Anyone else have an HH Scott 433 digital tuner. This appears to be rare tuner, I was able to find the schematics and was trying to get the auto scan feature working again. It has a Perfectune circuit that I thought might be the problem as the station light isn't working which happened at the same time the auto scan stopped working so It might be related. Otherwise everything else works.
Anyone Else have Scott 433?
- Thread starter ottsm
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Well I found my problem with the autoscan. The individual before me had changed the incandescent bulb with an LED. This worked for awhile but isn't sized for the 25VDC source. Without the bulb the autoscan circuit cannot work as it is necessary to supply the voltage to the opamp output, basically the bulb is tied to the +25VDC and the other lead of the bulb is tied to the output opamp which is also tied to a 1.5K resistor to chassis ground. The output from the opamp also goes to the sequence code generator to make it scan if no station is detected. Now I need to find a 25VDC bulb or place a resistor in series with an LED to get the correct current to switch the opamp. I have another bulb with the same part number in the set for another application, I hooked it up to the the autoscan and things work again, with the bulb lit the full 25VDC can be measured across the bulb (explains why the LED burnt up, at least the LED opened and didn't short out).