recapping sx-850 for my son

D2 cathode 66.5
D4 cathode 66.5
D1 anode -67.7
D3 anode -67.7
Don't use the hold mode when checking voltage. You need to ohm out the 3 transistors and see if any of them are shorted, in particular Q2. Unplug the 850 and put your meter on ohms and check between the collector and emitter, collector and base, emitter and base, and tell me what it reads in ohms. That will tell you if it is shorted.
 
Did you say that the emitter of Q4 is 17.35 volts? If so that Zener you put in there is not working. Are you sure you installed it correctly? Anode to emitter of Q4 and cathode to ground?
 
do you think the transformer needs to be looked at? Q2 collector goes directly to D1,D3 anode so not sure how we would drop the voltage after that. I took some more measurements.
pin no.
16. 34.38 AC
17. 47.01 DC
18. 47 DC
19. 34.36 AC
22. 7.76AC
23. 7.97AC
24. 8.33AC
25. 49.61AC
26. 49.53 AC
27. 21.1 AC
28. 21.04 AC
 
do you think the transformer needs to be looked at? Q2 collector goes directly to D1,D3 anode so not sure how we would drop the voltage after that. I took some more measurements.
pin no.
16. 34.38 AC
17. 47.01 DC
18. 47 DC
19. 34.36 AC
22. 7.76AC
23. 7.97AC
24. 8.33AC
25. 49.61AC
26. 49.53 AC
27. 21.1 AC
28. 21.04 AC
Q2 drops the voltage through biasing. Please forget about the transformer and D1, D2, D3 and D4. I already know that is working! Please tell me the voltage on the emitter of Q4.
 
Q4 emitter -17. I'll check the zeener diode.
Did you say that the emitter of Q4 is 17.35 volts? If so that Zener you put in there is not working. Are you sure you installed it correctly? Anode to emitter of Q4 and cathode to ground?
83 volts from cathode to Q4 emitter
cathode to ground 65.8
 
Q4 emitter -17. I'll check the zeener diode.

83 volts from cathode to Q4 emitter
cathode to ground 65.8
Cathode of the Zener should be 0 volts when measured to ground. That diodes Cathode MUST be soldered to ground, or it will not work! The emitter of Q4 is supposed to be 13.6 or so volts, not 17.35. Another thing, all voltages are referenced to ground.
 
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-17.35 yes
The Anode of the Zener diode is either not connected to the emitter of Q4, or it is not installed properly, or it is bad! OR, it is not the right diode!

Until you correct this problem, there is not much more we can do! The emitter of Q4 MUST be 13 volts.
 
I'll change it out with a new one. Glad I bought a kit so i would have plenty to spare.
Well now my concern is, why didn't the one you put in there work? Polarity is a must. Cathode to chassis ground and Anode to the emitter of Q4.
 
................B............C..........E
Q2 - 50.13.......-67.6......-49.54
Q4 -13.45........-50.16.....-12.93
Q6 -19.91.......-44.32......--17.44
 
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