A500: Paula and Denise inverted...

jurassicman · 15 August 2019, 22:33

Hi there!
I accidentally inverted Paula and Denise on an A500 rev. 6A mainboard.

Obviously when I powered the system on it didn't start.
I switched on the PSU a few times after having checked the various connections and I also left the computer on for a few minutes before checking if the chips were all correctly plugged in.

Then I noticed my mistake...
After plugging Paula and Denise on their correct sockets the system turned on but now I'm having a weird problem when I read a floppy. The drive starts reading but after a bit I get all those colored lines that you get with some games when you have to switch the floppy disk (see attached picture).

Is this correlated to my mistake? Did I break anything? If so, what? Paula, Denise, something else?
Please, let me know if there are more tests I can do...

E-Penguin · 15 August 2019, 23:18

Try re-seating the chips. Otherwise I think you'll need to head off to eBay to find some replacements....

jurassicman · 16 August 2019, 00:10

Quote:

Originally Posted by E-Penguin

Try re-seating the chips. Otherwise I think you'll need to head off to eBay to find some replacements....

Any ideas about which chips?
Most probably Paula, isn't it?

jurassicman · 26 August 2019, 10:41

At the end, the only issue was that I was trying to run programs/demos that required 1MB without the 512KB expansion. Using programs/demos that requires 512KB everything works perfectly.

Tigerskunk · 26 August 2019, 11:14

Would be cool if you had experienced a completely different computer system with much greater capabilities than OCS when switching on.

jurassicman · 26 August 2019, 11:44

Quote:

Originally Posted by Steril707

Would be cool if you had experienced a completely different computer system with much greater capabilities than OCS when switching on.

At least now I know that it is safe to do so... just in case I want to play a joke on a friend...

whaka · 26 August 2019, 17:28

hmmm... paula have -5V on pin 27, and denise +5V on 19.
so, paula and denise took something really wrong where it should not.
they seems to be very tolerant

Agilent · 26 August 2019, 17:33

Quote:

Originally Posted by jurassicman

At least now I know that it is safe to do so... just in case I want to play a joke on a friend...

Don't think its safe to do… So, try avoiding loosing a friend

jurassicman · 26 August 2019, 17:52

Quote:

Originally Posted by whaka

hmmm... paula have -5V on pin 27, and denise +5V on 19.
so, paula and denise took something really wrong where it should not.
they seems to be very tolerant

Good to know... fortunately they are tolerant... if they were my mother and my mother in law that would have been a problem...

@Agilent
Of course not... I have already so few Amigans friends...

Kin Hell · 27 August 2019, 10:17

How on earth did you manage to insert the Chips the wrong way?
All Amiga Custom Chips which fit in Sockets are Keyed on one corner & only go in one way....

This is no joke to play on a friend either.....

If you've been lucky enough not to blow the Chips, high chances are you've screwed the Sockets!

These sockets become very brittle with age & will now have hair line fractures for incorrect insertion & will probably need replacing.

jurassicman · 27 August 2019, 10:32

@Kin Hell
I don't know how I inverted the chips, when I removed them I placed them on the desk and I thought that I put them in the right position, however Denise and Paula are absolutely identical from outside, 48 pins each so it isn't so difficult to exchange them if you don't pay attention of what you are doing.

Daedalus · 27 August 2019, 10:41

Quote:

Originally Posted by Kin Hell

How on earth did you manage to insert the Chips the wrong way?
All Amiga Custom Chips which fit in Sockets are Keyed on one corner & only go in one way....

No, they're not - at least not on the A500. Paula, Denise and Gary are all in identical 48-pin DIP packages, and there's no mechanical reason you can't swap them. They also fit perfectly when rotated 180 degrees. So you only have the visual indicators to determine both orientation and location.

Quote:

These sockets become very brittle with age & will now have hair line fractures for incorrect insertion & will probably need replacing.

I think you're seriously confusing the chips with some other chips. Nothing was inserted incorrectly, mechanically at least, so the sockets won't have been damaged any more than if the correct chips were inserted. On the A500 there's only one PLCC custom chip, so that can't be confused.

Kin Hell · 31 August 2019, 11:43

Quote:

Originally Posted by Daedalus

No, they're not - at least not on the A500. Paula, Denise and Gary are all in identical 48-pin DIP packages, and there's no mechanical reason you can't swap them. They also fit perfectly when rotated 180 degrees. So you only have the visual indicators to determine both orientation and location.

I think you're seriously confusing the chips with some other chips. Nothing was inserted incorrectly, mechanically at least, so the sockets won't have been damaged any more than if the correct chips were inserted. On the A500 there's only one PLCC custom chip, so that can't be confused.

Sincere apologies guys....

I was of course, relating to Buster & such which utilise keyed sockets if not surface mounted.

Sorry for being so single minded.

lord of time · 31 August 2019, 12:54

Quote:

Originally Posted by Kin Hell

Sincere apologies guys....

I was of course, relating to Buster & such which utilise keyed sockets if not surface mounted.

Sorry for being so single minded.

no harm done - there are many different Amigas with many different chips so sometimes its easy to get them a little mixed up!!! I remember back in the day buying an Amiga 500 ram expansion and being totally confused when the bugger wouldnt slot onto my A1200's expansion slot!!!! we live and we learn!

jurassicman · 31 August 2019, 18:53

The only thing I can add to this discussion is: "All's Well That Ends Well"

Thanks all for your comments.

Kin Hell · 01 September 2019, 10:51

Quote:

Originally Posted by lord of time

no harm done - there are many different Amigas with many different chips so sometimes its easy to get them a little mixed up!!! I remember back in the day buying an Amiga 500 ram expansion and being totally confused when the bugger wouldnt slot onto my A1200's expansion slot!!!! we live and we learn!

Indeed we do... (hangs head)

At my age in Life's Cycle, I'm 0ld enough to know better & still daft enough to drop a clanger from time to time....

Forever young eh!

Really pleased your issue worked out jurassicman.

15 August 2019, 22:33	#1
jurassicman Registered User Join Date: Dec 2017 Location: Sassari/Italy Posts: 867	A500: Paula and Denise inverted... Hi there! I accidentally inverted Paula and Denise on an A500 rev. 6A mainboard. Obviously when I powered the system on it didn't start. I switched on the PSU a few times after having checked the various connections and I also left the computer on for a few minutes before checking if the chips were all correctly plugged in. Then I noticed my mistake... After plugging Paula and Denise on their correct sockets the system turned on but now I'm having a weird problem when I read a floppy. The drive starts reading but after a bit I get all those colored lines that you get with some games when you have to switch the floppy disk (see attached picture). Is this correlated to my mistake? Did I break anything? If so, what? Paula, Denise, something else? Please, let me know if there are more tests I can do... Attached Thumbnails

27 August 2019, 10:17	#10
Kin Hell 0ld0r Git Join Date: Mar 2009 Location: Cornwall, UK Posts: 1,570	How on earth did you manage to insert the Chips the wrong way? All Amiga Custom Chips which fit in Sockets are Keyed on one corner & only go in one way.... This is no joke to play on a friend either..... If you've been lucky enough not to blow the Chips, high chances are you've screwed the Sockets! These sockets become very brittle with age & will now have hair line fractures for incorrect insertion & will probably need replacing. Last edited by Kin Hell; 27 August 2019 at 10:23.

27 August 2019, 10:32	#11
jurassicman Registered User Join Date: Dec 2017 Location: Sassari/Italy Posts: 867	@Kin Hell I don't know how I inverted the chips, when I removed them I placed them on the desk and I thought that I put them in the right position, however Denise and Paula are absolutely identical from outside, 48 pins each so it isn't so difficult to exchange them if you don't pay attention of what you are doing. Attached Thumbnails

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15 August 2019, 23:18	#2
E-Penguin Banana Join Date: Jul 2016 Location: Darmstadt Posts: 1,213	Try re-seating the chips. Otherwise I think you'll need to head off to eBay to find some replacements....

26 August 2019, 10:41	#4
jurassicman Registered User Join Date: Dec 2017 Location: Sassari/Italy Posts: 867	At the end, the only issue was that I was trying to run programs/demos that required 1MB without the 512KB expansion. Using programs/demos that requires 512KB everything works perfectly.

26 August 2019, 11:14	#5
Tigerskunk Inviyya Dude! Join Date: Sep 2016 Location: Amiga Island Posts: 2,770	Would be cool if you had experienced a completely different computer system with much greater capabilities than OCS when switching on.

26 August 2019, 17:28	#7
whaka Registered User Join Date: Jan 2017 Location: France Posts: 102	hmmm... paula have -5V on pin 27, and denise +5V on 19. so, paula and denise took something really wrong where it should not. they seems to be very tolerant

31 August 2019, 18:53	#15
jurassicman Registered User Join Date: Dec 2017 Location: Sassari/Italy Posts: 867	The only thing I can add to this discussion is: "All's Well That Ends Well" Thanks all for your comments.

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