Sansui AU-X901 voltage problem.

[Hyperion]

All 4 trimmers set at 14mv across their respective resistor. Is this ok for further testing?….I hate to connect to normal power and then fry something…

Just turn the bias down until it is just noticeable on the meter say 2mV (remember to do all four!!) - then switch to full mains... and re-adjust.

 

[anderslober]

Ok..will do. How important for full power start-up is the hot/cold/earth/speaker procedure?

 

[anderslober]

Full power applied….same stuff….still blinking in protection. The main rails are +28.5vdc and -26.8vdc…seems low…..should be near 35vdc.
Nothing frying or burning…..I am stumped atm. All lights/selectors work as they should. I dunno’ what I am overlooking/missing….

 

[anderslober]

The ONLY tr that was blown was q6. Base voltages are not good….still to high q54/q55/etc. I have changed the 4 100ohm resistors each side. All others measure completely normal. Am I looking in the right place? On the E and B of the right channel main outputs, I have +/-11-14vdc. Could it be coming from the small protector boards?

 

[anderslober]

Ok guys…with a probe at the kathode of d53, I adjusted vr2 from about -11vdc to -1.8vdc(as on scat)…and BAM…..relay clicked! No more blinking! I think the owner self-adjusted all the adjusters completely out of whack…..anyway, hopefully recovering now! Ok….we continue!

 

[anderslober]

3mv each side at the speaker terminals! I am happy. MANY adjustments on this amp! Very, very sensitive trimmers. Vr1/vr2 both sides was waaaaaay of…..soon music test!