SX-737 Project

Discussion in 'Pioneer Audio' started by Motnick, Jul 4, 2017.

  1. loweran

    loweran AK Subscriber Subscriber

    Messages:
    757
    Location:
    Austin, Texas
    Yep pretty much all the caps will be smaller than the originals. I too got a relay that was WAY bigger than the original. I just inspected the original and left it in there. No way that replacement was going to fit.
     
  2. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    I took a closer look at the solder that I have on hand. It is 63/37 .020". Should I go ahead with that, or is their a better choice for doing this work?
     
    Last edited: Jul 11, 2017
  3. loweran

    loweran AK Subscriber Subscriber

    Messages:
    757
    Location:
    Austin, Texas
    Mine is .031". You might want to get some larger diameter solder for the job.
     
  4. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,803
    Location:
    Glen Burnie Md.
    Either is fine on the 737. I find the 020 is great for very small connections and pcb's, with the .031 being almost as good. The 031 is stiffer, and holds it's shape longer if I bend it to a long arc, where the .021 won't hold an arc as long in length. But again the size here with these two is immaterial. If you got it, USE IT.
     
  5. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    Here is the BOM for the power supply board. I have these parts on hand already. Before I begin, can someone please have a look at this list and let me know if I should indeed replace all of these parts? Please let me know if anything seems wrong with my parts list, or if anything is missing from this list.

    AWR057,8 c7 1000 50 647-UPW1H102MHD
    AWR057,8 c8 330 50 647-upw1h331mpd
    AWR057,8 c9 330 50 647-upw1h331mpd
    AWR057,8 c10 330 50 647-upw1h331mpd
    AWR057,8 c11 220 16 647-UPW1V221MPD
    AWR057,8 c12 220 50 647-upw1h221mpd
    AWR057,8 c13 100 50 647-UPW1H101MPD
    AWR057,8 c16 220 16 647-UPW1V221MPD
    AWR057,8 c17 22 25 UPW1H220MDD1TD
    AWR057,8 c18 100 16 647-UPW1E101MED
    AWR057,8 c19 100 35 647-UPW1H101MPD
    AWR057,8 q1 2sd313 512-KSC2073TU
    AWR057,8 q2 2sc945 512-KSC2383YTA
    AWR057,8 q3 2sd313 512-KSC2073TU
    AWR057,8 q4 2sc945 512-KSC2383YTA
    AWR057,8 d1 sr3am-4 512-1N5404
    AWR057,8 d2 sr3am-4 512-1N5404
    AWR057,8 d2 sr3am-4 512-1N5404
    AWR057,8 d4 sr3am-4 512-1N5404
    AWR057,8 d5 1s1886 512-1n4004
    AWR057,8 d6 1s1886 512-1n4004
    AWR057,8 d7 1s1886 512-1n4004
    AWR057,8 d8 wz-130 512-1N5243B
    AWR057,8 d9 wz-140 512-1N5244B
    AWR057,8 r3 280-CR5-180-RC
     
    Last edited: Aug 4, 2017
  6. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    I have also reviewed the transistor data sheets, and it looks like all of the replacement transistors for the power supply board have the same pin configuration as the originals. Can someone also please confirm I am interpreting the data sheets correctly?


    2SD313 (BCE) ----> KSC2073TU (BCE)

    2SC945 (ECB) -----> KSC2383YTA (ECB)
     
    Last edited: Jul 14, 2017
  7. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    Looking through the parts that I have on hand for the power supply it looks like C7, 647-UPW1H102MHD is not correct. This part has radial terminals, but the cap on the board has axial terminals.

    Did I order the wrong part?

    [​IMG]

    [​IMG]

    The first cap on the first board. This isn't starting off very good.:)
     
    Last edited: Jul 19, 2017
  8. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,803
    Location:
    Glen Burnie Md.
    The radial might be a weird fit, but it will work. When I replace an axial with a radial, I either heatshrink the POS (+) side or offset the cap so the POS (+) SIDE is on top of the hole and extend the NEG(-) lead. It will work the same.

    The pin outs on the two transistors and their replacements are the same.

    Yes, replace all of the parts on the power supply. Consider this analogous to a Total overhaul of an engine that has had a thermostat that is rated higher than the norm for the engine (195*F vs. 160*F). The extra heat is not good for the parts and they weaken over time. So you replace with parts that have a higher temp resistance, and are heavier duty than the originals. You wouldn't replace a crank without new bearings, or new pistons with old rings, use old gaskets, etc. You replace everything except the block, (you bore and hone the cylinders, bore, hone and true the crank bearing housings, and the same with the cam bearing housings, clean all passages), etc. Then add new or rebuilt parts. The power supply is literally the engine, with the AMPLIFIERS the Transmission and Differential. Think of the EQ, and Tone Controls as intermediate gears internal to the amp. If the Engine doesn't work right, you don't get power to the transmission, or the wheels.
     
  9. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    Wonderful! Thank you for the feedback.

    I did make up a dim bulb tester today, and it seems to be working well. My plan is to lay out all of the parts that I will need for this board before I begin. That is how I came across this radial Vs. axial capacitor difference.

    I noticed at least one of the capacitors on my power board seems to have swollen, as the outside wrap has slid down off of the top of the capacitor. You can see the capacitor I am talking about in the picture of the power supply board that I already posted. I believe that it is C8 on the board. C17 also seems to show the same symptom, but to a lesser degree. Is my assumption correct that this capacitor has an issue, or does that capacitor look okay to you? I am still trying to learn what to look for in regards to bad caps.
     
    Last edited: Jul 15, 2017
  10. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,803
    Location:
    Glen Burnie Md.
    99% of the time it's the Vinyl covering that SHRINKS, rather than the cap bulging. When a cap bulges, you'll notice it. I don't see anything on those caps outof the ordinary, other than the vinyl covering is shrinking. Sometimes if the cap has a plastic cover on top, the vinyl wrap shrinks and pulls on the outer edge of the plastic disc, which makes the disc distort. This distortion is often incorrectly taken as the cap bulging and no good. If you can push down on the plastic disc, and the sides aren't bulged out, chances are the cap is not physically leaky. However if you can access the bottom, look for a seam, and whether it's open or not. Good cap it's closed. Some caps have the seam on the top.
     
  11. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    Thanks for all of the feedback. As this is my first rebuild I am taking things very slowly before I start. I want to be sure that I have a complete plan for this power supply board before I begin.

    I now have the PS board loose from the chassis. I was able to remove the wires from the plastic retainers, and that gave me enough slack to flip the board out on its side with just enough room to work on both sides.

    My next step will be to layout all of the pieces in order, and ensure they are the correct replacements for the originals in my amp.

    Hopefully by taking all of these steps things will go smoothly once I begin. Once I have all of the parts replaced I will power up the amp with my new DBT and see what happens.

    I'll report back with my progress once I have completed the PS board, and hopefull you guys will guide me on next steps.
     
  12. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    One more question regarding my BOM for the power supply board...

    For d8 and d9 it looks like I made a mistake in my Mouser order. The part numbers for these two diodes are very close! According to the BOM these two diodes are not the same. The service manual also shows two different part numbers for these diodes.

    I ordered two 512-1N5243B diodes, instead of one 512-1N5243B and one 512-1N5244B. Is it possible to just use the two that I have, or do I need to order one 512-1N5244B to correct my ordering mistake?
     
  13. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    How's this?

    [​IMG]
     
    Last edited: Jul 19, 2017
  14. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    I am making good progress on the power supply board. Just taking it slowly and building some confidence as I go along.

    I have all of the caps replaced now. I powered the amp up on the DBT after completing the cap replacement and everything worked fine. Came out of protection after about 5-6 seconds. That was a good feeling!

    Now I have moved onto the transistors. Q3 is screwed onto a small heat sink. Do I need to put any thermal paste between this heat sink and the new transistor?

    I did buy some thermal paste from mouser part # 532-250. Can I use this paste here?
     
    Last edited: Jul 31, 2017
  15. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    I decided to work on the power supply diodes today and I encountered my first lifted pad. It's still all there, but probabaly about half of it is sticking up. How would you guys go about dealing with this? Not sure if I can just go ahead and solder the diode in since I still have the entire loop or not.
    [​IMG]
     
    Last edited: Jul 18, 2017
  16. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    Does anybody have any feedback regarding this pcb pad? I have been searching the forum for other repairs like this, but I am mostly finding threads related to repairing pcb pads that have missing sections. In my case I still have the entire loop, its just lifted off of the pcb some.

    Can I super glue this back down flat to the pcb?
     
  17. zebulon1

    zebulon1 This summer heat slowed me down. Subscriber

    Messages:
    3,944
    Location:
    Las Vegas Nevada
    Super glue works good but don't get any on the trace or you'll have to scrape it off. If you can, when installing the component, make sure you seat that lead and component to the board tightly, sandwiching the board between the pad and component. that will hold it tightly. If it is a transistor, I would glue the trace back and use a toothpick end of supper glue on the top side and spare a drop on the transistor leg and board.
     
  18. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    Thanks for the advice. Unfortunetly, as soon as I touched the loop to add the super glue one side cracked through. Bummer!

    I went ahead and let the glue do its thing anyway. But the cracked loop still bugged me. I followed some advice from another thread that I had read today, and made a lead with two loops to jump over to the next component on the pad.

    I was able to solder my jumper down to the pcb pads without filling up the holes for the components. After getting the jumper soldered into place, I cleaned everything up and then reinstalled the components through the pcb and through the loops in my jumper. Then I fluxed and soldered everything up. Hopefully this is an okay way to repair this?

    I powered the amp back up on the DBT after making the repair, and everything powered up fine. Hearing the protection relay click always puts a smile on my face!

    [​IMG]
     
    Last edited: Jul 31, 2017
  19. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,803
    Location:
    Glen Burnie Md.
    Your fix for the pad is fine. You can also fix the part to the top tightly, and scrape the protective coating off the trace back about 1/2" and lay the lead down on the trace then solder it down.

    The Thermalloy paste is good. It's like Brylcreem.....a little dab'll do ya. An opaque coating on the transistor back (just enough so it squeezes out to the edge and no farther. And a very small edge at that. Go ahead and put a small dab on Q3. It'll help it transfer the heat better and keep the transistor cooler.

    The cap looks good! You can leave it as is or later on down the pike if you get OCD over it, replace it. It's one of those Factory vs aftermarket part things. It still does the job, it just looks different. Unless you open it up and display it open, nobody will know except you. And it's not one of those critical RF parts on a tube tuner where you have to have a certain lead length, bent in a certain way and installed over one part and under another or it won't work.

    Zener Diodes; One's a 13V (512-1N5243B) and one's a 14V(512-1N5244B). That's one of those questions where it could go 1/2 a dozen one way and 6 the other. But considering it's in the power supply and a 1 volt variance might be out of tolerance, I'd put that one on the notes and order a new one with the next order.
     
  20. Motnick

    Motnick Active Member

    Messages:
    128
    Location:
    Wyandotte Michigan
    I went ahead and used a very light coat of the paste on the transistor. Nothing really squeezed out at all. I can see a small amount around the edges of the transistor now that it is in place. I am not sure if that might have ended up there when I applied the paste to the transistor, or if it was from squeezing out. I've read that this paste is only intended to fill in the imperfections in the surface of the transistor and the heat sink. So a very light coat is all that's needed. Too much is a bad thing. I assume that I should continue to use this same paste throughout the project anytime that I have a transistor to heat sink connection?

    I have already began building my next parts order. I have added this diode to the list as I would rather not take a chance with using the wrong one. I have also added some other parts that I missed. Including the insulators for the output transistors, and the R3 resistor for the power supply board. Can you please check me on these part numbers?

    AWR-057,8 R3 180 5W 280-CR5-180-RC

    Output Transistor Insulator 534-4662

    I have also added a different protection circuit relay (653-LY2F-DC24) since the relay that I included on my first Mouser order (653-LY4F-DC24) was way to big. According to the data sheet this relay is smaller and should fit. It looks like MTF lists both relay part numbers in the Pioneer relay replacement thread.

    I have read some threads about adding a fly back diode to the protection board pins. The part number that I found in those old threads is obsolete now, and it's alternative on the mouser site is back ordered until January 2018. Any chance you can suggest a part number for this as well? I'd love to add it to my next order if I can.
     
    Last edited: Jul 21, 2017

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