Sx 980 not working, no ac reading from pin 1???

parkus33

parkus33

Member
Hello to all the Pioneer experts. hope I can have some help and guide to fix SX 980 here. first of all, sorry for my broken English skill. English is not my native language. [emoji27] Anyway, I got non working SX 980 from local craigslist. light on but no sound and no relay kicking. I read couple forums about repairing SX 980 here. I opened SX 980 and tried to read DC and AC on AWM 124 by DMM and no AC reading from pin1. there is no reading coming from pin14. so far i found these numbers:

pin 10 +71 dc
pin 9 +9v dc
pin 2 -51v dc
pin 1 no reading AC

can anybody kindly guide where I start to repair my SX980?
thanks for your consideration. :)
 
Last edited:
Thanks for your reply. I did continuity test for fuse and found it is still okay. I will check connection for fuse holders and let you know soon. Thanks again for your help. ^^
 
check ac volts at fuse holder .if still not there trace back to wire from transformer and test there .
 
While I trace back all connection from transformer, by somehow I got ac reading, 19.8 from pin1

I checked voltages for AWM 124 again and now I got

P10 +71 Vdc

P9 +13.51VDC

P8 +0.18VDC

P2 -52VDC

P5 -0.098VDC

P1 +19.8 AC

FROM POWER SUPPLY BOARD
PIN22 +52.19

P23/24 +22.49

P25/26 -24.95

P27 -52

P28 -13

P20 +35

which part should I start replace to get my SX980 work again?
 
And I clearly hear relay click after I turn on my sx980, around after 5 second. All Lights are on, but no sound. I do not know what to do. :(
 
Last edited:
I think pre amp jumper is working fine. I HAVE some pIctures for my SX980 here
284f0eeb7f6fde3f05145c510fefc6f1.jpg
5b1558ecd0ef836635921c85bbca7d1d.jpg
9969c56133bd6cb095dbc6838b444737.jpg
e760425227d0170535f9666c7339b8a8.jpg
749c6c31f39e0983989ee1ae355fcf24.jpg
 
1d20fdea5552bc42733ba539d694b5c9.jpg

I connected speakers again and set volume max. I do not know it is good or bad. I hear very very weak sound coming out from one side of speakers. Right side, but very weak. You have to put your ear to hear. :(
 
petehall347 said:
try with all toggle switches up
Click to expand...
Yes I did, but nothing happened. Today I cleaned all pods on front panel. With relay clicking, suddenly FM starts working, producing very loud sound, but not perfect way. Right channel is making way louder sound than left channel. AUX, AM, PHONO SECTION are still weak. With volume max, I barely hear weak sound from both channels through other selectors(aux, phono, and am). Things about my SX980 are getting complicated than I though.
 
petehall347 said:
try cleaning all the switches again .
Click to expand...
I will do that soon. Do you think I need any part replacement other than cleaning switches again? I posted DC voltages for couple boards ealier and I am still curious about those numers are within acceptable ranges.[emoji4]
 

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from what you said cleaning brought it back to life a little . i think more cleaning will cure it .
will look over the voltages when i get chance .
 
I checked voltages for AWM 124 again and now I got

P10 +71 Vdc /+65v

P9 +13.51VDC /+13v

P8 +0.18VDC / L channel dc offset

P2 -52VDC / -50v

P5 -0.098VDC /R channel offset

P1 +19.8 AC /21v AC

FROM POWER SUPPLY BOARD
PIN22 +52.19 / 50v

P23/24 +22.49 /23v

P25/26 -24.95 /-23v

P27 -52 / -50v

P28 -13 / -13v

P20 +35 / 33v .


i added schematic voltages after your readings . they all look fine to me .
however pin 10 is a little high . its unregulated and comes from pin 19 power supply board .
its looking like your house power is a bit high for the unit . i suspect all will be fine as long as the bias is set correctly .

also left channel dc offset could do with coming down somewhat .
 
petehall347 said:
I checked voltages for AWM 124 again and now I got

P10 +71 Vdc /+65v

P9 +13.51VDC /+13v

P8 +0.18VDC / L channel dc offset

P2 -52VDC / -50v

P5 -0.098VDC /R channel offset

P1 +19.8 AC /21v AC

FROM POWER SUPPLY BOARD
PIN22 +52.19 / 50v

P23/24 +22.49 /23v

P25/26 -24.95 /-23v

P27 -52 / -50v

P28 -13 / -13v

P20 +35 / 33v .


i added schematic voltages after your readings . they all look fine to me .
however pin 10 is a little high . its unregulated and comes from pin 19 power supply board .
its looking like your house power is a bit high for the unit . i suspect all will be fine as long as the bias is set correctly .

also left channel dc offset could do with coming down somewhat .
Click to expand...
Thanks for your help. Like you suggested, I cleaned and cleaned all switches over again really hard. Now it works and make very loud sound, but not evenly. L channel is making way louder sound than right one. Meters for wattage s on front panel also showing up that. I adjusted vr1 and vr2 for center voltage and idle current. Do I need more cleaning for uneven balance issue or now it is for something else?
 
petehall347 said:
I checked voltages for AWM 124 again and now I got

P10 +71 Vdc /+65v

P9 +13.51VDC /+13v

P8 +0.18VDC / L channel dc offset

P2 -52VDC / -50v

P5 -0.098VDC /R channel offset

P1 +19.8 AC /21v AC

FROM POWER SUPPLY BOARD
PIN22 +52.19 / 50v

P23/24 +22.49 /23v

P25/26 -24.95 /-23v

P27 -52 / -50v

P28 -13 / -13v

P20 +35 / 33v .


i added schematic voltages after your readings . they all look fine to me .
however pin 10 is a little high . its unregulated and comes from pin 19 power supply board .
its looking like your house power is a bit high for the unit . i suspect all will be fine as long as the bias is set correctly .

also left channel dc offset could do with coming down somewhat .
Click to expand...
when I turn volume knob clockwise just little bit, sound for left channel got very loud quickly while sound from right channel seem to work normally. :(
 
looks like the vol pot has got bad . maybe there is still dirt inside . it could also be a poor solder connection on one of its pins .
 
PETEHALL, I OWE YOU ALOT. Thanks for your reply. I will clean the volume pot one more time with alot of Deoxid tonight and check all solder connections on its pins. This is a headach job, but I feel I am getting really close with your big help. Thanks again.
 
petehall347 said:
looks like the vol pot has got bad . maybe there is still dirt inside . it could also be a poor solder connection on one of its pins .
Click to expand...
I cleand the volume pot one more time and checked all connections and solderings. I cannot find any problems in there. Still have uneven balance sound problem. I tested my SX980 as preamp and still have same problem. sound from right channel is way more louder than one from left at low volume stage. When I turned volume knob for high(more than 12 o'clock), seems like the problem is gone and worked fine. What should I check and look for repairing? Thanks
 
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