Bought KS 3.1 for A500 but it has 42 pins not 40

[Starglider 2]

Oops. I bought a Kickstart 3.1 chip for my A500 Rev 5. I was all set to do the soldering required as shown at these links...

https://drive.google.com/file/d/0BwT...Ylk/view?pli=1
http://www.kipper2k.com/amiga/a500rev31mod.jpg
http://www.area536.com/fileadmin/_pr...ce1646b95c.jpg

...when I realized the chip I bought has 21 pins on each side, not 20. Turns out it's a "switchable" Kickstart 1.3 and 3.1 in one chip. I only need Kickstart 3.1.


Not my photo. Note the pins hanging over the right edge. Note the centre nub is on the right not the left.


Now here's how I've installed it:

My photo. Note the pins hang over the edge just as in picture 1.

When I switch on I get a copper colored screen, then a low waveform sound and weird colors on screen.

The guy I bought it off got it in a job lot of equipment, didn't mention all this, and doesn't know much about it, or speak good English. Could someone please kindly tell me:

1. How do I install this chip – just as I have done above in picture 2?
2. Does it matter that the cable that usually goes to "Pin 21" seems to have been soldered to Pin 22 (see picture 1 above).
3. How do I make sure it's in "Kickstart 3.1 mode", once it works?

Here's a link to a similar (not the one I bought) chip also with 42 pins: http://www.ebay.it/itm/Amiga-500-200...-/171037672800

[Arnie]

The 2 extra pins are used for switching between KS 1.3 & 3.1. One pin is grounded and the other has a 5v supply. Try each side until you get KS 3.1 appear.

[Supamax]

Originally Posted by Starglider 2

Now here's how I've installed it:

My photo. Note the pins hang over the edge just as in picture 1.

Uuuh, very bad soldering here .
Try using some solder paste or similar, or use a better lead (or better soldering iron).
The better the soldering, the more reliable the result will be .

[Starglider 2]

Thanks First soldering I've done in a while, but the connection seems solid.

I'm more concerned in where "pin 21" is meant to be. Right now I have pin 31 connected to what is actually pin 22, because that's how it seemed on the original picture of the chip.

Should I move the top right wire one pin to the left?

[Arnie]

The one at the back is +5v, it needs to go on one of the extra pins.

The one in the middle is ground, it needs to go on the other extra pin.

[Starglider 2]

Originally Posted by Arnie

The one at the back is +5v, it needs to go on one of the extra pins.

The one in the middle is ground, it needs to go on the other extra pin.

Sorry my friend, could you define "back" and "middle"? I want to make sure I'm doing what's in your mind.

A simple sketch would be fantastic. Not talking Van Gogh –Picasso will do

P.S. Remember this is a Rev 5 Amiga 500 so has to have pins 1, 21, 31 interconnected as per https://drive.google.com/file/d/0BwT...Ylk/view?pli=1

[Supamax]

Originally Posted by Starglider 2

I'm more concerned in where "pin 21" is meant to be. Right now I have pin 31 connected to what is actually pin 22, because that's how it seemed on the original picture of the chip.

Should I move the top right wire one pin to the left?

Wait!, looking at one of the pictures you linked (http://www.kipper2k.com/amiga/a500rev31mod.jpg) it would seem that you swapped sides.

In kipper's image, the "central" pin (lifted and soldered to two cables) looks like pin 10, not pin 31...

[Starglider 2]

I did this because I think the chip I bought is "backwards", looking at their original photo of it. Or am I mistaken?

[Supamax]

Hmmm... let's wait some expert's advice then .

[Arnie]

like this.......

[Supamax]

Originally Posted by Arnie

like this.......

Hi Arnie, Ok but... didn't he swap right/left sides? It would seem so...

P.S. I never heard of "backward pins numbering" Eproms... do they exist?

[Arnie]

Not sure whats going on to be honest. Hooking up +5v to ground seems wrong to me.

[Starglider 2]

Originally Posted by Arnie

like this.......

Thanks Arnie. Do I still need to also hack it using the wiring like this https://drive.google.com/file/d/0BwT...Ylk/view?pli=1 because the board is Rev 5, or do these switchable chips support Rev 5 out of the box?

[Arnie]

I'm not sure, try it and see.

[Starglider 2]

OK. BTW it says on the label:

"+5v 3.1 / G 1.3"

If I want 3.1, which way round would you wire things? Wire pin 1 to pin 21?

[Supamax]

Originally Posted by Starglider 2

https://drive.google.com/file/d/0BwT...Ylk/view?pli=1

Furthermore, it's not clear in this photo if the center nub is on top or bottom.

Perhaps "stupid" suggestion: since the motherboard nub is on the opposite side in respect of your Eprom, you could try mounting the chip 180° rotated.

EDIT: sorry, this is REALLY stupid suggestion! Don't do it, the soldered pins would be in the wrong position!

[Starglider 2]

Originally Posted by Supamax

Furthermore, it's not clear in this photo if the center nub is on top or bottom.

Perhaps "stupid" suggestion: since the motherboard nub is on the opposite side in respect of your Eprom, you could try mounting the chip 180° rotated.

Pretty sure it's top.

Trying it now...

[Supamax]

Originally Posted by Starglider 2

Pretty sure it's top.

Trying it now...

NO, wait!
Yes, I suppose it's top, too.
But if you simply rotate the chip, pins positions will not be correct!

[Starglider 2]

I'm rewiring everything as we speak.

- Pin 21 (5v) to the top-right extra pin
- Pin 31 to pin 21
- Pin 1 to socket 31

I'll report back when done.

[Starglider 2]

Originally Posted by Arnie

like this.......

Arnie, I just want to confirm. In your diagram you have 5v as pin 21 of a regular chip.

In this image, pin 21 is wired to pin 31 to get 3.1 working with Rev 5: http://www.kipper2k.com/amiga/a500rev31mod.jpg

Combining both bits of work means I have a wire going from pin 21 -> pin 31 and a wire from pin 21 -> the extra top-right pin on my specific chip?