Hello everyone have a Saturn here giving me the blues. No carrier or modulation found the finals were blown. Changed them out now I have 2 watts carrier no matter where I set the pots. Still no modulation. It receives great shows carrier but no modulation. Put it in PA works great mic gain works echo works. Checked D77-65 ok. IC 4 voltages ok. Am regulator ok. Even had a fellow tech look at it and come up with no answer either and help would be appreciated.
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Galaxy Saturn
- Thread starter Kung Fu Panda
- Start date
If the old finals overloaded the modulator circuit, TR51, the 2SB754 may be damaged. The smaller transistor that drives it, TR50 may also be bad. Whenever we replace TR51, we also replace TR50 without bothering to test it.
Do you have a way to test TR51?
73
Do you have a way to test TR51?
73
Next one I would check is TR52. If it shorts, you'll get way too much AM carrier, no modulation and sideband will be okay on transmit.
Simply removing the solder from the center pin of TR52, so the pin doesn't touch the rim of the foil pad will reveal if it's the culprit.
If it still does the same thing, try the same trick isolating the center pin of TR49 from the solder pad.
And if that makes no difference, we're running out of likely suspects.
73
Simply removing the solder from the center pin of TR52, so the pin doesn't touch the rim of the foil pad will reveal if it's the culprit.
If it still does the same thing, try the same trick isolating the center pin of TR49 from the solder pad.
And if that makes no difference, we're running out of likely suspects.
73