ПК-01 ЛЬВОВ

Here you are.


You can use BC847B or similar instead of КТ315.

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.

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 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

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

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.

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.

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?

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.

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.

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?

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?