Marantz 2270 Power Amplifier Board Parts BOM

Discussion in 'Marantz Audio' started by PhilInAudio, Sep 10, 2017.

  1. PhilInAudio

    PhilInAudio New Member

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    I am in the process of fully restoring a Marantz 2270 receiver that I've owned for almost 8 years. Restoration is not new to me. I have done restorations before on several stereo components, but never a Marantz receiver. This is my first! (I did restore a Marantz 250M power amplifier which now sounds completely amazing! But I digress...)

    What started this Marantz project was the fact that my left channel was dying and making strange noises. I isolated the problem to the left channel Power Amplifier Board and decided to rebuild all of the components on both boards including the capacitors, transistors and diodes. I figured why replace one part when I could refresh the entire board and give them another 20 years of (hopefully) maintenance free life. So I am starting with the Power Amplifier Boards and will refresh the pre-amp board and others next.

    Much to my horror, tracking down parts is not easy for this, and my guess other, Marantz receivers. Over the past week or so, I've spent an enormous amount of time researching replacement parts. As a former electrical engineer, I have some knowledge in doing this. I know just enough to be dangerous. For example, I now use a voltmeter instead of my tongue! :)

    After developing my first BOM, I was fortunate to bump into "Catrafter" on this AK site who was kind enough to review my BOM and make valuable recommendations. Given the enormous effort that went into this BOM, we both felt that sharing this BOM would be extremely valuable to the AK community.

    For simplicity, I broke the BOM into two sections; one for capacitors and one for transistors and diodes. I have cross-referenced all of the Marantz parts to excellent replacement parts that can be purchased at Mouser.

    Here is the BOM for the capacitors:

    2270 Power Amp Board Capacitor List_AK_090717_01.jpg

    Below are the URL (links) for the Mouser Parts:
    C751 http://www.mouser.com/ProductDetail/Nichicon/QAK2E105KTP/?qs=sGAEpiMZZMv1cc3ydrPrFw0ydM5up7OWR4cEle/VKzU=
    C752 http://www.mouser.com/ProductDetail/Vishay-BC-Components/K101J15C0GF53L2/?qs=sGAEpiMZZMt3KoXD5rJ2N6ZV8M58kCCvr8m2zfpSmIA=
    C753 http://www.mouser.com/ProductDetail/TDK/FG26C0G2J102JNT06/?qs=sGAEpiMZZMt3KoXD5rJ2N5U4Cys/UpTlDtc8rH3ThbKiCoTDK/qRmA==
    C754 N/A
    C755 http://www.mouser.com/ProductDetail/Vishay-Cera-Mite/561R10TCCQ10/?qs=sGAEpiMZZMuMW9TJLBQkXi2JfE4zIBPntlv3T299%2bgs=
    C756 http://www.mouser.com/ProductDetail/TDK/FK26C0G2J151J/?qs=sGAEpiMZZMt3KoXD5rJ2N/PvFyU07Yc/7R4pu2uhREE=
    C757 http://www.mouser.com/ProductDetail/Nichicon/QXK2E104KTPTZH/?qs=sGAEpiMZZMv1cc3ydrPrF5paIYTtxDrh3%2bgyFK6Blgk=
    C758 http://www.mouser.com/ProductDetail/Nichicon/QXK2E104KTPTZH/?qs=sGAEpiMZZMv1cc3ydrPrF5paIYTtxDrh3%2bgyFK6Blgk=
    C759 http://www.mouser.com/ProductDetail/Nichicon/UKZ2A100MPM/?qs=kArNe9LFxXkw0uvoEkQ2fQ==
    C760 http://www.mouser.com/ProductDetail/Nichicon/UKZ2A100MPM/?qs=kArNe9LFxXkw0uvoEkQ2fQ==
    C761 http://www.mouser.com/ProductDetail/Panasonic/EEA-FC1A220/?qs=sGAEpiMZZMtZ1n0r9vR22ZGaUoI0JcRfWiIOYLZVx40=
    C762 http://www.mouser.com/ProductDetail/Nichicon/QXK2E104KTPTZH/?qs=sGAEpiMZZMv1cc3ydrPrF5paIYTtxDrh3%2bgyFK6Blgk=
    C763 http://www.mouser.com/ProductDetail/Nichicon/QXK2E224KTPTZH/?qs=/ha2pyFaduhhzQrbX9IKrvzci9AIYDQg1ivEB2lvaA2e0z%2bHkSqgPw==


    Here is the BOM for the transistors and diodes:

    2270 Power Amp Board Transistor List_AK_090717_01.jpg

    Below are the URL (links) for the Mouser Parts:
    H751 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSA992FBU/?qs=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91Okk2WNWq80Dmc=
    H752 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSA992FBU/?qs=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91Okk2WNWq80Dmc=
    H753 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSC945CYTA/?qs=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91OkBoeYyqB98%2bc=
    H754 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSC1845FTA/?qs=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91Ok7yYQ9zR8%2b88=
    H755 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSC1845FTA/?qs=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91Ok7yYQ9zR8%2b88=
    H756 http://www.mouser.com/ProductDetail/Central-Semiconductor/2N5415/?qs=sGAEpiMZZMshyDBzk1/Wiw99kSkYzPxmP0eyM4VXuOM=
    H757 http://www.mouser.com/ProductDetail/Central-Semiconductor/2N3440/?qs=sGAEpiMZZMshyDBzk1/Wiw99kSkYzPxmMIS8JFtI%2bdw=
    H758 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSC2073TU/?qs=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91OkrD/dBwjYg1o=
    H759 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSA940TU/?qs=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91OkC0Oyvc5tfcQ=
    H760 http://www.mouser.com/ProductDetail/ON-Semiconductor/MJE243G/?qs=/ha2pyFadujPAfDbZ1O4119iCHWS1MoxlP1WJgk3Tt8=
    H761 http://www.mouser.com/ProductDetail/ON-Semiconductor/1N4007G/?qs=sGAEpiMZZMtqO%2bWUGLBzeDbi29SPb2By
    H762 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/1N4744A/?qs=sGAEpiMZZMtQ8nqTKtFS/D313Kx94AdFdSPLy44WWjs=
    H763 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/1N4744A/?qs=sGAEpiMZZMtQ8nqTKtFS/D313Kx94AdFdSPLy44WWjs=
    H764 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/1N5236B/?qs=sGAEpiMZZMtQ8nqTKtFS/D313Kx94AdF9xRoM4tauXg=
    H765 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/1N5236B/?qs=sGAEpiMZZMtQ8nqTKtFS/D313Kx94AdF9xRoM4tauXg=
    H766 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSA992FBU/?qs=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91Okk2WNWq80Dmc=
    H767 http://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSA992FBU/?qs=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91Okk2WNWq80Dmc=
    H768 N/A
    H769 N/A
    H001 http://www.mouser.com/ProductDetail/ON-Semiconductor/MJ21193G/?qs=/ha2pyFaduhYR/YNuos/yPrr6J3ZPw3fA%2bbv/1AROoc=
    H002 http://www.mouser.com/ProductDetail/ON-Semiconductor/MJ21194G/?qs=/ha2pyFadugQPhP9m%2bAR7wx%2bmvwh4wsKHB%2b1mdhDUX1oT/PHwheTdA==
    H003 http://www.mouser.com/ProductDetail/ON-Semiconductor/MJ21193G/?qs=/ha2pyFaduhYR/YNuos/yPrr6J3ZPw3fA%2bbv/1AROoc=
    H004 http://www.mouser.com/ProductDetail/ON-Semiconductor/MJ21194G/?qs=/ha2pyFadugQPhP9m%2bAR7wx%2bmvwh4wsKHB%2b1mdhDUX1oT/PHwheTdA==

    I ordered all of the above parts on Friday and hope to get them this coming week. I can't wait to get started installing them!!! I'll update everyone on my progress as I rebuild my Marantz 2270 Power Amp Board with brand new parts!!! :) :)

    In the meantime, I hope that everyone finds this information helpful and please feel free to share any thoughts that you have.

    Phil
     
    Last edited: Sep 13, 2017
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  2. catrafter

    catrafter Marantz Specialist Subscriber

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    That's a lot of info!
    Good work!

    Tom
     
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  3. PhilInAudio

    PhilInAudio New Member

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    Thanks for your contribution! :)

    Phil
     
  4. runningdog

    runningdog AK Subscriber Subscriber

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    Very thorough. Thank you!
     
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  5. quadtech

    quadtech Active Member

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  6. PhilInAudio

    PhilInAudio New Member

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    Quadtech, thanks for adding this link! This is some wonderful information, plus you have parts information on some of the other boards that I was going to tackle next. I will go through this information over the next week or so and post any updates that I find. In short, I'll compile and post an updated BOM based on the great work that's already been done. Thanks so much and feel free to share any more links that you feel would be helpful. I'm going to try to cover all the replacement parts for the 2270 in this one thread. By the way, in addition to my next BOM covering all the replacement transistors, diodes and caps, I think I'm going to add resistors too.

    Some would argue that resistors are stable and don't change value much over time. This is generally true in DC applications, however in audio filtering and applications where the voltage across the resistor changes, such as audio signal processing, the old carbon composition resistors were never that great because they always had a high Voltage Coefficient of Resistance (VCR) that had a tendency to color the audio signal. In short, the older carbon composition resistors found in Marantz and other 70s audio gear had resistors that performed in non-linear ways when processing audio signals! After 30 or 40 years of use, its totally impossible to say if these carbon composition resistors are making the sound worse now. But I think it's reasonable to conclude that the VCR issue in these resistors is not getting better over time. Plus I'm taking apart my 2270 anyway, why not change the resistors too???

    By the way, here is a great post I found that covers the Voltage Coefficient of Resistance issue: http://mojoshout.com/uncategorized/choosing-the-right-resistor-for-your-amplifier-project/

    So going forward, I think I'm going to rebuild all my Marantz gear with the inclusion of metal film resistors. Metal film resistors are extremely linear and will probably outlive the amp. It certainly can't hurt and, who knows, the sound might make a huge leap forward in quality. I'm sure that some will argue that metal film resistors may change the vintage sound of the Marantz amp. My response is, who can say what the vintage sound really is some 40 year later? The only way to determine the vintage sound is to go back in time 42 years to 1975, buy a new 2270 and listen to it. Since none of us can do that, I think using the "vintage sound" argument is not the way to look at it. I think the better test is, do you like the resulting sound? So my approach to this resistor upgrading idea is incremental and is as follows: I'm going to rebuild the left and right channel power amplifier boards on my 2270 with new transistors, diodes and caps...but on the right channel I'm going to also install new metal film resistors and then compare the sounds of the two channels. I think that this is the way to go and it will be a fun experiment too! I'll post the results!!! :)

    I'd love to hear any comments on the above. Has anyone else done this? Does it make sense? What am I missing? Is metal film the way to go? What brand of resistor is best? Anyone, please feel free to validate or punch holes in this idea. All comments are welcome. :)

    Thanks.

    Phil
     
  7. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    I believe AK member MBuras (Mike) has done some rebuilds with all new metal film resistors. You might PM him and see if he thinks it was worth the effort.
    Steve
     
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  8. PhilInAudio

    PhilInAudio New Member

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    Thanks Steven Tate! I'll reach out to MBuras as you suggest.

    I just got the new parts from Mouser for my 2270! I audited the parts I received with the BOM I sent to Mouser and everything arrived perfectly! I'm very happy! :) OK, now the real work begins...I just need to find the time to install the new parts and test my refreshed 2270! :) A nice problem to have. :) Wish me luck! If you see a mushroom cloud outside your window over the next couple of days, please be understanding if you never see a post from me again!!! :)
     
  9. Fairlane

    Fairlane AK Subscriber Subscriber

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    Great write up and good luck!
     
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  10. PhilInAudio

    PhilInAudio New Member

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    Thanks Fairlane!

    OK...after doing some research on resistors, I think I opened up a Pandora's box of issues.

    The following link summarizes a lot of what I found:

    http://www.diyaudio.com/forums/the-lounge/64538-resistor-sound-quality.html

    Clearly, resistors do have an impact on sound quality much more than I thought. At this point the resistor issue is too big for me to deal with now. I'll come back to it later when I have more time to devote to researching it.

    Right now I'll concentrate on rebuilding the Power Amp Board with caps, transistors and diodes.

    I've already done some tests and have results that I'd like to share with everyone. Before replacing the parts on the left channel power Amp Board, I tested the new OnSemi output transistors below on my right channel board to see if I could detect any sound differences with the original Marantz parts.

    The new OnSemi part numbers:
    H001 - MJ21193G OnSemi
    H003
    - MJ21193G OnSemi
    H002
    - MJ21194G OnSemi
    H004
    - MJ21194G OnSemi

    Fortunately, there is some really great news here! In my opinion, the new OnSemi parts are what we called in the business, a perfect "pin-for-pin compatible, fit-form and functional replacement" for the original 2270 output transistors. In short, these new OnSemi transistors sounded great! I could not tell any difference from the original transistors. These results are very surprising to me because these same transistors are also a perfect output transistor replacement in my Marantz 250M that I just finished restoring a few weeks ago!!! By the way, the 250M is by far the best sounding amplifier that I've ever owned!!! Seriously...the best!!! Hopefully, after being rebuilt, the 2270 will give the 250M a run for its money! :)

    With this output transistor test successfully completed, I'll now start replacing the other parts on the left channel board. For now, I'll keep the original parts on the right channel board (the good channel) so I can do audio comparison testing with the left channel board when it's rebuilt.
     
    Last edited: Sep 15, 2017
  11. PhilInAudio

    PhilInAudio New Member

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    12
    I did something to my Marantz 2270 that I'd like to share. At the very beginning of this project, I modified my Power Amplifier Boards (P750) and 2270 chassis by adding connectors to the boards and chassis so that I can easily connect or disconnect the Power Amplifier Boards from my 2270 receiver chassis. There are major benefits to adding these connectors: 1) From a completely assembled 2270, with the connectors, I can disassemble and remove both Power Amplifier Boards in less than 5 minutes! 2) With the connectors, I can easily connect a board, power it up and test it without having to reinstall it! 3) Adding the connectors makes servicing the 2270 relatively pain free. :)

    Here are some pictures of the connectors that I used. Note the boards still have their original Marantz parts on them:

    DSC_0173.JPG

    DSC_0176.JPG

    DSC_0181.JPG

    If you are interested in adding the connectors I used, below is a picture of the connector packaging that includes the brand and sku#:

    DSC_0184.JPG


    You'll need 16 gauge wire in 6 colors: Red, White, Blue, Green, Yellow and Black. AutoZone has the perfect 16 gauge wire for this application. Their 16 gauge wire is not stiff like so many others. The AutoZone links for 30 foot rolls are:

    Red - http://www.autozone.com/miscellaneo...-wire/electrical-wire-primary-wire/163444_0_0
    White - http://www.autozone.com/miscellaneo...-wire/electrical-wire-primary-wire/768395_0_0
    Blue - http://www.autozone.com/miscellaneo...-wire/electrical-wire-primary-wire/163410_0_0
    Green - http://www.autozone.com/miscellaneo...-wire/electrical-wire-primary-wire/150807_0_0
    Yellow - http://www.autozone.com/miscellaneo...-wire/electrical-wire-primary-wire/163428_0_0
    Black - http://www.autozone.com/miscellaneo...-wire/electrical-wire-primary-wire/163451_0_0

    Marantz built my 2270 with 18 gauge wire. I don't know if this was standard practice, but I like using the thicker 16 gauge. The 16 gauge wire just simply has better conducting capability than the 18 gauge and it worked extremely well for me.

    Regarding the connectors, the connector contacts have crimp tabs. I used the crimp tabs and then soldered the wire, which resulted in really solid wire connections to the contacts.

    If someone else has worked on your 2270, expect that you'll need to rewire a part of the chassis' power lines because you'll find that the previous person had burned too much insulation exposing wires and/or created very tight wire connections by cutting wires too short and re-soldered them to their terminals anyway.

    If done properly, it will take you about 2 hours to make the necessary modifications to add the connectors.

    If you are not very experienced in electronics and soldering or don't know what you are doing...do not attempt to do this or anything else in this thread. Hire a professional! :)

    Good luck all...please feel free to comment.

    Phil
     
    Last edited: Sep 18, 2017 at 10:11 AM
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  12. PhilInAudio

    PhilInAudio New Member

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    Hello everyone...here is an update:

    Little more than an hour ago, I finished replacing the all caps, transistors and diodes in the left channel Power Amp Board using the parts identified in the parts BOM above.

    After power up, the board instantly sounded vibrant, rich and wonderful while playing Steely Dan (Aja) and others during low to moderate volume testing. All the transistors ran cool...not the slightest bit warm which means that my bias setting maybe somewhat decent. Most importantly, the sound was just a good, if not better, than the right channel that still had its original vintage parts!!! This is a truly amazing result given the fact that so many transistors where change to different current generation parts. Cudos to Marantz for having such a brilliant circuit design for this amplifier section!!! :)

    I'll listen to it for another hour tonight. I'm too tired to do anything more. However, tomorrow I'll check the DC Offset and the bias. After this is done, I'll do high power tests to see how the 2270's new parts perform under stress.

    For now, I am totally pleased with the results!!! :) Again, I'd like to give a shout out to "Catrafter" for his contribution to the Power Amp Board BOM list.

    Please let me know if anyone has any questions or comments.

    Phil
     
  13. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    Love the connector mods. If it's good enough for later models (2275, 2325, etc.)., it should be good enough for the trusty 2270. I'm sure many purists would not like modifying the unit in ways not recommended by Marantz, but if you plan on keeping the unit long term, why not? :thumbsup:
    Steve
     
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  14. cemerson

    cemerson AK Subscriber Subscriber

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    Location:
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    Phil,

    Great work! Would there be anyway to get this in the original Excel Spreadsheet, if it wouldn't be too much to ask?

    Thanks, Chris
     
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  15. PhilInAudio

    PhilInAudio New Member

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    Cemerson...I just checked this thread for a quick second. I'll be happy to post the spreadsheet tomorrow morning along with a progress update on the rebuilding of my 2270 Power Amp Boards (P750). It's 3:15am right now and I'm just too tired to do it now. Keep an eye out for my post tomorrow. :)
     
  16. PhilInAudio

    PhilInAudio New Member

    Messages:
    12
    Thanks for the thoughts Steven Tate!

    OK...everyone...here is the update on my 2270 Power Amp Boards (P750) rebuild project:
    1) The project was a complete success!
    2) The audio performance of the 2270 with the new parts from the BOM was spectacular!
    3) During the installation, all parts fit as they should...especially the transistor EBC pin orientations.
    4) The DC Offset on both the left and right channel boards set perfectly to Zero.
    5) The bias on the right channel set perfectly to 5.0 mV DC, as measured from J754 and J756.
    6) The best bias setting I could get on the left channel was 0.0 mV DC, as measured from J754 and J756.
    7) With the exception of H756 and H757, all transistors ran extremely cool, even under heavy load!
    8) Transistors H756 and H757, for the new and original parts, ran warm at all volume levels with little temperature variation due to load.
    9) The thermal performance of the Power Amp Boards was excellent under heavy load due to thermal compound being applied between transistors H751 and H752, applied on the H756 and H757 transistors and heat sinks, and applied to the H001, H002, H003 and H004 transistors and mica insulators.
    10) The only parts not replaced on the Power Amp Boards (P750) were: H759, H758, H760, H761, H768, H769 and all the resistors.
    11) The music listening test period as approximately 3.5 hours.
    12) The music included, but was not limited to: Steely Dan (Aja), Chicago (Group Portrait Vol 1), Dean Brown (From Here to Here), David Sancious (Forest of Feelings), Michael Jackson (Thriller), James Taylor (Your Smiling Face), Nils Landgren (Redhorn) and Crosby, Stills, Nash and Young (Deja Vu).
    13) On all music, the Marantz 2270 sounded smooth, well balanced, articulate, brilliant and vibrant while maintaining excellent full body bass.
    14) The performance of the Marantz 2270 came very close to, if not matched, the Marantz 250M.
    15) The results of this project exceeded my wildest expectations. Put simply...I am thrilled! :)
    16) My confidence in the above parts BOM for the 2270 Power Amp Board (P750) is very high!

    Regarding "6" above, I have not taken or had the time to trouble shoot this issue. If the problem was over-biasing the output transistors, I would have stopped everything to trouble shoot the problem. However, this was not my problem. My problem was that I was technically under-biasing the output transistors. On one level, this means nothing to me because the sound coming from this channel is absolutely flawless! On another level, I'm curious as to why I can not adjust R763 to achieve the ideal 5 mV bias setting. I'm going to burn-in the 2270 with the new parts a little more before I tackle this final and completely non-critical issue. By the way, I may have made a mistake. I never checked the bias on this board before replacing the parts. Maybe this board had bias adjustment issues before I replaced the parts. My bad for not checking!

    By the way, if anyone has any ideas on what I should do next to solve this problem, please feel free to share your thoughts.

    And now...the pictures!!! :)

    Here is a picture of my left channel board with the original Marantz parts on it:

    DSC_0224.JPG

    Here is a picture of my right channel board with the news parts installed:

    DSC_0009.JPG

    Cemerson asked me to share the parts BOM in Excel format. I've attached it to this post.

    OK...I hope everyone likes this update and post.

    Please comment, ask or share any thoughts that you have.

    Thanks everyone!

    Phil
     

    Attached Files:

    Last edited: Sep 18, 2017 at 10:19 AM
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  17. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    Excellent work and great info with the BOM. Thanks for posting!:thumbsup:
     
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  18. quadtech

    quadtech Active Member

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  19. quadtech

    quadtech Active Member

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  20. PhilInAudio

    PhilInAudio New Member

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    Steven Tate...thanks for the kind thoughts!

    Quadtech:
    1) Thanks for the Bourns trim pot idea. I wasn't crazy about the original Marantz pots. Yes...I will buy and install the Bourns.
    2) Regarding the bias issue, I was really hoping that you would say, "just flick switch number xxx and your bias problem will go away!" OK...clearly I need to invest more time if I'm going to make this issue go away. Why does one board work perfectly and the other has a minor bias issue??? Ugh...
    3) Thanks so much for taking the time to share your thoughts! Extremely helpful! :)

    By the way, I'm new to AK and I'm constantly impressed with the AK community. AK appears to have a ton of great guys that really know their stuff! Some of the Marantz rebuilds that I've seen on AK are just drop-dead gorgeous!!! Some guys are seriously dedicated to restoring Marantz units to new condition...not "like new"...but "new" condition. Awesome! :)

    I was really hoping to move on and create a BOM for the pre-amplifier section. Unfortunately, I am out of time. Work is pulling me into another direction right now so I am going to put the pre-amp project on hold for a couple weeks.

    In my next post, I'll share the "voltage across all resistors" data I pulled from my right channel Power Amplifier Board (P750) prior to the new parts being installed. This information will provide two things: 1) A list of all the resistors on the board. 2) The voltage across each resistor from a perfectly working board. This information could be extremely valuable for someone who is trying to trouble shoot a problematic Power Amplifier Board.

    I need to run now. I'll post the voltage data in a day or so.

    Thanks everyone!

    Phil
     

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