Pioneer SX-1250 recap and restoration thread!

mattsd

Super Member
I just bought my first SX-1250 from fellow AK'er roadie1 for $75, a big thank you to him for letting me have it at that price, the thread on finding it is here: http://www.audiokarma.org/forums/showthread.php?t=420677. It's in beautiful condition and a great candidate for a restore, all the outputs are original, everything is original with the exception of the stabilizer board, it has several of the small caps replaced on it with a mix of stuff.

Problems are as follows: one: the control amp is not working, you flip the tone switch and the receiver will go into protection, bad tantalum caps are the cause, two: the indicator lamps and tuner are not working, cause is some open transistors on the stabilizer board. It also has a few controls and switches that are dirty.

Here are some before photos I posted of it in my thread on finding it: http://www.audiokarma.org/forums/showpost.php?p=5368785&postcount=3

I'm going to be doing a big restore to this thing, stay tuned!
 
Very nice pick, almost free, I got mine about 4 years ago for $50, I have totally rebuilt every board. I will be watching this thread with much interest, I need to put it back together and start her up....It's been sitting in pieces for awhile now.
 
tsd71 .... come on ... throw some gas on it and fire it up .. LOL !!!!

good luck guys.. :banana:



John M
 
NICE!..........keep us posted. Remember to post pic's.

There are only a very few true, legendary audio classics......the sx1250 is one of them.

ENJOY!;-))
 
Very cool. If there's a model worthy of a restoration and for others to learn from, it's the 1250.

While I'm posting, the 880 you restored (and that I bought) has a new home with a coworker. I'm moving and could not take my entire collection. Let me tell you, he yaps about how awesome this receiver is every day. We have a new vintage fan in the house!
 
Pioneer SX-1250 recap list

Excellent JT! :thmbsp: BTW, I thought it was an SX-850 that I sold you. :scratch2:

Here is my recap list for the SX-1250, I visually checked every board against the service manual and confirmed the caps for the the board numbers listed below, my 1250 was made Dec 1976. FYI I'm using a few Panasonic FM and FC caps in the preamp areas instead of PW caps.

Pioneer SX-1250 recap list (Updated 10/3/17, added soft start relay replacement)

Equalizer Amp Board (AWF-021-A) (Q1 & 3 and Q2 & 4 recommended for gain matching, but is not required)

AWF-021-A: C11: 470uF 6.3v CEA: 667-EEU-FM1E471B 470uF 25v
AWF-021-A: C12: 470uF 6.3v CEA: 667-EEU-FM1E471B 470uF 25v
AWF-021-A: C17: 3.3uF 50v CEANL: 647-UKL1H3R3KDDANA 3.3uF 50v
AWF-021-A: C18: 3.3uF 50v CEANL: 647-UKL1H3R3KDDANA 3.3uF 50v
AWF-021-A: C25: 22uF 16v CSZA: 647-UKL1V220KEDANA 22uF 35v
AWF-021-A: C26: 22uF 16v CSZA: 647-UKL1V220KEDANA 22uF 35v
AWF-021-A: C27: 220uF 63v CEA: 667-EEU-FC1J221 220uF 63v
AWF-021-A: C28: 220uF 63v CEA: 667-EEU-FC1J221 220uF 63v
AWF-021-A: C29: 100uF 35v CEA: 667-EEU-FM1H101 100uF 50v
AWF-021-A: C30: 22uF 16v CSZA: 647-UKL1V220KEDANA 22uF 35v
AWF-021-A: C31: 22uF 16v CSZA: 647-UKL1V220KEDANA 22uF 35v
AWF-021-A: C32: 100uF 35v CEA: 667-EEU-FM1H101 100uF 50v

Q1: 2SA726: 512-KSA992FBU
Q2: 2SA726: 512-KSA992FBU
Q3: 2SA726: 512-KSA992FBU
Q4: 2SA726: 512-KSA992FBU
Q5: 2SC1775: 512-KSC1845FTA:
Q6: 2SC1775: 512-KSC1845FTA:
Q7: 2SC1775: 512-KSC1845FTA:
Q8: 2SC1775: 512-KSC1845FTA:
Q9: 2SA872: 512-KSA992FBU
Q10: 2SA872: 512-KSA992FBU
Q11: 2SC1735: 512-KSC2383YTA
Q12: 2SC869: 512-KSC2383YTA
Q13: 2SA850: 512-KSA1013YBU
Q14: 2SA628A: 512-KSA1013YBU

Function Switch Board (AWS-094)

AWS-094: C1: 220uF 6.3v CEA: 667-EEU-FM1A221 220uF 10v

Flat Amp Board (AWG-042-0)

AWG-042-0: C7: 330uF 63v CEA: 667-EEU-FC1J331 330uF 63v
AWG-042-0: C8: 330uF 63v CEA: 667-EEU-FC1J331 330uF 63v
AWG-042-0: C9: 22uF 16v CSZA: 647-UKL1V220KEDANA 22uF 35v
AWG-042-0: C10: 22uF 16v CSZA: 647-UKL1V220KEDANA 22uF 35v
AWG-042-0: C11: 22uF 16v CSZA: 647-UKL1V220KEDANA 22uF 35v
AWG-042-0: C12: 22uF 16v CSZA: 647-UKL1V220KEDANA 22uF 35v
AWG-042-0: C21: 100uF 10v CEA: 667-EEU-FM1E101 100uF 25v
AWG-042-0: C22: 100uF 10v CEA: 667-EEU-FM1E101 100uF 25v
AWG-042-0: C27: 220uF 16v CEANL: 647-UKL1C221KPDANA 220uF 16v
AWG-042-0: C28: 220uF 16v CEANL: 647-UKL1C221KPDANA 220uF 16v
AWG-042-0: C31: 330uF 35v CEA: 667-EEU-FM1V331 330uF 35v
AWG-042-0: C32: 330uF 35v CEA: 667-EEU-FM1V331 330uF 35v

Q1: 2SC1775: 512-KSC1845FTA:
Q2: 2SC1775: 512-KSC1845FTA:
Q3: 2SA872: 512-KSA992FBU
Q4: 2SA872: 512-KSA992FBU
Q7: 2SA725: 512-KSA992FBU
Q8: 2SA725: 512-KSA992FBU

Control Amp Board (AWG-041-A)

AWG-041-A: C1: 4.7uF 25v CSZA: 647-UKL1H4R7KDDANA 4.7uF 50v
AWG-041-A: C2: 4.7uF 25v CSZA: 647-UKL1H4R7KDDANA 4.7uF 50v
AWG-041-A: C3: 4.7uF 25v CSZA: 647-UKL1H4R7KDDANA 4.7uF 50v
AWG-041-A: C4: 4.7uF 25v CSZA: 647-UKL1H4R7KDDANA 4.7uF 50v
AWG-041-A: C11: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C12: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C13: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C14: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C17: 100uF 10v CEA: 667-EEU-FM1E101 100uF 25v
AWG-041-A: C18: 100uF 10v CEA: 667-EEU-FM1E101 100uF 25v
AWG-041-A: C19: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C20: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C27: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C28: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C29: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C30: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C33: 100uF 10v CEA: 667-EEU-FM1E101 100uF 25v
AWG-041-A: C34: 100uF 10v CEA: 667-EEU-FM1E101 100uF 25v
AWG-041-A: C35: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C36: 2.2uF 50v CEANL: 647-UKL1H2R2KDDANA 2.2uF 50v
AWG-041-A: C37: 100uF 16v CEA: 667-EEU-FM1E101 100uF 25v
AWG-041-A: C38: 100uF 16v CEA: 667-EEU-FM1E101 100uF 25v
AWG-041-A: C39: 100uF 16v CEA: 667-EEU-FM1E101 100uF 25v
AWG-041-A: C40: 100uF 16v CEA: 667-EEU-FM1E101 100uF 25v
AWG-041-A: C43: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWG-041-A: C44: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v

Q1: 2SC1312: 512-KSC1845FTA:
Q2: 2SC1312: 512-KSC1845FTA:
Q3: 2SC1312: 512-KSC1845FTA:
Q4: 2SC1312: 512-KSC1845FTA:

Filter Amp Board (AWM-089-0)

AWM-089-0: C3: 4.7uF 25v CSZA: 647-UKL1H4R7KDDANA 4.7uF 50v
AWM-089-0: C6: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v
AWM-089-0: C9: 4.7uF 25v CSZA: 647-UKL1H4R7KDDANA 4.7uF 50v
AWM-089-0: C12: 10uF 25v CSZA: 647-UKL1E100KDDANA 10uF 25v

Q1: 2SC1313: 512-KSC1845FTA:
Q2: 2SC1313: 512-KSC1845FTA:

Power Amp Board (AWH-048-A) (This list times two for the two amp boards) (Q1 and 2 recommended for gain matching, but is not required)

AWH-048-A: C2: 10uF 16v CEANL: 647-UKL1E100KDDANA 10uF 25v
AWH-048-A: C5: 220uF 16v CEANL: 647-UKL1C221KPDANA 220uF 16v
AWH-048-A: C11: .22uF 10v CSZA: 80-F612JF224J063A .22uF 63v
AWH-048-A: C15: 470uF 80v CEA: 647-UPW2A471MHD 470uF 100v
AWH-048-A: C16: 470uF 80v CEA: 647-UPW2A471MHD 470uF 100v

Q1: 2SA750: 512-KSA992FBU
Q2: 2SA750: 512-KSA992FBU
Q11: 2SC869: 512-KSC1845FTA

VR1: 470 ohm multi offset: 652-3296P-1-501LF 25 turn
VR2: 470 ohm single bias: 652-3386H-1-501LF 1 turn

TO-3 micas (Need a total of 8): 534-4636 (optional)

Protection Board (AWM-091-A)

AWM-091-A: C1: 470uF 6.3v CEA: 647-UPW1C471MPD 470uF 16v
AWM-091-A: C2: 470uF 6.3v CEA: 647-UPW1C471MPD 470uF 16v
AWM-091-A: C3: 4.7uF 35v CEA: 647-UPW1V4R7MDD 4.7uF 35v
AWM-091-A: C4: 100uF 16v CEA: 647-UPW1E101MED 100uF 25v
AWM-091-A: C5: 100uF 50v CEA: 647-UPW1H101MPD 100uF 50v
AWM-091-A: C6: 100uF 50v CEA: 647-UPW1H101MPD 100uF 50v

Q4: 2SC945: 512-KSC2383YTA
Q5: 2SC1166 (2SC1384): 512-KSC2690AYS
Q6: 2SC1166 (2SC1384): 512-KSC2690AYS

S1: ASR-010 MY4-02-DC24 relay: 653-MY4-02DC24

Stabilizer/Power Supply Board (AWR-106-A)

AWR-106-A: C1: 220uF 80v CEA: 647-UPW2A221MHD 220uF 100v
AWR-106-A: C2: 220uF 80v CEA: 647-UPW2A221MHD 220uF 100v
AWR-106-A: C5: 47uF 35v CEA: 647-UPW1H470MED 47uF 50v
AWR-106-A: C6: 47uF 35v CEA: 647-UPW1H470MED 47uF 50v
AWR-106-A: C7: 22uF 50v CEA: 647-UPW1J220MED 22uF 63v
AWR-106-A: C8: 22uF 50v CEA: 647-UPW1J220MED 22uF 63v
AWR-106-A: C9: 100uF 35v CEA: 647-UPW1H101MPD 100uF 50v
AWR-106-A: C10: 100uF 35v CEA: 647-UPW1H101MPD 100uF 50v
AWR-106-A: C11: 47uF 80v CEA: 647-UPW2A470MPD 47uF 100v
AWR-106-A: C12: 47uF 80v CEA: 647-UPW2A470MPD 47uF 100v
AWR-106-A: C13: 1000uF 25v CEB: 647-TVX1V102MCD 1000uF 35v
AWR-106-A: C15: 47uF 10v CEA: 647-UPW1C470MDD 47uF 16v
AWR-106-A: C16: 22uF 10v CEA: 647-UPW1C220MDD 22uF 16v
AWR-106-A: C17: 220uF 16v CEA: 647-UPW1V221MPD6 220uF 35v
AWR-106-A: C18: 47uF 10v CEA: 647-UPW1C470MDD 47uF 16v
AWR-106-A: C19: 47uF 10v CEA: 647-UPW1C470MDD 47uF 16v

Q1: 2SD313: 863-MJE15032G
Q2: 2SC869: 512-KSC2383YTA
Q3: 2SC1318: 512-KSC1845FTA
Q4: 2SC1384: 512-KSC2690AYS
Q5: 2SB507: 863-MJE15033G
Q6: 2SA628A: 512-KSA1013YBU
Q7: 2SA720: 512-KSA992FBU
Q8: 2SA684: 512-KSA1220AYS
Q9: 2SD325: 863-MJE15032G
Q10: 2SC945: 512-KSC2383YTA
Q11: 2SC945: 512-KSC1845FTA
Q12: 2SD325: 863-MJE15032G
Q13: 2SC945: 512-KSC2383YTA
TO-220 micas (need 2 of them): 534-4672

D1: WZ-240: 512-1N5252B
D2: 1S2473: 512-1N4148
D3: WZ-240: 512-1N5252B
D4: 1S2473: 512-1N4148
D5: WZ-061: 512-1N5234B
D6: 1S2473: 512-1N4148

VR1: 4.7K Ohms single turn: 652-3386H-1-502LF
VR2: 4.7K Ohms single turn: 652-3386H-1-502LF

Soft start relay: LY2-DC48: 653-LY2-DC48 (NOTE: The new relay can fit into the old case without any modifications, just pop the new and old relay cases off and swap the old case to the new relay and remount it.)

Power Supply Board (AWR-107-0)

AWR-107-0: C6: 470uF 100v CEB: 647-TVX2A471MCD 470uF 100v
AWR-107-0: C7: 470uF 100v CEB: 647-TVX2A471MCD 470uF 100v
AWR-107-0: C8: 470uF 25v CEA: 647-UPW1V471MPD 470uF 35v
AWR-107-0: C9: 470uF 25v CEA: 647-UPW1V471MPD 470uF 35v

BOM List

647-UKL1H4R7KDDANA | 6
647-UKL1H2R2KDDANA | 12
647-UPW1V4R7MDD | 1
647-UPW1V221MPD6 | 1
647-UPW1H101MPD | 4
647-UKL1H3R3KDDANA | 2
647-UKL1E100KDDANA | 6
80-F612JF224J063A | 2
647-UPW2A471MHD | 4
647-UPW1E101MED | 1
647-UKL1V220KEDANA | 8
647-UKL1C221KPDANA | 4
667-EEU-FM1E471B | 2
667-EEU-FM1E101 | 10
667-EEU-FC1J221 | 2
667-EEU-FM1H101 | 2
667-EEU-FM1V331 | 2
667-EEU-FC1J331 | 2
667-EEU-FM1A221 | 1
647-UPW1C471MPD | 2
647-UPW1V471MPD | 2
647-UPW2A221MHD | 2
647-UPW1H470MED | 2
647-UPW2A470MPD | 2
647-UPW1C470MDD | 3
647-UPW1J220MED | 2
647-UPW1C220MDD | 1
647-TVX1V102MCD | 1
647-TVX2A471MCD | 2
512-KSA992FBU | 15
512-KSC1845FTA | 16
512-KSC2383YTA | 6
512-KSA1013YBU | 3
512-KSC2690AYS | 3
863-MJE15032G | 3
863-MJE15033G | 1
512-KSA1220AYS | 1
512-1N5252B | 2
512-1N4148 | 3
512-1N5234B | 1
534-4636 | 8
534-4672 | 2
653-MY4-02DC24 | 1
653-LY2-DC48 | 1
652-3296P-1-501LF | 2
652-3386H-1-501LF | 2
652-3386H-1-502LF | 2
 
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Just went and viewed your pictures ---What a beautiful unit well worthy of a nice restoration.
Take pictures and keep us posted.
I own 2 Echowars restored 1250's in pristine condition and I'll NEVER let them go.
 
If I told you the following work was done on my SX-1250, what would be left that could potentially improve the sound quality?

All new 22,000 mfd power supply caps. All new electrolytic caps in the power regulator board, relay board, and driver boards. All new + - regulator transistors in the power supply board. Power supply and output section voltages set per service manual. The OP transistors are all original and have been tested and reseated with new heat sink compound.
 
You didn't recap any of the preamp boards, control amp, flat amp etc? If not, then yes, recapping those will improve the sound quality greatly, the preamp boards are what affect the sound the most and is what gives the receiver its sound characteristics, bad or worn out components on these boards will make the receiver perform at less then optimal, both in tone and quality and can make it sound bad without you realizing it.
 
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Yes Mattsd, that is correct. None of the Preamp boards have been recapped. So, I need to do Flat Amp, Control Amp..where's Preamp? Not seeing on the list above, unless that's equilizer amp board. I will say my 1250 sounds really good right now. It would be nice to finish the job and have it 100% recapped. I plan on keeping this sucker a looong time.
 
The preamp is made up of the control amp, flat amp, equalizer amp (phono amp) and filter amp boards, those are the ones that need recapped. I always replace all the transistors on those boards while I'm in there as well, at minimum the 2SA725 and 726 transistors should be replaced.
 
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Here are some photos of the boards before being redone:

EQ amp board

SX-1250+equalizer+amp+before.JPG


Left power amp board

SX-1250+left+power+amp+before.JPG


Right power amp board

SX-1250+right+power+amp+before.JPG


Protection board

SX-1250+protection+board+before.JPG


Stabilizer board, several of the small caps have been replaced on this board, some of them are the wrong values!

SX-1250+stabilizer+board+before.JPG


Power supply board

SX-1250+power+supply+before.JPG


Left channel old filter caps

Left+ch+old+filter+caps+bottom.JPG


Right channel old filter caps

Right+ch+old+filter+caps+bottom.JPG


And last of all, this cap top came right off when I brushed it with my elbow!

SX-1250+loose+cap+top.JPG


More to follow!
 
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Yes I did, I found some recent posts by markthefixer that helped me confirm the list. Order away!
 
Just a quick update, I ordered the parts the 3rd and they shipped today, should be here the 8th. The wait is about to drive me up a wall! :D I want so bad to get my hands in this thing and get it working again, then I'll finally get to hear what a restored SX-1250 sounds like, something I've been wanting to do for a long time.
 
Matt, I ordered mine too at around the same time you did. I'll keep you posted on how my recap goes. I'm sure I'll be following your lead!
 
Got my parts today! The filter caps are still coming, they hopefully will be here in the next day or two.

SX-1250+parts.JPG
 
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