kcmoejoe
Active Member
sx-939 static / protection issues
I'm new here to the board but looks like I've come to the right place for vintage receiver help. I'm hoping someone can guide me in the right direction.
I picked up an sx-939 that looks really clean. I've used deoxit on the switched and knobs and reflowing solder joints that looked slightly cracked.
I can tune to FM station and get good sound, but it does have lots of loud static (mostly in the left channel) and the protect relay was kicking in and out and then died apparently. I can jumper pin 4 & 9 on the protect. board and get it to kick on and work but still get the static (guessing C1384 transistor is bad?), also when I remove the jumper connectors on the back for L/R I get complete silence on both channels.
From reading, I gather that the SX-1010 is almost exactly the same as my SX-939 unit? so am I safe to assume the parts list for rebuilding are the same?
sounds like I need to do a rebuild with parts for the protection board and maybe also to power supply board...what do you think? (one or both?).
here is the list I found for the ps board, but I couldn't locate a list for the protection board AWM-062...
------------------------------------
sx-1010 AWR054 power supply rebuild
--------------------------------------------------------------------------------
I'll get a under 5(? w/o shipping) buck list together to do the power supply pass transistors and a few resistors. That's how I conquered maddarts power supply problem.
I should have just stressed that from the start.
Q4 2sb507
one 512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
Q1 Q7 2sd313
two 512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54 ea
Q8 2sc1384 (ecb)
one 512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40
or one 512-KSC2682YSTU to-126 ecb 180v .1a 1.2/8w 200mhz 100-320hfe $0.31 (preferred, the current is below 0.1 amp)
Q5 Q6 2sa628 (BCE)
two 512-KSA1013YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea
Q2 Q3 2sc869 (ecb)
two 512-KSC2383YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea
D8 D9 wz-032
two 512-1N5257B Fairchild 33 V, 0.5W zener $0.05 ea
D10 wz-014
one 512-1N5244B Fairchild 14 V, 0.5W Zener $0.05
two ten ohms 1/4 watt metal film 660-MF1/4DC10R0F 0.06 ea
one 3.3 ohms 1/4 watt metal film 660-MF1/4DC3R30F 0.06
was the power supply recapped?
ok, here's the caps:
C7 & C8 470uf (80v) 100v 647-UPW2A471MHD $1.87 ea
C10, C11 100uf (63v) 100v 647-UPW2A101MHD $0.87 ea
C12 & C13 100uf (35v) 63v 647-UPW1J101MPD1TD $0.37 ea
C14 47uf 50v 647-UPW1H470MED $0.25
C18 1000uf (35v) 50v 647-UPW1H102MHD1CV $0.98
C19 220uf (16v) 35v 647-UPW1V221MPD $0.41
C20 & C21 2200uf 10v 647-UPW1A222MHD $0.80 ea
extra parts just in case somebody's looking :
D1 D2 D3 D4 SIB01 100v 1amp
D5 D6 D7 1S1885 100v 1amp
512-1n4004 conventional rectifier 1a 400v $0.06 ea
__________________
Thanks for any advice and guidance!
Joe
I'm new here to the board but looks like I've come to the right place for vintage receiver help. I'm hoping someone can guide me in the right direction.
I picked up an sx-939 that looks really clean. I've used deoxit on the switched and knobs and reflowing solder joints that looked slightly cracked.
I can tune to FM station and get good sound, but it does have lots of loud static (mostly in the left channel) and the protect relay was kicking in and out and then died apparently. I can jumper pin 4 & 9 on the protect. board and get it to kick on and work but still get the static (guessing C1384 transistor is bad?), also when I remove the jumper connectors on the back for L/R I get complete silence on both channels.
From reading, I gather that the SX-1010 is almost exactly the same as my SX-939 unit? so am I safe to assume the parts list for rebuilding are the same?
sounds like I need to do a rebuild with parts for the protection board and maybe also to power supply board...what do you think? (one or both?).
here is the list I found for the ps board, but I couldn't locate a list for the protection board AWM-062...
------------------------------------
sx-1010 AWR054 power supply rebuild
--------------------------------------------------------------------------------
I'll get a under 5(? w/o shipping) buck list together to do the power supply pass transistors and a few resistors. That's how I conquered maddarts power supply problem.
I should have just stressed that from the start.
Q4 2sb507
one 512-KSA940TU_Q pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54
Q1 Q7 2sd313
two 512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.54 ea
Q8 2sc1384 (ecb)
one 512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40
or one 512-KSC2682YSTU to-126 ecb 180v .1a 1.2/8w 200mhz 100-320hfe $0.31 (preferred, the current is below 0.1 amp)
Q5 Q6 2sa628 (BCE)
two 512-KSA1013YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea
Q2 Q3 2sc869 (ecb)
two 512-KSC2383YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17 ea
D8 D9 wz-032
two 512-1N5257B Fairchild 33 V, 0.5W zener $0.05 ea
D10 wz-014
one 512-1N5244B Fairchild 14 V, 0.5W Zener $0.05
two ten ohms 1/4 watt metal film 660-MF1/4DC10R0F 0.06 ea
one 3.3 ohms 1/4 watt metal film 660-MF1/4DC3R30F 0.06
was the power supply recapped?
ok, here's the caps:
C7 & C8 470uf (80v) 100v 647-UPW2A471MHD $1.87 ea
C10, C11 100uf (63v) 100v 647-UPW2A101MHD $0.87 ea
C12 & C13 100uf (35v) 63v 647-UPW1J101MPD1TD $0.37 ea
C14 47uf 50v 647-UPW1H470MED $0.25
C18 1000uf (35v) 50v 647-UPW1H102MHD1CV $0.98
C19 220uf (16v) 35v 647-UPW1V221MPD $0.41
C20 & C21 2200uf 10v 647-UPW1A222MHD $0.80 ea
extra parts just in case somebody's looking :
D1 D2 D3 D4 SIB01 100v 1amp
D5 D6 D7 1S1885 100v 1amp
512-1n4004 conventional rectifier 1a 400v $0.06 ea
__________________
Thanks for any advice and guidance!
Joe
Last edited: