 drive lying around, in DS0 mode) but the same happens: the kickstart logo disappears, the diskdrive gives 3 clicks and I get the kickstart logo back.
It could be both drives are broken, but I think that would be strange. Anything worth trying?
I wanted to swap the drive from another A500 that is so yellow and has a German keyboard layout (we use the US layout around here) but that drive was definatly broken, made all the wrong noises ;)
Attached: LED colors.
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Sorry, didn't see your last posts before I posted mine. I had the window open for quite a while. I should have refreshed before psosting. Anyway....
Just curious, what version of Agnus do you have on the mother board?
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Only thing is: it doesn't read a single disk. I've swapped diskdrives (had a spare A2000 drive lying around, in DS0 mode) but the same happens: the kickstart logo disappears, the diskdrive gives 3 clicks and I get the kickstart logo back.
It could be both drives are broken, but I think that would be strange. Anything worth trying?
You tried cleaning the heads of the drive? Cleaning disk? Swabs?
Also, the lubricant can dry up in the spindle bearings. If the disk doesn't spin at the correct RPM, you get errors.
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You tried cleaning the heads of the drive? Cleaning disk? Swabs?
Also, the lubricant can dry up in the spindle bearings. If the disk doesn't spin at the correct RPM, you get errors.
Also make sure the track 0 sensor is clean. If it's not the drive will always think it's on track 0 even if it's not.
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Excellent! That's the best one! You should have the 2MB Agnus in there and can easily add the extra chips to the motherboard and trapdoor expansion to bring it up to full ECS, A500+ capability. Lucky you! :)
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I've tried using a cleaning disk (not one with the alcohol fluid, but a dry one that doesn't spin) but that did not work.
Strange thing is: both diskdrives do the same, shouldn't I look somewhere else for the drive error?
About the Agnus, I'll look later today what it says.
@Mike: what trapdoor expansion was in the A500+ originally? I've played on one about 19 years ago, a friend of mine had one, but I've never opened his A500+ :P
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I've tried using a cleaning disk (not one with the alcohol fluid, but a dry one that doesn't spin) but that did not work.
Strange thing is: both diskdrives do the same, shouldn't I look somewhere else for the drive error?
I have one that doesn't read disks, but what I didn't realise is that it actually corrupts track 0 of every disk you put in and try to boot off it. Not sure if that is paula/cia or something else.
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I'll try both drives in my A2000 today, I know that machine is in perfect working order as I fixed and tested it yesterday.
I do have an A500 for spare parts, but that's an older version, I don't know if they're interchangable.
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A problem I've found on several of my disk drives is that the sensor that detects if a disk is inserted can get dirty and stuck. It's a tiny little vertical black plastic post located very near the mouth of the drive. A normal cleaning disk won't get it, but a Q-tip with some isopropyl alcohol freed mine right up. You might need to take the cover off the drive to get to it.
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I've got it running now. The head was stuck because of old grease, or at least that's my best guess. Put some new grease on, cleaned the heads and now it's running perfectly.
I put a KCS power board in the trap door: also works (or at least the 512K expansion works). Without it it's just another Amiga 500 with 512K, but the keyboard itself is an A500+ as well: it has two blank keys on the US layout.
One right of the left shift and one left to the bottom of the Return key.
About the Agnus chip, see attachment:
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I've tried using a cleaning disk (not one with the alcohol fluid, but a dry one that doesn't spin) but that did not work.
Strange thing is: both diskdrives do the same, shouldn't I look somewhere else for the drive error?
About the Agnus, I'll look later today what it says.
@Mike: what trapdoor expansion was in the A500+ originally? I've played on one about 19 years ago, a friend of mine had one, but I've never opened his A500+ :P
A500+ originally had 1MB of chip memory on the motherboard with an optional 1MB chip in the trapdoor (A500+ boards came without the battery-backed clock since A500+ already had a clock on the motherboard). When Commodore stock dried up on the original A500's they started selling a lot of A500 systems with A500+ motherboards, minus some of the extra chips. Full A500+ would have had ECS Agnus & Denise, 2.04 ROM, and the 1MB on the board. From the photo you posted it looks like you'd just need to solder on the extra chips to bring yours up to capacity; you can probably find those on a dead A500+ board (lots out there, killed by battery leakage) or remove from any A501-style memory expansion board.
Re: the floppy drive, try swapping out Paula and the CIA's, perhaps?
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I've got it running now. The head was stuck because of old grease, or at least that's my best guess. Put some new grease on, cleaned the heads and now it's running perfectly.
I put a KCS power board in the trap door: also works (or at least the 512K expansion works). Without it it's just another Amiga 500 with 512K, but the keyboard itself is an A500+ as well: it has two blank keys on the US layout.
One on the right of the left shift and one left to the bottom of the Return key.
Excellent! Keyboard is just a C= cost-cutting measure, it's an international keyboard, the blank keys would have different symbols on them in some foreign markets. I've seen them in A1200's and various other systems over the years. :p
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I edited my post, attached a picture of the Agnus chip now ;)
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Check this auction for pics of full A500+ motherboard and memory expansion. There's usually a lot of the 1MB trapdoor cards on ebay if you poke around. ;)
http://www.ebay.com/itm/Amiga-500-Plus-system-w-2mb-chip-ram-expansion-68010-Full-ECS-KS-3-1-PS-/151071809969?pt=US_Vintage_Computers_Mainframes&hash=item232c94e1b1
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I edited my post, attached a picture of the Agnus chip now ;)
Yes, that is the correct chip, supports up to 2MB of chip RAM. :-)
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That's great. Now let's see if I have the ECS Denise as well, if so I actually have a A500+ except for the chipmem/kickstart (I do have 2 2.04 chips lying around).
I also have some A501-like cards here and there.
Always wanted an A500+ :P
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SysInfo says 1MB ECS Agnus, but the chip is actually the 2MB one.
The Paula chip seems to be the ECS version as well.
The 1.3 kickstart is actually smaller than the socket, the 1st pin is not used.
Even stranger: the 1.3 chip I had lying around that did not work on my A2000 (where a 2.04 and 1.2 chip did) works just fine when I skip the 1st pin on the socket.
How should I put in the 2.04 chip, also skipping the 1st pin? Or do I need a completely different chip?
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SysInfo is a horrible, horrible program. ;) Your best bet is to either crack her open or use something more updated like WhichAmiga to detect what you've got inside. Also there is no ECS Paula, C= never updated the old gal, even A1200/4000 have the same Paula. Not sure about installing the chip in the socket minus one pin (you mean one row of pins?). I'd wait for someone more knowledgeable to come along, or maybe just get a correct 3.1 chip off ebay?
Oh, here you go. Probably way more information than you possibly need, here:
https://en.wikipedia.org/wiki/Amiga_Enhanced_Chip_Set
http://en.wikipedia.org/wiki/Amiga_500_Plus
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Yeah the top 2 pins
. . << not used
. .
. .
. .
Actually I meant ECS Denise and it's there ;)
So this really is an A500+ except memory, battery (happy me!) and kickstart.
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If you're bringing it up to 2.04, just put the new ROM in the exact same position as the old one. So if there are empty pins with 1.3, you should have the same empty pins with 2.04.
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It does not boot with the 2.04 chip I tried (that one did work on my A2000)
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It does not boot with the 2.04 chip I tried (that one did work on my A2000)
Is there a jumper wire between 2 pins on the chip? You might have to remove it for the A500+.
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Is there a jumper wire between 2 pins on the chip? You might have to remove it for the A500+.
Not that I've seen, no, but I didn't pay that much attention to it.
For as far as I know it's just the chip itself, I have 2 versions though.