Pioneer SPEC-2 recap and restoration thread!

Discussion in 'Pioneer Audio' started by mattsd, Nov 19, 2017.

  1. mattsd

    mattsd AK Subscriber Subscriber

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    Man, it has been awhile since I posted one of these threads! Everything has taken off so fast in the past couple of years, I've been crazy busy keeping up with everything. Some background on this unit, I got this from a guy who I restored a SPEC-1 and SPEC-2 for about a year and half ago. Long story short, he had a second one in the basement and gave it to me for free! He reads AK and I believe he's a member here, so if you read this Rick, thank you very much!

    It is not without problems though, it would not come out of protection. Upon inspection of the boards I found the caps and transistors had been replaced on both power amp boards with a weird mix of good and bad replacements. Let us start with the left power amp board, as it has some interesting things done. Side note: I got a new camera and it is much better than my previous one. The first three images are the old camera, the rest of them are the new one.

    The left channel STV diodes had homemade replacements made from three 1N4007 diodes in series for the STV-3H and four 1N4007 diodes in series for the STV-4H in a weird plastic case screwed to the heatsink.

    [​IMG]

    Some close ups with the plastic cases removed:

    [​IMG]

    [​IMG]

    An interesting way to replace the STV diodes, however not ideal for good thermal tracking. I managed to find (with the help of AK :thumbsup:) an original STV-3H diode from a seller in Germany. The STV-4H came from a parts receiver that I had here. The 4H diodes are not easy to find, so I was thankful I had a parts unit with one in it.

    Board before (note I have already replaced the STV diodes):

    [​IMG]

    Molex pins (note I cleaned the right 2 to show the differences):

    [​IMG]

    A cool thing I noted when I was looking for a polypropylene replacement for the input cap, the board actually provides pads and lead holes for bigger capacitors than the little tantalum being used currently. It allows for, in addition to the 5mm lead spacing of the tantalum, 10mm, 15mm and 22.5mm lead spaces via the trace here:

    [​IMG]

    And after! In total 8 caps, 14 transistors, 6 diodes, 3 variable resistors and the bias relay were replaced.

    [​IMG]

    Molex pins:

    [​IMG]

    Bias relay, the bottom molex pins were also cleaned:

    [​IMG]

    STV-3H and STV-4H diodes back in place:

    [​IMG]

    [​IMG]

    Close up of the new input cap and transistors, I matched the differential pair to 1% and then heatshrinked them face to face for better thermal stability. Maybe a little overkill, but hey, I'm going a little crazy on this unit anyway. :D

    [​IMG]

    The outputs were also replaced by the previous tech, however they do not look good, some look like somebody hit them with a punch and they are dented pretty good in the middle of the case. Not going to trust them.

    [​IMG]

    Have to wait on new micas for the outputs, forgot to add them to the order so I'm currently waiting on them to arrive. A big thank you to @EchoWars for the bias relay mod and @markthefixer for part recommendations. More to follow soon!
     
    Last edited: Dec 12, 2017

     

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  2. mattsd

    mattsd AK Subscriber Subscriber

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    Got the micas and we're back in business!

    Here is the left channel outputs after, all new micas and thermal paste.

    [​IMG]

    Now for the right channel. The STV diodes were all original on this board, but it still had questionable cap and transistor replacements. Some of the transistors were replaced with the correct On-Semi MJEs however.

    [​IMG]

    And after! All the molex pins were cleaned and all the other replacements parts are the same as the left channel.

    [​IMG]

    The left channel outputs were good originals, but in the interest of symmetry, I replaced them as well with the On-Semi MJ outputs

    [​IMG]

    And after:

    [​IMG]

    Next post will be the power supply and the meter amp board. It's coming along somewhat slowly as I have a 1280 I'm doing concurrently which I'll also be posting here as I do not believe there is a complete restore thread on a 1280. More to come!
     
  3. moodydan

    moodydan I love the punk rock. Subscriber

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    Great work, Matt!
     
  4. slow_jazz

    slow_jazz Lunatic Member

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    Awesome job...
     
  5. mattsd

    mattsd AK Subscriber Subscriber

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    Location:
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    And here is the rest of it! We'll begin with the power supply:

    [​IMG]

    And after! 2 caps and both relays were replaced.

    [​IMG]

    Last, the meter amp board. This board has had a few transistors and caps replaced already.

    [​IMG]

    The primary surge relay on this board is pretty easily replaced, the case can be transplanted onto the new relay with no mods needed.

    [​IMG]

    Old vs new:

    [​IMG]

    New relay, old case:

    [​IMG]

    I added spade connectors to the wires for easier removal later if necessary.

    [​IMG]

    The wires with the spade connectors do clear the transformer.

    [​IMG]

    One unique thing on this board is the 10uF 160v bi-polar cap they use to pass current until the relay closes. It is pretty much impossible to find a electrolytic replacement, but you can find a polyester film in that size. The only issue is that the poly cap is much bigger and so is the lead spacing, however you can use the lead hole that's circled and it allows you to fit a bigger cap.

    [​IMG]

    And after! The cap clears the power switch easily and does not impede anything else.

    [​IMG]

    All done! 18 caps, 17 transistors, 2 trim pots and the relay were replaced.

    [​IMG]

    Last thing to do will be the filter caps, powering it up and testing it and then cosmetic work. Almost there!
     
    Last edited: May 17, 2018
    Hipocrates and gslikker like this.
  6. mattsd

    mattsd AK Subscriber Subscriber

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    Here is the recap list for the Pioneer SPEC-2. Note I used some different components compared to the list.

    Power Amp Board (AWH-045) (Times 2) (Check board revision, later board revisions add C19 and Q20)

    C1: 4.7uF 35v CSZA: 647-UKL1H4R7KDDANA 4.7uF 50v
    C4: 10uF 35v CEA: 647-UPW1H100MDD 10uF 50v
    C5: 10uF 35v CEA: 647-UPW1H100MDD 10uF 50v
    C6: 22uF 35v CEA: 647-UPW1H220MDD 22uF 50v
    C19: .22uF 25v CSSA: 80-F612JF224J063A .22uF 63v

    Q1: 2SA798 dual: 512-KSA992FBU (2) (Must be closely gain matched!)
    Q2: 2SA872: 512-KSA992FBU
    Q3: 2SA872: 512-KSA992FBU
    Q4: 2SD610A: 863-MJE15032G
    Q5: 2SD610A: 863-MJE15032G
    Q6: 2SD610A: 863-MJE15032G
    Q7: 2SB630A: 863-MJE15033G
    Q8: 2SA733: 512-KSA733CYTA
    Q9: 2SC945: 512-KSC945CYTA
    Q10: 2SC945: 512-KSC945CYTA
    Q11: 2SA733: 512-KSA733CYTA
    Q12: 2SD610A: 863-MJE15032G
    Q13: 2SB630A: 863-MJE15033G
    Q20: 2SC1885: 512-KSC2383YTA

    D2: BZ-340: 512-1N5247B (2)

    RL1: 934-HE3621A2400, Reed SPST 1A 24V

    VR1: 652-3386H-1-501LF
    VR2: 652-3386H-1-101LF
    VR3: 652-3386H-1-101LF

    Power Supply Board (AWR-093)

    C11: 470uF 35v CEA: 647-UPW1H471MHD 470uF 50v
    C12: 1000uF 35v CEA: 647-UPW1H102MHD 1000uF 50v

    RL1: LY2-DC24: 653-LY2-0-DC24
    RL2: LY2-DC24: 653-LY2-0-DC24

    Meter Amp Board (AWM-081)

    C1: 1uF 25v CSZA: 505-MKS2C041001FJC00 1uF 63v
    C2: 1uF 25v CSZA: 505-MKS2C041001FJC00 1uF 63v
    C3: 1uF 25v CSZA: 505-MKS2C041001FJC00 1uF 63v
    C4: 1uF 25v CSZA: 505-MKS2C041001FJC00 1uF 63v
    C5: 220uF 6.3v CEA: 647-UPW1A221MED 220uF 10v
    C6: 220uF 6.3v CEA: 647-UPW1A221MED 220uF 10v
    C7: 220uF 6.3v CEA: 647-UPW1A221MED 220uF 10v
    C8: 220uF 6.3v CEA: 647-UPW1A221MED 220uF 10v
    C9: 470uF 6.3v CEA: 647-UPW1A471MPD 470uF 10v
    C10: 470uF 6.3v CEA: 647-UPW1A471MPD 470uF 10v
    C11: 470uF 16v CEA: 647-UPW1E471MPD 470uF 25v
    C14: 22uF 35v CEA: 647-UPW1H220MDD 22uF 50v
    C15: 22uF 35v CEA: 647-UPW1H220MDD 22uF 50v
    C16: 10uF 35v CEA: 647-UPW1H100MDD 10uF 50v
    C17: 10uF 35v CEA: 647-UPW1H100MDD 10uF 50v
    C19: 10uF 160v CEA Bi-Polar: 667-ECQ-E2106KFB 10uF 250v Poly
    C20: 10uF 35v CEA: 647-UPW1H100MDD 10uF 50v
    C21: 10uF 35v CEA: 647-UPW1H100MDD 10uF 50v

    Q1: 2SC1312: 512-KSC1845FTA
    Q2: 2SC1312: 512-KSC1845FTA
    Q3: 2SA725: 512-KSA992FBU
    Q4: 2SA725: 512-KSA992FBU
    Q5: 2SA725: 512-KSA992FBU
    Q6: 2SA725: 512-KSA992FBU
    Q7: 2SC1312: 512-KSC1845FTA
    Q8: 2SC1312: 512-KSC1845FTA
    Q9: 2SC1312: 512-KSC1845FTA
    Q10: 2SC1312: 512-KSC1845FTA
    Q11: 2SA733: 512-KSA733CYTA
    Q12: 2SC1384: 512-KSC2383YTA
    Q13: 2SC945: 512-KSC945CYTA
    Q14: 2SC1384: 512-KSC2690AYS
    Q15: 2SC1384: 512-KSC2690AYS
    Q16: 2SD313: 512-KSC2073TU
    Q17: 2SB507: 512-KSA940TU

    VR1: 652-3386H-1-101LF
    VR2: 652-3386H-1-101LF

    RL1: LY2S-DC48: 653-LY2-DC48 (remove the case of the original relay to fit on the new one)

    BOM List (With C19 and Q20 from AWH-045 added):

    647-UKL1H4R7KDDANA | 2
    647-UPW1H100MDD | 8
    667-ECQ-E2106KFB | 1
    647-UPW1H220MDD | 4
    647-UPW1A221MED | 4
    647-UPW1A471MPD | 2
    647-UPW1E471MPD | 1
    647-UPW1H471MHD | 1
    647-UPW1H102MHD | 1
    80-F612JF224J063A | 2
    505-MKS2C041001FJC00 | 4
    512-KSA992FBU | 12
    863-MJE15032G | 8
    863-MJE15033G | 4
    512-KSA733CYTA | 5
    512-KSC945CYTA | 5
    512-KSC2383YTA | 2
    512-KSC2690AYS | 2
    512-KSC2073TU | 1
    512-KSA940TU | 1
    652-3386H-1-501LF | 2
    652-3386H-1-101LF | 6
    512-1N5247B | 4
    653-LY2-0-DC24 | 2
    653-LY2-DC48 | 1
    661-E36D101N223TDB7M | 4
    934-HE3621A2400 | 2
     
    Last edited: Mar 6, 2018

     

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  7. kevzep

    kevzep Its all about the Music Subscriber

    Very nice work there!! So good to see these threads, so much incredibly valuable information here!!
    Thanks for posting all your work and information.
     
  8. mattsd

    mattsd AK Subscriber Subscriber

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    And last up, the filter caps. I upgraded these to 22000uF 100V, same as the SX-1250.

    Before (note I removed one before taking the photos):

    [​IMG]

    [​IMG]

    New vs old:

    [​IMG]

    And after!

    [​IMG]

    [​IMG]

    And it's ready to fire up! Fired it up on a DBT, checked bias to make sure it set properly, everything passed so I turned it back to 0 and hooked it up on line power. Reset the bias:

    [​IMG]

    And then hooked up my speakers and source, sat back and pressed play:

    [​IMG]

    Words fail to express how good this thing sounds. The soundstaging has razor sharp definition, the highs sparkle and the bass is very tight and authoritative. It is now the best sounding piece of Pioneer gear I own, including the 1980. Granted, I never upgraded the signal path caps in the 1980 to polypropylenes like I did here, so it's not surprising.

    Beauty shots coming soon!
     
  9. M.fate

    M.fate New Member

    Messages:
    4
    Hello,
    This is my first post and I’m just getting into vintage audio and vinyl.
    I have in opportunity to get a Spec 2 very cheap. The owner said it needs new transistors. I would like to take the plunge and fallow your lead and repair it. I have a friend who builds CNC controllers for fun to help me with the technical stuff. My concern is parts availability. How difficult is tracking down all the parts? Is there one place to get it all? Last is there any recommendations for reading so I myself can get a better grasp on how all the components work?

    Thank you in advance
    Sean
     
  10. xXColdShotXx

    xXColdShotXx Active Member

    Messages:
    185
    Location:
    Lexington, Kentucky
    I need replacements for 647-LGY2A102MELA30, 647-UPW1A471MPD, 512-KSC2690AYS,
    667-EEU-FM1A471, 505-MKS2C041001FJC00 they are backordered on mouser.
     
    Last edited: May 16, 2018
  11. xXColdShotXx

    xXColdShotXx Active Member

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    185
    Location:
    Lexington, Kentucky
    .
     
    Last edited: May 23, 2018 at 11:32 PM

     

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