L8300/P3000 Monitor output..?

[Thrash75]

Hello smart people,

I recently got hold of a Power 3000. I already had two Lambda 8300. When I use the "monitor" output (which I assume is composite, or what?) to connect to my modern LCD TV, I get an all white image. But if I connect it to my old PHILIPS CM8833 crt monitor, the picture looks fine. I assume something is "missing" in the signal, which the old crt does not care about, but the newer LCD screen demands to show the picture. Or what?

Is it possible to modify the Lambda computer, so the signal is accepted on modern screens?

[1024MAK]

Hello and welcome. You may want to introduce yourself in the welcome area here.

A monitor output is indeed a composite video output.

It is possible that Lambda does not produce the part of the video signal that is known as ‘the back porch’. The purpose of this part of the video signal is to tell the TV / monitor to set the normal black level it will use to the level of the video signal at this point in time. Black and white / monochrome TVs / monitors generally and some colour TVs / monitors will work okay without this part of the video signal. But other colour TVs / monitors will not be happy. The most common symptom is either a black display, or a very dark display with very poor contrast. I’ve not heard of a white display before.

Please also note that if the problem is the missing ‘back porch’, it can affect colour CRT, LCD, LED and plasma TVs. But amazingly some (but not many) LCD TVs will work okay.

But before going any further, I have some questions.

Are you sure that the TV settings are correct for a composite 625 line, 50Hz (sometimes known as a ‘PAL50’) video signal and the correct source (input socket) has been selected?

Is this the same for the all three computers? Do you have any ZX81s to try? Or indeed, any other 1980s 8 bit computers with composite video outputs to try?

Have you tried different brightness and contrast settings on the TV?

Do you have any other TVs to try your Lambda on?

Have you tried the RF output?

It is also possible that there is a different problem. But may be difficult to diagnose without measuring the video output of the Lambda using expensive test equipment.

There is a solution to ZX81s that don’t produce a ‘back porch’. In fact, there are a number of different solutions, both DIY, ready build modules and professional fitting services. These should work with a Lambda, if the problem is in fact a missing ‘back porch’.

One of the popular modules is PokeMon’s ZX8-CCB available here.
The main competitor is ZXVid. Both involve soldering. The ZXVid can be professionally fitted.

Mark

[mrtinb]

Great to see another Dane in the forum. I've posted my discoveries with Lambda 8300 here in these parts of the forum. Most discussions on this page is about the ZX81 though.

P.S. If you have any printed material on the Lambda in either English or Danish please let us know. (We already have the manual in Danish, English, German and Chinese scanned, and we have the PC8300 ROM Buch scanned, and personally I have a Danish software book that covers both ZX81 and Lambda 8300)

[Thrash75]

Hello Mark,

Hello and welcome. You may want to introduce yourself in the welcome area.

Thank you! Done.

It is possible that Lambda does not produce the part of the video signal that is known as ‘the back porch’.

The most common symptom is either a black display, or a very dark display with very poor contrast. I’ve not heard of a white display before.

I'm glad to throw another puzzle into the mix. Tech can be so strange. See attached picture.

Are you sure that the TV settings are correct for a composite 625 line, 50Hz (sometimes known as a ‘PAL50’) video signal and the correct source (input socket) has been selected?

No. My TV don't provide an option for selecting this manually. I think it's done automatically. But I have tried different "Colour Space" settings (Normal or "x.v.Colour"), and "Colour System" settings (Auto, PAL, SECAM, NTSC3.58, NTSC4.43). None make a difference. Oh, and I'm sure it's showing the picture from the Lambda, as the screen goes momentarily black for a short while, if I press RESET.

Is this the same for the all three computers? Do you have any ZX81s to try? Or indeed, any other 1980s 8 bit computers with composite video outputs to try?

I do not have a ZX81, unfortunately. Only the Lambda clones. Yes, all three show white picture on my LCD TV, and all three show picture fine on my PHILIPS CM8833. I have tried connecting a C64 to composite on my LCD TV, and that displays fine.

Have you tried different brightness and contrast settings on the TV?

Yes, I have. No change, other than changing the whiteness to some degree.

Do you have any other TVs to try your Lambda on?

Uh, yes. But it's in storage, and it's a whole process to dig it out. But I can do it, if you insist.

Have you tried the RF output?

No. I looked for an RF antenna cable for about half an hour, but I can't find any.

It is also possible that there is a different problem. But may be difficult to diagnose without measuring the video output of the Lambda using expensive test equipment.

All I have is a multimeter..

One of the popular modules is PokeMon’s ZX8-CCB available here.
The main competitor is ZXVid. Both involve soldering. The ZXVid can be professionally fitted.

Interesting! Especially the first one, since it's inexpensive. I don't mind soldering, as long as the difficulty is not too high. I hate SMD stuff..

Thank you for assisting me!

[Thrash75]

Hejsa Martin,

Great to see another Dane in the forum. I've posted my discoveries with Lambda 8300 here in these parts of the forum. Most discussions on this page is about the ZX81 though.

Thanks, yeah. It was somewhat popular in Denmark. I have read some. I will read more in-depth. I saw some software restoration projects. So cool you guys do that. Much respect! I hope to load some games onto it, somehow. Maybe the iPod could work for that..

P.S. If you have any printed material on the Lambda in either English or Danish please let us know. (We already have the manual in Danish, English, German and Chinese scanned, and we have the PC8300 ROM Buch scanned, and personally I have a Danish software book that covers both ZX81 and Lambda 8300)

Seems like I can't contribute, then.. All I have, is two Danish printed Lambda 8300 manuals. That book of yours sound interesting.

[mrtinb]

(One problem with the Lambda 8300 is that it comes with two different ROMs. ROM version 1 is black screen with blinking cursor. ROM version 2 is the text READY, and a blinking cursor. ROM version 2 supports the Lambda Colour Pack if attached. Software made for version 1 won't work on version 2 and the other way around. So if the software does not work, it could be a corrupt load, but it could also be made for a different ROM version. ROM version 1 was too similar to ZX81, and because of a lawsuit ROM version 2 was changed quite much.)

[Thrash75]

Thanks for info, Martin. I will watch for that. Mine is version 1.

[Crud3]

Hello everyone!

I recently got hold of a Your Computer/Lambda 8300 in really nice condition and in working order!
There are some wierd graphical issues though, both through RF and through Monitor (composite)...
See attached images!

What can this problem be down to and how could I go about fixing it?

Connected via RF:



Connected via Monitor (composite)

[1024MAK]

See attached images!

I’ve edited your post because using the image link does not work unless the forum detects a valid picture/photo/image file. What you linked to are web pages.

Either link to a valid picture/photo/image file, or attach the picture/photo/image to the post by using the Attachments tab below the text edit box and upload them to the forum.

What PSU are you using? What is it rated at? And if you have a multimeter, what is the actual on-load (when connected up to the computer) DC voltage?

Mark

[mrtinb]

First of all, a LCD is not guaranteed to work, as it's too modern for these computers.

My experience with these old machines is, that the voltage supplied can corrupt the image. I have a cheap powersupply, that can provide 3V, 4.5V, 6V, 7.5V, 9V and 12V. Sometimes it can help to change the voltage, and get a better picture. If you then add external hardware like 16k RAMpack, a printer or Colour Pack, you need to add more volts as well.