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Thread: Howdy from East Texas. Hamfist mechanic attempting PL repairs

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    Howdy from East Texas. Hamfist mechanic attempting PL repairs

    I own a PL4000 & 400 that my late brother bought new in 9/74. A few months later both were returned for a zener diode replacement and some RCA jacks resoldered. He passed away in 2/76 and the PL's went into storage for the next 40 years. My other brother pulled them out 30 years later and found the controls noisy and one channel barely emitting sound so put them back up. Six years ago my sons snuck them out when I was gone and freaked out when the good channel began to motorboat/flub-flub then make a loud thump before going dead with a blown fuse. They put them back and fessed up recently when I tried them out before having an estate sale. I looked inside both and noticed the 4000's big C2 cap behind the jacks had oozed white stuff out so figured that caused the weak channel signal. I didn't see any obviously damaged components inside the 400. Both power up with the lights coming on. I've downloaded both of their service manuals from HiFi Engine to attempt their repair. Figure I don't need to go whole hog replacing all the caps, etc. since both had seen limited use and what went out often did when new. I haven't messed with circuits since the age of 13 when I built a Heathkit radio to earn a merit badge. Pray for me!

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    Administrator Fast Forward's Avatar
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    Forum Veteran Northwinds's Avatar
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    Welcome to Phoenix!!! Hope your successful with your repair but I have to say, any caps are drifted way beyond spec. You might get it working but $10 says something else will blow shortly. These amps and preamps really need a full redo for reliability. I am sure others will voice their opinions on this also
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    Halfbiass...Electron Herder and Backass Woof
    Welcome to Phoenix Dirtywerk.

    Even with electrolytic caps not being used much, they still have a limited shelf life. They are based on water compounds and eventually dehydrate. You might check the WOPL archives on forming power capacitors for ways to also test them. Replacing the power caps on both units is a good start, then after getting both units up and running, then consider a complete re-cap of the 4000 and then some White Oak goodies for the 400......


    Have fun and don't take things too seriously around here!!!
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    Halfbiass...Electron Herder and Backass Woof
    With the 400's being 40 years old now I would not test it on a good set of speakers. With no DC protect circuit if an output blows you will get 80 volts DC with lots of associated current to go with it. There are aftermarket DC protect boards that are available to cure that problem and it's a relatively easy fix. Cheap tpoo, about 100.00 Contact forum member wattsabundant ( Don Imlay) fotr those. They work and work well , My 8,000.00 Kornerhorns can attest to that....they were spared an ignominious demise after I had an output go south on a 700 going almost full tilt boogie. The DCP did it's job, sacrificing a 15.00 relay to the cause....
    taking something that's already good, and making it better...........and for the knowing smiles that cross their faces.......Nando-2011...

    "Silence cannot be Misquoted"--Lazarus Short-2012 "

    " I Just Collect Smiles Craig......Cheap Smiles!-----Fishoz-2017

    "anything can be done, it's finding the easiest way that's hard"-----Bobbysdad--2014

    " Synth percussion is deadly to children, house pets and shitty power supplies"---Stephen Evans 2014

    " You have not reached the point of diminishing returns, you've just ran out of money

    " The Pioneer U-24, unfortunately, is just too expensive and rare to find. That's why I have one."--Nando-2014

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    Forum Veteran Fishoz's Avatar
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    Welcome to Phoenix DW. You'll have those PL's up and running real soon if you stick around here. Good luck and pay attention. Lotta crap gets thrown around here but still have never seen a tech question go unanswered. Irreverence (that word gets tossed around here a lot) is just our way of dealing with temporary frustrations.

    Have fun!
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    Halfbiass...Electron Herder and Backass Woof
    Irreverence is our way of dealing with almost ANYTHING around here!!
    taking something that's already good, and making it better...........and for the knowing smiles that cross their faces.......Nando-2011...

    "Silence cannot be Misquoted"--Lazarus Short-2012 "

    " I Just Collect Smiles Craig......Cheap Smiles!-----Fishoz-2017

    "anything can be done, it's finding the easiest way that's hard"-----Bobbysdad--2014

    " Synth percussion is deadly to children, house pets and shitty power supplies"---Stephen Evans 2014

    " You have not reached the point of diminishing returns, you've just ran out of money

    " The Pioneer U-24, unfortunately, is just too expensive and rare to find. That's why I have one."--Nando-2014

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    Forum Veteran Fishoz's Avatar
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    That too!
    Oppo BDP-83, Pro-Ject 1Xpression III, Pro-Ject Speed Box S, Cambridge Audio Azur 651P, Acurus L10, LL WOPL 400, B & W 808's.

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    Quote Originally Posted by Fishoz View Post
    Welcome to Phoenix DW. You'll have those PL's up and running real soon if you stick around here. Good luck and pay attention. Lotta crap gets thrown around here but still have never seen a tech question go unanswered. Irreverence (that word gets tossed around here a lot) is just our way of dealing with temporary frustrations.Have fun!
    Thanks. I just want sound coming out of both channels so they'll be easier to sell. A pair of Bose 901's were stored with them so will have in-line fuses attached to their cords in case the 400 goes berserk. I was wondering where to shoot contact cleaner inside the dials and switches since they appear to be sealed up.

  10. #10
    Forum Veteran marcok's Avatar
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    I'm very curious about any tech item
    Welcome aboard !!!
    I have restored 2 Pl 4000 and it's necessary to replace all caps and the rear connectors .
    Anyway remove all boards except tone board and logic board .
    This is the simplest config and so start from this point .
    It must sound .
    In this config you have to replace approx. only 10 caps .
    Have a good fun .
    Ciao
    Marco

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