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Thread: Phase Linear 700 ??

  1. #46
    Senior Member MikeBrewster77's Avatar
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    Quote Originally Posted by Othello View Post
    I have a Phase Linear 400 which is about to go DC on me, right now it passes intermittent DC into my speakers
    With all due respect, unless you want to trash your speakers, might I respectfully suggest that you immediately disconnect the amp and take it to a qualified tech for diagnostics?!?!?!?!

  2. #47
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    Quote Originally Posted by MikeBrewster77 View Post
    With all due respect, unless you want to trash your speakers, might I respectfully suggest that you immediately disconnect the amp and take it to a qualified tech for diagnostics?!?!?!?!

    Well sure, I disconnected the speaker.
    But sending it out for diagnostics?!? that is not going to happen, I will have to figure that out myself.
    But I had hoped for help, often these failure modes are similar from one amp to the next and it would help to hear about the most likely failure-easier to troubleshoot that way...
    I looked at the diagram, I don't think it's a faulty power supply, it only happens in one channel. The meter jerks violently in that channel, but intermittently. Hopefully some members here have hands-on experience with these amps.
    Uwe

  3. #48
    Senior Member ratitifb's Avatar
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    Quote Originally Posted by Othello View Post
    But I had hoped for help, often these failure modes are similar from one amp to the next and it would help to hear about the most likely failure-easier to troubleshoot that way...
    I looked at the diagram, I don't think it's a faulty power supply, it only happens in one channel. The meter jerks violently in that channel, but intermittently. Hopefully some members here have hands-on experience with these amps.Uwe
    What are the power transistors type (MJ15003 is a bad choice due to the low Vceo value compared to the +/- DC voltage supply and some instability) ?
    In that case you have to change all power trans (don't mix power trans types) of the faulty channel plus probably drivers. Bias and output offset and no instability behavior have to be doublechecked after servicing process ...

    Please take a look at
    http://synthetizer-sche.chez-alice.f...ear/repair.htm


  4. #49
    Senior Member jcrobso's Avatar
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    ratitifb, Thanks for the PL link.

    If you read to the bottom where it talks about how much more power the PL amps can put out compared to their rated power.
    Bob Carver called this dynamic head room, because of this the amps became very popular for live sound. The downside is that they were designed for the consumer market, I feel the this is why they ended up getting a bad name.

  5. #50
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by jcrobso View Post
    Bob Carver called this dynamic head room, because of this the amps became very popular for live sound. The downside is that they were designed for the consumer market, I feel the this is why they ended up getting a bad name.
    I've seen plenty of blowed-up 400s. Never saw any used in "pro" applications. Doesn't deny that people used them for pro use, just that they blew regardless. There's plenty of discussion of why this is and what it takes to fix them and make them safe elsewhere on the Internet, including Bob Carver, himself. Fun diversion but nothing new here.

    I had a friend who blew-up a 400 at a yard party driving one pair of ARs. No such problem with my baby Crown D150 even driving my 030s loud enough outside to be heard clear to the Blue Ridge from the Doyles River. To show how hard I was driving it, the Crown had one thermal-shutdown incident because it was the early model version with no faceplate and I played it on it's side on a shelf with the logo pointing out when the feet were intended for the logo to be up. I lifted the amp by shoving a pencil underneath it and it played without further incident for at least eight more hours. That was over thirty-years ago and it's still working fine today.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  6. #51
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    My +20 year old Adcom was dumping DC into both channels. The repair was $240 which is slightly less than the FV of an equivalent working unit. Repair shops know this value, so be advised.

    I no longer buy older electronics for this reason.

  7. #52
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    I'd have to dig for a link, but Carver recently (within the last year or so) has come out with a flat fee to refurbish any Carver amp. I'm not sure if PL would be covered or not. Seems like it was $170 + shipping.

  8. #53
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by JeffW View Post
    I'd have to dig for a link, but Carver recently (within the last year or so) has come out with a flat fee to refurbish any Carver amp. I'm not sure if PL would be covered or not. Seems like it was $170 + shipping.
    You can try this link but I may have posted this information previously:
    Rita Helm and I (Bob Carver) have opened a new shop for fixing and restoring all vintage Carver Corp, Phase Linear and Sunfire audio equipment.
    We also restore ALL vintage tube amps as well. Rita's Vintage Audio Repair.

    Each unit will be repaired, updated and gone through from top to bottom, restored to the same performance and condition as it was the day it was built.

    A flat fee of $175 dollars + shipping covers it all. Our minimum inspection fee is $35 dollars.

    The address is:
    Rita Helm, Old Sunfire building
    1920 Bickford Ave
    Snohomish WA 98290

    Phone 425-530-9557. Ask for Harry Abbott.


    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XX

    Updated post from another thread. This is from Lisa at Bob's repair shop..............and I quote.......

    Hi Everyone,
    I am Lisa from Rita's Vintage Audio Repair. Here is some helpful info:

    Here is our info:

    Rita's Vintage Audio Repair
    1920 Bickford Ave.
    Snohomish, WA 98290
    360-568-4700
    ritasvintageaudio@gmail.com

    Our Charges:

    $175.00 Flat Fee
    $175.00 for active drivers ONLY if it needs it
    $75.00 for passive drivers ONLY if it needs it
    $75.00 for tech labor time on unit over 3hrs.
    $ 20.00 ONLY IF box & packing material are needed or wanted.
    Customer pays Shipping & Handling both ways.
    We ship UPS Ground for return UNLESS customer chooses otherwise, also we insure for $999.00 for return.
    Please include all contact info when shipping to us. We will not ship your unit back until we receive payment.
    Billing will occur at the time of return shipment. Please include the best time to contact you for payment.
    We warranty any work We performed for one year.

    Any questions please feel free to call.
    P.S. Occasionally Mr. Carver finds time to drop by & we can get him to sign units!:-"

    Thank You,
    Lisa Selph
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  9. #54
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    Yep, that's what I remembered seeing.

  10. #55
    Senior Member jcrobso's Avatar
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    Here is anothr thread about PL amps.


  11. #56
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    Quote Originally Posted by ratitifb View Post
    What are the power transistors type (MJ15003 is a bad choice due to the low Vceo value compared to the +/- DC voltage supply and some instability) ?
    In that case you have to change all power trans (don't mix power trans types) of the faulty channel plus probably drivers. Bias and output offset and no instability behavior have to be doublechecked after servicing process ...

    Please take a look at
    http://synthetizer-sche.chez-alice.f...ear/repair.htm


    Well, thank you for your help and for the link to the article.
    I opened the amp and found an original set of transistors.
    The amplifier works and the DC appears intermittently on one channel.
    Since I don't believe that semiconductors can have intermittent behavior I am looking at the amplifier trying to identify passive components which could be responsible for a on/off appearance of DC at the output.

    I will report back.

    Uwe

    PS. I have to say I was a bit disappointed regarding the workmanship of this amplifier, the innards seem not to deliver what the nice front panel promises...

  12. #57
    Senior Member ratitifb's Avatar
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    PL400II servicing

    i just downloaded free of charge this doc after having paid 22$ for a paper copy on the bay

    Front panel led indicator has to be adjusted according to the measured RMS output power
    Attached Images Attached Images

  13. #58
    Senior Member Woofer's Avatar
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    Quote Originally Posted by ratitifb View Post
    i just downloaded free of charge this doc after having paid 22$ for a paper copy on the bay
    Is there a trick to seeing the contents of your attached .pdf?
    When I try to open it, it opens up as a series of blank pages.
    I might be deaf, but I can still hear da bells! (Quasimodo)
    .... Oh, and the Kick Drum.

  14. #59
    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by Woofer View Post
    Is there a trick to seeing the contents of your attached .pdf?
    When I try to open it, it opens up as a series of blank pages.
    I opened it just fine on my Mac - cover page says HiFi Engine, last page looks great, rest seem ok too ...
    HiFi Engine folks are great,
    got a Yamaha and a Denon manual from them last year myself
    2ch: Oppo, JoLida 502CRC, JBL L212, 18ti,240ti; Heath AS101, Von Schweikert VR4
    7.1: Oppo BDP103D, B&K, UREI 809A, JBL B460

  15. #60
    Senior Member Woofer's Avatar
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    Quote Originally Posted by hjames View Post
    I opened it just fine on my Mac - cover page says HiFi Engine, last page looks great, rest seem ok too ...
    HiFi Engine folks are great,
    got a Yamaha and a Denon manual from them myself
    Most unusual....
    Did it open by default in Preview or did you use Acrobat, Heather?

    UPDATE: Doesn't matter H, opens up on my other Mac OK.
    (Most strange. Other .pdf's open fine!!)
    I might be deaf, but I can still hear da bells! (Quasimodo)
    .... Oh, and the Kick Drum.

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