Author Topic: C128 Video DAC thread (Read 8945 times)

Richard42 · « **on:** September 17, 2011, 11:40 AM »

The PCBs arrived today. I built up two of them and tested one with the GBS-8220. It looks good. I've attached a few pictures: the built board alone, as it looks plugged into the C128, and a shot of the VGA monitor connected via the GBS-8220. I'll get more pictures this weekend of the Avery AV-1 VGA output at 50hz and 60hz.

Richard42 · « **Reply #1 on:** September 18, 2011, 02:18 PM »

Today I wired the second board up to the Ambery AV-1 and did some testing.. It does sync at both 50hz and 60hz, though it doesn't look nearly as good as it does with the GBS-8220. I have attached some pictures. There's a fair amount of ringing or oscillation on the edges and even in the middle of solid colors. I'm not sure why this is; the same board plugged into the GBS-8220 looks fine. I may re-connect the prototype breadboard to the AV-1 and see if I can improve the picture by tweaking the resistors.

RCtech · « **Reply #2 on:** September 18, 2011, 06:31 PM »

Woah, the pic really looks bad. I have found an interesting adapter, the SVT-908. It's like a double version of the CVT-910 which is working with the Amiga in 50 Hz. It also two features audio inputs and one audio output. I've contacted some companies who're selling this thing, but didn't get a replay yet.

I also have contact with the guy who has written the web page with the tests. He says that the CVT-910 is fully PAL-compatible and his tests were made connected to a TFT which could display frequencies only from 56 Hz up. The advantage is that it handles a lot of frequencies automatically and allows an output up to 1920x1200. The disadvantage is that it's image quality is not so good like the AVC-011 he tested. During games this is not the problem, only during text mode - which would be important for the VDC. But if this converter really is $35 only... Maybe the SVT-908 has a better quality.

But don't forget: A good VGA cable is always very important! I have cables which look optically very good, with ferrite beads and golden connectors, but the signal quality is so bad, yecch. Even small resolutions are blurry, and if you display it on a TFT with a higher native resolution it gets even blurrier. For european customers I have found a very good seller on ebay, Kabelzentrum. I bought various DVI and VGA cables here, and they have a very good quality. 1600x1200 with a 2 metre cable in best quality, with good prices and no shipping costs.

Hydrophilic · « **Reply #3 on:** September 19, 2011, 07:55 AM »

The GBS-220 looks good, but yeah the AVR-1 looks crappy. But it has been reported the AVR has a poor quality in comparison, so there might not be much you can do. Anyway, the board layout is great. There's no way it should interfere with any other connectors, being your design is the same width as the DB9 connector itself. Bravo!

Richard42 · « **Reply #4 on:** September 19, 2011, 12:22 PM »

Quote from: Naquaada on September 18, 2011, 06:31 PM

But don't forget: A good VGA cable is always very important! I have cables which look optically very good, with ferrite beads and golden connectors, but the signal quality is so bad, yecch. Even small resolutions are blurry, and if you display it on a TFT with a higher native resolution it gets even blurrier. For european customers I have found a very good seller on ebay, Kabelzentrum. I bought various DVI and VGA cables here, and they have a very good quality. 1600x1200 with a 2 metre cable in best quality, with good prices and no shipping costs.

I'm also thinking that the cable may be part of the problem. Tonight I connected the prototype on the breadboard to the AV-1 and it actually looks much better than the PCB with the VGA cable. I'll try a different connection with the PCB and see if that improves the situation.

RCtech · « **Reply #5 on:** September 19, 2011, 03:58 PM »

The prototype looks better than the PCB version? Weird. Are the resistors on the board to close together, might that interfere? If so you could try soldering them wilth an alternating height on the next board.

When you're doing new tests, best check out a TFT too, if you have one available. But the converter has to set to the native resolution of the monitor, in case of 14-17" monitors that's usually 1024x768 oder 1280x1024. Otherwise it would look blurry even with a good cable.

Richard42 · « **Reply #6 on:** September 21, 2011, 03:24 PM »

Good news. I soldered on a DB-15HD female connector and the results with the AV-1 were better. I attached a picture of the board and some shots of a CRT and an LCD monitor connected with this setup. I think the cable caused the degradation with the previous setup. I think the AV-1 may sample the pixels on the edges instead of the centers, because the edges still don't look as good as with the GBS-8220. But at least the oscillation in the solid areas is gone. Overall, I would say the visual quality with the AV-1 is not great, but it's decent. Subjectively, the 50hz mode looks better to me than the 60 hz. And the colors are better than what these pictures suggest. They're more saturated and not as washed out as they look in these images.

Richard42 · « **Reply #7 on:** September 22, 2011, 02:37 AM »

What it is: I'm selling a circuit which converts the digital RGBI+H+V "80-column" video output signal on a C128 into an analog 0.7v CGA with composite sync signal. This type of video signal is common in the arcade world, so you can use cheap and easily available CGA->VGA converter boards to do the frequency conversion and display your C128's 80-column video output on a VGA monitor.

Compatibility: This converter has been tested and verified to work with 2 Arcade CGA->VGA converters: the Gonbes GBS-8220 and the Ambery AV-1. The final VGA video quality looks best with the GBS-8220, but this converter does not support 50Hz (PAL) frequencies. The AV-1 supports both 50Hz and 60Hz modes. I have posted pictures of the video output in earlier posts on this thread. The C128 Video DAC may work with other CGA-->VGA converters (such as http://www.weiya.com.tw/products_detail.asp?le=english&fid=127&pid=203&top_fid= or http://www.jammaboards.com/store/cv-04-rgb-to-ntsc-pal-tv-converter-pcb/prod_253.html), but I have not tested it with these.

Interfacing: The C128 Video DAC has a DB-9 connector on one end, so you can plug it directly in to the C128. You may also optionally use a serial extension cable such as this one: http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10212&cs_id=1021201&p_id=4880&seq=1&format=2. The board also requires 5v power and the video output is given via a row of 6 pins. For interfacing with the GBS-8220, the supplied power and video "pigtail" cables may be soldered to the C128 Video DAC and plugged directly in. Interfacing with the AV-1 is a little more complicated, as a separate 5v power source is required, and a female DB-15HD connector should be soldered to the DAC board with short wires.

Pricing: I'm selling 3 different configurations, priced as indicated here. All prices include shipping.

1. Kit
Contains: bare PCB and components
What you need to do: solder components on board and connect to your own CGA->VGA converter and power supply.
Total for US: $32.00
Total for Intl: $37.00

2. Board
Contains: populated PCB
What you need to do: Connect with your own CGA->VGA converter and power supply.
Total for US: $47.00
Total for Intl: $52.00

3. System
Contains: populated PCB, GBS-8220, power supply
What you need to do: Plug in your VGA cable
Total for US: $111.00
Total for Intl: $119.00

Shipping: For those ordering a Kit, I will ship within 1-2 days. Orders for Boards may take an addition day or two since I will have to build it up. Orders for Systems will take 1-2 weeks, since I will have to purchase the GBS-8220 and test the final system before shipping.

Ordering: I have received orders for all 15 units, so I am not taking any more orders at this time. I'm working on getting more parts to build 10 more units, so I expect to begin taking orders again in a couple of weeks. If you are interesting in buying a converter, you can drop me an email at "richard42g@gmail.com" and let me know. I'll alert you when I'm ready to start taking orders for the final batch.

wte · « **Reply #8 on:** September 22, 2011, 08:19 AM »

Hello Richard,

I made my payment, ordered two

But didn't mention in my PayPal payment the type of board: populated PCB
But this should be obvious by the amount of money ...

I'm looking forward.

Regards WTE

airship · « **Reply #9 on:** September 22, 2011, 09:31 AM »

Just sent payment for a built-up board. Thanks!

Richard42 · « **Reply #10 on:** September 24, 2011, 12:13 AM »

Thanks for all of the orders. Half of the boards are now spoken for. I'll start shipping them out on Monday. I have ordered a batch of GBS-8220s and power supplies; they should be here early next week.

BloodyCactus · « **Reply #11 on:** September 24, 2011, 09:27 PM »

paypal'd for one system! (yeah I'm one of those wire+solder inept dudes). Yay for being able to get rid of the 1902A time to put that thing on ebay.

airship · « **Reply #12 on:** September 25, 2011, 01:27 AM »

Quote from: BloodyCactus on September 24, 2011, 09:27 PM

paypal'd for one system! (yeah I'm one of those wire+solder inept dudes). Yay for being able to get rid of the 1902A time to put that thing on ebay.

Unless, of course, you ever want to use a lightpen or light gun. Or a demo that uses fancy smearing tricks for the graphics. Or...

RobertB · « **Reply #13 on:** September 25, 2011, 08:07 PM »

Quote from: airship on September 25, 2011, 01:27 AM

Unless, of course, you ever want to use a lightpen or light gun. Or a demo that uses fancy smearing tricks for the graphics.

However, if he were to use a VGA CRT monitor...

Picture tubes!
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug

BobPhoenix · « **Reply #14 on:** September 26, 2011, 10:55 AM »

In for one system sent tonight!

Richard42 · « **Reply #15 on:** September 26, 2011, 10:29 PM »

Please note that I have received orders for all 15 units, so I am not taking any more orders at this time. I'm working on getting more parts to build 10 more units, so I expect to begin taking orders again in a couple of weeks. If you are interesting in buying a converter, you can drop me an email at "richard42g@gmail.com" and let me know. I'll alert you when I'm ready to start taking orders for the final batch.

A status update for those who have already placed their orders: I built up 8 boards on Saturday. I actually ran out of solder.

The power supplies have arrived but I'm still waiting on the GBS-8220s. They should be here in the next few days. I need to wait for these converters to arrive before I can ship out any of the boards, because I have to set up a test rig where I can test each one before shipping. I'll be shipping out the kits tomorrow.

RCtech · « **Reply #16 on:** September 30, 2011, 03:39 AM »

I got a reply of the company who sells the video converters CTV-910 and STV-908, see post #2. I attached the information sheets as PDF.

rmelick · « **Reply #17 on:** October 04, 2011, 12:44 PM »

Quote from: Richard42 on September 26, 2011, 10:29 PM

Please note that I have received orders for all 15 units, so I am not taking any more orders at this time. I'm working on getting more parts to build 10 more units, so I expect to begin taking orders again in a couple of weeks. If you are interesting in buying a converter, you can drop me an email at "richard42g@gmail.com" and let me know. I'll alert you when I'm ready to start taking orders for the final batch.

A status update for those who have already placed their orders: I built up 8 boards on Saturday. I actually ran out of solder. The power supplies have arrived but I'm still waiting on the GBS-8220s. They should be here in the next few days. I need to wait for these converters to arrive before I can ship out any of the boards, because I have to set up a test rig where I can test each one before shipping. I'll be shipping out the kits tomorrow.

Just got my system in the mail today.

Best. Thing. Ever. Period.

I love it, love it, love it and thank you 1000 times over!

Richard42 · « **Reply #18 on:** October 06, 2011, 05:06 AM »

Quote from: rmelick on October 04, 2011, 12:44 PM

Just got my system in the mail today.

Best. Thing. Ever. Period.

I love it, love it, love it and thank you 1000 times over!

That's great! I'm really happy that you like it so much. I just shipped out 3 systems yesterday; I'm going to build and ship the last 3 this weekend.

I also got a whole bunch of AD8044 chips from China, so tonight I'll place a digi-key order for the remaining parts, and next week when the parts arrive I'll start taking order for the last 10 units. After these are gone I'll have no more PCBs.

dabone · « **Reply #19 on:** October 06, 2011, 08:21 PM »

Waiting for that email....

I want one for my 128 and for use on my Tandy 1000sx.
I'm not using a scan converter because I actually have 3 lcd monitors that sync to 15k.

Later,
dabone

azog · « **Reply #20 on:** October 06, 2011, 10:45 PM »

Sent mail yesterday, hoping I can get in on this deal (and registered just so I could reply here!)

maraud · « **Reply #21 on:** October 07, 2011, 01:38 AM »

I got my two kits which I need to assemble. I'm looking forward to being able to no long being stuck with the one "converter board" with a resistor hack (which I found on this board), as I can't find that board anymore.

Richard42 · « **Reply #22 on:** October 07, 2011, 03:36 AM »

I have the email addresses of everyone who's expressed interest in purchasing a board from the second batch, so you'll all be at the front of the line. I'm also in discussions with a rep from Uniworks Intl regarding the STV908 board that RCTech linked above. That actually looks very promising. If the negotiations go well then I will purchase a batch of these units and sell them with the next Video DAC batch instead of the GBS-8220s. It will be a little more expensive, but the advantage of using this board is that it has many more inputs: it has 1 composite, 1 svideo, 1 component, and 2 RGB. This means you could connect both C128 video outputs plus several others to the same converter.

BloodyCactus · « **Reply #23 on:** October 09, 2011, 04:24 AM »

my system arrived but have not had the chance to test it yet! cheers mate!

airship · « **Reply #24 on:** October 09, 2011, 07:54 AM »

Mine arrived yesterday. Hope to get it hooked up this week - my C128's pretty dusty!

-Mark

Author Topic: C128 Video DAC thread (Read 8945 times)

BobPhoenix