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AuthorTopic: Weird A500 problem  (Read 536 times)

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Offline Everblue

Weird A500 problem
« on: January 08, 2009, 06:13:58 PM »
Today I got 2 x A500 machines and I was testing them out. One worked 100% ok but the other wont read the floppy drive. When I switch the thing on, the "Insert Disk" icon appears. I insert a floppy disk (which worked fine on the other machine), and after three 'clicks' the "Insert Disk" icon appears again.

I have used a number of (tested and working floppy disk drives) as well as cables from the other machine. All with the same result. This means that the A500 is at fault. I looked at its motherboard but I can find nothing 'strange'. Anyone knows where could the problem be?

Thank you in advance,


E'Blue
 

Offline Metalguy66

Re: Weird A500 problem
« Reply #1 on: January 08, 2009, 06:47:41 PM »
Swap both the 8520s (u7 and u8) from the working machine to the non-working machine and see if the problem goes away.. If this corrects the problem, swap them BACK one at a time.. When the problem reappears, you know the chip you just installed is bad.
------------------------------------------------------------------
kjones66@earthlink.net  http://www.rasterline.com
AMIGA & ATARI 8-BIT repairs, upgrades, mods, restoration.
 

Offline Tenacious

Re: Weird A500 problem
« Reply #2 on: January 08, 2009, 07:09:33 PM »
Also, the actual drives are subjuct to age and contamination.  Try one those cleaning disks (if you can find one) that you put few drops of isopropyl in and then insert it.  Don't overdo it!

The spin rate of the disk can also be out of spec.  This is harder to diagnose.  I have seen photocopy patterns for use with a strobe.  

You could also swap the drives and then look for a replacement.
 

Offline Metalguy66

Re: Weird A500 problem
« Reply #3 on: January 08, 2009, 07:20:40 PM »
He said hes already tried it with a number of known good drives & cables.
------------------------------------------------------------------
kjones66@earthlink.net  http://www.rasterline.com
AMIGA & ATARI 8-BIT repairs, upgrades, mods, restoration.
 

Offline Tenacious

Re: Weird A500 problem
« Reply #4 on: January 08, 2009, 07:36:27 PM »
Oops!  I was speed reading, grin.
 

Offline Everblue

Re: Weird A500 problem
« Reply #5 on: January 08, 2009, 07:58:04 PM »
Quote

Metalguy66 wrote:
Swap both the 8520s (u7 and u8) from the working machine to the non-working machine and see if the problem goes away.. If this corrects the problem, swap them BACK one at a time.. When the problem reappears, you know the chip you just installed is bad.



Did exactly that .... problem solved! I have one duff CIA chip.
Thanks a lot for help!