recapping sx-850 for my son

[1MEGΩ]

Wish I would have seen your post earlier. Already took it out to replace it.

No problem. Can you check the resistance from pin 14 to ground? Also since the transistor is out of the circuit, check to see if it is open from base to emitter. Is there a diode test on your meter?

 

[nackesww]

2.28

 

[1MEGΩ]

2.28

What do you mean, 2.28?

 

[nackesww]

I set the meter to ohms and got 2.28 k resistance from pin 14 to ground

 

[nackesww]

Q 2 has been replaced. turn it on and check the voltage reading?

 

[1MEGΩ]

I set the meter to ohms and got 2.28 k resistance from pin 14 to ground

Very good. Just replace Q2 and that should fix it.

Yes turn it on now.

 

[nackesww]

hmmm...readings on pins 13,14 and 15 hasnt changed.

13. -0.01
14. -3.40
15. .28

 

[nackesww]

When I take a reading on Q2 collector and anything on that trace It will flash -60 volts and quickly drop down to -OL.

 

[nackesww]

I really appreciate the help you have given me and I feel bad for taking so much of your time.

 

[1MEGΩ]

I really appreciate the help you have given me and I feel bad for taking so much of your time.

No problem. Can you tell me what the DC voltage is on the base of Q2?

 

[nackesww]

B. -4.25
E. -3.52
C. -OL to -65 when I touch the lead to the collector it flashed -65 and dropped almost instantly to -OL

 

[1MEGΩ]

B. -4.25
E. -3.52
C. -OL to -65 when I touch the lead to the collector it flashed -65 and dropped almost instantly to -OL

I don't know what kind of meter you are using, but I assume OL means no reading? Leave the 850 powered up, check the voltage again on the collector of Q2, and when you see OL, check the voltage on the anode of D1 and tell me what that voltage is.

 

[nackesww]

I'm getting -OL on both Q2 collector and on the cathode D1

I have a Fluke 87V

 

[1MEGΩ]

I'm getting -OL on both Q2 collector and on the cathode D1

I have a Fluke 87V

Does the meter read OL when you aren't testing anything? Oh and you need to check voltage at the ANODE of D1, NOT the cathode! The Cathode of D1 is connected to the power transformer secondary and has AC on it.

 

[nackesww]

After going to Flukes website I made a change on my settings. Now at Q2 collector I'm getting -67.3 and it does not change.

 

[nackesww]

cathode -67.3

I love this new meter but not knowing everything about it will bite me in the ass

 

[1MEGΩ]

After going to Flukes website I made a change on my settings. Now at Q2 collector I'm getting -67.3 and it does not change.

Ok and what is the voltage on the base of Q2?

 

[nackesww]

Im sorry I meant anode

 

[nackesww]

base
3.92

 

[1MEGΩ]

base
3.92

Base should be 52 volts DC. There are two 1.5 k ohm resistors in series connected to the base and collector of Q2. Make sure they are not open. Also C20 could be shorted or leaking. you need to check this. Have you recapped the power supply?