K4040B ensemble du circuit sous haute tension

Kits Audio Hi Fi Projects
1

Traduction automatique …

Hello to all.
I am sorry I know how to speak and write only in French.
My problem:

My amplifier K4040B worked very well for 2 years.
I wanted to change tubes…
I went(took) up Electro-harmonix for 3 small tubes.
I went(took) up JJ ELECTRONIC for the EL34.
I put the regulations of bias at least.
At the end of 30 seconds, a resistance R 101 of the 10 ohms slammed(clicked).
The amplifier was extremely warmly. The tube EL34 seems to have held(liked).
I went back up(raised) a resistance.
I removed all the tubes and I took measures on the circuit.
All the high voltage parts(parties) are 425 V except R 84 and R 87 which should be 100 V and which are 0 V.
The part(party) low voltage is 7,4 V on SK3 and SK4 I do not find this low voltage on support of the EL34: some mV.
Please, help me, I like, I love my 4040 B
Merci.
Pierre.

Bonjour à tous.
Je suis désolé je ne sais parler et écrire qu’en français.
Mon problème :

Mon amplificateur K4040B fonctionnait très bien depuis 2 ans.
J’ai voulu changer les tubes …
J’ai monté des Electro-harmonix pour les 3 petits tubes.
J’ai monté des JJ ELECTRONIC pour les EL34.
J’ai mis les réglages de bias au minimum.
Au bout de 30 secondes, une résistance R 101 de 10 ohms a claqué.
L’amplificateur était trés trés chaud. Le tube EL34 semble avoir tenu.
J’ai remonté une résistance.
J’ai retiré tous les tubes et j’ai pris des mesures sur le circuit.
Toutes les parties haute tension sont à 425 V sauf R 84 et R 87 qui devraient être à 100 V et qui sont à 0 V.
La partie basse tension est à 7,4 V sur SK3 et SK4
Je ne retrouve pas cette basse tension sur les support des EL34 : quelques mV.

Please, help me, I like, I love my 4040 B
Merci. Pierre.

2

Why did you change the tubes, that is not necessary ?
Probably, you have turned the bias all the way up instead of down.
Check resistors and PCB tracks in 100V part of the circuit.
Filament voltage: make sure you measure on the correct pins. Check for mechanical problems such as interruptions of PCB tracks or wires.
CAREFUL: Measuring on a live amp is dangerous. You should not do this unless you have quite some experience. Even when turned off, the caps can remain at a dangerous voltage for a while. Be extremely careful. Keep one hand in you pocket at all times.
If you are unable to solve the problem, you can return the amp for inspection/repair.

3

Hello Electromaniac.
I make simple sentences to use an IT translator.
Please have fast answered my message.
I wanted to change tubes because it seems that those whom I bought are better (forums)
To replace an EL34 by another EL34 should not be a problem…
I verified all the resistances: they are good.
When the accident occurred, RV1 until RV8 was 0, to the left.
R101 of 10 ohms slammed (clicked).
F1 the fuse slammed (clicked).
It is everything… The circuit seems as nine.
I wonder if IC1 always works ?
I have enough knowledge to repair. Who can make him (it)? Where do I have to send the amplifier?
May I send also the tubes which gave the accident?
Thank you for your answer. My amplifier already misses me…
Very sincerely.
Pierre.

4

Sorry, but this electornic translation is terrible.
Please post in french, that is no problem for us.