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!
Howdy from East Texas. Hamfist mechanic attempting PL repairs
- Thread starter Dirtywerk
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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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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!!!
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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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....
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!
Have fun!
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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.
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
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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Stock 400s working or not sell for around close the same price usually. Cosmetics dictate end value more then anything else with them. Most people buy these 400s knowing full well they need to be upgraded so working or not (unless completely serviced) means not a lot. You never know what your going to see inside from a "serviced" amp LMAO!!! You might notice if you look that we have 100s of lurkers here daily who are looking at info the White Oak repair kits and upgrades and the amp builds themselves for those tackling the project
Not sure what kind of return your looking for but your looking at $200 in parts minimum to safely get the amp running (new power caps and a DCP). Then prey the kids did not fry the outputs or control board. As for the 4000, that is a very complicated beastie and most techs run screaming from them if it is a series I. You should also check the 901's, you may be in for a additional expense surprise if the surrounds are shot on the 9 little woofers in each speaker. You should also have a small Bose EQ that you need to even use those speakers (not a regular audio eq!!!)
Don't take my post wrong in anyway, just my opinion. This is a deal where if you are looking to make decent money, your probably going to have to spend some decent money. We can offer advice and tips, in the end, it's up to you what path you want to take
Not sure what kind of return your looking for but your looking at $200 in parts minimum to safely get the amp running (new power caps and a DCP). Then prey the kids did not fry the outputs or control board. As for the 4000, that is a very complicated beastie and most techs run screaming from them if it is a series I. You should also check the 901's, you may be in for a additional expense surprise if the surrounds are shot on the 9 little woofers in each speaker. You should also have a small Bose EQ that you need to even use those speakers (not a regular audio eq!!!)
Don't take my post wrong in anyway, just my opinion. This is a deal where if you are looking to make decent money, your probably going to have to spend some decent money. We can offer advice and tips, in the end, it's up to you what path you want to take
The Pl's are Series 1 and so are the 901's which have the paper surrounds. I have their EQ but am unable to use it with the speakers attached to my Aiwa receiver. The speakers sound just fine (no highs nor lows so must be Bose). The PL's and their walnut cabinets still look like new with a little discoloration on the big dials from hand oil or lotion residue. The 901's cabinets are in great shape except for a few corners where a dusting rag snagged the veneer and pulled off a tiny piece not long after their purchase. That can be concealed using a shellac stick. I will be trying to sell the PL's, 901's along with my nice Pioneer PL-51 turntable on EBay before attempting any DIY repairs. Have been trying to sell them since April 1st. at my estate sale as a system for $1100 or separately (PL's for $400, 901's w/EQ for $450, PL-51 for $250) without receiving any counter-offers so might as well try reaching a larger market. I have an inkling they won't sell due to shipping costs so will wind up attempting repairs anyways.
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They are notably better in the air to my ear and I was so happy to not fight over the reflecting space with my wife.
OP: i don't think there is a scenario where you make more money by working on them, as stated before the 4000 is quite a project and the 400 will be almost completely rebuild so it wouldn't make sense to pay you to "fix" the amp only to tear everything out again.
cosmetics are the only thing anyone really cares about in these amps
I wouldn't pay $400 for a non-working 400 and 4000... certainly not with out cabinets.
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