Luxman L-430 faulty or not ?

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Chavagnac
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#1 erstellt: 01. Feb 2010, 23:36

As I like vintage amplifier I bought a Luxman L-430 which was faulty; i am not the first user
Frequently, due to direct voltage on the left channel, the output relay switched.
After spending lot of time i found the problem: the variable resistor was faulty.
This one (22K)adjust the offset of the output, with two resistors arround it. I have replaced the variable resistor.
Since few days it works, BUT
-----> on the service manual the value of resistors are 56K (R805 and R806) , on the printed circuit board the value are 5.6K. As they seems to be new, I wonder if it could be an error (the last owner try to repair it).

In order to have the best result I like to know who is faulty (service manual or resistor on printed circuit board)

Another thing: service manual seems to be faulty too, on the L-430 PCB they are 6LED on a channel but shematic show 4.It seems that some parts are inverted (preamplifier)

Can somebody could help to solve my problem?

Danke
Dominique

shabbel
Inventar

#2 erstellt: 02. Feb 2010, 11:31

It is always diffcult to gain reliable information on the vintage Luxman audio gear. Best adress for Luxman service should be "K & N Audio-Video-Service". Maybe ask them.

Be shure you really set the voltage on both channels below 0,1 Volts after the Luxman has warmed up (15 - 30 min.)

If you like adjust both resistors, afterwards disconnect them and measure the resistance they have.

charlymu
Inventar

#3 erstellt: 02. Feb 2010, 12:02

Here the adress

http://www.kn-service.info/index.html

Dieter is an Luxman-Expert.

greetings

Dirk

detegg
Inventar

#4 erstellt: 02. Feb 2010, 12:41

Hi Dominique,

nice to have you here!

First of all, I don´t own the L-430 nor I´ve the manual.

The R805/806 are in series with the VR22k ?! The VR provides the base voltage to the correspondent offset-transistor?!
Then 56k - 22k - 56k should be the accurate values.

:-) Detlef

[Beitrag von detegg am 02. Feb 2010, 12:43 bearbeitet]

Chavagnac
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#5 erstellt: 02. Feb 2010, 20:12

Hallo,

Thanks for responses, i am happy to read them.
Yes i have adjusted outputs to have in average 5mV.
Yes R+VR+R adjust the offset.

In fact I have made and error.
The service manual don't tell values for R+VR+R.
On service manual 56K are in paralell of them, but on my PCB 56K are not in place (so 5.6K +VR22K +5.6K could be the right values)
I don't know if i am clear. I try to post a photo but Goethe langage is not easy for me!
I will contact Dieter to ask him.

(for informations my Luxman drives Cabasse Drakkar speakers whit a tweaked CD723 Philips and for me it sound great!)

Danke
Dominique

Chavagnac
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#6 erstellt: 02. Feb 2010, 21:47

Hallo

http://s2.directupload.net/file/d/2058/kzbi34yb_jpg.htm

so:
R803 and R804 are not on the printed circuit board.
Service manual says it should be 56K.

R805=R806=5.6K
VR801=22K

Service manual do not indicate any value for this resistors.
Can somebody open his superb amplifier and tell me what are those values?

Danke

detegg
Inventar

#7 erstellt: 03. Feb 2010, 11:17

Dominique,

I´ve just placed a link within the Luxman-Fan-

Forum. May be there is someone who can help you with your specific problem.

:-) Detlef

Chavagnac
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