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Old 21 May 2021, 10:41   #1
Sim085
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A500+ stopped working

I was using my A500+ and all of a suddent the picture froze. This happened when I was accessing the hard disk to display files in a directory. I then restarted the Amiga and only got a black screen. Power light turns on. Capslock works. But no click from floppy disk and black screen. I removed every expansion and the behavior was the same. I made sure every chip was well seated but no improvement. This A500+ had a minor battery leak but I had treaed it with lemon juice and isopropyl alcohol.


Anyone has any idea what could have gone wrong? or areas to check for these kind of symptoms?
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Old 21 May 2021, 17:58   #2
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Quote:
Originally Posted by Sim085 View Post
I was using my A500+ and all of a suddent the picture froze. This happened when I was accessing the hard disk to display files in a directory. I then restarted the Amiga and only got a black screen. Power light turns on. Capslock works. But no click from floppy disk and black screen. I removed every expansion and the behavior was the same. I made sure every chip was well seated but no improvement. This A500+ had a minor battery leak but I had treaed it with lemon juice and isopropyl alcohol.


Anyone has any idea what could have gone wrong? or areas to check for these kind of symptoms?
Im no expert at diagnostics, and maybe you should get Chucky's DiagROMs..
But if Id venture a guess, faulty CIA chips could probably produce black diagnostic color.
(And they are known to fail more often than most other chips in the Amiga.)
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Old 21 May 2021, 21:14   #3
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I bought a DiagRom 1.2 something. Will wait for it to arrive and see what it reports.
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Old 22 May 2021, 00:11   #4
solarmon
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Check the reset and halt signals. Remove keyboard and floppy drive to - just to see if it does boot.
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Old 22 May 2021, 08:54   #5
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Maybe also try swapping the CIAs around?
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Old 24 May 2021, 11:47   #6
Sim085
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Reset signal does work. I mean when I press the reset buttons the capslock turns on for a moment and then switches off like a normal restart.

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Check the reset and halt signals. Remove keyboard and floppy drive to - just to see if it does boot.
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Old 26 May 2021, 10:15   #7
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I have swapped the CIA chips with ones working from another A500. Still nothing. I also confirmed the CIA chips work by trying them on the working A500. So it does not look to be CIA chips related. I have tested all the other chips, apart from Agnus, and these work fine.

When I switch on this A500+ (the one not working), both the Power and Floppy Disk light on the keyboard turn on. Capslock turns on when clicked and off when clicked (i.e. - how it normally works). Floppy Disk does not do any click however.

Could it be a power or Capacitor issue?
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Old 26 May 2021, 10:20   #8
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Does the power LED change brightness during boot?

Is the floppy LED always on? If so then that could be one of two things:

1. Floppy data cable is reversed.
2. No power getting to the floppy drive.
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Old 26 May 2021, 12:14   #9
Sim085
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Power LED does not change colour.
Floppy LED stays always on.

I have changed the floppy drive to a known working one (A500 Chinon)
I can hear the Floppy Drive spinning but not clicking.
I get same behavior even with no floppy drive connected.

Does this mean it is some power issue along the way?

Any points I can test with a multimeter?

Quote:
Originally Posted by solarmon View Post
Does the power LED change brightness during boot?

Is the floppy LED always on? If so then that could be one of two things:

1. Floppy data cable is reversed.
2. No power getting to the floppy drive.

Last edited by Sim085; 26 May 2021 at 12:20.
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Old 21 June 2021, 17:57   #10
Sim085
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Bought another A500+ motherboard. Moved all chips from one to the other and (to be honest I was expecting it) I got the same result. I therefore concluded one of the chips must have been fried (even though I was convinced I had already tried them on an A500 motherboard). In the end I found the fried chip name was Gary.

I looked around the area where Gary used to sit and I found C5 looks broken. Could Gary have died because of that? (although not sure when C5 broke off - that is before symptoms started or when I was replacing chips around).
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Old 22 June 2021, 09:22   #11
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Unlikely that the cap caused it I think, but how do the legs on the broken Gary look?

Often the battery acid makes it all the way over to Gary and can get up and into the IC and cause internal damage, it can also dissolve some of the pins of the socket so it's possible that needs replacing too
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Old 22 June 2021, 15:12   #12
Sim085
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Good to know. I will try the socket with a multimeter and if in doubt unsolder and re-solder. The thing is that the acid damage was so little, nothing compared to some of the photos I see on line.

The pins look ok, but definitely the chip does not work as I tried it on another board.

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Originally Posted by LIV2 View Post
Unlikely that the cap caused it I think, but how do the legs on the broken Gary look?

Often the battery acid makes it all the way over to Gary and can get up and into the IC and cause internal damage, it can also dissolve some of the pins of the socket so it's possible that needs replacing too
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Old 22 June 2021, 18:57   #13
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These old chips just quit working sometimes. They weren't really even designed to run for more than a few years, according to some that worked at MOS/CSG. The ones we use now are the lucky survivors... the best of the bunch.
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Old 22 June 2021, 20:25   #14
DarrenHD
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Have you tried changing the CPU? I had a 68000 CPU die on my A2000. If the Power LED does not start DIM then go bright, it can mean the CPU is not alive.
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