Search found 54 matches
- Sun May 09, 2021 6:17 pm
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
Re: Dragon 32 RGB SECAM and video tests
Here are the schematics.
- Sun May 09, 2021 6:15 pm
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
Re: Dragon 32 RGB SECAM and video tests
I have looked on my Dragon 32 SECAM at the RGB conversion which is part of the PSU board. On my schematics below, we can see that phi A (R-Y) and phi B (B-Y) signals of the 6847 are mixed to make the (G-Y) information. The LUM, which is a clone of (- Y) information is inverted and then combined with...
- Tue Apr 13, 2021 6:16 pm
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
- Tue Apr 13, 2021 6:14 pm
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
Re: Dragon 32 RGB SECAM and video tests
Hi Stew and John Thank you for your advices. For the moment, I can't reduce the oscillation which causes the vertical lines by putting caps on the power supplies near the 6847 circuit. I will carry on my investigations. My two Dragon RGB have the same behaviour. In RGB output, the vertical lines are...
- Sat Apr 10, 2021 7:02 pm
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
- Sat Apr 10, 2021 6:59 pm
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
Re: Dragon 32 RGB SECAM and video tests
Thank you Stew for all thoses precious advices, I will look at the power supply. I have taken a picture of the screen with the bars. And also a view of the Y signal given by IC 6847 compared with the Video Clock (oscillo at 0,2 µS per division) When I read the 6847 data sheet, in the case of a 14,21...
- Sat Apr 10, 2021 9:53 am
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
Re: Dragon 32 RGB SECAM and video tests
My motherboard is like this one. https://archive.worldofdragon.org/images/c/cb/Dragon_32_PCB_Top_%28PN41503_Issue3%29.jpg We can see on the picture that the 8 x OKI M3732H RAMs have the caps. and also that caps have been added, by exemple near the 6809. I don't understand what you mean by "The board...
- Fri Apr 09, 2021 3:09 pm
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
Re: Dragon 32 RGB SECAM and video tests
RGB tests I have tested the RGB on the Scart input of different LCD TVs. It gives a nice picture, but with vertical lines. However, there are 2 things to fix (see schematics for explainations) : - the voltage at pin 16 of the Scart is too low to switch the RGB ; if not corrected, you could only get...
- Fri Apr 09, 2021 3:02 pm
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
- Fri Apr 09, 2021 2:55 pm
- Forum: Dragon Hardware
- Topic: Dragon 32 RGB SECAM and video tests
- Replies: 36
- Views: 33425
Dragon 32 RGB SECAM and video tests
Hello. I have got two Dragon RGB SECAM and I think I'm not the only one here. The motherboard PN 41503 (issue 2 and issue 2A for me) and the SECAM PSU board PN 41504 are already in the hardware section. The quartz frequency is 14,2180 MHz. This machine has two interesting properties : - a RGB circui...