Pioneer SX-980 No Relay Click
- Thread starter gpdavis
- Start date
Looks like Q3 (shorted), please post voltages:
q3 e s/b -13v is:
q3 b s/b -13.6v is:
q3 c s/b -50.0v is:
-71.4v to -71.7v = -0.4v across 6.8 ohms is 59mA. Not an exorbitant power load.
q3 e s/b -13v is:
q3 b s/b -13.6v is:
q3 c s/b -50.0v is:
-71.4v to -71.7v = -0.4v across 6.8 ohms is 59mA. Not an exorbitant power load.
Replace
Q3 2sa850
also because of potential overstress:
q4 2sb682
d9 mz-130
although considering the effort, a full rebuild of the board will not add much expense or effort, with an increase in reliability.
q1 2sd712 100v 4a 30w 55-300hfe 8mhz
512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
q4 2sb682 100v 4a 30w 55-300hfe 8mhz
512-KSA940TU pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
neither side is going to come close to an amp of current, no less 4 amps
q2 2sc1735 100v 0.5a 0.8w 55-300hfe 130mhz
512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17
q3 2sa850 100v 0.5a 0.8w 55-300hfe 130mhz
512-KSA1013YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17 (R=60-120, O=100/200, Y=160/320)
Q5 2sd712 512-KSC2073TU
q6 2sc945a eCb 50v .15a .25w 300mhz 40-700hfe
512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17
d8 mz-140 512-1N5244B Fairchild 14 V, 0.5W Zener
d9 mz-130 512-1N5243B Fairchild 13 V, 0.5W Zener
awr-164
c19,c20 4.7uf 50v 647-UPW2A4R7MDD 4.7uf 100v $0.14
c17,c18 47uf 16v 647-UPW1V470MED 47uf 35v $0.16
c24,c25 47uf 25v 647-UPW1V470MED 47uf 35v $0.16
c11,c12,c15,c16 220uf 80v 647-UPM2A221MHD 220uf 100v $1.02 ea
c13 220uf 35v 647-UPW1V221MPD 220uf 35v $0.28
c23 2200uf 35v 647-UPW1H222MHD 2200uf 50v $1.49 ea
---mouser bom tool --- entry text block ------
512-KSC2073TU
512-KSA940TU
512-KSC2383YTA
512-KSA1013YBU
512-KSC2073TU
512-KSC2383YTA
512-1N5244B
512-1N5243B
512-1N4748A|2
647-UPW2A4R7MDD|2
647-UPW1V470MED|4
647-UPM2A221MHD|4
647-UPW1V221MPD
647-UPW1H222MHD
right now there is a month lead time on the backordered ksc2383YTA, so ksc2383OTA can be substituted.
about 14 bucks in parts, with another 6 to 8 for shipping.
Q3 2sa850
also because of potential overstress:
q4 2sb682
d9 mz-130
although considering the effort, a full rebuild of the board will not add much expense or effort, with an increase in reliability.
q1 2sd712 100v 4a 30w 55-300hfe 8mhz
512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
q4 2sb682 100v 4a 30w 55-300hfe 8mhz
512-KSA940TU pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
neither side is going to come close to an amp of current, no less 4 amps
q2 2sc1735 100v 0.5a 0.8w 55-300hfe 130mhz
512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17
q3 2sa850 100v 0.5a 0.8w 55-300hfe 130mhz
512-KSA1013YBU to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17 (R=60-120, O=100/200, Y=160/320)
Q5 2sd712 512-KSC2073TU
q6 2sc945a eCb 50v .15a .25w 300mhz 40-700hfe
512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe $0.17
d8 mz-140 512-1N5244B Fairchild 14 V, 0.5W Zener
d9 mz-130 512-1N5243B Fairchild 13 V, 0.5W Zener
awr-164
c19,c20 4.7uf 50v 647-UPW2A4R7MDD 4.7uf 100v $0.14
c17,c18 47uf 16v 647-UPW1V470MED 47uf 35v $0.16
c24,c25 47uf 25v 647-UPW1V470MED 47uf 35v $0.16
c11,c12,c15,c16 220uf 80v 647-UPM2A221MHD 220uf 100v $1.02 ea
c13 220uf 35v 647-UPW1V221MPD 220uf 35v $0.28
c23 2200uf 35v 647-UPW1H222MHD 2200uf 50v $1.49 ea
---mouser bom tool --- entry text block ------
512-KSC2073TU
512-KSA940TU
512-KSC2383YTA
512-KSA1013YBU
512-KSC2073TU
512-KSC2383YTA
512-1N5244B
512-1N5243B
512-1N4748A|2
647-UPW2A4R7MDD|2
647-UPW1V470MED|4
647-UPM2A221MHD|4
647-UPW1V221MPD
647-UPW1H222MHD
right now there is a month lead time on the backordered ksc2383YTA, so ksc2383OTA can be substituted.
about 14 bucks in parts, with another 6 to 8 for shipping.
Last edited:
You're a lifesaver, mark! Thanks so much for taking the time to compile that list for me. I owe you a beer once this is all done with 
Quick question about R6. Should I go ahead and do the full replacement of it with the piggybacked resistors (as in, properly soldering them in)? There's no harm in leaving those in as a replacement for R6?
Quick question about R6. Should I go ahead and do the full replacement of it with the piggybacked resistors (as in, properly soldering them in)? There's no harm in leaving those in as a replacement for R6?
arrrgh - I gotta add the resistor...
they were for testing only. lotsa reasons why.
edit - jeezze you almost gave me a heart attack... that's R EIGHT!!!
6.8 ohms 1/4 watt carbon film flameproof
660-CFP1/4CT52R6R8J
they were for testing only. lotsa reasons why.
edit - jeezze you almost gave me a heart attack... that's R EIGHT!!!
6.8 ohms 1/4 watt carbon film flameproof
660-CFP1/4CT52R6R8J
Last edited:
Shit, sorry about the typo. I triple check these things before I replace or measure components, but I was clearly being hasty in my response. Didn't mean to freak you out.
I already placed my order for the other components. Can you elaborate on why those resistors in parallel shouldn't be used permanently? I called an audio repair shop in the area to see if they had the replacement resistor, and the guy seemed insistent that there's some leeway in the ohmage and recommended I just use two 12ohm or 15 ohm resistors in parallel if I can't find the 6.8ohm locally. But I know there must be a reason you don't recommend leaving those in, so I wanted to ask why. Just trying to avoid paying another $7 in shipping for a single resistor if at all possible.
Thanks!
I already placed my order for the other components. Can you elaborate on why those resistors in parallel shouldn't be used permanently? I called an audio repair shop in the area to see if they had the replacement resistor, and the guy seemed insistent that there's some leeway in the ohmage and recommended I just use two 12ohm or 15 ohm resistors in parallel if I can't find the 6.8ohm locally. But I know there must be a reason you don't recommend leaving those in, so I wanted to ask why. Just trying to avoid paying another $7 in shipping for a single resistor if at all possible.
Thanks!
Parallel increases wattage, and these are intended to act as SHTF fuses.
Putting two in parallel doubles the amount of energy needed to pop one of these. That's why they are small, 1/4 watt, and carbon film. They are intolerant of overload.
That's also why they are "flameproof" - which really is just a varnish coating that suppresses flame and just smokes like a volcano.
Carbon comp could short out while burning, which is why they are not used in a power circuit interrupter / protection function.
Putting two in parallel doubles the amount of energy needed to pop one of these. That's why they are small, 1/4 watt, and carbon film. They are intolerant of overload.
That's also why they are "flameproof" - which really is just a varnish coating that suppresses flame and just smokes like a volcano.
Carbon comp could short out while burning, which is why they are not used in a power circuit interrupter / protection function.
Ah, I see. So that must have been what happened then; the shit hit the fan.
Okay, I'll make sure to get the proper flameproof resistor then. Is it also critical that it's made of carbon film and not metal film? My university has an IEEE lounge where they sell components, and I'm going in to pick it up tomorrow, but I'm not sure about the specifics. The site just says they have 6.8ohm 1/4watt resistors.
Another question: I used the part list you provided to make my order, and I noticed you included two 512-1N4748A diodes, but didn't detail which components they're intended to replace. I triple checked the rest of the components to make sure they're correct before I begin replacement, and I noticed these didn't have corresponding parts listed.
Okay, I'll make sure to get the proper flameproof resistor then. Is it also critical that it's made of carbon film and not metal film? My university has an IEEE lounge where they sell components, and I'm going in to pick it up tomorrow, but I'm not sure about the specifics. The site just says they have 6.8ohm 1/4watt resistors.
Another question: I used the part list you provided to make my order, and I noticed you included two 512-1N4748A diodes, but didn't detail which components they're intended to replace. I triple checked the rest of the components to make sure they're correct before I begin replacement, and I noticed these didn't have corresponding parts listed.
4 zeners on board.
2 are 1/2 watt 14 volt voltage references
these 512-1N4748A diodes are 22v 1 watt zeners (D10, D11)
this was a total replacement parts list from my notes, bulk copied. They snuck in.
2 are 1/2 watt 14 volt voltage references
these 512-1N4748A diodes are 22v 1 watt zeners (D10, D11)
this was a total replacement parts list from my notes, bulk copied. They snuck in.
yes. it was just that mouser didn't have any.
if not flameproof, no problem. metal / carbon film and 1/4 watt are the important factors.
if not flameproof, no problem. metal / carbon film and 1/4 watt are the important factors.
Well, I replaced the necessary components last night and it works great! I'm going to wait to replace the rest until I can get one of my EE friends to help me, since I'm not the best at soldering and I don't want to risk ruining the pads in an attempt to increase reliability.
Thanks so much, Mark. I really appreciate you taking the time to walk me through this
Thanks so much, Mark. I really appreciate you taking the time to walk me through this
Mark I am also an owner of a SX 980 with protection circuit issues. Unit does power up but protection fires somewhat randomly. I checked DC on output. Was -.240 and + .335V. I adjusted the offset pots and got to under .015V. I checked and adjusted the bias current to 30mV (across the two .5 ohm emitter resisters ) is 30mA was only slightly off. Still get the relay to trip. Looking at pin 4 on the PA3004. I can see that it is normally close to zero .013V. There are 3 paths to that pin/ C2 cap. The left and right channel outputs looking for DC offset through 75K resistors. I do not find any voltages on speaker output (before relay contacts)that look out of line when it triggers (relay opens) but voltage on pin steps up to a couple of volts and then discharges and relay closes. I don't think this is the problem path. The third path is the output transistor protect path driven by Q1 on AWM 124. His base is at about 21VDC and my multimeter (Fluke) can see it spike low. Voltage on PA3004 pin 4 charged and then discharges. This circuit is driven by Q8 on each channel AWH 077. Looks like open collector ORing.
This circuit looks like it is monitoring emitter current across R18 and R19. With scope I watch that voltage (which is the idle current DC plus audio). I cannot see a spike on either channel but my scope is not a storage scope. I noted that the output transistors Q101 and Q102 are off board and on the heat sink. They are connected by Molex style connectors (Qty 4). I pulled them and found black oxidation on all 3 pins. I cleaned the pins, seemed to help, but still trips. Tried to clean the female connector inside the housing with Deoxit. I then added a small amount of silver conductive grease. Rep rate is now once an hour. By the way this amp will run with the output transistor pairs disconnected and still makes sound. via Q6 and 7. In this mode relay does not fire. But connecting both transistors on left channel still trips. Or connecting both on right channel still trips (Left channel disconnected).
So I am still not sure which channel is the issue. I am about to disconnect pin 2 on AWH 077 left which goes to AWM 124 pin 4. I think it should run but I could fry a speaker/transistor since protection is now disabled for that channel. But only way I see to try to limit search to one board or indicate a common problem (power?spike +- 53V). I have removed and cleaned all fuses and cleaned fuse contacts.
Please shoot down any assumptions you find incorrect. Any commonly failing parts in this circuit? I have tried to do everything I can think of before bothering you. Thanks, my name is also Mark and I had to dissolve my dads estate also.
This circuit looks like it is monitoring emitter current across R18 and R19. With scope I watch that voltage (which is the idle current DC plus audio). I cannot see a spike on either channel but my scope is not a storage scope. I noted that the output transistors Q101 and Q102 are off board and on the heat sink. They are connected by Molex style connectors (Qty 4). I pulled them and found black oxidation on all 3 pins. I cleaned the pins, seemed to help, but still trips. Tried to clean the female connector inside the housing with Deoxit. I then added a small amount of silver conductive grease. Rep rate is now once an hour. By the way this amp will run with the output transistor pairs disconnected and still makes sound. via Q6 and 7. In this mode relay does not fire. But connecting both transistors on left channel still trips. Or connecting both on right channel still trips (Left channel disconnected).
So I am still not sure which channel is the issue. I am about to disconnect pin 2 on AWH 077 left which goes to AWM 124 pin 4. I think it should run but I could fry a speaker/transistor since protection is now disabled for that channel. But only way I see to try to limit search to one board or indicate a common problem (power?spike +- 53V). I have removed and cleaned all fuses and cleaned fuse contacts.
Please shoot down any assumptions you find incorrect. Any commonly failing parts in this circuit? I have tried to do everything I can think of before bothering you. Thanks, my name is also Mark and I had to dissolve my dads estate also.
