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Pioneer SX-950 Restoration Project

Timothy Flath

Timothy Flath

Well-Known Member
Thought I would share my project video series from a restoration I recently did of a tired old Vintage SX-950 receiver I recently finished restoring. It now has a new lease on life and will still serve for many more decades to come. Jump to the last part to see the final outcome. Here is part 1:

Part 1 (General Intro and Case Build):
 
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Congratulations. Great Receiver. Thanks for sharing.

Not sure if you are using a dim bulb tester…. but you might want to consider building one on your future projects. It has saved my bacon more than a few times.

Have done this set 850/950 four times and cannot express how amazing these turnout.
 
Super Noob said:
Congratulations. Great Receiver. Thanks for sharing.

Not sure if you are using a dim bulb tester…. but you might want to consider building one on your future projects. It has saved my bacon more than a few times.

Have done this set 850/950 four times and cannot express how amazing these turnout.
Click to expand...

Thanks S.N.
I actually do have a dim bulb tester that I built for a Chinese Tube amp I built from a kit with very bad instructions - All I got with it actually was a dodgy schematic that was wrong. I did consider using it on the SX-950 project but figured I was doing it incremental enough to not need it. In total retrospect I think I will start using it more because a couple of times I probaby came real close to frapping something bad:thumbsup::

Here is that tuber in action when I completed her:
 
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O. Friend said:
I'm following your videos, very well done! I have an SX-950 I just got my hands on and will be doing the same to restore it, and you videos are going to be very helpful, thank you!
Click to expand...

Thanks O.F.
Hope it helps. I don't profess to be an expert but please feel free to contact me if you have any questions I did not explain well in my "Amateur Hour" videos:jump:
 
Thanks, Timothy. By chance do you have an updated parts list/BOM based on your recent experience with the SX-950? I was going to order from the one in another thread, but noticed a few times you said the parts were different on your boards. I'm also in the middle of a restoration of a Sansui G5500, and I went through each board and documented the actual caps I found, and did like you and tested them after removing. Many were not TOO bad, which kind of surprised me. But during that, I had to place 4-5 orders from Mouser (haha) and would like to avoid that and get a good initial order if possible. Thanks for any help on that!
 
O. Friend said:
Thanks, Timothy. By chance do you have an updated parts list/BOM based on your recent experience with the SX-950? I was going to order from the one in another thread, but noticed a few times you said the parts were different on your boards. I'm also in the middle of a restoration of a Sansui G5500, and I went through each board and documented the actual caps I found, and did like you and tested them after removing. Many were not TOO bad, which kind of surprised me. But during that, I had to place 4-5 orders from Mouser (haha) and would like to avoid that and get a good initial order if possible. Thanks for any help on that!
Click to expand...

Here you go (if you PM me your email address I can scan the actual install/check sheet I had where I annoted values of most items pulled as well as installed plus info on the LED light kit etc):
Vinatge Pioneer SX-950 Receiver Updated Parts list
BOM List:
647-UKL1H2R2KDDANA | 10
647-UKL1H010KDDANA | 4 Substitute Elna REA4R7M1JBK-0511P
647-UKL1H3R3KDDANA | 2
647-UKL1J4R7MDD | 4
647-UKL1A101KEDANA | 4
647-UKL1E100KDDANA | 4
667-EEU-FM1C331 | 4 Substitute EEU-FM1C331BJ
667-EEU-FM1H101 | 2 EEU-FM1H101B
667-EEU-FM1A101 | 2 United Chemi-Con EKZE100ETD101ME11D
667-EEU-FM1V221 | 4
667-EEU-FM1V330 | 2
667-EEU-FC1V470 | 2
80-F612JF224J063A | 4
667-ECO-S1KP681BA | 2 Cornell Dublier SLP681M100A1P3
667-ECO-S1HA222BA | 1 Nichicon LLS1H222MELZ
647-UPW1A331MPD | 2 Kemet 80-ESY337M010AG3AA
647-UPW1V4R7MDD | 1 Vishay Sprague 517D475M035JA6AE3
647-UPW1H101MPD | 1 Nichicon UHD1H101MPD
647-UPW1V101MPD | 1
647-UPW2A101MHD | 1 United Chem Con (UCC) 661-ELXV101ELL101MK2
647-UPW1V102MHD | 1 Nichicon UPW1V102MHD1TO
647-UPW1C221MPD | 1 Nichicon UPW1C221MPD1TD
647-UPW2A471MHD | 1 United Chemi-Con EKYB101ELL471MLN3S
647-UPW1E470MDD | 2 Panasonic EEU-FM1E470
647-UPW1J470MPD | 1
647-UPW1H470MED | 1 Nichicon UPW1H470MED1TD
863-MJE15032G | 3
863-MJE15033G | 1
512-KSA992FBU | 8 no replacement (Got from Newark)
512-KSC1845FTA | 8 no replacement (Got from Newark)
512-KSC2383YTA | 6
512-KSA1013YBU | 2
512-KSC2690AYS | 2
652-3386H-1-101LF | 2
652-3296P-1-103LF | 2
Pioneer SX-950 Recap List
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 (Updated 9/08/18)
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: 667-EEU-FM1C331 330uF 16v
AWF-011: C8: 330uF 6.8v CEA: 667-EEU-FM1C331 330uF 16v
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: 667-EEU-FM1H101 100uF 50v
AWF-011: C18 220uF 25v CEA: 667-EEU-FM1V221 220uF 35v
AWF-011: Q1: 2SA725: 512-KSA992FBU
AWF-011: Q2: 2SA725: 512-KSA992FBU
AWF-011: Q3: 2SC1313: 512-KSC1845FTA
AWF-011: Q4: 2SC1313: 512-KSC1845FTA
AWF-011: Q5: 2SC1313: 512-KSC1845FTA
AWF-011: Q6: 2SC1313: 512-KSC1845FTA
If the B version:
AWF-011: C??: 100uF 6.3v CEA: 667-EEU-FM1A101 100uF 10v
AWF-011: C??: 100uF 6.3v CEA: 667-EEU-FM1A101 100uF 10v
Switch Assembly Board (AWS-094)
AWS-094: C1: 220uF 6.8v CEA: 667-EEU-FM1V221 220uF 35v
Flat Amp Board (AWG-038)
AWG-038: C1: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-038: C2: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-038: C5: 4.7uF 50v CEANL: 647-UKL1J4R7MDD 4.7uF 63v
AWG-038: C6: 4.7uF 50v CEANL: 647-UKL1J4R7MDD 4.7uF 63v
AWG-038: C13: 220uF 35v CEA: 667-EEU-FM1V221 220uF 35v
AWG-038: C14: 220uF 35v CEA: 667-EEU-FM1V221 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: 647-UKL1J4R7MDD 4.7uF 63v
AWG-038: C24: 4.7uF 50v CEANL: 647-UKL1J4R7MDD 4.7uF 63v
AWG-038: C25: 100uF 10v CEANL: 647-UKL1A101KEDANA 100uF 10v
AWG-038: C26: 100uF 10v CEANL: 647-UKL1A101KEDANA 100uF 10v
AWG-038: C27: 100uF 50v CEA: 667-EEU-FM1H101 100uF 50v
AWG-038: Q1: 2SC1885: 512-KSC2383YTA
AWG-038: Q2: 2SC1885: 512-KSC2383YTA
AWG-038: Q5: 2SA725: 512-KSA992FBU
AWG-038: Q6: 2SA725: 512-KSA992FBU
Tone Amp Board (AWG-039)
AWG-039: C13: 2.2uF 25v CSZA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-039: C14: 2.2uF 25v CSZA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-039: C15: 2.2uF 25v CSZA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-039: C16: 2.2uF 25v CSZA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-039: C19: 100uF 10v CEANL: 647-UKL1A101KEDANA 100uF 10v
AWG-039: C20: 100uF 10v CEANL: 647-UKL1A101KEDANA 100uF 10v
AWG-039: C21: 47uF 35v CEA: 667-EEU-FC1V470 47uF 35v
AWG-039: C22: 47uF 35v CEA: 667-EEU-FC1V470 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: 80-F612JF224J063A .22uF 63v
AWG-039: C26: .22uF 35v CSZA: 80-F612JF224J063A .22uF 63v
AWG-039: C29: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: C30: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-039: Q1: 2SC1312: 512-KSC1845FTA
AWG-039: Q2: 2SC1312: 512-KSC1845FTA
Power Amp Board (AWH-059) (Q1 and Q3 & Q2 and Q4 should be gain matched)
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: 667-EEU-FM1V330 33uF 35v
AWH-059: C6: 33uF 16v CEA: 667-EEU-FM1V330 33uF 35v
AWH-059: C11: 330uF 10v CEA: 667-EEU-FM1C331 330uF 16v
AWH-059: C12: 330uF 10v CEA: 667-EEU-FM1C331 330uF 16v
AWH-059: Q1: 2SA726: 512-KSA992FBU Did not receive - short shipped not installed
AWH-059: Q2: 2SA726: 512-KSA992FBU Did not receive - short shipped not installed
AWH-059: Q3: 2SA726: 512-KSA992FBU Did not receive - short shipped not installed
AWH-059: Q4: 2SA726: 512-KSA992FBU Did not receive - short shipped not installed
VR1: 10K ohm multi offset: 652-3296P-1-103LF 10K ohm 25 turn not installed - old triimmers cleaned with D5 and worked with no issues
VR2: 10K ohm multi offset: 652-3296P-1-103LF 10K ohm 25 turn not installed - old triimmers cleaned with D5 and worked with no issues
VR3: 100 ohm single bias: 652-3386H-1-101LF 100 ohm single turn not installed - old triimmers cleaned with D5 and worked with no issues
VR4: 100 ohm single bias: 652-3386H-1-101LF 100 ohm single turn not installed - old triimmers cleaned with D5 and worked with no issues
Protection Circuit Assembly (AWM-062)
AWM-062: C1: .22uF 10v CSSA: 80-F612JF224J063A .22uF 63v
AWM-062: C2: .22uF 10v CSSA: 80-F612JF224J063A .22uF 63v
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
AWR-062: Q1: 2SC869: 512-KSC1845FTA
AWR-062: Q2: 2SC869: 512-KSC1845FTA
AWR-062: Q6: 2SC945: 512-KSC2383YTA
AWR-062: Q7: 2SC1318: 512-KSC2690AYS
1N4004 flyback diode is added between pins 9 (anode) and 10 (cathode)
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
Tuner Board:
C22: 47uf 25v CEA / Nichicon 47uF 50v (UPW) *Nichicon UKA1H470MED1TD (Believe this ended up being a 4.7uF actually installed)
C24: 10uf 16v CEA / Nichicon 10uF 25v (UPW) *Nichicon UPW1E100MDD6TE
C25: .47uf 50v CEA / WIMA .47uF 63v *WIMA MKS2C034701C00JSSD
C26: 10uf 16v CEA / Nichicon 10uF 25v (UPW) *Nichicon UPW1E100MDD6TE
C31: 1uf 50v CEA / WIMA 1uF 63v *WIMA MKS2C041001F00JSSD
C33: 100uf 16v CEA / Panasonic 100uF 50v (FM Series) *Panasonic EEU-FM1H101B
C34: 47uf 16v CEA / Nichicon 47uF 50v (UPW) *Nichicon UKA1H470MED1TD
C37: 1.5uf 25v CSZA / WIMA 1.5uF 63v *WIMA MKS2C041501H00JI00
C38: 3.3uf 25v CSZA / WIMA 3.3uF 50v *WIMA MKS2-3.3/50/10A
C42: .22uf 25v CSSA / WIMA .22uF 63v *WIMA MKS2C032201B00JA00
C43: 10uf 16v CEA / Nichicon 10uF 25v (UPW) *Nichicon UPW1E100MDD6TE
C44: 10uf 16v CEA / Nichicon 10uF 25v (UPW) *Nichicon UPW1E100MDD6TE
C45: 10uf 16v CEA / Nichicon 10uF 25v (UPW) *Nichicon UPW1E100MDD6TE
C46: 10uf 16v CEA / Nichicon 10uF 25v (UPW) *Nichicon UPW1E100MDD6TE
C52: 4.7uf 25v CEA / WIMA 4.7uF 63v *WIMA MKS2C044701M00JSSD
C53: 47uf 6.3v CEA / Nichicon 47uF 16v (UKA) *Nichicon UFG1C470MEM1TA
C57: .1uf 25v CSSA / WIMA .1uF 63v *WIMA MKS0C031000C00KI00
C58: 10uf 16v CEA / Nichicon 10uF 25v (UPW) *Nichicon UPW1E100MDD6TE
C60: .1uf 25v CSSA / WIMA .1uF 63v *WIMA MKS0C031000C00KI00
C63: 220uf 16v CEA / Panasonic 100uF 35v (FM Series) *Panasonic EEU-FC1V101
C66: 4.7uf 16v CEA / WIMA 4.7uF 63v *WIMA MKS2C044701M00JSSD

Most items were from Mouser but some trannies came from Newark Electronics I believe (including the large filter caps). Compromises were made based on non-availability of many items so I used the "Find Similar" search within Mouser mostly.
Cheers
Tim
 
I find your signature "if it ain't broke, don't fix it" a bit ironic, given you are restoring a unit that was working.... haha!
 
EastPoint said:
The 2SA725s in the amp section NEED to be replaced. The trimmers should be as well.
Click to expand...
I agree - I recall seeing that if the trimmers fail it can take out a bunch of key components. I actually ordered a stack of those trannies with my Pioneer TX-8500II order yesterday since they were cheap. Still researching how to properly match the transistors:dunno:. There sure are a lot of different methods on YT and the web with fancy gear!:eek:o_O Finally getting around to doing this one (the SG-9800 shown will be the last that needs it):
 
Hi Folks
In need of some ideas or confirmation. Here is what has happened since my last post:
1. I completely rebuilt a new case for the Sx-950. I disliked the blotchy game of the stain on the wood so this time around I used a lighter stain and used pre-stain which has made it a lot nicer looking. By making another case I also fixed some fit issues and screw alignment and centering problems. Glad I did it.
2. I replaced the bad mpx board switch that was bad after receiving the part from the US
3. I attempted to clean the speaker relay with paper soaked in D5 deoxit and then dry paper gently on both sides where contacts meet. This is where I think things may have gone wrong.
4. I replaced the old V1 to V4 trimmers on the amp board with new trimmers I had on hand from the original parts order as per the recommended AK recap list. Then I did dc offset and bias trim as per the service manual - same procedure I employed to get it working in part 9 in the thread above.
5. I assembled everything and powered up with DBT and relay kicked in as per usual - of course I connected up the pre out main in and removed the 5.1kohm shunt resistors on the rca jacks I made up.
6. Sound was very weak and distorted on both channels. Isolated it to the amp by plugging my phone directly into the mai in on receiver to bypass the preamp. Sound problem is definitely on the amp side and not the preamp side.
7. Tried cleaning the relay again thinking all the current goes through it while playing and noted a bent contact when I disassembled it the second time - but it still makes contact inside. Relay does kick in after 4 to 5 seconds on power up.
8. Redid dc offset and bias trim procedure and tried again by using the main in only and my phone playing music through 3.5 mm mini to 2 rca starting out at low volume. Same issue.
9. Pulled all 8 of the output transistors (and regreased while I was st it) on both channels and checked with Peak DCA55. All read good with no leakage and appropriate PNP and NPN readings etc.
10. Beginning to think I pooched the relay since it is the same issue on both channels - very weak output with scratchy thin sound. Does this sound feasible Any? Any thoughts from anyone on troubleshooting?
I did look over the amp board very closely and it looks good....
Thanks
Tim
 
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