• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

SX-850 Intermitant Crackle

Stevesmullen

Stevesmullen

Well-Known Member
Hey All.
I have a SX-850 with a random crackle out of the speakers.
DC balance has been set to 0mv and Idle current is at 20mv.
Thanks Steve
 
Register to hide this ad
Stevesmullen said:
Hey All.
I have a SX-850 with a random crackle out of the speakers.
DC balance has been set to 0mv and Idle current is at 20mv.
Thanks Steve
Click to expand...

Both channels at the same time? Use headphones to see if it is mono (like it's in the middle of your head), which would be power supply. If switching into and out of mono doesn't affect it, then it's after the switch.

disconnect the pre-power jacks and see if the amp(s) crackle without the preamps.

if one channel, use the pre-power jacks with cables to swap sides and see if it moves.

If it's the preamps, turn off the tone control and see if it goes away, and turn off the high and low filter buttons as well.

I am assuming deoxiting has been done....

look at the block diagrams in the front of the 950 manual, and see what I'm talking about in terms of signal flow.... they're close enough (850 & 950) that the manuals can sub for each other a lot, plus the 850 manual is a disappointment.
 
Hey Mark.
The previous owner was using it as a Preamp only for this reason.
At this point it is very random (once every 30 minutes or so).
I have not deoxit myself as it was supposedly just done and all controls are quiet and smooth.
Given that it appears to only do it after the jumpers that seems to eliminate alot of would be suspect circuits.
Sorry I did not mention this in the first post (thought of it as I was driving home).
I will look at the block diagram and try to get a better idea of which side or sides when I can get it to act up.
Thanks Steve
 
sx-850 amp transistors and replacements

Stevesmullen said:
The Noise is not your normal scratchy dirty pot sound,it is a snap crackle pop sound.(no not the cereal kind:D)
Click to expand...


We KNOW it's in the power amps, BUT we need to know if BOTH channels are popping at the SAME time, which would mean the power supply is at fault.

Twenty20Man said:
mark..differential trannies ?
Click to expand...

Right, otherwise, if it's not the power supply, then it's the diffs... 2sa726's

well, here's them all just in case..... most are pretty cheap...

--- differential inputs
Q1 2sa726 to-92 bce 50v .1a .12w 100mhz 500hfe >>> KSA992
Q3 2sa726 to-92 bce 50v .1a .12w 100mhz 500hfe >>> KSA992
*** you need to get a bunch and match Q1 & Q3 hfe's for best performance.....
--- bias circuit
Q5 2sa818 case? ebc 180v .05a 1w 100mhz 70-240hfe >>> KSA910
Q7 2sc1628 case? ebc 160v .05a 1w 120mhz 70-240hfe >>> KSC2310
--- drivers
Q9 2sd381 to-220 bce 120v 1.5a 20w 40mhz 40-250hfe >>> KSC2073
Q11 2sb536 to-220 bce 120v 1.5a 20w 40mhz 40-250hfe >>> KSA940
--- outputs
Q13 2sd271 npn to-3 xxx 160v 6a 50w 5mhz 40-240hfe >>> MJ21194
Q15 2sb531 pnp to-3 xxx 160v 6a 50w 5mhz 40-240hfe >>> MJ21193


Thus, Fairchild parts numbers from mouser.com:

512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea

512-KSA910YBU to-92 ecb 150v .05a .8w 100mhz 40-240hfe $0.12 ea
512-KSC2310YBU to-92 ecb 150v .05a .8w 100mhz 40-240hfe $0.11 ea

512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
512-KSC2073TU_Q npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.53

863-MJ21193G pnp to-3 250v 16A 250W 4mhz 8-75hfe $4.10
863-MJ21194G npn to-3 250v 16A 250W 4mhz 8-75hfe $4.10
 
Hey Mark.
Im pretty sure that it was just out of the right channel but it doesnt do it all that often so I just need to run the stereo when I can pay attention to it.
Am I correct that if the power supply is okay that this isnt the kind of problem that you can go in and start testing suspect components it is better to narrow it down and then replace those suspect components.
Thanks Steve
 
Stevesmullen said:
Hey Mark.
Im pretty sure that it was just out of the right channel but it doesnt do it all that often so I just need to run the stereo when I can pay attention to it.
Am I correct that if the power supply is okay that this isnt the kind of problem that you can go in and start testing suspect components it is better to narrow it down and then replace those suspect components.
Thanks Steve
Click to expand...

The only sure way is to swap them between the channels until the problem moves, But that's not the only way...
so replace either group by group, or all at once.

The more intermittent it is, the harder it is to find. BUT you can heat and cool things to push it over the edge. The lower the q number, the more likely it is in this circuit.

Remember this: ? ( at $0.05 each, just swap them, if it goes away, you got it, and can match another pair & put them in.)

markthefixer said:
We KNOW it's in the power amps, BUT we need to know if BOTH channels are popping at the SAME time, which would mean the power supply is at fault.



Right, otherwise, if it's not the power supply, then it's the diffs... 2sa726's

well, here's them all just in case..... most are pretty cheap...

--- differential inputs
Q1 2sa726 to-92 bce 50v .1a .12w 100mhz 500hfe >>> KSA992
Q3 2sa726 to-92 bce 50v .1a .12w 100mhz 500hfe >>> KSA992
*** you need to get a bunch and match Q1 & Q3 hfe's for best performance.....


--- bias circuit
Q5 2sa818 case? ebc 180v .05a 1w 100mhz 70-240hfe >>> KSA910
Q7 2sc1628 case? ebc 160v .05a 1w 120mhz 70-240hfe >>> KSC2310
--- drivers
Q9 2sd381 to-220 bce 120v 1.5a 20w 40mhz 40-250hfe >>> KSC2073
Q11 2sb536 to-220 bce 120v 1.5a 20w 40mhz 40-250hfe >>> KSA940
--- outputs
Q13 2sd271 npn to-3 xxx 160v 6a 50w 5mhz 40-240hfe >>> MJ21194
Q15 2sb531 pnp to-3 xxx 160v 6a 50w 5mhz 40-240hfe >>> MJ21193


Thus, Fairchild parts numbers from mouser.com:

512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea

512-KSA910YBU to-92 ecb 150v .05a .8w 100mhz 40-240hfe $0.12 ea
512-KSC2310YBU to-92 ecb 150v .05a .8w 100mhz 40-240hfe $0.11 ea

512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
512-KSC2073TU_Q npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.53

863-MJ21193G pnp to-3 250v 16A 250W 4mhz 8-75hfe $4.10
863-MJ21194G npn to-3 250v 16A 250W 4mhz 8-75hfe $4.10
Click to expand...
 
--- differential inputs
Q1 2sa726 to-92 bce 50v .1a .12w 100mhz 500hfe >>> KSA992
Q3 2sa726 to-92 bce 50v .1a .12w 100mhz 500hfe >>> KSA992
*** you need to get a bunch and match Q1 & Q3 hfe's for best performance.....
--- bias circuit
Q5 2sa818 case? ebc 180v .05a 1w 100mhz 70-240hfe >>> KSA910
Q7 2sc1628 case? ebc 160v .05a 1w 120mhz 70-240hfe >>> KSC2310
--- drivers
Q9 2sd381 to-220 bce 120v 1.5a 20w 40mhz 40-250hfe >>> KSC2073
Q11 2sb536 to-220 bce 120v 1.5a 20w 40mhz 40-250hfe >>> KSA940
--- outputs
Q13 2sd271 npn to-3 xxx 160v 6a 50w 5mhz 40-240hfe >>> MJ21194
Q15 2sb531 pnp to-3 xxx 160v 6a 50w 5mhz 40-240hfe >>> MJ21193


Thus, Fairchild parts numbers from mouser.com:

512-KSA992FBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea
512-KSC1845UBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea This is the npn version of the ksa992, and is VERY useful.


512-KSA910YBU to-92 ecb 150v .05a .8w 100mhz 40-240hfe $0.12 ea
512-KSC2310YBU to-92 ecb 150v .05a .8w 100mhz 40-240hfe $0.11 ea

512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
512-KSC2073TU_Q npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.53

512-KSA1142YSTU to-126 ecb 180v .1a 1.2/8w 200mhz 100-320hfe $0.28 ea
512-KSC2682YSTU to-126 ecb 180v .1a 1.2/8w 200mhz 100-320hfe $0.31 ea


863-MJ21193G pnp to-3 250v 16A 250W 4mhz 8-75hfe $4.10
863-MJ21194G npn to-3 250v 16A 250W 4mhz 8-75hfe $4.10

With the amount of work you are doing I would get a LOT of the first four transistors ksa992, ksa910, ksc2310 & ksc1845 because they are both cheap and widely used all the way up to the driver stages of the power amps. Then I would get merely a bunch of ksa940 & ksc2073 because they can be used in a LOT of the power supplies as well as the power amp driver stages. I would also get some ksa1142 & ksc2682 transistors because they sub in at some useful spots.

Having all eight (in varying quantities) of these inexpensive transistors will be a leg up, in whatever pioneer stuff you do, on most of the boards. There are some extra other numbers to get, but as of yet I haven't needed any of them...
 
Hey Mark.
While Im waiting for parts I have been trying to track down why there is -36.3 volts at pin#15 of the voltage supply out to the EQ Amp pin#2 (desired-19).
I have replaced R17,18.
Voltages at Q6
Collector -50vdc
Emiter -36
Base -37
Voltage at pin#15 (-51.5)
Someone has been in here before me and replaced most of the transistors and C23.
The voltages look good at every other place that I could think to check the problem seems to be right at Q6,R17,R18 and C23.
The voltage is good (+28) on pin #6 of the EQ Amp
Any help would be greatly appreciated.
Thanks Steve
 
Stevesmullen said:
Hey Mark.
While Im waiting for parts I have been trying to track down why there is -36.3 volts at pin#15 of the voltage supply out to the EQ Amp pin#2 (desired-19).
I have replaced R17,18.
Voltages at Q6
Collector -50vdc
Emiter -36
Base -37
Voltage at pin#15 (-51.5)
Someone has been in here before me and replaced most of the transistors and C23.
The voltages look good at every other place that I could think to check the problem seems to be right at Q6,R17,R18 and C23.
The voltage is good (+28) on pin #6 of the EQ Amp
Any help would be greatly appreciated.
Thanks Steve
Click to expand...

Have you tried measuring the base voltage with Q6 removed? That's the first step. Have you tested Q6, or replaced it? Is it the correct polarity? 2sa is pnp....? as long as the cap isn't shorted or installed backwards (but that would LOWER the voltage). this is the simplest regulator circuit out there. I suspect the transistor, especially if the junction or R17 & R18 goes to -19v with the transistor out.


the phono amp's current draw is low enough that a 50 ma 0.8w ksa910 would work, or a bigger 100ma 1.2/8w KSA1142 if the 910 gets too hot (it shouldn't)
 
Hey Mark.
With Q6 removed the voltage does drop to the -19.And backfeed voltage at Pin#15 was only 5 volts or so.
I had removed and tested Q6 before and I just removed it and retested it and it still passes the DMM test.The polarity is correct (PNP).
Your right it is such a simple circuit that is why I couldnt understand the high voltage readings
I Had a new Q6 (ksa992fbu) and put it in there and it cured it,we now have -19vdc at pin#15.:banana:
I was going to replace Q6 next but I was just guessing at that point and I did not know the replacement# I tried to cross it it Mousers but came up with nothing.
As far as disconnecting a component and powering up the circuit I DO NOT do that unless I (we) have done it before or you tell me to do so.
Thanks Again.
Steve
 
Hey Mark.
The parts came in on friday and I finally had time to get back to it.
I went through the KSA992 transistors until I had a matched set for Q1 qnd Q3.
At that point I went ahead and replaced Q1,Q3,Q5,Q7,Q9 and Q11,(thanks for the pin layout in your parts list as Mouser.com did not have a data sheet for Q9 and Q11 replacement transistors).
Double checked everything and fired it up on the Dim bulb tester all looks good,so I plugged it in to full power and set the DC Balance and Idle Current.
So far it sounds great no popping and the Phono section is working.
I have New and used Q13s and Q15s left over from a SX-1050 repair if I need to replace those I will.
Who do I get with to get Backlight and function bulbs?
Thanks once again for your paitenece and skills.:thmbsp:
Steve
 
Stevesmullen said:
Hey Mark.
The parts came in on friday and I finally had time to get back to it.
I went through the KSA992 transistors until I had a matched set for Q1 qnd Q3.
At that point I went ahead and replaced Q1,Q3,Q5,Q7,Q9 and Q11,(thanks for the pin layout in your parts list as Mouser.com did not have a data sheet for Q9 and Q11 replacement transistors).
Double checked everything and fired it up on the Dim bulb tester all looks good,so I plugged it in to full power and set the DC Balance and Idle Current.
So far it sounds great no popping and the Phono section is working.
I have New and used Q13s and Q15s left over from a SX-1050 repair if I need to replace those I will.
Who do I get with to get Backlight and function bulbs?
Thanks once again for your paitenece and skills.:thmbsp:
Steve
Click to expand...

AK'er dgwojo, and give him a few days to respond (just in case)...
 
You must log in or register to reply here.

Similar threads

Stevesmullen
SX-850 SX-950 Fix for Phono Crackle
Replies
16
Views
4K
glen65
G
mizmazzle
Surge of sound on start up sx-850
Replies
2
Views
231
mizmazzle
mizmazzle
grindfix
Pioneer SX-727 Crackle and pop
Replies
12
Views
2K
jj1977
J
jimhannon
Pioneer sx-850
Replies
3
Views
556
merlynski
merlynski
BeEvil
Naked SX-850
Replies
5
Views
1K
BeEvil
BeEvil
Back
Top Bottom