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SX-727 Stereo Indicator Lamp Problem

AJD1964

AJD1964

Well-Known Member
Hello. I’ve been away from the Pioneer group for a while, spending too much time with the turntable geeks I suppose... Now I need a little advice.

Anyway – to the point; My SX-727 has a strange symptom with the FM stereo indicator lamp. When I am in any mode OTHER than FM stereo, the indicator lamp seems to want to faintly flicker when it is not supposed to be on. This also seems to be temperature related. When stone cold at startup, it’s ok, but after the unit is on a few minutes, the indicator lamp starts faintly flickering, like for example, when in phono mode. When on a stereo FM station, it works fine – bright and stable.

After searching here, I suspect the problem is a failing Q19 transistor on the AWE-015 board, or relating components around it; i.e. diode, cap, etc... but I was not able to find the exact Mouser part numbers for the Q19 or its relating components. Any links or advice would be greatly appreciated!

Regards, AJD

EDIT: Note the change in Board Identifier to AWE-015. I had the wrong one noted by mistake.
 
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I am not familiar with the 727's but you can search Google for the equivalent.
For example: Type "2SA726: audiokarma" in the search box, this will bring several Threads or posts with info pertaining to a replacement. The "2SA726" would be the original transistor discovered in the set or on the schematic. Look for listings with the most recent date.
Check the Database for the set. If it's there post the recap list so the grues can vet it. I know MTF was working on a similar set and was updating the list so check the most recent posts for a current discussion.
 
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I did find this at the Database:
Pioneer SX-727 recap and transistor list:

Head Amp Board (W21-002)

W21-002: C1: 22uF 10v CEA: 647-UPW1C220MDD6 22uF 16v
W21-002: C2: 22uF 10v CEA: 647-UPW1C220MDD6 22uF 16v
W21-002: C3: 4.7uF 16v CEA: 647-UPW1V4R7MDD 4.7uF 35v
W21-002: C4: 4.7uF 16v CEA: 647-UPW1V4R7MDD 4.7uF 35v
W21-002: C5: 10uF 25v CEA: 647-UPW1E100MDD 10uF 25v
W21-002: C6: 10uF 25v CEA: 647-UPW1E100MDD 10uF 25v
W21-002: C15: 220uF 25v CEA: 647-UPW1E221MPD 220uF 25v

If board is the W21-002, then:

Q1: 2SC458: 512-KSC1845FTA
Q2: 2SC458: 512-KSC1845FTA
Q3: 2SC458: 512-KSC1845FTA
Q4: 2SC458: 512-KSC1845FTA
Q5: 2SC458: 512-KSC1845FTA
Q6: 2SC458: 512-KSC1845FTA

AF Board (AWK-010)

AWK-010: C7: 47uF 50v CEA: 647-UPW1H470MED 47uF 50v
AWK-010: C8: 47uF 50v CEA: 647-UPW1H470MED 47uF 50v
AWK-010: C13: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWK-010: C14: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWK-010: C15: 47uF 6.8v CEA: 647-UPW1C470MDD 47uF 16v
AWK-010: C16: 47uF 6.8v CEA: 647-UPW1C470MDD 47uF 16v
AWK-010: C21: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWK-010: C22: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWK-010: C27: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWK-010: C28: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWK-010: C29: 100uF 6.8v CEA: 647-UPW1C101MED 100uF 16v
AWK-010: C30: 100uF 6.8v CEA: 647-UPW1C101MED 100uF 16v
AWK-010: C31: 47uF 50v CEA: 647-UPW1H470MED 47uF 50v
AWK-010: C32: 47uF 50v CEA: 647-UPW1H470MED 47uF 50v

Power Amp Board (AWH-011)

AWH-011: C7: 22uF 6.8v CEA: 647-UPW1C220MDD6 22uF 16v
AWH-011: C8: 22uF 6.8v CEA: 647-UPW1C220MDD6 22uF 16v
AWH-011: C9: 220uF 10v CEA: 647-UPW1E221MPD 220uF 25v
AWH-011: C10: 220uF 10v CEA: 647-UPW1E221MPD 220uF 25v
AWH-011: C15: 100uF 50v CEA: 647-UPW1H101MPD 100uF 50v
AWH-011: C16: 100uF 50v CEA: 647-UPW1H101MPD 100uF 50v

Power Supply Board (AWR-011)

AWR-011: C6: 100uF 50v CEA: 647-UPW1H101MPD 100uF 50v
AWR-011: C7: 100uF 50v CEA: 647-UPW1H101MPD 100uF 50v
AWR-011: C9: 220uF 35v CEA: 647-UPW1V221MPD6 220uF 35v
AWR-011: C10: 220uF 16v CEA: 647-UPW1E221MPD 220uF 25v
AWR-011: C11: 220uF 16v CEA: 647-UPW1E221MPD 220uF 25v

Protection Board (AWM-011 or AWM-027) (The “D” version of the 027 board has C1 and 2 as .22uF electrolyte caps instead of Mylar caps)

(“D” version board) AWM-027: C1: .22uF 16v CSSA: 667-ECQ-V1H224JL2 .22uF 50v
(“D” version board) AWM-027: C2: .22uF 16v CSSA: 667-ECQ-V1H224JL2 .22uF 50v
AWM-027: C3: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v
AWM-027: C4: 330uF 6.8v CEA: 647-UPW1A331MPD 330uF 10v
AWM-027: C5: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v
AWM-027: C6: 100uF 16v CEA: 647-UPW1C101MED 100uF 16v

BOM List:

647-UPW1E100MDD | 2
647-UPW1E221MPD | 5
647-UKL1H2R2KDDANA | 6
647-UPW1A331MPD | 2
667-ECQ-V1H224JL2 | 2
647-UPW1H470MED | 4
647-UPW1V221MPD6 | 1
647-UPW1V4R7MDD | 3
647-UPW1V101MPD | 1
647-UPW1H101MPD | 4
647-UPW1C470MDD | 2
647-UPW1C220MDD6 | 4
647-UPW1C101MED | 3
 
Hi Zeb,
Thanks for the info, but this list does not cover the Q19 transistor. I'll just try to match something out of the parts list in my manual and see what comes up on the Mouser site. I'm still kinda green as a buyer..
AJD
 
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AJD1964 said:
Hi Zeb,
Thanks for the info, but this list does not cover the Q19 transistor. I'll just try to match something out of the parts list in my manual and see what comes up on the Mouser site. I'm still kinda green as a buyer..
AJD
Click to expand...

Not a good idea.

I did, use the ksc1845 there.
 
I think I got things mess up. I had only used the "2sc726" as an example.
 
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zeb, NOTHING was aimed at you, the "not a good idea" was aimed at:

I'll just try to match something out of the parts list in my manual and see what comes up on the Mouser site. I'm still kinda green as a buyer..
Click to expand...

because NOBODY references back the the 2sc870 transistor anymore.
 
Zeb / Mark, - Now I am confused.

The attachment that Zeb posted is what I also found during a search, and I am looking at a print out of it in front of me. My interpretation of that transistor identification is a Q19 NOT a 13, as Zeb has noted.

I am assuming the attachment Zeb posted is a section from the “big” schematic. I am also looking at my “Hi-Fi Engine” copy of the SM, page 24, AM/FM unit AWE -015 (I made a mistake on the original post of the thread calling it AWR-011, which is a different board, and edited the error). Pin 5 on AWE-015 is labeled “IND” – This is the Stereo Indicator Lamp – Correct? It traces to the collector of what also looks like Q19. These copies are hard to read.

Mark indicated that the transistor is originally a 2SC870. I do see an 870 on this board, but the identifier is Q17 according to the SM parts list on page 29, and it is in a different part of the board. This also confuses me. I believe the original is a 2SC968. I just need to verify that the ksc1845 is really the correct replacement.

I have attached a copy of the AWE-015 form the SM page 24. Hopefully the yellow highlights & notes will help explain my confusion.

AWE 015 AM_FM Unit SX 727.jpg
 
ok, pin 5 lamp current sink 2sc968, 50v 0.5a 0.5w hfe 160 70mhz

different animal, sorry... not rereading the whole thread and then a smeary pdf led me astray.

use 512-KSC2383YTA to-92L ecb 160v 1a .9w 50mhz 160-320hfe
 
I am to blame!
I was looking at the blurred docs and misinterpreted the transistor Q19 for Q13. I think we are closer to talking about the same circuit! :banana:
Also removed the image of the schematic on post 7.
 
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Thanks for helping me staighten this out. I appreciate your fast responses! :banana:

I'll send a note to confirm whether it fixed it or not.

Man - I need to get me some original SM copies!
 
Best place on the net for repro's is Rick Stout @ www.stereomanuals.com. They are extremely well done, NO PDF'S online. I've gotten all of my "hard" manuals from Rick and they are nothing less than outstanding. MTF considers them his "GOLD STANDARD" for manuals. Well worth the $$ you put out for them.

NO AFFILIATION! JUST A REPEAT CUSTOMER!
 
larryderouin said:
Best place on the net for repro's is Rick Stout @ www.stereomanuals.com. They are extremely well done, NO PDF'S online. I've gotten all of my "hard" manuals from Rick and they are nothing less than outstanding. MTF considers them his "GOLD STANDARD" for manuals. Well worth the $$ you put out for them.

NO AFFILIATION! JUST A REPEAT CUSTOMER!
Click to expand...

Oh Yea! stereomanuals.com I've read about them here before!

Thanks Larry!
 
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