Luxman L 230  & L 235 & L 225

General: 

This Luxman L230 audio amplifier made & produced by Luxman in the late 1980’s. .

 

Photos:

front and back

details front

Bottom with badly restored pcb, incorporating wrong power transistors.         Unrestored interior, lamps on front also to be replaced by leds..

Power supply.                                                                                             unrestored preamp.

part of the pcb unrestored                                                                          restoration in proces: new electrolytic capacitors.

RIAA-amp with new caps

Restored amp with new resistor and changed circuit to feed the new leds on the front panel, the zenerdiode is obsolete now.

The new final power transistors from Sanken mounted in their places, the amp is operational now.

Specifications & Special features:

           User manual of the L200 series download click here

This Luxman L230  audio amplifier is a affordable yet high quality amp made by Luxman.
It incorporates Duo-Beta ® feedback and the tone control is not the usual, it is in the feedback line of the power amp.
No traditional tone amp is to be found in this amplifier.
It has "single pcb policy" and has the power transistors directly soldered to the main pcb.
The power supply is simple, but has sufficient capacity to feed a 2x50W basic amp.
It has a MC & MM/MD pick-up amp.
The protection circuits are rather simple, so you can easely damage your amp when used improperly.
It has a fully symmetric and complementary bipolar transistor power output with
high speed & high current plastic power transistors.
 

Schematic:

            Click here to see the service manual of the L225-L235

            Click here to see the L200 series main schematic diagram in PDF format

            Click here to see the L200 series power supply schematic diagram in PDF format

 

Modifications:

On the photos you can see that several electrolytic capacitors are to be replaced.

The zener diode D112 needs to be replaced by a 2 Watt type and extra cooling applied, when original light bulbs are applied,
the original power design of this schematic part is incorrect, your pcb will probably be burnt like on the photo above.
When the light bulbs are replaced by leds (that I prefer), the zenerdiode D112 is obsolete and can be removed,
the 300 Ohm resistor R153, can than be replaced by a 1,5 KOhm 2W type as on the photo and you have the correct power design,
take 3 leds of different color: red, yellow and green, thats what I applied, if you like blue better, that can be used also.

Replace C104 a b, C103 a b, C113 a b, C107, C108 a b, C130, C131, C129, C133, C132, C120 a b, C122 a b, C118 a b and C301 a b.

The power transistors of this particular model were broken, and were replaced in the past by TI BD249/BD250 by
a repair man who did not know what he was doing, that are of course not the right transistors, so I removed and replaced them by correct transistors.
I used 2SA1694 & 2SC4467 of Sanken as you can see on the photo above, cheap and great performance, even better than the original.
The power-amp input capacitors need to be replaced: C118, they may be small polyester 4,7 uF 100V of Wima as on the photo.
The power supply main capacitors C134, C135 of 10000 uF (4700 uF in L200) need to be decoupled by small HF capacitors,
add 2x 0,01 uF 100V ceramic, parallel to C134 and C135.

I also did some experiments with different "loudness" switch capacitor values, as I found the loudness switching too agressive in the sound image.
I used 0.005 and 0.01 uF.

I found the muting circuit also to be vulnerable to defective parts, so I checked and changed the transistors and some other parts:
Q114, Q114a and Q115, R150,  R151 and D109 / C132, all can be defective in some cases,
check also working voltages of the caps in this circuit as I found some with incorrect values.

There may be some other things subject to modification, but this is the main mod I made.

 

Sound:

This amplifier is a member of the cheaper Luxman series, but very good in sound quality.

These series of "High Quality" audio components soon got ledgendary of their outstanding quality and excelent sound quality.

© Hans Hilberink - PE1MMK ® - Last update: 14-07-2010.