Luxman L410 Elkotausch

Poetry2me hat recht!! Manchmal vergisst man hier seine guten Umgangsformen.

Sorry!!

Mein Beitrag war absolut nicht als Spott gemeint, sondern versucht lediglich zu erklären, wieso mancher ewige Zeiten sucht und sucht, wo jemand mit viel mehr Erfahrung (und einem sinnvollen Messgerät) das Ganze in wenigen Minuten hätte klären können. Erfahrungen mus man schließlich erst einmal sammeln...

Grüße
Lennart

Hallo in die Runde,

ich nehme es gelassen und freue mich über die gelungene Reparatur und bedanke ,mich für eure Hilfe, ohne die es nicht geklappt hätte. Die Vorstellung, dass der Fehler außerhalb des Gerätes zu suchen war, war mir so fremd, dass ich da erst ganz zum Schluss drauf gekommen bin. Als Laie kennt man natürlich auch nicht die systematischen Fehlersuchverfahren.

Dank an die Runde und bis zum nächsten Mal. Ich habe noch einen Thorens Plattenspieler, der auch etwas Zuwendung braucht.

Liebe Grüße

luxi124

Hello . Can you tell me the value of resistors R901a,b and R902a,b? For example, the manual says that R901a,b have 120 ohm 1/2W. In the amplifier it seems that this resistance has another, lower value. But does R902 have the correct value of 4.7 ohms from the manual?

Please forgive me, I am not an electronics technician and German is not my native language.

When You look at the head of the table (parts list) you will see, that one row is for the L410 and theother for the L430.

L410:
R901a/b 120Ohm (measured on pcb: ~112Ohm)
R902a/b not existent

L430:
R901a/b: not existent
R902a/b: 4,7Ohm

As I just have a L410 with open case on my working bench, I checked it. The service manual is correct - as written above.

p.s.
If R901 is not 120Ohm but about 10Ohm, both power transistors are short.

CarlM. (Beitrag #56) schrieb:

When You look at the head of the table (parts list) you will see, that one row is for the L410 and theother for the L430. L410: R901a/b 120Ohm (measured on pcb: ~112Ohm) R902a/b not existent L430: R901a/b: not existent R902a/b: 4,7Ohm As I just have a L410 with open case on my working bench, I checked it. The service manual is correct - as written above. p.s. If R901 is not 120Ohm but about 10Ohm, both power transistors are short.

I put a 120 ohm resistor in place of R901b but it caught fire immediately. Can you give me a picture of channel a and b? Maybe another resistor is missing from that board.

It would be more helpful if you would make photos. Use IMG-function to put them into the thread.

power amp: both sides of pcb (= soldering side as well).
main pcb: both sides
In many cases the main reason is located on the main-board.

BTW. you should put a normal bulb (230V~ 60W) into the phase of the power cable. This will limit the current to less than 0.25A.
If the bulb lits brightly ----> shortcut.

@CarlM. thank you for your help .

dadix (Beitrag #57) schrieb:

I put a 120 ohm resistor in place of R901b but it caught fire immediately. Can you give me a picture of channel a and b? Maybe another resistor is missing from that board.

ATTENTION !!

R901b (b = right ch) is the main working resistor of the driver stage and must have the value 120 Ohms (1/2 Watt), no matter what version, L-410 or L-430 !!!
I would say the parts list has an ERRATUM regarding the difference in R901 value. There is no way, this resistor can be 4,7 Ohms !!
Even in our "upgrade" projects L-410 to L-430 we never exchanged this resistor when putting in an additional pair of power transistors.

BTW: It has an "F" marking in the schematic which I think means it is a Fuse Resistor type. These age much faster and should be replaced anyway if exposed to constant heat. I replaced these with normal metal film resistors in my own L-410.

- Johannes

If R901b goes up in smoke after replacement there seems to be transistor damage in at least one power transistor (Q903b, Q904b) or driver transistor (Q901b, Q902b).

Hier findet sich der Schaltplan eines Endstufenkanals mit farblich markierten Stufen und Spannungsangaben.

http://www.hifi-foru...d=18913&postID=22#22

Da "dadix" definitiv einen L410 besitzt, interessieren aktuell die den L430 betreffenden Fehler nicht. Deshalb schreibe ich dazu auf deutsch.

Es ist korrekt, dass die parts list diverse Fehler beinhaltet. In den mir bekannten Fällen ist dann der zugehörige Schaltplan zu konsultieren.
1. Es ist korrekt: auch der L430 besitzt R901 mit 120 Ohm 1/2W (fehlt in part list)
2. Es ist nirgends geschrieben worden, R901 durch einen Widerstand mit 4,7Ohm zu ersetzen.
Es geht um R902 (und auch R905) 4,7 Ohm 1/2W die in den Zuleitungen zu den Basen der zusätzlichen Transistoren sitzen und deshalb nur beim L430 vorhanden sind.
3. In der Folge sind weitere Fehler vorhanden, die u.a. R906 120Ohm (korrekt) angegeben 220Ohm betreffen.

Danke für die Klärung

Q901b, Q902b are ok, they are not short-circuited.
I found the Q903b damaged and changed it. But R901b, which I set to 120 ohm, still burns.

As I wrote above:
Shoot some photos and use the IMG-function to load them up into the thread :
p.c.b. of the power amp and main p.c.b. (including the soldering side).

Uploading photos:
- press Img



- choose options as in the graphic
- choose photo to upload (one photo)

You have to repeat the procedure for each photo.

Typical damage I used to find in Luxman L-410:

http://www.hifi-foru...ead=16618&postID=4#4
try translating all troubleshooting hints in this thread.

Make sure that the resistors on the "motherboard" R824b/25b/26b are ok. These I have seen damaged many times.

You should definitely check the Emitter resistors R908b und R909b near the power transistors.

Next, check all parts of the over-current protection:
Q907 /Q908 /Q909 /Q910 b, inluding all surrounding resistors and the diodes.
These parts ususally sacrifice themselves and burn through.

Another frequent problem with Luxman L-410/L-430 is that through years of thermal stretch & shrink the most TO-126 transistors on the motherboard have bad solder joints and thus cause multiple different serious damages, depending on the which solder joint is affected first.
TO-126 transistors are the flat types, mainly in stage 3 (red) and four (green).

I redid all the soldering and even replaced the electrolytic capacitors, about 3 years ago.
I think I'll take it to someone who knows how to fix it before I completely ruin it.

Thank you @CarlM. and @Poetry2me for the time given and the information provided.
I wish you all a Happy New Year!

Just curious if you had it repaired meanwhile and what the problem was in the end.

- Johannes

Hello . I sold the machine. I moved on and purchased other machines. The audio journey continues. I can say that I liked the sound of this unit and in the future I may buy another Luxman unit, maybe not the same model.