'97 LM6100 bias

Hi
I just disassembled the amplifier. C209 is out of tolerance. I will change both C209 and C210. Then I will re-install the original resistors.
AMS ! Thank you so much for the help!
You are the master of the amplifiers.

Espera un segon. Encara hi ha alguna cosa malament. Se suposa que C 209 i C210 són condensadors electrolítics. Hi ha certa confusió.


Quin esquema utilitza? Podeu publicar fotografies de tancament de la pissarra?


No canvieu més parts fins que veiem la placa de circuit i mirem l’esquema. No toqueu més l’amplificador.



Wait a second.
There is still something wrong. C 209 and C210 are supposed to be electrolytic filter capacitors.
There is some confusion.

What schematic are you using?
Can you post close up pictures of the board?

Don't change any more parts until we see the circuit board and look at the schematic.
Don't play the amp any more.
 
Last edited:
Was a confusion C211 C212 with C209 C210.
Again I'm sorry.

Envieu més fotos perquè puguem veure tota la taula amb claredat.

Feu molta llum perquè no hi hagi més pregunta.

Post more pictures so we can see the whole board clearly.

Use plenty of light so there is no more question.
 
After replace C211 C212 and re-install 22k R213 I get 49,79 Vdc on pin 5. C211 was bad. Only 7,2 nf on a 47nf cap. All is ok.
Thanks a lot AMS.
 
After replace C211 C212 and re-install 22k R213 I get 49,79 Vdc on pin 5. C211 was bad. Only 7,2 nf on a 47nf cap. All is ok.
Thanks a lot AMS.


M'agradaria molt veure la placa de circuit només per estar segur. Però heu avançat bé, bon treball. Assegureu-vos que els condensadors C211 C212 tenen una potencia superior a 600 volts o superior.

I would really like to see the circuit board just to be sure.
But you did make some good progress, nice job.
Please make sure that the capacitors C211 C212 are rated 600 volts or higher.
 
Thanks AMS.
Stock C211 C212 are 47 nf 250vac class X caps. I installed 47nf 275vac class X caps. Right now I'm playing with It. I will post some board pics. On C209 C210 you can install radial and axial type caps.
 
Thanks AMS.
Stock C211 C212 are 47 nf 250vac class X caps. I installed 47nf 275vac class X caps. Right now I'm playing with It. I will post some board pics. On C209 C210 you can install radial and axial type caps.


Crec que és millor utilitzar els taps d’alta tensió per a C211 i C212. Això podria explicar per què fallen els taps.

I think you better use higher voltage caps for C211 and C212.
That might explain why the caps are failing.
 
Yeah! The bias is good. On these amp it's really important thing. Now the channel 2B 2C sounds great. Before fix It with a hot bias amp the channel 2B 2C sounded to bass and dull.
I think It sounds really good. The amp works and sounds like should be.
At least right now.
I'm happy. I hate have an amp with an issue.


:acoustic:
 
Thanks AMS.
Stock C211 C212 are 47 nf 250vac class X caps. I installed 47nf 275vac class X caps. Right now I'm playing with It. I will post some board pics. On C209 C210 you can install radial and axial type caps.


Volia agrair-vos els vostres esforços. Heu solucionat un problema amb molt de temps a l'amplificador 6100. Cada vegada que algú comet aquest tipus de falles, ajuda moltes altres persones. Hi haurà molts altres amplificadors solucionats i molts problemes resolts a causa dels esforços que heu realitzat. Sens dubte agraïm el vostre temps i dedicació, gràcies. Ara passarem aquesta informació a altres persones que tinguin el mateix problema.

Però volia esmentar que el condensador no hauria d’haver fallat. El condensador tipus X està pensat per ser altament fiable. Per a totes les reparacions futures, recomano augmentar la velocitat de tensió del condensador per millorar la fiabilitat a llarg termini. Si us plau, també utilitzeu un condensador tipus X per substituir-lo i no utilitzeu un condensador normal. El condensador de tipus regular no està pensat per a l'ús en circuits d'acoblament d'energia.

I wanted to thank you for your efforts.
You solved a long standing problem in the 6100 amplifier.
Every time somebody does this type of fault finding, it helps many other people.
There will be many other amplifiers fixed and many problems solved because of the efforts you have made.
We certainly appreciate your time and dedication, Thank You.
Now we will pass this information to other people who are having the same problem.

But I wanted to mention that the capacitor should not have failed.
This type X capacitor is intended to be highly reliable.
For all future repairs, I am recommending that the voltage rating of the capacitor be increased to improve long term reliability.
Please also, use a Type X capacitor for replacement, and do not use an ordinary capacitor.
The regular type capacitor is not intended for usage in power coupling circuits.
 
Many thanks AMS! The repair has ben possible because your support, knowledge, experience and questions on the amp issue.
Maybe if I install a big voltage caps on C211 C212 they will not fit properly on the board.

When I bought my JCM900 mk3 used It had red plate on power tubes. The culprit was a 47nf 250vac class x cap on bias circuit too. This time the cap was open.
 
Many thanks AMS! The repair has ben possible because your support, knowledge, experience and questions on the amp issue.
Maybe if I install a big voltage caps on C211 C212 they will not fit properly on the board.

When I bought my JCM900 mk3 used It had red plate on power tubes. The culprit was a 47nf 250vac class x cap on bias circuit too. This time the cap was open.


Voleu saber quina distància es troba entre els plats X? (en mm)

Do you know what the lead spacing is on those X caps? (in mm)
 
Not right now. I'll take measurements.


Vaig a intentar trobar alguns condensadors amb una tensió més alta que s’adaptin a l’espai entre els plats de la placa. Aleshores, podríem millorar la fiabilitat.

I'm going to try to find some higher voltage X rated capacitors which fit the lead spacing of the board.
Then we might be able to improve the reliability.
 
I think the problem will be lead spacing with both caps because they are to much close. I will post measurements and pictures.
 
Hi all, specially a Big Hello to AMS.

Yesterday I tested bias from my LM6100. I think It has an issue. It works and sound properly. Without power tubes I get on pin5 -49,33 Vcc to -39 Vcc in all 4 power tubes sockets. But when I put power tubes It has a high bias on V11. 455Vcc on plate. 36 mv on V8 V9 and V10. 42 mv on V11. Do is It correct? I think It has a problem on V11. :unsure:
Thanks.
 
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