mateusz.viste MDA is fine on dreamblaster's boards, see this shot I made:

I also think colors will be correct with more precise resistor networks, there is no reason for them not to be

keropi wrote:

mateusz.viste MDA is fine on dreamblaster's boards, see this shot I made:

Yes, I did see it - I was just saying that if he'd happen to have a 'failed' unit that still works with MDA, instead of throwing it out I'd happily buy it since I'm not interested in EGA/CGA anyway. I need it only for debugging programs - a dual screen VGA/MDA setup would be extremely helpful when working on etherdfs (tsr), dosmid (full screen app) and many other of my projects.

ah OK yes this is a nice idea actually having dual monitors... I think a couple of games also supported that as well!

dreamblaster wrote:

The 2.0 project is already on his site. I am working on a version that can be factory assembled. Lessons learned so far : for ne […]
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mateusz.viste wrote:

@retrocanada76 - from your website I understand that you are working on a new, improved v2.0, so I will probably wait for that before assembling anything. One humble suggestion I would have: is there any chance that the v2.0 could come in a "MDA only" variant? This would be nice for people (like me) that do not care about EGA/CGA, but are very interested in monochrome MDA/herc, while not being very handy with a soldering iron at the same time... I assume here that a MDA/herc-only version would need less elements (even if only a few resistors and dip switch).

The 2.0 project is already on his site.
I am working on a version that can be factory assembled.
Lessons learned so far : for next prototypes, I will use better tolerance resistor networks, as the colors seem to differ a bit.
A prototype is on its way to retrocanada, for evaluation.
If it all works well, I'll have a small batch machine assembled.

Hey, I use 5% resistors on mine. I don't think this was the problem. Have you noticed that one of the resistor arrays is isolated and the other bussed ?

Can you tell me which resistor networks did you use for the project ?

isolated: https://www.digikey.ca/products/en?keywords=4608X-2-102LF-ND

bussed: https://www.digikey.ca/products/en?keywords=4606X-1-102LF-ND

ok, my tolerance is 2% but the version 1.0 I used regular 5% 1/4w

I use all isolated resistor networks (all the same part).
The first prototypes had 5% tolerance. (also in the packet I sent you).
Now I ordered parts with 1% tolerance.
We'll see if this solves the issue

can you send me the schematics ?

retrocanada76 wrote:

can you send me the schematics ?

yeah of course, see attachment
RN1 to RN6 are the 1k resistor packs.
I initially used 5% packs. Now I ordered 1% replacements.
(the 1k resistors R1,R2, R3 are already 1%)

can you measure the resistance from each color pin ? From keropi pictures the problem seems to be on B3,G3,B3 they seem to be too bright. These pins should be 500 Ohms each.

B3,R3,G3: 500 ohms
B2,R2,G2: 1K
B1,R1,G1: 2K
B0,R0,G0: 4K

on mine it all seems close enough

So it seems right.

Dreamblaster, did you try another monitor / tv ? just for the sake. If the voltages are correct there is nothing wrong with the unit.

Use the last FW, and show the colorbars using a different monitor/TV.

do you know where I can by the PCB or complete board for MDA/CGA/EGA to VGA ?

retrocanada76 wrote:

can you measure the resistance from each color pin ? From keropi pictures the problem seems to be on B3,G3,B3 they seem to be to […]
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can you measure the resistance from each color pin ? From keropi pictures the problem seems to be on B3,G3,B3 they seem to be too bright. These pins should be 500 Ohms each.

B3,R3,G3: 500 ohms
B2,R2,G2: 1K
B1,R1,G1: 2K
B0,R0,G0: 4K

All these check out on my board as well.
Tried latest fw and also a completely different lcd screen, did not help. I will try again once I have installed the 1% resistor networks.

Sorry, It can't be the resistors. It makes no sense! If your values are correct, them there is no need to replace them. Just do a sanity check and make sure they are not shorted. Specially cross-color, like Bx is not shorting any of the Rx, Gx and remaining Bx's.

It would be wise to take a look on the shift level 74LVC245 as well as the voltages sent from your board. What is the EGA card are you using ?

Do you have another EGA card ? What if you jumper it to CGA display ? Does the text color color bar change ?

It looks like your reds are too bright. I don't see dark red in the gobliins game.

Yes reds are too bright, almost hot red.
I have tested with 4x EGA cards (at least I have a healthy stock now 🤣 )

I did see quality differences but the color balance was constant in all 4 cards. I will wait for those 1% networks and solder them again that way I will also eliminate the possibility of a short.
Not sure how I can check the 74LVC245 though soldering looks great on it.

I am waiting my board from the overseas but it seems the snail mail is coming on top of a sea turtle... 😀

arteq wrote:

do you know where I can by the PCB or complete board for MDA/CGA/EGA to VGA ?

Hello arteq and others here at Vogons. This is my first time posting here. Some of you might recognize my handle from Vintage Computer Forums. I've been a member there since 2010. I've been selling assembled MDA/CGA/EGA TO VGA V2.0 units to VCF members and am currently working on a new batch to sell. They sell for $110 shipped in the US lower 48. If interested, please email me at gregsaling@comcast.net from your PayPal email and I can send you an invoice to get your order rolling.

Greg

PS
I can ship to other countries as well. It just costs a little more.

@keropi;
I see you have and ATI EGA Wonder. Would you consider trading for an assembled V2.0 MDA/CGA/EGA to VGA converter?! We each pay our own shipping? What do ya think? Counter Offer?

Greg