pioneer sx 1250

[zebulon1]

Minimum restore.
Power Supply Board (AWR-107-0)
Stabilizer/Power Supply Board (AWR-106-A)
Protection Board (AWM-091-A)
Power Amp Board (AWH-048-A) (This list times two for the two amp boards)

Maybe someone will test and check the large filter caps for you.
I have a set I removed from a working set. They are in OK shape as they have not vented. Might be persuaded to let them go. PM me if you want them.

 

[maclvrbr]

sx 1250

Thanks guys is there any way to isolate the component creating my issue? Are there too may variables and possibly multiiple component failures?

 

[markthefixer]

Thanks guys is there any way to isolate the component creating my issue? Are there too may variables and possibly multiple component failures?

There is a cascade of possibilities, and a game of whack a mole in the future, where the whacking incrementally adds damage as each board is removed and worked on a little bit.

You could post measurements of the protect board after the relay clicks out - to try to see if the protect board is justified in it's actions.
Then the power regulator board voltages as well.

If you are lucky, it's a weak relay driver transistor.

But without readings, we can play an extremely time wasting what if game - but WE won't include ME.

 

[maclvrbr]

sx 1250

I appreciate all of the help. I have began rebuilding the R-L amps protect and stabilizer boards. I have completed amps and protect and have started on stabilizer. I have discovered previous work. Most all of the caps have been replaced with higher voltage caps obviously not stock. I have replaced them with caps in thread but discovered something unusual. D1 was missing. I aslo discovered a diode taped to the inside of the metal board mount. Any ideas what to do here. Thanks again for the help.

 

[zebulon1]

JF, D1 needs to be installed. You won't get your +25v or +65v regulated.
The last guy didn't want to loose it.
Use this Thread to compare your boards and drivers:
http://www.audiokarma.org/forums/showthread.php?t=420950 (mattsd)
Do you have some 1N5252B's?

 

[maclvrbr]

sx 1250

Thanks , yes I do have them and have replaced D1 and D3. Can you explain what was to be accomplished by removing D1? I was hoping to understand the reasoning. I have completed the stabilizer board.

 

[markthefixer]

JF, D1 needs to be installed. You won't get your +25v or +65v regulated.
The last guy didn't want to loose it.
Use this Thread to compare your boards and drivers:
http://www.audiokarma.org/forums/showthread.php?t=420950 (mattsd)
Do you have some 1N5252B's?

Thanks , yes I do have them and have replaced D1 and D3. Can you explain what was to be accomplished by removing D1? I was hoping to understand the reasoning. I have completed the stabilizer board.

Remember when I posted this:

pin 11 86.6v // +65.0v regulator running wide open or shorted

Removing D1 caused the regulator to run wide open. Insanity and damaging.
You would need to test that diode that was taped in there to see if it was damaged,
but I'm unable to warp my mind far enough to find justification for what was done, under any circumstances.

 

[maclvrbr]

sx 1250

I installed a new one for D1 and D3.

 

[larryderouin]

but I'm unable to warp my mind far enough to find justification for what was done, under any circumstances.

Your signature says it all, MARK!!

 

[maclvrbr]

sx 1250

After rebuild and installation of boards and large caps receiver comes out of protection. DC offset was adjusted very close to O and bias adjusted. I however had a problem adjusting bias on left channel. Meter shows no movement no matter how much I adjust trimpot. Meter worked fine on right channel . Any ideas. Thanks for all who have helped me.

 

[rcs16]

Adjusting the bias trimmer should change the voltage drop across the bias generator, STV3's and R's, thus the 6 vbe drops across the 6 transistors as part of the triple push-pull pairs. 1.8V * 2 = 3.6V. Supposed to be 2mA through the vbe generator, Q4,6
What is the V across the o/p emitter R's?
V between Q7,8?
Could measure the var R when powered off. It is 470 ohm

 

[maclvrbr]

sx 1250

Thanks for the reply. Can you be a bit more specific? I don't quite understand but want to. Exactly which resistor on the board should I check resistance? Also which part of each transistor should I check? With power on or off? Thanks for trying to help.

 

[rcs16]

What is the V across the o/p emitter R's?
Measure with power applied,
1)This would be the DCV across each R28,R29(0.5ohm/5W) for the top half of 2SD555 bjts.
and would be R32,R33(0.5ohm/5W) for the bottom half of 2SB600 bjts
2) V between Q7,8? DCV in circuit with power applied. This voltage should increase as you adj the pot VR2.
3) Could first measure VR2 when powered off. It is close to 470 ohm when turned one way and around 0 when truned the other way. if you see it jumping around that is not a good thing, either clean vr2 with de-oxit or replace it which is always the best thing to do.

In the adj procedure you are to adjust vr2 for 100mV across TP7 & 19
So 100mV/1 ohm(0.5x2) = 100mA of bias current through each output pair

4) You could measure the voltage in circuit with power applied for R20 (620). This will determine the current through the diff pair Q3,4. So the (DCV across 620)/620 ohm will determine the current. This current should be the sum of the currents through R15,16(220ohm). Measure powered up, DCV across R15 and R16/220ohm. This will determine how well the differential pair Q3,4 are in balance and what is the bias current through the diff pair.

Good luck
Rick

 

[maclvrbr]

sx 1250

Thanks Rick, so far I checked R33 and R32 they fluctuate between -3.2 and -4.0V. R 29 and R 28 -2.8and -3.6V. VR 2 would adjust up to 412mv. How can I get a probe on R 20. 15, 16 with power on? Does it matter which side of the resistor is checked? Again thanks for the help

 

[markthefixer]

The voltage is ACROSS the named 0.5 ohm resistors, one dmm probe on each side of the resistor at the same time. The readings will be at or below 0.1 volt (100 millivolts)

This measurement is NOT ground referenced.

They can be easily accessed at pins 7 and 19 on the outer corners of each amplifier board, very close to the transistor connectors. Have you cleaned all those connector pins BEFORE doing anything with the board?

Haven't you downloaded the hi res sx-1250 service manual?

 

[rcs16]

Thx mtf, yes he has to realize what measurements are ground referenced. All, except where noted, the voltages on the schematics are ground referenced, but the bias measurements are across the o/p bjt emitter ballast R's.
R28,R29(0.5ohm/5W) for the top half of 2SD555 bjts.
R32,R33(0.5ohm/5W) for the bottom half of 2SB600 bjts

 

[maclvrbr]

sx 1250

Thanks guys. I did check measurements to ground. I will recheck across resistors and get back to you. I had also cleaned the connectors. I have also downloaded the 1250 scan. I assume its easy to check the voltages to transistors if I removed heatsink with outputs attacked and the amp metal mount bracket to access safe probe connection to amp board. Again thank you.

 

[markthefixer]

if I removed heatsink with outputs attacked and the amp metal mount bracket to access safe probe connection to amp board. Again thank you.

HUH? There's some dangerous disconnections in there...

I TOLD YOU:

They can be easily accessed at pins 7 and 19 on the outer corners of each amplifier board, very close to the transistor connectors. Have you cleaned all those connector pins BEFORE doing anything with the board?

They were PUT THERE to make ACCESS EASY!!! The manual will show you.

disconnect NOTHING and then apply power., without checking with me or a very few others, before you let magic smoke out.

you are scaring me. and I don't scare easily.

 

[maclvrbr]

sx 1250

I trust you guys do not get frustrated with me. I was looking at the schematic and don't see that R 28, 29 and R32, 33 tie into pins 7 and 19. Yes it would seem a lot safer and do not want to damage anything. I did remove protect board and reattach under receiver and was able to get to R28,29, R32 and 33 on my lowest scale I had 0 volts across these resistors with power on. Also what is safest way to access voltage across R20, R15 and 16? Also where should I measure voltages between Q7 and Q8 , R25 or R24? Thanks

 

[PooPoo]

Originally Posted by mattsd View Post
Excellent JT! BTW, I thought it was an SX-850 that I sold you.

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

Equalizer Amp Board (AWF-021-A) (Q1 & 3 and Q2 & 4 should be gain matched)

AWF-021-A: C11: 470uF 6.3v CEANL: 647-UKL1C471KPD 470uF 16v
AWF-021-A: C12: 470uF 6.3v CEANL: 647-UKL1C471KPD 470uF 16v
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 should be gain matched)

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: 667-ECQ-V1H224JL2 .22uF 50v
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

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

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-MY2-02DC24

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

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-UKL1C471KPD | 2
647-UKL1H4R7KDDANA | 6
647-UKL1H2R2KDDANA | 12
647-UPW1V4R7MDD | 1
647-UPW1V221MPD6 | 1
647-UPW1H101MPD | 4
647-UKL1H3R3KDDANA | 2
647-UKL1E100KDDANA | 6
667-ECQ-V1H224JL2 | 2
647-UPW2A471MHD | 4
647-UPW1E101MED | 1
647-UKL1V220KEDANA | 8
647-UKL1C221KPDANA | 4
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 | 14
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-MY2-02DC24 | 1
652-3296P-1-501LF | 2
652-3386H-1-501LF | 2
652-3386H-1-502LF | 2

Is the power amp doubled in the order in this BOM?