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recapping sx-850 for my son

nackesww said:
I have recapped the power supply. I'll check on the resistors.
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Are you sure C20 is installed correctly? Check every cap in the power supply and make sure none of them are incorrectly installed. Especially C20. If the polarity is not right, it will bring the Q2 base voltage down with it. The base voltage has to be negative or -52 volts DC.
 
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nackesww said:
Thats it!! It is shorted. I'll have to order some.
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Good deal. D12 is a 13 volt 1/2 watt zener. I would go with a 13 volt 1 watt zener. The pioneer schematic shows it as D12. Just make sure it is the diode connected to the Q4 emitter.
 
I disagree with replacing the 500mW zener with a 1W part. The smaller current through a 1W part inhibits the purpose of regulating voltage past the knee of the curve.

ZD1: WZ-140 14Vz 500mW: TZX14B, TZX14C
ZD2: WZ-130 13Vz 500mW: TZX13C

If you sold this down the road and I saw a 1W zener where there should have been a 500mW part as the engineering team specified, I wouldn't trust any circuit in there.
Now is your chance to get in the habit of doing things right the first time instead of making compromising tech decisions.
 
deltalight said:
I disagree with replacing the 500mW zener with a 1W part. The smaller current through a 1W part inhibits the purpose of regulating voltage past the knee of the curve.

ZD1: WZ-140 14Vz 500mW: TZX14B, TZX14C
ZD2: WZ-130 13Vz 500mW: TZX13C

If you sold this down the road and I saw a 1W zener where there should have been a 500mW part as the engineering team specified, I wouldn't trust any circuit in there.
Now is your chance to get in the habit of doing things right the first time instead of making compromising tech decisions.
Click to expand...
Putting a 1 watt Zener diode in place of a 1/2 watt Zener diode will work just fine and will be more reliable! Quite a few components in Pioneer equipment are over rated. I know, I've done it too many times over the last 4+ decades.
 
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Good news!!!! the new Zener diode fixed it. The relay still isn't kicking in though. I'll check all the transistors on the protection board AWM-062 next. I'll post the new values of power supply 101 in case you think the numbers aren't right.
Black are my measurements and blue is what the measurement should be.

AWR-101
1. ground
2. 5.40 5.4
3. 5.36 5.4
4. 13.59 13.9
5. 13.60 13.9
6. 50.88 51.5
7. 50.12 51.5
8. 36.44 36.5
9. 36.47 36.5
10. 36.48 36.5
11. 27.67 28
12. ground
13. -17.30 -13.5 high
14. -64.15 -51.5 high
15. -23.12 -19 high
 
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Here is the pin measurements on the protection board AWM-062
1. -.12
2. -17.11 seems high should be -13.5 ?
3. -.14
4. ground
5. -.13
6. -.12
7. -.14
8. -.14
9. 36.33
10. 36.36
11. 36.37
12. AC 7.98

Could somebody please provide me with the what the values should be?
 
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The higher than normal voltage coming out of pins 13,14 and 15 started to really bother me, so I went back with my DIMM and checked the transistors Q2,4 and 6. And sure enough Q2 collector was OL. I'll change it out and hopefully the voltage comes down to where it should be.
 
Checking the measurements with my DIMM yesterday to see if changing out Q2 made a difference and ended up with a very depressing outcome. I didnt have power to half my circuit. I tossed my hands in the air and screamed. So after making another pot of coffee I went to work. After 6 hours of studying the schematics and testing components I found another burnt out zeener diode (WZ-140) and what surprised me was the new 2200 35v nichicon cap went bad, I had a reading of 2.15mf. Not sure what the mf is all about. I have every thing working again but the higher than normal voltage. Replacing the Q2 didn't make a difference, still getting OL, I didn't think it would bing it tested ok. I decided to get readings on all the transistors on the power supply to help me( or anyone else that might be willing to help) narrow down the problem. Even with all the problems I'm having I've certainly enjoying this project. I'm learning so much.


the top row is my measurements and what the correct voltage should be is beneath it.
red is high and blue is low.
AWR-101 transistors

B C E
Q1 51.27 65.59 50.72
........52.1 60.7 51.5
Q2 -64.39 -OL - 64.63
........-52.6 -62.8 -51.5
Q3 14.70 51.45 14.09
........15.2 52.1 14.6
Q4 -17.80 -65.87 -17.32
.......-14.1 -52.6 -13.6
Q5 36.94 41.92 36.35
........37.3 41.7 36.5
Q6 -24.51 -63.34 -24.03
.......-19.5 -50.6 -19
Q7 28.32 30.60 27.74
........28.7 35.2 28
Q8 14.22 26.75 13.59
........14.6 23.8 13.9
Q9 6.07 29.02 18.66
.........6 16.5 5.4
Q10 6.55 18.66 6.08
........ 6.6 16.5 6
 
1. Your fluke 87 V should not read OL when measuring voltage. Set the meter on DC volts and it should Auto range, and make sure it shows AUTO on the bottom of the display. This meter is capable of measuring up to 1000 volts DC.
2. Check Q2, Q4 and Q6 for short.
3. Mf means micro-farrad
4. Where is the 2200 Mf 35 volt capacitor located? What board?
5. Are you testing this capacitor in the circuit? If so, you must remove it from the circuit to test it. What are you using to test this capacitor?
 
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Hi 1MEGO . I've been using the auto hold feature on my fluke. Its a nice feature for testing live circuits. But oddly enough the collector on Q2 came back at -67.6 on auto mode. scratching my head over that one.
C12 capacitor went out and replaced it on the power supply 2.15mf was the reading i got after I pulled it out of circuit not the 2200uf like I was hoping.
 
New measurements on auto mode.

..........B..........C.........E
Q2 -64.33...-67.5...-63.90
Q4-17.71...-65.69...-17.35
Q4-23.42...-59.07...-23.45
 
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