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Pioneer SX-939 Revamp

Is the Pionner XS-939 worth fixing?

  • Oh Yeah!

    Votes: 13 100.0%

  • No Way!

    Votes: 0 0.0%

  • Get a life newb.

    Votes: 0 0.0%
  • Total voters
    13
  • Poll closed .
TinaTurner

TinaTurner

New Member
Hello, I recently obtained this SX-939 in really nice cosmetic condition. The only problem that I noticed was that it would drop FM signal after about 10 seconds of powering up and then remain off. All other inputs seem to be working fine. After cracking it open to take a look I noticed that the power supply board looks like it has been cooked.
SX-939 Power Supply Board Top

SX-939 Power Supply Board Top

SX-939 Power Supply Board Bottom

SX-939 Power Supply Board Bottom


I've decided I want to put new capacitors and transistors in the power supply board. I also want to order all the components listed by larry and mark in larryderouin's rebuild thread for an eventual total preventative revamp.

I'm having trouble finding the following capacitor components from their list on mouser:
6x 598-DSF050J474 OR 667-ECQ-V1H474JL
5x UKL1H010KDDANATD
2x 598-DSF050J224 OR 667-ECQ-V1H224JL
3x 598-DSF050J334 OR 667-ECQ-V1H334JL
1x ECQ-V1H104JL

I was also wondering if anyone has a good suggestion for the 2 big filter caps?
The ones suggested on their list (DCMC123U75EH2B) look like they need to be special ordered.

Thanks in advance to anyone willing to help out. Shout out to larryderouin, markthefixer, and anyone else who helped pave the way!
 

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After checking the post voltages on the power supply board these are the results:

1 = ~10mv
2 = 8.1v
3 = 0.0v (problem seems to be c24 and c22)
4 = 0.0v (problem seems to be q6 that nasty looking one my finger is pointing at in the pic)
5 = 35.1v
6 = 47.5v
7 = 0.0v (problem seems to be c15 and c16)
8 = 25.9v
9 = 33.0v
10 = 14.2v
11 = 24.7v

I could really use a shaman right about now..
 
Just redid a 939 two days ago. Absolutely use Nichicon PW or similar 105 rated caps for the power supply!!!! Bump all those red resistors up in wattage by one and space them, bump the 1/2 watts to 1 watt. Replace all transistors on that board as well. It without question needs it.

Just use normal caps for the big ones and use some sort of foam around them to make sure they stay.
 
Okay here are a couple concerns I still have:

598-DSF050J224 OR 667-ECQ-V1H224JL -------------> 505-MKS20.022/63/5
For C1 & C2 of protection circuit.
Is 63v instead of 50v okay here? ​

ECQ-V1H104JL -----------> 647-QYX1H104JTP
For C60 of tuner assembly.
These are only rated at +85°c, is this okay for tuner assembly?
I'm not going to mess with the tuner assembly anytime soon, I just want to have the parts on hand.​

I decided to go with the 647-LKG1J103MKN for the filter caps, not sure what the difference is between the KG and LKG.

I still need to figure out which resistors to order for the power supply. Thanks for the help, I should be posting my component order list in the near future.
 
TinaTurner said:
Okay here are a couple concerns I still have:

598-DSF050J224 OR 667-ECQ-V1H224JL -------------> 505-MKS20.022/63/5
For C1 & C2 of protection circuit.
Is 63v instead of 50v okay here? ​

ECQ-V1H104JL -----------> 647-QYX1H104JTP
For C60 of tuner assembly.
These are only rated at +85°c, is this okay for tuner assembly?
I'm not going to mess with the tuner assembly anytime soon, I just want to have the parts on hand.​

I decided to go with the 647-LKG1J103MKN for the filter caps, not sure what the difference is between the KG and LKG.

I still need to figure out which resistors to order for the power supply. Thanks for the help, I should be posting my component order list in the near future.
Click to expand...
LKG is KG. It's a part number thing. L is the type (LUG) Yes, you can use the 63v WIMA. You can also use MKS2 (Polyester film) or MKP2 (Polypropylene upgrade) WIMA for C60. It's rated over 100C

https://www.mouser.com/ProductDetail/WIMA/MKP2D031001F00JI00?qs=sGAEpiMZZMv1cc3ydrPrF7l45uRd9dVhmRaXqq4128Q=
 
Last edited:
TinaTurner said:
Okay here are a couple concerns I still have:

598-DSF050J224 OR 667-ECQ-V1H224JL -------------> 505-MKS20.022/63/5
For C1 & C2 of protection circuit.
Is 63v instead of 50v okay here? ​

ECQ-V1H104JL -----------> 647-QYX1H104JTP
For C60 of tuner assembly.
These are only rated at +85°c, is this okay for tuner assembly?
I'm not going to mess with the tuner assembly anytime soon, I just want to have the parts on hand.​

I decided to go with the 647-LKG1J103MKN for the filter caps, not sure what the difference is between the KG and LKG.

I still need to figure out which resistors to order for the power supply. Thanks for the help, I should be posting my component order list in the near future.
Click to expand...
Higher voltage is always ok, it makes the caps last longer. Capacitance, it depends. 85 is fine, but I like to do 105 everywhere so it'll all last the same amount of time, hopefully another 40 years.
I wouldn't do the tuner on the 939, as you have to restring the dial if you do. Things may get unaligned as well.
 
You can do the tuner without restringing, just tape the string to the tuning capacitor wheel and use a rubber band to hold the wheel back towards rear of unit.

Caps won't throw off the alignment, but do NOT replace the transistors here. I can easily see why ivandezande recommended not to touch the tuner though as some people may get in there and fiddle with things and possibly cause issues.

Good call from DeltaB on the Wima MKP's as an upgrade in the smaller values with 5mm lead spacing (MKP2).
 
Okay, here is my list so far. Anything I should change or add to my shopping list? I noticed some insulators on some other lists, can anyone tell me what those are for? Also, should I buy some new fuses for the power supply? The ones in there look good but also very old. Thanks everyone!

SX-939 Revamp

AWF-013 Equalizer Amplifier
  • C1 2.2UF 25V cssa 647-UKL1H2R2KDDANA
  • C2 2.2UF 25V cssa 647-UKL1H2R2KDDANA
  • C5 470UF 6V ceanl 647-UKL0J471MPD
  • C6 470UF 6V ceanl 647-UKL0J471MPD
  • C9 100UF 6V ceanl 647-UKL1E101KPDANATA
  • C10 100UF 6V ceanl 647-UKL1E101KPDANATA
  • C11 10UF 10V ceanl 647-UKL1C100MDDANATD
  • C12 10UF 10V ceanl 647-UKL1C100MDDANATD
  • C19 100UF 25V ceanl 647-UKL1E101KPDANATA
  • C20 100UF 25V ceanl 647-UKL1E101KPDANATA
  • C21 220UF 16V ceanl 647-UKL1C221KPDANA
  • Q1 512-KSA992FBU
  • Q2 512-KSA992FBU
  • Q3 512-KSA992FBU
  • Q4 512-KSA992FBU
AWG-027 Control Amplifier
  • C1 .33UF 25V cssa 505-MKS2B033301A00JF
  • C2 .33UF 25V cssa 505-MKS2B033301A00JF
  • C7 100UF 10V cea 647-UPW1E101MED
  • C8 100UF 10V cea 647-UPW1E101MED
  • C13 2.2UF 25V cssa 647-UKL1H2R2KDDANA
  • C14 2.2UF 25V cssa 647-UKL1H2R2KDDANA
  • C15 4.7UF 35V cea 647-UPW1V4R7MDD
  • C16 4.7UF 35V cea 647-UPW1V4R7MDD
  • C23 4.7UF 25V ceanl 647-UKL1H4R7KDDANA
  • C24 4.7UF 25V ceanl 647-UKL1H4R7KDDANA
  • C25 10UF 16V cea 647-UPW1E100MDD6
  • C26 10UF 16V cea 647-UPW1E100MDD6
  • C29 100UF 10V cea 647-UPW1E101MED
  • C30 100UF 10V cea 647-UPW1E101MED
  • C31 4.7UF 35V cea 647-UPW1V4R7MDD
  • C32 4.7UF 35V cea 647-UPW1V4R7MDD
  • C39 4.7UF 25V ceanl 647-UKL1H4R7KDDANA
  • C40 4.7UF 25V ceanl 647-UKL1H4R7KDDANA
  • C41 10UF 16V cea 647-UPW1E100MDD6
  • C42 10UF 16V cea 647-UPW1E100MDD6
  • C45 100UF 10V cea 647-UPW1E101MED
  • C46 100UF 10V cea 647-UPW1E101MED
  • C47 2.2UF 25V cssa 647-UKL1H2R2KDDANA
  • C48 2.2UF 25V cssa 647-UKL1H2R2KDDANA
  • C49 100UF 16V cea 647-UPW1E101MED
  • C50 100UF 16V cea 647-UPW1E101MED
  • C51 100UF 16V cea 647-UPW1E101MED
  • C52 100UF 16V cea 647-UPW1E101MED
  • Q1 512-KSA992FBU
  • Q2 512-KSA992FBU
AWH-030 Power Amplifier
  • C1 .47UF 25V cssa 505-MKS2B034701B00KO
  • C2 .47UF 25V cssa 505-MKS2B034701B00KO
  • C3 1UF 25V cssa 647-ULD1H010MDD1TD
  • C4 1UF 25V cssa 647-ULD1H010MDD1TD
  • C5 33UF 16V cea 647-UPW1C330MDD
  • C6 33UF 16V cea 647-UPW1C330MDD
  • C11 330UF 10V cea 647-UPW1A331MPD
  • C12 330UF 10V cea 647-UPW1A331MPD
  • Q1 512-KSA992FBU
  • Q2 512-KSA992FBU
  • Q3 512-KSA992FBU
  • Q4 512-KSA992FBU
  • Q5 512-KSA1381ESTU
  • Q6 512-KSA1381ESTU
  • Q7 KSC2690AYS (from ebay)
  • Q8 KSC2690AYS (from ebay)
AWM-062-0 Protection Circuit
  • C1 .22UF 10V cssa 505-MKS20.022/63/5
  • C2 .22UF 10V cssa 505-MKS20.022/63/5
  • C3 330UF 6V cea 647-UPW1A331MPD
  • C4 330UF 6V cea 647-UPW1A331MPD
  • C5 4.7UF 25V cea 647-UPW1V4R7MDD
  • C6 100UF 16V cea 647-UPW1E101MED
  • Q6 512-KSD1616AGBU
AWR-052-0 Power Supply
  • C11 47UF 63V cea 647-UPW2A470MPD
  • C12 47UF 50V cea 647-UPW2A470MPD
  • C13 470UF 80V ach-038 647-UPW2A471MHD
  • C14 470UF 80V ach-038 647-UPW2A471MHD
  • C15 100UF 63V cea 647-UPW1J101MPD
  • C16 100UF 63V cea 647-UPW1J101MPD
  • C17 47UF 16V cea 647-UPW1E470MDD
  • C18 47UF 16V cea cea 647-UPW1E470MDD
  • C21 47UF 50V cea 647-UPW2A470MPD
  • C22 2200UF 10V cea 647-UPW1A222MHD
  • C23 220UF 16V cea 647-UPW1C221MPD
  • C24 1000UF 35V ach-039 647-UPW1V102MHD
  • Q1 512-KSC2073TU
  • Q4 512-KSA940TU
  • Q6 512-KSC2073TU
  • R9 5.6K 0.5W Carbon Film 294-5.6K-RC 1W
  • R10 2.7K 1W Metal oxide 603-RSF200JB-73-2K7 2W
  • R11 820 2W Metal oxide 660-MOS3CT631R821J 3W
  • R12 820 2W Metal oxide 660-MOS3CT631R821J 3W
  • R17 150 0.5W Carbon Film 294-150-RC 1W
  • R20 4.7K 0.5W Carbon Film 660-SPR1CT52A472J 1W
AWM-063 Muting Assembly
  • C1 4.7UF 25V cea 647-UPW1V4R7MDD
  • C2 4.7UF 25V cea 647-UPW1V4R7MDD
  • C3 1UF 25V cssa 647-ULD1H010MDD1TD
AWE-041-0 Tuner Assembly
  • C22 4.7UF 25V cea 647-UPW1V4R7MDD
  • C24 10UF 16V cea 647-UPW1E100MDD6
  • C25 .47UF 50V cea 505-MKS2B034701B00KO
  • C26 10UF 16V cea 647-UPW1E100MDD6
  • C31 1UF 50V cea 647-ULD1H010MDD1TD
  • C33 100UF 16V cea 647-UKL1E101KPDANATA
  • C34 47UF 16V cea 647-UPW1E470MDD
  • C37 .33UF 25V cssa 505-MKS2B033301A00JF
  • C38 1UF 10V cssa 647-ULD1H010MDD1TD
  • C39 .47UF 25V cssa 505-MKS2B034701B00KO
  • C42 100UF 16V cea 647-UKL1E101KPDANATA
  • C43 2.2UF 25V cea 647-UKL1H2R2KDDANA
  • C44 2.2UF 25V cea 647-UKL1H2R2KDDANA
  • C45 .47UF 50V cea 505-MKS2B034701B00KO
  • C46 .47UF 50V cea 505-MKS2B034701B00KO
  • C52 4.7UF 25V cea 647-UPW1V4R7MDD
  • C53 4.7UF 6V cea 647-UPW1V4R7MDD
  • C58 10UF 16V cea 647-UPW1E100MDD6
  • C60 .1UF 25V cssa 505-MKP2D031001FJI00
  • C63 220UF 16V cea 647-UKL1C221KPDANA
Filter Caps
  • C1 10000UF 50V 647-LKG1J103MKN
  • C2 10000UF 50V 647-LKG1J103MKN
Dial Lamp Board
  • Dial Lamp Board 220UF 16V 647-UPW1C221MPD
 
So I ran into a problem. I blew the board tracing between pin 13 and C8 and D6 on the power supply board. This happened after installing the new filter capacitors. I did not replace capacitors C5, C6, C7, C8 or D5, D6, D7, D8. Should I replace all of these now? Not sure what to do. Anybody have any thoughts?
 
Is it normal for the unit to go into protect mode when connected to a DBT, speakers and the volume turned up loud? Doesn't seem to go into protect mode when I disconnect the DBT.
 
Yes. The DBT will limit current as well as voltage. When you crank it, you're basically strangling the parrot(protection board is sensing a problem), so to speak with a voltage drop.
 
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