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:UK => Hardware => Topic started by: Wolfgang on 2020.September.15. 16:43:43

Title: RF signal only black&white
Post by: Wolfgang 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?

Title: Re: RF signal only black&white
Post by: John Fante 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? :)

Title: Re: RF signal only black&white
Post by: Wolfgang on 2020.September.16. 22:09:04

Quote from: John Fante 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? :)

Scart worked right away.

Title: Re: RF signal only black&white
Post by: Judge 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 ...

Title: Re: RF signal only black&white
Post by: Wolfgang 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. :) 

Title: Re: RF signal only black&white
Post by: Zozosoft on 2020.October.01. 11:04:25

Quote from: Wolfgang on 2020.September.24. 16:33:23

In the end, changing the 4.433619MHz oscillator solved the color issue. :)

Good do know it! It is used for the PAL colour subcarrier.