Does anyone know if there's a replacement for the neon bulb NL1? The original is hard to come by and I don't want to replace it with LED (would be last resort). Perhaps I can use NE-2 with resistor, but I don't know the specs of the NL1.
NL1 would be a tag identifying a neon lamp on a schematic. It is not a part number. If it had wire leads look carefully at the base, there may be molded in a number 2!
The resistor value for an NE-2 can safely start at 100,000 ohms and then if it is not bright enough reduce it.
The lamps maximum power should be 1/12 watt. If you know the voltage feeding it and allow for a 60 volt lamp drop you can calculate the minimum resistance. So a maximum current of .001 amp, but for longer life half that or less.
The resistor value for an NE-2 can safely start at 100,000 ohms and then if it is not bright enough reduce it.
The lamps maximum power should be 1/12 watt. If you know the voltage feeding it and allow for a 60 volt lamp drop you can calculate the minimum resistance. So a maximum current of .001 amp, but for longer life half that or less.
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Is there a way to test the old bulb? (in case it doesn't work because of an other defective part)
As this is in a turntable it will be fed directly from the AC power line. So spending the 25 cents on a new neon bulb is the best solution.
NL1 is fed from a frequency controlled oscillator, not directly from the mains.
There should be 220v DC on one side and about 80v on the other.
There is a fuse, F5 100mA that is prone to blow as the supply components do. Check for dry joints and open circuit R709. If C413 dries out there will be no drive to the current stop transistor.
If the neon is not physically damaged/broken glass etc, it is likely to be OK.
Cunning way to work but very good.
There should be 220v DC on one side and about 80v on the other.
There is a fuse, F5 100mA that is prone to blow as the supply components do. Check for dry joints and open circuit R709. If C413 dries out there will be no drive to the current stop transistor.
If the neon is not physically damaged/broken glass etc, it is likely to be OK.
Cunning way to work but very good.
To test the circuit you can swap in an NE-2 with a 47K series resistor using the two outer leads. But the neon lamp looks like a custom part and is probably only available from Sony Service Centers.
It's been a while since I posted an update. I have reflowed the solder on the power supply and did a full recap of the turntable. Unfortunately I still haven't got the right voltages. What's next? Should I unsolder the transistors in the power supply to check if they're still ok? I have measured the diodes in circuit and they appear to be working. Any thoughts?