1MB CHIP RAM replacement board for A500+ - Page 2

Mick · 19 June 2019, 22:24

Has this been all tested then? (any pics?) is clearance with the keyboard okay when the Amiga is all put back together? it uses the same memory chips as used in the A600/A1200(rev1.x) right? I just got an A1k board and considering one of these instead of the old chips, it seems a lot better for reliability as there's 6 less chips to fail.

katarakt · 22 June 2019, 16:41

Well, about the cipram replacement board ...these IS41C16257-35 are all listed (mouser) as obsolete

Does it fit with keyboard mounted in closed case?

Anyways, thanks for the replacement board.

project23 · 23 June 2019, 02:18

Kai has done some great designs, but most (all?) of his stuff is as yet untested. There may be some mistakes or issues that aren't ironed out yet.

Don't let that put you off - if you're keen to develop things like this then you should absolutely go ahead!

But as far as i'm aware they're not ready-to-go tried and tested designs.

katarakt · 24 June 2019, 20:02

ok, thanks for info

Kai · 03 July 2019, 21:20

PCBWay delivery came in today!

Everything lines up BANG ON! Pin spacings for the SOJ's and the DIP socket pins both nice and accurate

@Project23 - i'm going to be sending you one of these and some DRAM's if you want

Mick · 04 July 2019, 21:04

Sweet.

My boards have gone to manufacture but this sort of converter will be great for the DIY community going forward.

katarakt · 11 July 2019, 23:26

Will there be a version for rev.5 boards with 16 ram chips?

Kai · 15 September 2019, 14:43

Quote:

Originally Posted by katarakt

Will there be a version for rev.5 boards with 16 ram chips?

Probably in the future, should be easy enough to adapt, or for someone else to fork the project.

Here's the rev0 DRAM board working in a v2.1 Amiga 500++ reproduction board, DIAGROM output for proof:

Rev 0.1a has moved the SOJ's further back into the dead space between the RAM & Agnus, as rev0 does NOT clear the keyboard if socketed, currently.

katarakt · 20 September 2019, 18:25

Very nice!!!

Just want to say that you should move the soj rams near the edge between ram and aguns so that they keyboard fit. Is this on the A500++ picture the new rev ?

Ah, and where can i find A500++ ? I don't need it because i have project red, but it's good to know for others.

redblade · 21 September 2019, 00:56

Great work Kai. Looks awesome

Kai · 16 October 2019, 23:44

v3 Boards now available, and the gerbers are up on github.

https://www.pcbway.com/project/share...ent_Board.html

esel · 17 October 2019, 04:30

How about a 4 Chip Version ?
So you will have 2 mb Chip and dont Need a trapdoor RAM expansion.

Kai · 20 October 2019, 01:02

Quote:

Originally Posted by esel

How about a 4 Chip Version ?
So you will have 2 mb Chip and dont Need a trapdoor RAM expansion.

Going to test this, hopefully just cascading them should work.

Vypr · 03 November 2019, 15:55

I've bought 5 PCBs each of the V2 & V3 boards.
The V2 board works perfectly in my A500++ board but teh V3 will not.
Booting from a 3.1.4 ROM just gives you a yellow screen and a reboot cycle. booting from DiagROM and running a extended gives a pass but there are graphical corruptions. I built two of the V3s and got the same results on both chips. I'm wondering if extending the track lengths to move the chips into the dead space has introduced some latency into the signals.

cmorley · 03 November 2019, 16:08

Looks like a faulty memory chip to me. Diagrom has manual memory edit which you can use to view/edit memory and work out which chip is dead (if you know which chip maps to what memory region). Then replace that chip.

Vypr · 03 November 2019, 17:07

Quote:

Originally Posted by cmorley

Looks like a faulty memory chip to me. Diagrom has manual memory edit which you can use to view/edit memory and work out which chip is dead (if you know which chip maps to what memory region). Then replace that chip.

That's what I though too, so I built another one with different memory chips and got the same result.

cmorley · 04 November 2019, 10:10

Is the donor RAM known good or sourced from China? It could well be you have several bad chips in the batch. I'd take the RAM from a working V2 board and try that on a V3 PCB.

If it is not the RAM then I'm intriuged to know what the fault is.

Vypr · 04 November 2019, 20:24

The donor chip was this:

https://www.utsource.net/itm/p/456204.html

I've just built another V3, same visual corruption, almost exactly the same pattern as well. it starts with a single strip of green dots about an inch from the left hand side of the screen and then gradually begins to appear in other locations.

I'm waiting for another batch of chips from a different source. COuldn;t find any suppliers that hd 416257's in stock so got some 416256's instead

Nrg · 01 January 2020, 16:43

Quote:

Originally Posted by Vypr

I've just built another V3, same visual corruption, almost exactly the same pattern as well. it starts with a single strip of green dots about an inch from the left hand side of the screen and then gradually begins to appear in other locations.

I'm waiting for another batch of chips from a different source. COuldn;t find any suppliers that hd 416257's in stock so got some 416256's instead

Hi. Were you able to get V3 working for you?

Kai · 24 January 2020, 12:57

The only difference between the different v2 and V3 is the placement on the board - the routing is automatic - nothing other than a layout change. It *could* be the distance in this case - I've been buying the NoS chips for this from eBay - Polish seller, has them by the reel.

19 June 2019, 22:24	#21
Mick Registered User Join Date: Jan 2004 Location: Yorkshire Posts: 710	Has this been all tested then? (any pics?) is clearance with the keyboard okay when the Amiga is all put back together? it uses the same memory chips as used in the A600/A1200(rev1.x) right? I just got an A1k board and considering one of these instead of the old chips, it seems a lot better for reliability as there's 6 less chips to fail. Last edited by Mick; 19 June 2019 at 22:30.

03 November 2019, 15:55	#34
Vypr Registered User Join Date: Dec 2016 Location: East Kilbride, Scotland Posts: 451	I've bought 5 PCBs each of the V2 & V3 boards. The V2 board works perfectly in my A500++ board but teh V3 will not. Booting from a 3.1.4 ROM just gives you a yellow screen and a reboot cycle. booting from DiagROM and running a extended gives a pass but there are graphical corruptions. I built two of the V3s and got the same results on both chips. I'm wondering if extending the track lengths to move the chips into the dead space has introduced some latency into the signals. Attached Thumbnails

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22 June 2019, 16:41	#22
katarakt Registered User Join Date: Jul 2017 Location: Germany Posts: 205	Well, about the cipram replacement board ...these IS41C16257-35 are all listed (mouser) as obsolete Does it fit with keyboard mounted in closed case? Anyways, thanks for the replacement board.

23 June 2019, 02:18	#23
project23 Used Register Join Date: Jul 2018 Location: Liverpool Age: 41 Posts: 437	Kai has done some great designs, but most (all?) of his stuff is as yet untested. There may be some mistakes or issues that aren't ironed out yet. Don't let that put you off - if you're keen to develop things like this then you should absolutely go ahead! But as far as i'm aware they're not ready-to-go tried and tested designs.

24 June 2019, 20:02	#24
katarakt Registered User Join Date: Jul 2017 Location: Germany Posts: 205	ok, thanks for info

03 July 2019, 21:20	#25
Kai Registered User Join Date: Apr 2011 Location: Brighton, UK Age: 41 Posts: 114	PCBWay delivery came in today! Everything lines up BANG ON! Pin spacings for the SOJ's and the DIP socket pins both nice and accurate @Project23 - i'm going to be sending you one of these and some DRAM's if you want

04 July 2019, 21:04	#26
Mick Registered User Join Date: Jan 2004 Location: Yorkshire Posts: 710	Sweet. My boards have gone to manufacture but this sort of converter will be great for the DIY community going forward.

11 July 2019, 23:26	#27
katarakt Registered User Join Date: Jul 2017 Location: Germany Posts: 205	Will there be a version for rev.5 boards with 16 ram chips?

20 September 2019, 18:25	#29
katarakt Registered User Join Date: Jul 2017 Location: Germany Posts: 205	Very nice!!! Just want to say that you should move the soj rams near the edge between ram and aguns so that they keyboard fit. Is this on the A500++ picture the new rev ? Ah, and where can i find A500++ ? I don't need it because i have project red, but it's good to know for others.

21 September 2019, 00:56	#30
redblade Zone Friend Join Date: Mar 2004 Location: Middle Earth Age: 40 Posts: 2,127	Great work Kai. Looks awesome

16 October 2019, 23:44	#31
Kai Registered User Join Date: Apr 2011 Location: Brighton, UK Age: 41 Posts: 114	v3 Boards now available, and the gerbers are up on github. https://www.pcbway.com/project/share...ent_Board.html

17 October 2019, 04:30	#32
esel Registered User Join Date: Jul 2012 Location: Kassel Posts: 160	How about a 4 Chip Version ? So you will have 2 mb Chip and dont Need a trapdoor RAM expansion.

03 November 2019, 16:08	#35
cmorley Registered User Join Date: Jun 2018 Location: Oxford, UK Posts: 66	Looks like a faulty memory chip to me. Diagrom has manual memory edit which you can use to view/edit memory and work out which chip is dead (if you know which chip maps to what memory region). Then replace that chip.

04 November 2019, 10:10	#37
cmorley Registered User Join Date: Jun 2018 Location: Oxford, UK Posts: 66	Is the donor RAM known good or sourced from China? It could well be you have several bad chips in the batch. I'd take the RAM from a working V2 board and try that on a V3 PCB. If it is not the RAM then I'm intriuged to know what the fault is.

04 November 2019, 20:24	#38
Vypr Registered User Join Date: Dec 2016 Location: East Kilbride, Scotland Posts: 451	The donor chip was this: https://www.utsource.net/itm/p/456204.html I've just built another V3, same visual corruption, almost exactly the same pattern as well. it starts with a single strip of green dots about an inch from the left hand side of the screen and then gradually begins to appear in other locations. I'm waiting for another batch of chips from a different source. COuldn;t find any suppliers that hd 416257's in stock so got some 416256's instead

24 January 2020, 12:57	#40
Kai Registered User Join Date: Apr 2011 Location: Brighton, UK Age: 41 Posts: 114	The only difference between the different v2 and V3 is the placement on the board - the routing is automatic - nothing other than a layout change. It could be the distance in this case - I've been buying the NoS chips for this from eBay - Polish seller, has them by the reel.

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