SX-950 Relay Bypassed and Burnt Resistors

[petehall347]

looks like a connection issue then from pin 12 protect to pin 23 power supply .

 

[Pageplayer]

My mistake... There is 5.8v AC on both pins. I forget to fill in that cell. Previous post image updated

 

[petehall347]

protect circuit
q6 and q7 base voltages ?

 

[Pageplayer]

Q5 a733GBU
B: 13.2v
C: 0.28
E: 13.8v
Q6 2383YTA
B: 0.28v
C: 1.70v
E: 0
Q7 c2690
B: 3.5v
C: 25.5v
E: 3.5v

 

[petehall347]

something is odd here .. q6 collector should be same as q7 base as they connect together .
q5 emitter should read less than its base ..
q6 should have -1v at its base but it at least shouldn't be turning on .it needs to be off
q7 should be on with 3.5v at its base so i suggest replacing q7 first
did you also change q3 and q4 ?
make sure all transistors are correct way round .
also check r28 . 220 ohms

 

[Pageplayer]

Yes.. Q3 & Q4 we're also changed at the time I did protect board, along with Q1&2 which are both c1845's
Q1 c1845
B: 0.01v
C: 12.9v
E: 0.001v
Q2 c1845
B: 0.01v
C: 12.6v
E: -0.005v


Q3 c2383
B: -0.01v
C: 12.8v
E: -0.56v
Q4 c2383
B: -0.01v
C: 12.8v
E: -.0.56v
-------------
Another set of readings to verify
Q5 a733GBU
B: 13.2v
C: 0.28v
E: 13.8v
Q6 2383YTA
B: 0.27
C: 4.77v
E: 0
Q7 c2690
B: 3.5v
C: 26.6v
E: 3.3v

 

[petehall347]

test r28 first .if good try a new q7 .

 

[Pageplayer]

R28 checks at 218ohms..
Pulled Q7, checks good, but replaced anyway.

REcheck of voltages.. off the DBT.
Power Supply
Pin
1. 0v
2. 5.8v
3. 5.8v
4. 13.1v
5. 13.1v
6. 48.6v
7. 48.6v
8. 34.7v
9. 34.7v
10. 34.7
11. 26.7v
12. 0
13. -14.6v
14. -54.89v
15. -19.8v

Protect Board
1. -.04v
2. -14.6v
3. -.05v
4. 0v
5. -.06v
6. -.02v
7. -.04v
8. -.07v
9. 8.26v
10. 34.7v
11. 34.7v
12. 7.65v AC

 

[petehall347]

34.7 -8.26=26v across the relay coil .. to check i worked that out now measure voltage between pins 13 and 14 protect board .

 

[Pageplayer]

Do you mean put a positive probe on 13 and negative on 14?

 

[petehall347]

other way round but wont matter unless you are using a swing meter ...
13 will be more negative than 14 ...

 

[Pageplayer]

Protect board only has 12 pins
Power Supply?

 

[petehall347]

sorry .. protect 9 to 11 ..9 will be more negative ..

 

[Pageplayer]

Negative on 9, (+) on 11, 25.3v

 

[petehall347]

relay should be clicked in then .. must have a mechanical issue and most likely why it was bypassed in the first place .. or maybe not quite the first place ...

 

[petehall347]

just in case please check volts between relay board pins 13 and 14 .. maybe bad solder at the relay to check too .
pin 13 more negative

 

[Pageplayer]

The relay is on at this time. But as mentioned, it intermittently started shutting down, and those protection board voltages have me concerned.

 

[petehall347]

sorry but off dbt i didn't see any problems .
which voltages are bothering you ? maybe i missed something ?

 

[Pageplayer]

This is a fresh set off DBT...


Are these highlighted values ok?

 

[petehall347]

yes look fine to me ..only thing i see wrong is voltages on the right column .