Welcome, Guest. Please login or register.


Author Topic: RF signal only black&white (Read 276 times)

Offline Wolfgang

  • Newbie
  • Posts: 16
  • Country: de
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 80.0 Firefox 80.0
    • View Profile
RF signal only black&white
« on: 2020.September.15. 16:43:43 »
While I get a good quality color picture on scart, I am unable to see color with my rf modulator. I already replaced LM1886, LM1889, TR6, C38,C39,C36 without any success. What else could be wrong?

Offline John Fante

  • EP fan
  • *
  • Posts: 136
  • Country: dk
  • OS:
  • Mac OS X 10.15.6 Mac OS X 10.15.6
  • Browser:
  • Chrome 85.0.4183.102 Chrome 85.0.4183.102
    • View Profile
Re: RF signal only black&white
« Reply #1 on: 2020.September.16. 20:48:22 »
Just curious but did you replace anything to get RGB/scart or was that going for the start? :)

Offline Wolfgang

  • Newbie
  • Posts: 16
  • Country: de
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 80.0 Firefox 80.0
    • View Profile
Re: RF signal only black&white
« Reply #2 on: 2020.September.16. 22:09:04 »
Just curious but did you replace anything to get RGB/scart or was that going for the start? :)
Scart worked right away.

Offline Judge

  • EP user
  • *
  • Posts: 351
  • Country: hu
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Chrome 85.0.4183.102 Chrome 85.0.4183.102
    • View Profile
Re: RF signal only black&white
« Reply #3 on: 2020.September.16. 23:28:42 »
SzörG wrote here that he stabilized the vibration of the RF modulator image with the R202 and put the colors back on it by tuning the C43 ...
Üdv.Judge

Offline Wolfgang

  • Newbie
  • Posts: 16
  • Country: de
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 80.0 Firefox 80.0
    • View Profile
Re: RF signal only black&white
« Reply #4 on: 2020.September.24. 16:33:23 »
Success!
This was a hard one. I replaced the LM1889, the LM1886, all electrolytic capacitors, the 78L12, most of the transistors and a couple of ceramic capacitors in the LM1889's oscillator circuitry. In the end, changing the 4.433619MHz oscillator solved the color issue. :) 

Offline Zozosoft

  • EP addict
  • *
  • Posts: 13727
  • Country: hu
  • OS:
  • Windows NT 10.0 Windows NT 10.0
  • Browser:
  • Firefox 81.0 Firefox 81.0
    • View Profile
    • http://enterprise.iko.hu/
Re: RF signal only black&white
« Reply #5 on: Today at 11:04 »
In the end, changing the 4.433619MHz oscillator solved the color issue. :)
Good do know it! It is used for the PAL colour subcarrier.