General:

Generously build high quality amp made in Japan by Nikko Electric Co Tokyo.

Front ^

 

Special futures:

Mic mixing facility. 4 channel option with extra adaptor.

 

 

 

User & service Manual:

Click here to download the full service manual PDF format.

 

 

Power-amp pcb ^

 

Schematic:

Power-amp section ^

 

Power transistors ^

Detail ^

Pre- and power amp ^

Detail ^

Restored & modified power-amp section ^

 

Modifications:

All electrolytic caps should be checked and exchanged when out of specs.
The main power caps are usually of good quality, but in case of flaws can be upgraded up to 10,000µF.
Check input transistors of the power amp section if they make noise.
Exchange the pots on the power board for 10 turns and align the power amp correctly.
You may heatsink the drivers transistors as well as the pre-drivers.
The input transistors of the power amp section can be joint together with a copper heat-joint to get the DC-offset more stable.
Set the power transformer to 240V in Europe.
The input el-caps of the power amp section can be replaced by small true MKT capacitors.
There are 2 versions of the power-supply of this amp, one with 4 diodes and one with a TO-3 bridge.
There are 2 versions of this amp produced: 1 general version with cinch sockets and one EU version with DIN sockets.
Consider a DC-sensing speaker protection-board, the amp has only AC & DC max. current protection.
Speaker wiring is rather thin and may be upgraded if you like.

 

 

Pre-amp ^

Pre-amp copper-side ^

 

Mixing mic board ^

 

Power supply rectifier bridge S2HB-10 Shindengen Japan ^

Power supply 2x33V ^

 

Power caps ^

 

Prepairing for a speaker protection board ^

 

Speaker protection board placed ^

 

Wiring of the LS-protection circuit complete ^

 

From another angle ^

 

Overview inside ^

 

Back ^

EU version back ^

 

 

Sound:

Excellent sound, quite the same high quality as the Sansui AU-666 and other amplifiers of the same kind.

 

 

 

Nice amplifier the Nikko TRM-600.

 

 

 

© PE1MMK-ON9MMK Hans Hilberink,  last update:  21-03-2020.