SX-950 preventative maintanence

I've been out of the game for a few years... (Thanks a LOT, Minecraft.)

It's time to build some real stuff again, and I need a slight refresher! I'm refreshing some recently acquired and working SX-950's for family. What are some specific preventative maintenance tips you could recommend, besides a recap?

I think Mark recommended replacing a transistor on the power supply board, but I can't find the thread.

Also, I've heard of a few of these that start popping on the phono input. Is there something on the phono board that commonly goes bad that I could replace before I send these things out?

Thanks again!

Clean and DeOxit Every control on Front and back.

Phono Board.
2sa725 replace with KSA992.

ALL OTHER BOARDS that have 2sa726 and 2sa725 replace with KSA992. I don't see Mark's all time Favorite problem child (2sc1451) so you're ok there.

Replace the Relay, as a matter of course. Burnishing the contacts will last about a week after it moves ot the new home.
There is a thread with complete parts lists. Post it up for vetting BEFORE you order. There may have been some updates of obsolete parts, new better parts, etc.

Zebulon1 will probably have the link.

You are looking for Q5 on the power supply board. It usually dies and messes with the protection circuit. Replace with KSC2690 from Mouser

Back emf diode, 1N4002-3-4 across relay coil!! Cathode to the hot side.

use the list so you only have to do each one once, rather than poke into it periodically - it's cheaper than the multiple shipping charges.

Check by posting the list to be sure it's got the latest obsoletes and out of stock parts weeded out.

larryderouin said:

Phono Board.
2sa725 replace with KSA992.

ALL OTHER BOARDS that have 2sa726 and 2sa725 replace with KSA992. I don't see Mark's all time Favorite problem child (2sc1451) so you're ok there.

Click to expand...

I'll second that. I just fired up my 950 last night for the first time in a while. The previously "quiet" phono/mic amp section now has a horrendous pop/sizzle/hiss going on (as if I needed another project). I guess it's time for both of us to perform some PM.

Thanks for the info - where do I find the phono board? Is it part of the flat amp board?

Taken from the SX-850 manual, works for the 950 as well

it's located on the bottom of the unit, all the way left looking from the front, not part of the flat amp

thanks!

Do not be afraid to ask questions. It iS easier to ask how or why rather oh $hi$ I did this to that and magic smoke came out.

download a copy of the service manual, and then at least LOOK at every page, there's a wealth of information in it.

The "where to find phono amp" would have been quite apparent from the manual.

get the 950 manual it's better than than Pioneer's 850 manual.

I couldn't find it labeled as such in the manual. Of course, now that I load it up I can see that I should have been looking for "equalizer amplifier assembly."

My bad.

This is mattsd's list from a Thread he had in 2012.
Thanks Matt!

Pioneer SX-950 recap below:
I will add the Bourns trimmers soon.

Matt "Here is my 950 recap list, hope it helps! It details each cap and its replacement. Also included are the transistors that are known to get noisy in this model and their replacements".

Pioneer SX-950 recap list

Equalizer Amp Assembly (AWF-011)

AWF-011: C1: 1uF 25v CSSA: 647-UKL1H010KDDANA 1uF 50v
AWF-011: C2: 1uF 25v CSSA: 647-UKL1H010KDDANA 1uF 50v
AWF-011: C7: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v
AWF-011: C8: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v
AWF-011: C11: 3.3uF 25v CEANL: 647-UKL1H3R3KDDANA 3.3uF 50v
AWF-011: C12: 3.3uF 25v CEANL: 647-UKL1H3R3KDDANA 3.3uF 50v
AWF-011: C17 100uF 35v CEA: 647-UPW1V101MPD 100uF 35v
AWF-011: C18 220uF 25v CEA: 647-UPW1V221MPD 220uF 35v

Q1: 2SA725: 512-KSA992FBU:
Q2: 2SA725: 512-KSA992FBU:

Switch Assembly Board (AWS-094)

AWS-094: C1: 220uF 6.8v CEA: 647-UPW1A221MED 220uF 10v

Flat Amp Board (AWG-038)

AWG-038: C1: 2.2uF 50v CEANL(NL): 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-038: C2: 2.2uF 50v CEANL(NL): 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-038: C5: 4.7uF 50v CEANL(NL): 647-UKL1J4R7MDD 4.7uF 63v
AWG-038: C6: 4.7uF 50v CEANL(NL): 647-UKL1J4R7MDD 4.7uF 63v
AWG-038: C13: 220uF 35v CEA: 647-UPW1V221MPD 220uF 35v
AWG-038: C14: 220uF 35v CEA: 647-UPW1V221MPD 220uF 35v
AWG-038: C17: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-038: C18: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-038: C23: 4.7uF 50v CEANL(NL): 647-UKL1J4R7MDD 4.7uF 63v
AWG-038: C24: 4.7uF 50v CEANL(NL): 647-UKL1J4R7MDD 4.7uF 63v
AWG-038: C25: 100uF 10v CEANL(NL): 647-UKL1C101KPDANA 100uF 16v
AWG-038: C26: 100uF 10v CEANL(NL): 647-UKL1C101KPDANA 100uF 16v
AWG-038: C27: 100uF 50v CEA: 647-UPW1H101MPD 100uF 50v

AWG-038: Q5: 2SA725: 512-KSA992FBU
AWG-038: Q6: 2SA725: 512-KSA992FBU

Tone Amp Board (AWG-039)

AWG-039: C13: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C14: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C15: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C16: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C19: 100uF 10v CEANL(NL): 647-UKL1C101KPDANA 100uF 16v
AWG-039: C20: 100uF 10v CEANL(NL): 647-UKL1C101KPDANA 100uF 16v
AWG-039: C21: 47uF 35v CEA: 647-UPW1V470MED1TD 47uF 35v
AWG-039: C22: 47uF 35v CEA: 647-UPW1V470MED1TD 47uF 35v
AWG-039: C23: 2.2uF 25v CSZA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-039: C24: 2.2uF 25v CSZA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-039: C25: .22uF 35v CSZA: 667-ECQ-V1H224JL2 .22uF 50v
AWG-039: C26: .22uF 35v CSZA: 667-ECQ-V1H224JL2 .22uF 50v
AWG-039: C29: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C30: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v

Power Amp Board (AWH-059)

AWH-059: C1: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWH-059: C2: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWH-059: C3: 1uF 25v CSSA: 647-UKL1H010KDDANA 1uF 50v
AWH-059: C4: 1uF 25v CSSA: 647-UKL1H010KDDANA 1uF 50v
AWH-059: C5: 33uF 16v CEA: 647-UPW1C330MDD 33uF 16v
AWH-059: C6: 33uF 16v CEA: 647-UPW1C330MDD 33uF 16v
AWH-059: C11: 330uF 10v CEA: 647-UPW1A331MPD 330uF 10v
AWH-059: C12: 330uF 10v CEA: 647-UPW1A331MPD 330uF 10v
AWH-059: VR1: BIAS 1K OHMS ?
AWH-059: VR2: BIAS 1K OHMS ?
AWH-059: VR3: IDLE 100 OHMS ?
AWH-059: VR4: IDLE 100 OHMS ?

Note: A nice detail is to gain match the paired 992's: Q1 and 3, and Q2 and 4.

AWH-059: Q1: 2SA726: 512-KSA992FBU
AWH-059: Q2: 2SA726: 512-KSA992FBU
AWH-059: Q3: 2SA726: 512-KSA992FBU
AWH-059: Q4: 2SA726: 512-KSA992FBU

Protection Circuit Assembly (AWM-062)
Added 07-30-2014: See next Post below for complete protect board rebuild.

AWM-062: C1: .22uF 10v CSSA: 667-ECQ-V1H224JL2 .22uF 50v
AWM-062: C2: .22uF 10v CSSA: 667-ECQ-V1H224JL2 .22uF 50v
AWM-062: C3: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v
AWM-062: C4: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v
AWM-062: C5: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v
AWM-062: C6: 100uF 16v CEA: 647-UPW1V101MPD 100uF 35v

Power Supply Board (AWR-101)

AWR-101: C10: 470uF 80v ACH-038, CEA: 667-EEU-FC2A471 470uF 100v
AWR-101: C11: 470uF 80v ACH-038, CEA: 667-EEU-FC2A471 470uF 100v
AWR-101: C12: 1000uF 35v ACH-039, CEA: 647-UPW1V102MHD 1000uF 35v
AWR-101: C13: 1000uF 25v CEA: 647-UPW1E102MPD6 1000uF 25v
AWR-101: C14: 220uF 10v CEA: 647-UPW1V221MPD 220uF 35v
AWR-101: C15: 470uF 63v CEA: 647-UPW1J471MHD 470uF 63v
AWR-101: C16: 47uF 16v CEA: 647-UPW1V470MED 47uF 35v
AWR-101: C18: 47uF 50v CEA: 667-EEU-FC1H470 47uF 50v
AWR-101: C19: 47uF 35v CEA: 647-UPW1V470MED 47uF 35v
AWR-101: C20: 100uF 63v CEA: 647-UPW1J101MPD6 100uF 63v
AWR-101: C21: 47uF 16v CEA: 647-UPW1V470MED 47uF 35v
AWR-101: C23: 100uF 35v CEA: 647-UPW1V101MPD 100uF 35v

BOM List

647-UKL1H2R2KDDANA | 6
647-UPW1C330MDD | 2
667-EEU-FC2A471 | 2
647-UPW1V102MHD | 1
647-UPW1E102MPD6 | 1
647-UPW1J471MHD | 1
667-EEU-FC1H470 | 1
647-UPW1J101MPD6| 1
647-UPW1V470MED | 3
647-UKL1H010KDDANA | 4
647-UKL1H3R3KDDANA | 2
647-UPW1A221MED | 1
647-UPW1V221MPD | 4
647-UKL1J4R7MDD | 4
647-UPW1H101MPD | 1
647-UKL1C101KPDANA | 4
647-UPW1V470MED1TD | 2
647-UKL1E100KDDANA | 8
667-ECQ-V1H224JL2 | 4
647-UPW1A331MPD | 6
647-UPW1V4R7MDD | 1
647-UPW1V101MPD | 3
512-KSA992FBU | 8

From Mark 2012:

Protection Circuit Assembly (AWM-062), total rebuild list

AWM-062: C1: .22uF 10v CSSA: 667-ECQ-V1H224JL2 .22uF 50v o/c sense must be stacked film, not little sky blue sanyo can electrolytic
AWM-062: C2: .22uF 10v CSSA: 667-ECQ-V1H224JL2 .22uF 50v o/c sense must be stacked film, not little sky blue sanyo can electrolytic
AWM-062: C3: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v 1/2 of make polarity free capacitor
AWM-062: C4: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v other half of make polarity free capacitor
AWM-062: C5: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v ac power sense
AWM-062: C6: 100uF 16v CEA: 647-UPW1V101MPD 100uF 35v timing capacitor
AWM-062: Q1-Q2 2SC869-C 512-KSC1845EBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea o/c sense
AWM-062: Q6 SSC945-Q 512-KSD1616ALBU to-92 ecb x60v 1a 0.75w 160mhz 135-400hfe $0.09 timing capacitor charge dump to turn off
AWM-062: Q7 2SC1384-R 512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40 relay drive transistor

don't forget to add the 512-1n4004 flyback diode to pins 9 (anode) and 10(cathode).

zebulon1 said:

From Mark 2012:

Protection Circuit Assembly (AWM-062), total rebuild list

AWM-062: C1: .22uF 10v CSSA: 667-ECQ-V1H224JL2 .22uF 50v o/c sense must be stacked film, not little sky blue sanyo can electrolytic
AWM-062: C2: .22uF 10v CSSA: 667-ECQ-V1H224JL2 .22uF 50v o/c sense must be stacked film, not little sky blue sanyo can electrolytic
AWM-062: C3: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v 1/2 of make polarity free capacitor
AWM-062: C4: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v other half of make polarity free capacitor
AWM-062: C5: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v ac power sense
AWM-062: C6: 100uF 16v CEA: 647-UPW1V101MPD 100uF 35v timing capacitor
AWM-062: Q1-Q2 2SC869-C 512-KSC1845EBU (ln)to-92 ecb 120v .05a .5w 100mhz 150-800hfe $0.05 ea o/c sense
AWM-062: Q6 SSC945-Q 512-KSD1616ALBU to-92 ecb x60v 1a 0.75w 160mhz 135-400hfe $0.09 timing capacitor charge dump to turn off
AWM-062: Q7 2SC1384-R 512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40 relay drive transistor

don't forget to add the 512-1n4004 flyback diode to pins 9 (anode) and 10(cathode).

Click to expand...

That list is a little out of date, Q1 and 2 replacement should be a 512-KSC1845FTA, Q6 replacement should be a 512-KSC2383YTA. The rest looks okay. Also, I recommend rebuilding the power supply transistors as well, a couple of them are under powered for what they are handling, namely Q5. Q7 is also a little under powered, but not as bad. This is my updated SX-950 power supply list, I've changed the bigger caps to snap-ins for a better fit and look:

Power Supply Board (AWR-101)

AWR-101: C10: 470uF 80v ACH-038 (Snap-in): 667-ECO-S1KP681BA 680uF 80v
AWR-101: C11: 470uF 80v ACH-038 (Snap-in): 667-ECO-S1KP681BA 680uF 80v
AWR-101: C12: 2200uF 35v ACH-039 (Snap-in): 667-ECO-S1HA222BA 2200uF 35v
AWR-101: C13: 1000uF 25v CEA: 647-UPW1V102MHD 1000uF 35v
AWR-101: C14: 220uF 10v CEA: 647-UPW1C221MPD 220uF 16v
AWR-101: C15: 470uF 63v CEA: 647-UPW2A471MHD 470uF 100v
AWR-101: C16: 47uF 16v CEA: 647-UPW1E470MDD 47uF 25v
AWR-101: C18: 47uF 50v CEA: 647-UPW1J470MPD 47uF 63v
AWR-101: C19: 47uF 35v CEA: 647-UPW1H470MED 47uF 50v
AWR-101: C20: 100uF 63v CEA: 647-UPW2A101MHD 100uF 100v
AWR-101: C21: 47uF 16v CEA: 647-UPW1E470MDD 47uF 25v
AWR-101: C23: 100uF 35v CEA: 647-UPW1H101MPD 100uF 50v

AWR-101: Q1: 2SD313: 863-MJE15032G
AWR-101: Q2: 2SB507: 863-MJE15033G
AWR-101: Q3: 2SC1318: 512-KSC2383YTA
AWR-101: Q4: 2SA720: 512-KSA1013YBU
AWR-101: Q5: 2SC1318: 512-KSC2690AYS
AWR-101: Q6: 2SA720: 512-KSA1013YBU
AWR-101: Q7: 2SC1318: 512-KSC2383YTA
AWR-101: Q8: 2SD313: 863-MJE15032G
AWR-101: Q9: 2SD313: 863-MJE15032G
AWR-101: Q10: 2SC869: 512-KSC2383YTA

For the AWH-059 trim pots:

VR1: 1K ohm multi offset: 652-3296P-1-102LF 1K ohm 25 turn
VR2: 1K ohm multi offset: 652-3296P-1-102LF 1K ohm 25 turn
VR3: 100 ohm single bias: 652-3386H-1-101LF 100 ohm single turn
VR4: 100 ohm single bias: 652-3386H-1-101LF 100 ohm single turn

"Tone Amp Board (AWG-039)

AWG-039: C13: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C14: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C15: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C16: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C19: 100uF 10v CEANL(NL): 647-UKL1C101KPDANA 100uF 16v
AWG-039: C20: 100uF 10v CEANL(NL): 647-UKL1C101KPDANA 100uF 16v
AWG-039: C21: 47uF 35v CEA: 647-UPW1V470MED1TD 47uF 35v
AWG-039: C22: 47uF 35v CEA: 647-UPW1V470MED1TD 47uF 35v
AWG-039: C23: 2.2uF 25v CSZA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-039: C24: 2.2uF 25v CSZA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-039: C25: .22uF 35v CSZA: 667-ECQ-V1H224JL2 .22uF 50v
AWG-039: C26: .22uF 35v CSZA: 667-ECQ-V1H224JL2 .22uF 50v
AWG-039: C29: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C30: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v"


What if mine has a 2.2uF in C13, 14, 15, 16
and a jumper across where C29 and 30 would be?

Seen this many times before, replace exactly what was there in the first place.

so, C 13-16 will be the same as C 23, 24.

I have done many 850-950's, and they are usually a little different just like yours. I always replace the same value that was installed in the factory. That receiver has been going for 40 years so Pioneer did something right. Yeah just replace a 2.2uf with a 2.2uf, and a 10uf with a 10uf....and so on.

Unless you want to reverse engineer ALL the changes (there may be MORE than changed caps) use the same values as you find from the factory.