A new member and his computer!

[orest]

Here you are.


You can use BC847B or similar instead of КТ315.

[Lesarthois]

Yeah, unless I gut off a Soviet radio I have around (do you know they were readily available in France in the 80's?) I won't be able to find that precise transistor, but it seems to be a rather generic one. I might even find an equivalent in the pile of transistors I have around. I'll try to make something this week or this week-end.

[doorsfan]

Zelya, please, just translate to our French friend my manual that was written some years ago on this forum.
I found it: quoted by gtament in
5th message in this branch http://lvovpc.ho.ua/forum/viewtopic.php?f=2&t=86
You need in 74LS02 IC

BTW more info about OREL BK08 enchanced clone of ZX-Spectrum (made in Dnepropetrovsk) You may find on mostly ZX Spectrum relative forum zx-pk.ru

[Zelya]

doorsfan
As I understand your video "upgrade" allows to invert colors too?
I'm not technical guy, and I don't understand your explanation, but I'll try to translate

Video output modification:
1. Connect +12V to the pin 1 through 300 Ohm resistor
2. Connect sound from beeper to pin 7 through 10K Ohm resistor
3. Remove 3 electrolytic capacitors at the border of motherboard, near TV jack
4. Solder 555ЛЕ1 above ДД62 (555ЛЛ1) with the next connections: pins 3, 6, 7, 8, 14 should be connected to ЛЛ1; pins 2, 5, 9 should be flexed to connect them with pins related to 3,6,8 (right?). Pins 11,12,13 - are not use, can be just flexed outside. Pins 1,4,10 should be flexed outside too and connected to "minus" positions of removed capacitors С54, С53, С55.

DIN7 to SCART connection:

1 - to 8 and to 16 though 390 Ohm resistor
2 - 20
3 - 7
4 - 11
5 -15
6 - 4 (optional to 5, 9, 13)
7 - 2,6


PC-01 Lviv schema is here:
http://www.lvovpc.cu.cc/files/lvov_sheet.rar

[Lesarthois]

Interesting things!

I think I'll try first the 3 transistors solution. It's cheap to do, and I can manage to put that on the video cable. The less I mess into the computer, the better I feel.
I even have ready-made solution for the cable : for some reason, megadrive sold in France had an additionnal box on the SCART cable :

What's more to ask for?

Good advice anyway on the sound output, I'll keep that in mind.

And I'm going to use the 12V.
In computers, the 5 V line is usually used for the RAM and CPU, so anything that draw current from it can cause troubles; on the other hand, that 12V being present on the extension port mean that it's made to draw power from it, so 3 transistors won't strain the power supply

I think I'm going to use a LM 1881 to get a better and standardized video sync. This mgiht solve the issue of the "upper screen ripping" I have seen on some video mods.

[Lesarthois]

Today I received DIN plugs to solder, so I opened the computer again to work on it.
And, I somewhat expected it, but the owner, when working on his RF video mod, used the DIN as a simple support for soldering his wires, and so, moved them out of place (for example, the pin 7 is populated, but pin 6 was empty.

This explains me why the video was so wobbly when I tried to wire it; there was no ground connected.

Anyway, I need to rewire this DIN plug correctly first, then check for a 12V line I can take power from.

[Lesarthois]

So I tested it quick. I get RGB out, with the help of an old 5+ power supply.

I noticed that I get brighter colors and the right one from the channel if I link together the sync wire and a color wire so, this lead me to question is maybe the Lvov output was in fact TTL RGB?


Everything linked normally :



Sync and green linked together :


Also I noticed that depending on the color channel, the screen upper ripping would get worse, with the blue channel even puttign the TV out of sync.
Regardless of any solution, I think that using a LM 1881 to get a clean sync signal is more than needed.

I found this page about the Byte ( Байт) computers :
http://zxbyte.ru/byte_connection_to_tv_and_monitors.htm

Google Translate isn't very at ease with it, but if I get it right, that's TTL RGB, and one of the given solutions for is is this schema :



There is an added part with the diodes, but else, it seems to be the same solution. Except that this one introduce brightness in the mix.
What do you think?

[orest]

Yes, it is a TTL level. That's why we're using those R5-R7 variables, to manually correct each color level on the input (very usable mod, by the way).
In my case final result is something like this. But much, much brighter colors.

[Lesarthois]

Oh, perfect!
So it's not some odd exotic video output, just a fade in the world of computers.
And that's plenty of designs I can try if the result isn't convincing for me.

In the meantime I think I'm gonna test some games on the computer as well. I saw a post somewhere on the forum to convert games to sound format.

[orest]

Oh, perfect!
So it's not some odd exotic video output, just a fade in the world of computers.
And that's plenty of designs I can try if the result isn't convincing for me.

In the meantime I think I'm gonna test some games on the computer as well. I saw a post somewhere on the forum to convert games to sound format.

It's TTL level signal, but not a TTL logic, i suppose. Sorry for misleading.

[Lesarthois]

I'll mess around when I'll get all the needed components and post about what I found. Anyway the result is unlikely to be 100% accurate, but as long as the display is "close enough" that will do.
Where is the fun if everything is too easy?

[Lesarthois]

Bumping the thread!

I finally received all the needed parts to make the circuit.. and I get nothing.
I have to check my wiring, and the circuit, but I also thing that the video out on the computer could be messed : as I explained before, a previous owner soldered wires on it to make a video RF out mod, and I think that he might have removed the wires and resoldered them on the video out at random.
Is there any document showing the exact originl point for the video out?