Sansui 9090 help!

[jFF_Bulbo]

Hello AKers

I am working on a 9090 unit, previosly not-so-good repaired.
After recap and resolder al the bad joints, i still having the problem before i treated the unit:

Sound come and go with some volume, more that 25% volumen and the unit behave as in the video:

https://youtube.com/shorts/PCpy4_FZtqI?feature=share

(hope link works.....)
What i´ve done:
-recap all the unit except FM/Am Section
-main caps news, 12000uf/100v instaled

I´ve tried:
On board F2547 all the mods are done. new 10a/250v fuses installed, 2SC1211 transitors replaced with C2383.
On board F2436-1 all the mods done except 7a 125v fuses (i can´t get them here...)
I tried to replace the C1722/A849 with C2690/A1220 transistors.... no success... witc c2690/a1220 unit makes a horrible pop at start....

Many bad soldering works on previos repair..... tjis unit deserve a second gold era.


Thank you in advance for you help.

 

[Hipocrates]

https://youtube.com/shorts/PCpy4_FZtqI?feature=share

Pos que onda?!

Remove the DBT
Then, adjust bias and offset

 

[w1jim]

Is the fm mute engaged?

 

[jFF_Bulbo]

Is the fm mute engaged?

hello.
the malfunction is present on AUX input too......

 

[jFF_Bulbo]

Pos que onda?!

Remove the DBT
Then, adjust bias and offset

i will try... but DBT is for a secure start. any other units hasn´t had problems working pluged to DBT...

regards

 

[AE Bob]

It takes a lot more power coming in the power cord to produce loud output. That additional power requirement is lighting your DBT, causing the symptom. The power amps begin to draw power, the DBT lamp lights, causing the power to the unit to drop, causing the internal voltages to drop, which causes the symptom. Take it off the DBT and it should work properly.

 

[jFF_Bulbo]

[QUOTE = "AE Bob, publicación: 15209035, miembro: 141080"] Se necesita mucha más energía en el cable de alimentación para producir una salida fuerte. Ese requisito de energía adicional está encendiendo su DBT, causando el síntoma. Los amplificadores de potencia comienzan a consumir energía, la lámpara DBT se enciende, lo que hace que la energía de la unidad disminuya, lo que hace que los voltajes internos disminuyan, lo que causa el síntoma. Quítelo del DBT y debería funcionar correctamente. [/ QUOTE]
THANK YOU A LOT!!
I PLUGGED TO 120V AND SOUNDS AMAZING!!!
Definitively a 9090 is a "must have" unit, i love this unit.

regards