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Luxman WL550/T550 FM tuner

 


 

General:

This Tuner was produced by Luxman corporation Japan in 1972.
This is one of the nicest tuners Luxman ever made and was widely sold.
Generously build and it has good reception capabilities and sound is good.
 


 

Scale ^

 

Special futures:

Muting switch - Noise switch - 2 tuning meters, also sold as T550.

 

Interior ^

 

Interior main pcb ^

 

FM IF section with discriminator and MPX ^

 

Predecessor WL500 (1971) ^

 

Schematic:

Click here to download the service manual diagram of the Luxman WL-(T)550 in PDF format

 

 

 

Modifications:

All electrolytic capacitors in the power supply can be replaced.
Some capacitors can be added to the power supply rail through the tuner to improve stability.

C272 & 277 of 0.47 µF can be replaced. Also C274 and C278 of 1µF, a better quality cap may improve the sound.

Also a anti birdies filter is employed by some local distributors as in the model above,
can be subject to upgrading or modification. (Audioscript Netherlands)
More simple and also effective anti birdies filters are possible. (Sherwood USA, Denon Japan)
On most of the anti-birdies filter boards low grade caps are used, you may replace them with high grade ones.
I made a modification to this little additional board, that made the sound even better.
Leaving it out of the circuit is the best solution, but your local FM reception situation must allow this.

The FM front-end is a good quality 4 gang variable capacitor, the IF is rather simple with 2 ceramic filters, 2 IC's and a set of coils.
The demodulator is a traditional diode-coil device. The MPX decoder is a NEC IC: µPC554C, that is proudly advertised
on the front of the tuner.

Users in Europe must consider to change the mains transformer tap used for the mains connection, it is historically set to 220V.
But since Europe is increasing main voltage to detrimental 240 V over a 20 years time frame, and now being on plus 230 V ~.
So using the 240 V tap is the most sane thing to do now.

The NEC & Toshiba IC's, µPC554C & TA7061P may suffer the same silver creaping desease as the old NEC transistors,
consequently the mpx stereo-decoding IC may brake down due to this phenomenon.
The NEC µPC555A has a metal can and gold-plated leads and will virtually last forever.

The main pcb is a small crowded board of medium quality, that has consequenses when exchanging aged parts,
check and recheck is the motto here: you may makes mistakes easely, luckely the copperside of the pcb is of good quality.

 

Sound:

Very good.

 

LUXMAN

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© PE1MMK Hans Hilberink last update:  15-09-2019.