sx 1050 protect circuit issue

[maclvrbr]

DC offset and bias are good however speaker relay has been engaging then disengaging a few times then not at all. I have a solid constant 60 volts coming in and -2 on pin 2. I desoldered base of q7 relay then engages. Went ahead and replaced q5 and q6 all soldered in but relay will not engage. Any help troubleshooting is appreciated. I do have a DBT in circuit running dim, thanks

 

[petehall347]

doesn't make sense .. q7 base needs to be switched on for the relay to click .
maybe you meant q6 ?

 

[petehall347]

-2 on pin 2 is the problem ..it should be -13v

 

[petehall347]

check voltage at pin 7 power supply -13v

 

[maclvrbr]

I apologize I am getting -12 at pin 2.

 

[petehall347]

i have seen a few times where q1 q2 are the culprit with this circuit .

 

[maclvrbr]

Should I remove and check them or can they be checked in circuit? thanks

 

[petehall347]

best removed . but maybe better checking other marked voltages as shown on schematic first

 

[maclvrbr]

Will do thanks

 

[maclvrbr]

Q 7 b=8mv, E=.4mv, C= 57v, Q 6 B= .7v, E= .4mv. C= 8mv. Q3 and Q4 emitters are steady at-.4v. Seems I am not getting positive 9 volts to Base of q7 or q6. I have not taken q1 and 2 out to test yet, thanks

 

[petehall347]

Q5 ?

 

[petehall347]

Q6 base should be negative .

 

[merlynski]

Pull Q1 and Q2 on Prot board, then power up, no input, volume minimized, see if relay pulls in. Replace with 512-KSC1845FTA from Mouser (or wherever you choose).

 

[maclvrbr]

Thanks guys so very much replaced Q1 and q2 and Its singing again. I oulled 1 leg of D8 and relay engages. Again thanks guys and Merry Christmas for unto us a son is born.

 

[petehall347]

so are you saying everything installed and now working ?

 

[maclvrbr]

yes I am and thanks. Sorry was unclear I first pulled 1 leg of d8 eliminating q1,2 powered on and relay engaged. Replaced q1 and q2, now working well, thanks

 

[petehall347]

well done

 

[maclvrbr]

Can't do it without you guys