Modifying the Sony ST-SB920 Tuner
from my own Personal Experience
Please be aware that mains voltages are present. Do not remove cover until unit is un-plugged from the Mains Electricity Supply. Do not plug in again until the cover is replaced.
Main Chassis removed from the tuner showing points of interest:
| 1 | Location of I.F. Filters |
| 2 | RF and Stereo Gain Controls |
| 3 | Location of Audio for Conrad RDS Manager |
| 4 | Squelch Links |
AUDIO FEED TO CONRAD RDS MANAGER
Firstly to connect the tuner to the Conrad RDS Manager. This can be done with out having to remove the chassis. So if you do not intend to replace the filters it is a quick and easy job.
Connections are at JW116 and the end of C269 by the connector, (which is the nearest Earth Point).
SQUELCH MOD
The second modification can also be carried out without removing the chassis. This is to disable the squelch or muting. Two links require cutting, they are JW 75 and JW 72. Location of the links can be seen from the picture below:
RF GAIN & STEREO SENSIVITY
The Gain control, RV231, is best adjusted just short of full. I noticed that in the full position quite a lot of noise is introduced on weak signals. The stereo control, RV251, can again be adjusted just short of full.
I.F. Filters
The tuner has four filters fitted, three 230kHz and one 150kHz in the narrow position (CF231).
To retain the important RDS facility for the PI codes and improve the selectivity I have fitted four 150KHz filters in my one receiver. In my other receiver I have fitted three 150KHz and one 110KHz.
I leave my receiver in the narrow mode all the time and luckily the memories retain this information. Below is a picture showing the location of the filters:
