17 February 2021, 11:10 | #441 |
Mighty Pirate
Join Date: Dec 2017
Location: On the borderline
Age: 44
Posts: 177
|
I think I've lost track a bit, could you please do a short recap of how the current working board compares to a common rev. 1.5, for instance? What did you do 1:1 and what did you change?
|
17 February 2021, 12:18 | #442 | ||
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
Quote:
Quote:
3.58MHz BPF (NTSC) Bandwidth or cutoff freq. = 2.8/4.3MHz (-3dB) Input / Output impedance = 1kohm 4.43MHz BPF (PAL) Bandwidth or cutoff freq. = 3.73/5.13MHz (-3dB) Input / Output impedance = 1kohm There are tutorials and calculators online for the BPF at least, that's how (I think) I would have been able to do it, no such luck with the delay line though. I was thinking of adding a 5V pin and using an active delay line but it would be better for original board owners if a passive delay line replacement can be made. It's more like a rev2B but with U49 added and the video area modified to take a CXA2075, so schematically it's a 2D. I've looked at a 2D and it seems to be just a modified 2B with bigger SOIC footprints crammed in and I'm wondering if C26 is connected to VCC at all on that revision and if so how. Last edited by Mick; 17 February 2021 at 12:29. |
||
17 February 2021, 13:05 | #443 |
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
If stedy or someone can design replacements for BPF and DL I will do a 1:1. Gerbers for Svideo are already in the zone.
|
17 February 2021, 15:14 | #444 |
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
I did some more digging and found what seems to be the original datasheet. Sony listed the NTSC part for PAL in their CXA1145 datasheet.
Filters for RGB Encoder H287BSJS-3108HWD Application = 3.58MHz BPF (NTSC) Impedence = 1kohm H287BSJS-4438HWD Application = 4.43MHz BPF (PAL) Impedence = 1kohm https://www.datasheetarchive.com/pdf...fe4723746d6eec There's also some typical characteristics graphs (fig. 1 & 2). |
17 February 2021, 15:46 | #445 | |
Registered User
Join Date: Oct 2016
Location: Berks, UK
Posts: 271
|
Quote:
- Better mounting points for any add-ons (or larger holes rather than relying on the small HDD cradle mounting holes) - DIP64 CPU instead of the PLCC (maybe limited by space but would make it much more expandable). - Breakout header for the RGB and clock pins from Denise to make connecting the RGBtoHDMI Pi Zero mod easier to fit Few other thoughts which although easy to add manually to any board, would be nice. - 2MB ChipRAM (and maybe RTC) - Clock port - A header for a switch to swap DF0 & DF1 (so you can use external drive as DF0) Sure others could add a few more ideas |
|
17 February 2021, 22:36 | #446 | |
Mighty Pirate
Join Date: Dec 2017
Location: On the borderline
Age: 44
Posts: 177
|
Quote:
The "video area modified to take a CXA2075" means you added a proper place for the 2.61k resistor? I don't understand why you don't want to add the original circuit for the 1145 as well and just leave it as untested. Someone will test it out sooner or later and report. It's simple enough and does not prevent using a CXA2075, so you could just have both, but I respect your choice. Actually I prefer the 2075 too, my suggestion was just to make a "more generic" board. I have checked C26 and actually the positive terminal goes to a via that is not connected to anything. It's probably a routing oversight that you could fix. I can't measure the exact values of C7, C8, C29, C36 as I would have to desolder them to do so. Since they are decoupling caps, their value is not too critical. I'd say just go with 100nF, but anything up to ~330nF could be fine. 2A schematics report 47nF and that sounds good as well. I can't find any C9 on my board. C28A, C28B seem to be 10nF. About the large footprints: I think most SOIC footprints on this board suit both narrow and large SOIC, they have two sets of pads on one side and I'm pretty sure I've seen this on 1.5 boards as well. Hope this helps. |
|
19 February 2021, 00:20 | #447 | |
Registered User
Join Date: Jan 2008
Location: United Kingdom
Age: 46
Posts: 733
|
Quote:
I'll check some of the other capacitors on my rev 2D board this weekend. |
|
19 February 2021, 02:21 | #448 |
French in Australia
|
Amiga 600 schematics nearly put into Kicad
@Lemaru: nice. Every new board of any model should now have a connector to pick Denise signal and allow for an adapter PCB to connect, yeah.
All other mods are good stuff but will interest hardware designers only if more than 1 person have them on its board (fixing holes, PLA CPU, etc. But good stuff! |
22 February 2021, 13:04 | #449 | ||||
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
Yeah it is unpopulated on all 2D's but Commodore added it for some reason, it's the only difference between 2B and 2D electrically, most of the difference is in appearance/layout which is why I describe mine as more of a 2B as I used images of a 2B.
Quote:
Quote:
Quote:
Quote:
Thanks for the help. Last edited by Mick; 22 February 2021 at 13:23. |
||||
22 February 2021, 13:12 | #450 | |
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
Quote:
Regarding capacitors if you can confirm they're 0.01uF I'll be happy. Last edited by Mick; 22 February 2021 at 18:21. |
|
22 February 2021, 13:33 | #451 |
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
I'd like to just do a 1:1 now, I'm sure other variations will follow, you might even make your own. It might seem unrealistic now but I hope that in the long run, with PCB's available, development of replacement chips (whether real or FPGA) and other parts (23-pin d-subs etc) will eventually follow. One hurdle at a time.
|
22 February 2021, 23:14 | #452 |
Registered User
Join Date: Jan 2008
Location: United Kingdom
Age: 46
Posts: 733
|
Hi,
C7, C8, C28 were all 10nF. Have not had a chance to trial the delay line or bandpass filter design with real hardware. Mick, you've done a 1:1 board, that's one of the boards I've been testing, as it has the original RF modulator pinout and no S-video. |
22 February 2021, 23:54 | #453 |
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
Cheers.
It didn't work though and it was my first attempt when I was using mm rather than mil and I autorouted it, not to mention using a ruler and printout instead of GIMP. I've learned loads since then. Looking back I'm a bit embarrassed I sent it to Acill but that's where I was in the learning process, I thought it was great at the time. I can send you the current files with SVideo if you want them but I want to do a really good 1:1 even if just for myself if/when the BPF/DL are available. The schematics will also be relevent to everyone that way. I think my main regret with the first board is not sticking with the manually routed power and using planes, that's probably what is preventing it from working. Last edited by Mick; 23 February 2021 at 00:00. |
23 February 2021, 00:39 | #454 |
Registered User
Join Date: Jan 2008
Location: United Kingdom
Age: 46
Posts: 733
|
Mick,
Send me the files for the board you have working, I'll upload them to github and I'll start the support Wiki, I have a few entries to add. From here, other users can take the designs, create forks and make their own versions, if they wish (and have the funds). The original board, sent to Acill, then myself is still WIP. I know what stops it working but not why. Website work got in the way this weekend, I plan to get back to it soon. |
23 February 2021, 18:33 | #455 |
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
Okay, will you still make BPF/DL though please?
What is it that stops the original board from working? Last edited by Mick; 23 February 2021 at 18:42. |
24 February 2021, 00:41 | #456 | |
Registered User
Join Date: Jan 2008
Location: United Kingdom
Age: 46
Posts: 733
|
Quote:
The original board is not working due to U26/U27 not passing the data through to the custom chips, which includes the CIAs/serial port. Not sure why yet, but at least I know where to look. The Github repository is up, I have the original, not-tested version and the S_Video branch, https://github.com/istedman/A600Reborn. I'll add some notes on build/testing to the wiki soon. |
|
24 February 2021, 00:58 | #457 |
Registered User
Join Date: Oct 2016
Location: Berks, UK
Posts: 271
|
Great work Mick. The photos on the GitHub look awesome. I think you should add some silkscreen with your name on it, as it was you who done the hard work.
How did you go about manually routing this? Did you trace an image or spend ages measuring everything? |
24 February 2021, 15:10 | #458 |
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
For placement I measured the same as the first one but I used mils instead of mm which was key to being able to manually route it in a really orderly way, I also went from 1:1 print outs and a ruler to using 1:1 images in Gimp and the measuring tool as it's a lot more accurate that way rather than squinting at a ruler, just find a reference point and measure a location (footprint/via) to the nearest 10mil. The routing is a bit different I didn't measure the length of traces or anything but it was a bit like doing a jigsaw once you have everything in place.
Last edited by Mick; 24 February 2021 at 16:37. |
24 February 2021, 18:11 | #459 |
Registered User
Join Date: Jul 2017
Location: Germany
Posts: 205
|
Yes, amazing work from Mick. Is the Svideo variant fully working? I thought it was mentioned before that there is no serial output or am i wrong?
|
24 February 2021, 19:01 | #460 |
Registered User
Join Date: Jan 2004
Location: Yorkshire
Posts: 735
|
It should be fully working, everything is connected where it needs to be. I'm not sure where you've seen that about serial.
If I were stedy I'd just delete all of the old stuff to prevent confusion, all of the progression is here in this thread. Last edited by Mick; 24 February 2021 at 19:13. |
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
Thread Tools | |
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Legal: Amiga schematics | michaelz | support.Other | 25 | 15 March 2017 13:13 |
First Amiga 600 FPGA Accelerator - Vampire 600 | majsta | Hardware mods | 736 | 18 July 2016 18:31 |
aminet Clean schematics Amiga Classics | cosmicfrog | support.Hardware | 14 | 12 March 2016 20:03 |
Amiga 2000 keyboard schematics | Brannigan | support.Hardware | 11 | 10 February 2014 08:24 |
What if DCE donated Amiga Hardware Schematics? | Yoto | Retrogaming General Discussion | 47 | 15 May 2012 15:04 |
|
|