Leningrad+

[Maciej]

Hello

I've got Leningrad+(personal computer composite) and have a problem with correct display.
http://img221.imageshack_.us/img221/6760/dc090611001.jpg
I seems like something is with synchronisation signal. Last time(before the forum failure) someone wrote to check:
http://img200.imageshack_.us/img200/5159/ljeningradideowy1.jpg
But this is older version - leningrad48. In my case it looks like:
http://img199.imageshack_.us/img199/1914/2xschematpopr.jpg
What should I concretely measure/check. Can I manage without oscilloscope?

Regards
Maciej

[rasmer]

Интересно, как в польшу попал ленинград?

[skyther]

вот тема про исправление видеовыхода ленинграда http://zx.pk.ru/showthread.php?t=1621

[balu_dark]

Hello

I've got Leningrad+(personal computer composite) and have a problem with correct display.

What should I concretely measure/check. Can I manage without oscilloscope?

Regards
Maciej

have you a logic probe? any simply thing which can show you logic level (TTL) and if possible - show what signals changed ( for example change from lo to high logic level or impulse sequence) ?

even usual LED with 470 ohm res can help - long pin of it - put via res 470ohm to +5v ( usually 14 pin of TTL chips- but not in all cases) shortt pin connect via short wire to needle and use this needle as probe to check levels at pins of D11 and D42.

[Ewgeny7]

вот тема про исправление видеовыхода ленинграда
Да там дело не в этом, судя по скрину синхроимпульс просто отсутствует. Бланк есть а синхры нет. Я и посоветовал ему не мучить кошку, а просто заменить ТМ2 (74LS74) на новую.

[Maciej]

Интересно, как в польшу попал ленинград?
I was also surprised. Have bought this from some drunkard on flea market.

вот тема про исправление видеовыхода ленинграда http://zx.pk.ru/showthread.php?t=1621
thanks, I'll check this out.

Да там дело не в этом, судя по скрину синхроимпульс просто отсутствует. Бланк есть а синхры нет. Я и посоветовал ему не мучить кошку, а просто заменить ТМ2 (74LS74) на новую.
Will do men.

have you a logic probe? any simply thing which can show you logic level (TTL) and if possible - show what signals changed ( for example change from lo to high logic level or impulse sequence) ?

even usual LED with 470 ohm res can help - long pin of it - put via res 470ohm to +5v ( usually 14 pin of TTL chips- but not in all cases) shortt pin connect via short wire to needle and use this needle as probe to check levels at pins of D11 and D42.
I'll check this with logic probe.
Can someone tell me what frequency and voltage level should be on pads "S" and "V".
Regards

[balu_dark]

usually must be +5v but some pcb makers leave some pins in air. connect them to +5.
is+5 present at 13 pin of d11.4? try to take sync directly from 9pin D42.2 via capasitor 22mFx16v and res 1k to ground after cap. and check 2 transistors on the way from 9pin D42.2 to TV, also - try use just cap - between scart and current video out from computer.

i got idea - tell which same model of TV you use and how you connect Leningrad. looks like you havnt right ground btw. both devices - put gnd ( or - from 5v source) to antena shield pin.

[Maciej]

usually must be +5v but some pcb makers leave some pins in air. connect them to +5.
is+5 present at 13 pin of d11.4? , also - try use just cap - between scart and current video out from computer.

At 13 pin of d11 are +5V

try to take sync directly from 9pin D42.2 via capasitor 22mFx16v and res 1k to ground after cap.
it doesn't help

and check 2 transistors on the way from 9pin D42.2 to TV
I've took 2 transitors and build this section "on wire". Also didn't help.

i got idea - tell which same model of TV you use and how you connect Leningrad.
TV is CRT Nokia 37 A1(but i've tried on others). Connecton via SCART (RGB-15,11,7); at 16 pin +5V via 220R; 20 pin - sync.; 21(CASE) - GND.

looks like you havnt right ground btw. both devices - put gnd ( or - from 5v source) to antena shield pin.
Everything was connected

Да там дело не в этом, судя по скрину синхроимпульс просто отсутствует. Бланк есть а синхры нет. Я и посоветовал ему не мучить кошку, а просто заменить ТМ2 (74LS74) на новую.
Was replaced 2 times. No solution.

It seems that the reason is somewhere deeper

[UncleDim]

Хочу обратить внимание на пару моментов.
На вход VideoIn телевизора подан Sync, на фото же видим черно-белое изображение с градациями. Я бы проверил следующие вещи:

Уменьшил бы резистор, подтягивающий 16й контакт scart с 220 до 75..150 Ом, или вообще бы убрал его, закоротив 16 и 20 контакты на скарте;

С 9го выхода D42 сигнал идет на базы двух транзисторов через _один_ резистор - вообще-то это не очень корректно (возможно "недооткрытие" одного из транзисторов из-за разброса параметров). Я разделил бы базовые цепи введением второго резистора.


try to take sync directly from 9pin D42.2 via capasitor 22mFx16v and res 1k to ground after cap.

it doesn't help
Вообще-то и не должно было - снимать следовало с 8го вывода, а не с 9го (после девятого выхода два каскада на транзисторах - один инвертирующий, второй повторяющий), да и насчет резистора 1к - толку с него, если входное сопротивление по видеовходу 75 Ом, что там от этой синхры останется..
Можно исключить первый (инвертирующий) каскад, подключив 8й вывод D42 непосредственно к второму каскаду (повторителю).

[balu_dark]

Хм. действительно - промухал я схему включения транзисторов. сорри.
боюсь что без осцила - не осилить :(. сам встретился при восстановлении( собственно сборке заново) платы пентагона48 - сигналы выполненые по схемам монтажное ИЛИ либо с RC цепочками - очень зависимы от номиналов резисторов подтяжки - либо в цепи. с осцилографом сразу видно где что-то не то происходит.

[UncleDim]

боюсь что без осцила - не осилить
ну если дело именно в аналоговых цепях - можно и перебором вариантов.
Для начала удалить транзистор, на котором смешиваются RGB. Посмотреть, не появится ли растр.

[Maciej]

Хочу обратить внимание на пару моментов.
На вход VideoIn телевизора подан Sync, на фото же видим черно-белое изображение с градациями. Я бы проверил следующие вещи...


Хм. действительно - промухал я схему включения транзисторов. сорри...


ну если дело именно в аналоговых цепях - можно и перебором вариантов...

I know that this is russian forum and I cannot require from you to write in english but these posts are to hard for translate by google(forgot to add that i don't understand russian). I'll be very grateful if someone could translate it into english(or into polish;))

Regards

[UncleDim]

I'll be very grateful if someone could translate it into english(or into polish;))


I think the picture would be better:)
You may try any of the following:

1. Cut D42.9-VT2.base wire and add R3 (in red on scheme2.jpg)
2. Remove R2, VT2, and add wire between D42.8 and VT3.base (in green)
3. Remove VT1

And (regardless of the choise) try to reduce SCART's 16pin pullup resistance from 220 to 75..150 Ohm.

Good luck!

[Maciej]

I think the picture would be better:)


Thanks, that cleared up everything:D


You may try any of the following:

1. Cut D42.9-VT2.base wire and add R3 (in red on scheme2.jpg)
2. Remove R2, VT2, and add wire between D42.8 and VT3.base (in green)
3. Remove VT1

And (regardless of the choise) try to reduce SCART's 16pin pullup resistance from 220 to 75..150 Ohm.

Good luck!
Unfortunatly it didn't help.

I've took another one TV(FUNAI MK5 TV-2000T) and connect via SCART. Turned on AV mode and it works :v2_thumb:, but:
-only with VIDEO signal(monochromatic); additionally screen is in negative
http://img265.imageshack_.us/img265/2513/dc090623004.jpg
-RGB and SYNC doesn't work.Following foto show case when D42.9 is connected directly to base of VT3(VT2&R2 removed)
http://img269.imageshack_.us/img269/7785/dc090623003.jpg
When i've puted +5V on RGB Status(16 pin)it did nothing because 16 pin of SCART is connected to the ground in this model:(

Regards

[UncleDim]

additionally screen is in negative
The first move - check/replace D11 (since it "prepares" both Inv and Sync sygnals)


Following foto show case when D42.9 is connected directly to base of VT3(VT2&R2 removed)
D42.9? or D42.8?


16 pin of SCART is connected to the ground in this model:(
This TV may have no RGB inputs on SCART (not sure).

[Maciej]

The first move - check/replace D11 (since it "prepares" both Inv and Sync sygnals)
OK


D42.9? or D42.8?
This TV may have no RGB inputs on SCART (not sure).
To D42.9. When connect to D42.8 the screen is almost black.
But it really doesn't matter since you've got right(this model hasn't got RGB input on SCART).
http://img269.imageshack_.us/img269/1970/dc090623006.jpg

Regards

[UncleDim]

When connect to D42.8 the screen is almost black.


It's Ok. It looks like Sync is correct but no RGB.
Have you tried combination "Sync on D42.8->VT3" and "5V directly to pin16" on Nokia TV?

btw, incorrect signal INV may be caused by wrong diodes (near D11) direction too.

[balu_dark]

When i've puted +5V on RGB Status(16 pin)it did nothing because 16 pin of SCART is connected to the ground in this model:(

Regards

look here : http://pinouts.ru/Home/Scart.shtml
and take attention to pin 8.
also check level of sync and other signals must be 0.7-1v if bigger - TV may not accept it or sync may gone.
Are you sure what you count right and pin 16 at ground? maybe you check pin 17 by mistake?

also - please give exact description which sygnal from computer to which pin of SCART you wass connect. This may help.

[Maciej]

It's Ok. It looks like Sync is correct but no RGB.
Have you tried combination "Sync on D42.8->VT3" and "5V directly to pin16" on Nokia TV?

Yep, but it doesn't even change the screen. I don't have original remote controler for NOKIA TV so I cannot switch on AV mode. I've tried to put 5-12V on 8 pin(Video status) of SCART. No result.
In a while I'll try another one TV. Hopefully it will works:)

Regards

[Ewgeny7]

На фото видно, что на телевизоре есть видеовход COMPOSITE. Надо сначала попробовать подключить компьтер через него (черно-белый), если всё в порядке - то пробовать через SCART.

[UncleDim]

На фото видно, что на телевизоре есть видеовход COMPOSITE
Так это ж фунайкин разъем, на фото выше уже видно что и как на нём работает...