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Pioneer SA-6300 Renovation

Discussion in 'Pioneer Audio' started by bc_leszcz, May 22, 2013.

  1. bc_leszcz

    bc_leszcz New Member

    Messages:
    8
    Location:
    Poland
    Hello everyone

    I have just finished renovation of Pioneer SA-6300.

    It was not just replacement of all electrolytic, but also a little upgrade, by means of capacity increase of some caps, diode replacement and also some transistors replacement.

    I've got this amp as faulty for equivalent of just 10$. After the fuse replacement the amp start to work, but it was unstable, sounded horribly, and after some wormup it blew fuses again. So I started to fix it.

    The first to go were capacitors. To my suprise, most of them, to be exact all with just exception of two pices, were fine and even hold the orginal capacity. However, I replaced all of them anyway.

    Recaping did not cure the amp. Idle current was still unstable, fluctuating from a few mV to almost 100mV which cause the fuse to blow. It turned out that some of the transistors (drivers) were not good. Not exactly broken but not working as expected - Hfe was only 30 when mesured on one of them! So I decided to replace some transistors to better ones. But I kept the output transistors, only replacing differential pair and drivers.

    Now, after I have finished, the amp is working perfectly, and to my suprise it really sounds very well. Probably, it sounds much better than when it was new. Bass is excelent, mid are rich, highs nice. Even it is a small amp it is still able to drive my B&W CDM7 speakers very well. Even at maximum volume there is no distrortion audible. Can't be compared to what it was before renovation.

    Here is a picture of the inside before modifications:

    [​IMG]

    and a picture of the inside after modifications:

    [​IMG]

    The most interesting modifications are probaly the transistors replacements:

    Q4,Q6 (Q5,Q7) 2SA763 -> changed to Toshiba 2SA970-GR
    Q8 (Q9) 2SC1318A -> 2SC2383-O
    Q10/Q12 (Q11/Q13) 2SC1318A/2SA720A -> 2SC2235-Y/2SA965-Y

    I rised a bit Ic on the drivers replacing R67,R69 (R68,R70) from 150ohm to 100ohm.
    I replaced R61, R62 to values that get me 10mV of idle current across output transistors emiter'ss resistors.
    I replaced R63, R64 to get 30mV after cutting Adj. wire.
    I left orginal output transistors, as well as Q18, Q2, Q3.

    I will add description of all others modifications if anyone is interested.

    To summary - it is a very little amp, not a power horse, but after some tuning and recapping it is one worth listening. For effective 8ohm speakers it is more than enough.

    The amp is only lacking a good protection circut with output relay, but such one can be easily added if one woud like to use that amp for an expensive speakers, just in case ....

    Few more pictures:

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     

     

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  2. Alienz

    Alienz Super Member

    Messages:
    1,247
    Location:
    The Netherlands
    Nice one :thmbsp:

    The 6300 was my first rebuild project, don't see this model often here on AK, maybe it was for the european market?

    I used Panasonic FC/FM and Elma Silmics but for the main PS caps I used some OEM brand cans, couldnt find any others that would fit physically. Wonder if I should change them for something better. Also thinking about changing the blue tantalum caps as well.
     
  3. bc_leszcz

    bc_leszcz New Member

    Messages:
    8
    Location:
    Poland
    The one I modified has US style power outlets at the back and is 5-Line voltage model, so it is definitely not European only model.

    I changed the two blue tantalum caps that were in audio path to Elna Silmic II, but left all in phono amp section, as I don't use it.
    I read somewhere that these tantalum are not bad. Electrically were perfect - capacity very close to the rated one, perfect within tolerance.
     
  4. Alienz

    Alienz Super Member

    Messages:
    1,247
    Location:
    The Netherlands
    Btw where did you buy those Nichicon's? I can't find a supplier for those in mainland Europe.
     
  5. Marty Socal

    Marty Socal Active Member

    Messages:
    405
    If you have a list of the capacitors required for this amp and will post them here, I'll add this thread to my recap link list! :thmbsp:
     
  6. Alexvallejo

    Alexvallejo New Member

    Messages:
    1
    @bc_leszcz,
    Hi there. I'm reading this with interest and hoping you can provide the full list and replacement parts you used on this renovation? I recently got the same amp that's exhibiting the same (bad) symptoms you described prior to your reno and I decided maybe I can replace the same things myself and expect a miracle.

    I can work on technical things but have no knowledge of electronics repair but willing to have a go at my amp as a "project" and learning experience. I don't care if I stuff it up in the end - do you think you can let me know all the original part numbers vs the replacement part numbers you used?

    I can't relate the schematic to the actual board in terms of locating the numbered parts i.e Q1, Q2, R3, R4 etc. on paper - so please if you can list it by original part number vs replacement part number I can physically look and locate it though.

    Apologies if I am requesting too much for a newbie on the forum, but I was thrilled when I read your reno and wish I could try and do the same and fix my amp -( that would be an accomplishment!) but I need all the expert help I can get.
    Thanks in advance
     

     

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  7. sallog

    sallog New Member

    Messages:
    14
    Hi,

    Excellent work. I too have this amplifier and having problems with left channel occasionally (it crackles). I have checked all the caps using ESR meter they seem fine. I have also inspected the entire PCB and I can't find any dried or crack joints and just touched up 1 or 2 areas but that has not solve my problems. Went through all resisters and they seem physically and functionally fine. Next transistors, I looking at pre drivers or driver transistors (deferential) - Q4,Q6 (Q5,Q7). Where is this located on the board as its not marked? Any help would be much appreciated.
     
  8. zebulon1

    zebulon1 Building a new bench. Finally! Subscriber

    Messages:
    4,916
    Location:
    Las Vegas Nevada
    Swap out the blue robin egg caps for stacked film for starts. See (or hear) what happens.
     
  9. craxx6969

    craxx6969 Well-Known Member

    Messages:
    879
    Location:
    Normal, IL
    +1 on the blue egg caps. They are a known problem.
     
  10. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

    Messages:
    21,125
    Location:
    Bensenville,Illinois
    Check to see that your 2sa763's haven't been subbed by 2sa725's or 2sa726's,

    Just look through the unit at the numbers on the transistors, I HAVE looked for a free downloadable service manual just now and the usual spots came up dry. And also for the SA-5300 which is very similar. Stereomanuals.com has an excellent paper reproduction manual for the SA-5300.

    If you find ANY 2sa725/6's replace them with ksa992's

    The blue egg caps - are identified by the sky blue color AND the Sanyo brand on them.
     
  11. zebulon1

    zebulon1 Building a new bench. Finally! Subscriber

    Messages:
    4,916
    Location:
    Las Vegas Nevada
    I have a scat but only the full scat. Nothing that breaks down to a board or any circuit parts descriptions.

    Transistors in the main amp:
    2SA763
    2SC1318
    2SC1384
    2SA720
    2AS488
    2SC789
     
    Last edited: Sep 26, 2015

     

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  12. sallog

    sallog New Member

    Messages:
    14
    Thank you for your help much appreciated, I have downloaded schematic for SA-6300 and I think I have located PNP transistors which are related to 4 q's. I have taken them out to measure but I am getting varying results, so I have replaced all 4 (2SA763) to BC556B - had to adjust pins as CBE were arranged differently (readings are stable in these). Lets see what happens in the next few days. If problems still persists, will replace replace rest of the Q's as well and I think some are NPN. BUt still having difficulties where q's are because Pioneer have not marked the board clearly like Sansui's and Marantz.
     
    Last edited: Sep 26, 2015
  13. sallog

    sallog New Member

    Messages:
    14
    Pioneer SA-6300 intermittent crackle on left channel

    Blue egg caps, are they small uf caps? if so they measure ok well within tolerance. I will target that next if this does not solve the problem. Thank you very much for this info.
     
  14. zebulon1

    zebulon1 Building a new bench. Finally! Subscriber

    Messages:
    4,916
    Location:
    Las Vegas Nevada
    They are usually under 4.5uf and can go to 50v. You won't find any smoking gun by measuring the components. They will test good but will exhibit unwanted noise when operating. Your method of replacement and checking will work better.
    You did Deox the controls?
     
    Last edited: Sep 26, 2015
  15. sallog

    sallog New Member

    Messages:
    14
    Yes, all switches and controls have been cleaned . It just happens while in operation without touching any controls (seldom); when trying to use any controls to clear this crackle on the left nothing works, its constant. More of a component related. So far its not returned but however I will look into those caps and replace them in the next few days.
     
  16. sallog

    sallog New Member

    Messages:
    14
    The crackle has not returned so I presume its fixed.
     

     

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  17. hoangngan

    hoangngan New Member

    Messages:
    5
    Thank you very much for this info!
     
  18. bc_leszcz

    bc_leszcz New Member

    Messages:
    8
    Location:
    Poland
    Some time has passed and the following:

    caused troubles. The amplifier came back to me from the owner - after some 20-30 minutes in one channel there were audible cracks, the guilty one was the 2SC1312 transistor. This should be replaced by a transistor with high Hfe, 2SC1845 is a good replacement, but beware of a different pin-out.

    I have also added a pot for idle current settings in place of R61, R63 and R62, R64, which is handy in setting the right idle current:


    Output transistors were also replaced, as the idle current was not stable vs temperature. At the end all is fine now once again. The amp is old, and original discreet elements start to give up.
     
  19. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

    Messages:
    1,772
    Location:
    Victoria, Australia
    Hi, glad to hear you have her sorted out again. Yeah those 2SC1312/13's are bad news, so are the 2SA725/26's. Good move on the adding the pots for setting BIAS, l did the same when l repaired a SA-5300 a while back, Pioneer were trying to save a few cents here l think :rolleyes:.
     
  20. digit

    digit New Member

    Messages:
    2
    Hello Audiokarma,
    I have just stumbled onto this Forum. I have a SA6300 amp which is great but, the little orange Power "On" light doesn't work. Does anyone out there have one they could sell me and tell me how to fit/replace it?
    Thanks.
    Peter (digit)
     
    Last edited: Apr 28, 2017

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