464+ working but black screen

[evenmore]

Hi everyone,

I have an Amstrad 464+. it seems to be working correctly, but I don't get any picture.
I do have a CPC 464, which works correctly on my Scart TV.

I can hear the Burning Rubber music playing, I can also run BASIC and press the DEL key and hear sound.
I have two Scart cables, one powered and one normal. Both show a black screen.
I have tried a couple of different power supplies, one 5v 2.4 amp and one 5v 3 amp.
I have also tried an OSSC upscaler with both Scart cables, which reports that the 464+ is outputting a signal but the image is black.
The OSSC overlay menu is visible, so the problem does not seem to be with my TV.

I opened it up and there doesn't seem to be any obvious issues with the circuit board, although I am not an electrician.

A video of the machine running on my TV is available here.

Thanks very much for any suggestions!

Regards,
  Chris

[Bryce]

Hi evenmore,
     do you have a multimeter to check some signals? If so, you should check the pins 2 to 9 and 11 to 14 on IC115 (AMS48464 - Video DAC) to see if the ASIC is outputting a video signal.

Bryce.

[tibbs1972]

Hi,

I'm a bit of a newbie to the plus range, started working on mine last week.

I found out that newer TV's might not handle the 464+/6128+ RGB output through the scart connection. 

Also, I tried a Scart to HDMI upscale, but that definitely didn't work, it was grey and garbled.

I was lucky, I had a 10year old Murphy TV that detected the RGB signals thorugh the scart lead. A possible cause might just be the TV can't handle the signals. 🤔

Regards
Tibbs

[evenmore]

Thanks everyone, I will get my dad to help me test the board with the multimeter.
It's strange that it should work for my CPC464, but not the Plus.
That makes me think it is something to do with the computer rather than the TV.
It is an old TV, over 20 years or so.
I will let you know what happens!
Thanks very much for the advice!
Chris

[eto]

Hi,

I'm a bit of a newbie to the plus range, started working on mine last week.

I found out that newer TV's might not handle the 464+/6128+ RGB output through the scart connection.

Also, I tried a Scart to HDMI upscale, but that definitely didn't work, it was grey and garbled.

I was lucky, I had a 10year old Murphy TV that detected the RGB signals thorugh the scart lead. A possible cause might just be the TV can't handle the signals. 🤔

Regards
Tibbs

then they probably don't detect that they should switch to RGB. They work in default mode and try to decode a (not present) composite video signal.

You need a Scart cable with power injection that puts the proper RGB detect signal on one of the pins.

You can find more detailed information on the Wiki.

[eto]

Thanks everyone, I will get my dad to help me test the board with the multimeter.
It's strange that it should work for my CPC464, but not the Plus.
That makes me think it is something to do with the computer rather than the TV.
It is an old TV, over 20 years or so.
I will let you know what happens!
Thanks very much for the advice!
Chris

What cable do you use? Can you take a picture of it? In the video it's not fully visible and looks slightly suspicious .

[McArti0]

I saw with my own eyes how scart didn't work because there was no audio connected.

TV has strange whims.

If you have disassembled the Plus cable, open it and show photos of what is soldered there.

[McArti0]

I have a tricky question yet: do these cables work well with this CPC464 without plus? 

[evenmore]

Thanks everyone, I will get my dad to help me test the board with the multimeter.
It's strange that it should work for my CPC464, but not the Plus.
That makes me think it is something to do with the computer rather than the TV.
It is an old TV, over 20 years or so.
I will let you know what happens!
Thanks very much for the advice!
Chris

What cable do you use? Can you take a picture of it? In the video it's not fully visible and looks slightly suspicious .

The cable from retro computer shack is powered. I'm not sure where I got the unpowered one.

[Bryce]

I saw with my own eyes how scart didn't work because there was no audio connected.

TV has strange whims.

If you have disassembled the Plus cable, open it and show photos of what is soldered there.

Wow, haven't seen that before! What TV needs audio for the RGB to work??

Regarding the question in your second post: The DIN connector is different, so he couldn't use the same cable on a non plus 464 without converting the cable.

Bryce.

[McArti0]

I saw with my own eyes how scart didn't work because there was no audio connected.

TV has strange whims.

If you have disassembled the Plus cable, open it and show photos of what is soldered there.

Wow, haven't seen that before! What TV needs audio for the RGB to work??

29PT8306