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Old 28 July 2002, 16:10   #1
lappen
 
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A500 Problems

Hello!

I tried to get my A500 to work yesterday but got some problems and I hoped someone could give me some suggestions

Problem1: My A500 seemed to work good when I switched the power on, got the white screen with a disk... I insert a disk it reads and when i see AmigaDOS i get a Read/Write ERROR press RETRY or CANCEL, RETRY doesnt work and CANCEL aborts.. have tried with several disks i know work...

Problem2: I took my A500 apart to check if the battery had leaked "noob" hehe couldn't find the battery (maybe i dont have one). I removed my extra memory and tried a pc floppy drive... didn't seem to work, put everything back together including my old A500 diskdrive,, now i get a GREEN SCREEN for 0.5sec before my WHITE SCREEN with a disk shows up... Insert a disk and the the DiskDrive start to spin but not load , nothing happens no error message just the white screen....

I hope someone can help me can't wait to get it to work
 
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Old 28 July 2002, 16:46   #2
RetroMan
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Hmmm, the read-write error results from either a corrupt disk (but you said, you know they work) or a dirty disk-drive ! After all here some suggestions :

- open the case again and check your cables, maybe the wrong way around ?
- you may have blew up the CIA, change the two chips and try again
- if it starts to boot again, open the disk-drive and clean the head
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Old 28 July 2002, 19:26   #3
lappen
 
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thanks i will check my cables, but what is a CIA?

EDIT: found this on the net, but is this the same problem I have i only see the "Green Screen" for a short moment then the White Screen with the Workbench 1.3 screen shows up...

A Green screen signifies an error found in Chip Ram. Solving this could be a problem as the ram was generally soldered directly to the motherboard. In this case, unless there is a visible problem you can see like the connectors being dirty/corroded, all you can do is take the machine to an amiga repair place to see if they can fix it. In the UK, there is analogic, alternatively I know of a repair place in france on

Last edited by lappen; 28 July 2002 at 19:35.
 
Old 28 July 2002, 20:18   #4
jmmijo
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The first thing to check is the Agnus chip, this should be marked on the A500 motherboard. Try pressing down on it a bit as this type of package that CBM used quite a bit has a tendancy to work itself loose and cause bad connections. This usually resolves the green screen problems.

As for the battery, well once your have the top of the case and keyboard removed, look for the trap door, if there is a 512k ram expansion board or some other expansion board there, then most likely you have a clock and battery setup. Look for the round silver colored lithium battery on this board

As for the drive, this could indeed be a dirty r/w head as was mentioned already, you can use a floppy disk cleaner and/or some denatured alcohol, 95% or better, and cotton swabs to clean the r/w heads or you can carefully take the drive mechanism from the metal cage and clean it out good This is what I do, but I've been a computer tech for 20+ years so this is a simple precedure for me
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Old 28 July 2002, 21:40   #5
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BE CAREFUL WITH THE DISKS.

Those yo usay that you "know" are working, might be dusty and can fuck up your drive. If when you insert the disk the drive starts to "sing", take it out immediately, or you'll manage to dealign it for good.

Take fresh disks whenever you can, or thsoe you knwo are perfectly dust-free.
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Old 28 July 2002, 22:05   #6
lappen
 
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Have checked the AGNUS chip should be connected now... No Green Screen but this Message

'BLACK SCREEN , RED BORDER , RED TEXT'
" Software Failure. Press Left Mouse Button to Continue
Guru Meditation #00000004.00001970 "

Could that be the diskdrive not properly inserted, or my extra 512K memory i removed from the trapdoor beneath the A500...

Also the 512K memory card is inside a metallic box can't get it open without force... is it a trick to get it open or is it uneccessary for me to open it... thought the battery would be in there because i don't have it on the board..

And to clean the floppy should i just unscrew all screws and open it up, / clean neccessary parts.... is it something i should avoid so i dont break it...
 
Old 28 July 2002, 22:15   #7
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The error message could indeed be the floppy drive cable not connected properly, however I've not diagnosed this kind of problem for a while

Make sure to line up the red stripe/dashed wire on the floppy drive data ribbon cable with the pin 1 marking on the A500 motherboard! You can unplug this and reconnect to make sure, also check for bent and/or broken pins here, it can be easy to do if you're aren't careful.

As for the trap door memory, yes CBM used to shield the ram and clock with the sheet metal can you see, it's kind of wedge shaped to fit into this slot properly! If memory serves me, there are some smal metal tabs that are bent over, use some pliers to straighten them out and see if the sheet metal will come apart, there could also be a solder joint or two around this sheet metal to keep it in place and give a good ground to the shielding!!!
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Old 28 July 2002, 22:15   #8
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Does it give the error message (called a GURU) without you inserting any disk?
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Old 28 July 2002, 23:25   #9
lappen
 
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jmmijo: i checked my pins for the diskdrive, one is missing but that wouldn't be a big problem right?

Akira: yes it gives the 'GURU' error message without inserting a disk



And now I don't get picture on the tv anymore
, well worst case is buying a new amiga, can't be that expensive right?
 
Old 29 July 2002, 01:29   #10
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Quote:
Originally posted by lappen
jmmijo: i checked my pins for the diskdrive, one is missing but that wouldn't be a big problem right?
Well not if it's a ground pin as there are many of these on the floppy connector, can you see if this missing pin matches a key on the floppy ribbon cable? Just look on the ribbon cable for a filled in hole, this is the keyhole so to speak If it matches then it's okay because some connectors do have this pin missing!!!
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Old 29 July 2002, 01:43   #11
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looks like your A500 is dead now
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Old 29 July 2002, 11:02   #12
lappen
 
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nope no pin in the connector, and yup seems dead but it was just waiting to happen, thanks for all the help though
 
Old 01 August 2002, 03:23   #13
dirkies
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Lightbulb no worries

been there, seen it before, fixed it

problem 1:
if head does not scratch, it's not a floppy disk fault
if it does: it could be a corrupted track or infected nibble disk

the reason why this happens is simply because it's a trackloader disk, thus ignoring a normal DOS format (no BAM) disk (and sometimes it's even in nibble, using a diff CRC instead of $4489, making the disk unreadable unless you boot it directly. The trackloader is located on the bootblock. If a bootblock virus infects the disk, it overwrites the bootblock, thus the game is screwed and you get this message.

problem 2:
reason 1: trackloader that tries to read from incomplete/corrupted/wiped area... sorry!

reason 2: Guru Meditation #00000004.00001970... aha, I remember that one:
typical for KICKSTART incompatibilities, I had this ALWAYS when trying to run KICKSTART 1.2-only programs on KICKSTART 1.3

00000004 -> memory read fault
00001970 -> actual area, this one was because of the trackloader allocates boot instruction data in an area which has been moved due to kickstart changes.

try another kickstart image

Had this also with my first A500, returned it and got new one: was because of a badly seated agnus. if it can't boot anymore it's both of the CIAs busted (if swapping them doesn't help).
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Old 01 August 2002, 06:07   #14
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Re: no worries

Quote:
Originally posted by dirkies
the reason why this happens is simply because it's a trackloader disk, thus ignoring a normal DOS format (no BAM) disk
Hmm.. he doesn't even mention which disk(s) he chucked into the machine, so how to know if it was NDOS or not? lappen, which disk did you chuck into the 500?

Anyway, you don't get picture anymore, so... it's kaput :P
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Old 01 August 2002, 11:55   #15
lappen
 
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yup no picture anymore
to bad spare parts is almost impossible to find in Sweden

The disks i was trying was North & South, Cabal, Speedball 2, etc.....
 
Old 01 August 2002, 18:09   #16
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All 3 games you mention we trackloaders! (NDOS disks)

try the standard workbench disk for a change
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Old 01 August 2002, 19:14   #17
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Quote:
Originally posted by dirkies
try the standard workbench disk for a change
Errr... but he gets no picture anymore. Not even the Workbench hand.
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Old 01 August 2002, 20:05   #18
lappen
 
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yup exactly =) ehr i mean
maybe i can open it up again and do some magic,,, anyway that doesnt matter my workbench disc supplied with the A500 is non functional
 
Old 01 August 2002, 21:41   #19
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I saw this once, just white blank screen, no floppy accepted

try:
unseat all unseatable chips and reseat them FIRMLY, but only after you cleaned the contacts with some electronics cleaner spray

then remove any add-on hardware (mem/joystick:hd/etc) to make sure it doesn't come from there

finally, try with a diff power supply

and for trying a dos disk, try a normal program (WP/soundtracker/coverdisk/etc)
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Old 01 August 2002, 23:25   #20
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Quote:
Originally posted by lappen
And now I don't get picture on the tv anymore
It's not even a white image, it's just nothing.
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