Phase Linear 400 & 4000 died while in storage


2016-06-02 2:32 am
I inherited my late brother's PL 400 and 4000 that he bought new in September of 1974 only to pass away in February of 1976. He was living at home during that time so couldn't play it loud or our mother would raise Hell. They had me place the units back in their boxes then into a hall closet. In 1995 they bought a smaller house so the units got relocated into it's basement sitting on top of an old table until 2004 when I moved my widowed mother in with me along with all of her stuff. I kept them inside a closet at my house until recently to sell in an estate sale. I did expect them to work but the 4000 just snapped when turned on (contacts engaging) with the power indicator lamp staying off and the 400 meter lights came on yet couldn't get any sort of sound out of the speakers. The 901's are OK since I've been using them with my other system. I did gradually warm up the PL's for a few days using a light bulb limiter. Started with a 40 watt bulb then went up to 60, 75 then 100 before plugging them into a strip outlet. Pulled them out of their cabinets and found one leaking cap (IEC 500mfd50v) in the back by a RCA connector that wasn't sitting flush against the back and was tilted back at an angle but was secure. Didn't see anything unusual inside the 400. Was looking over the PL's service manuals I had downloaded earlier when my youngest son called. Told him about the amps only to be filled in on how he and his brother pulled them out 10 years ago when I was at work and hooked up the system using the owner's manuals. When they powered the system up the 4000's dials and switches made noise thru the speakers when moved. Then when they started playing a LP the speakers barely emitted any sound. They turned up the volume which made one channel motor boat then make a very loud thump before going dead. That freaked them out so they put everything back where they found it and kept the incident to themselves. Later on I did hook up the 400 to my other amp to find one dead channel and the other barely emitting sound thru the 901.
I hope to find their failed components and replace them myself. About all of my electrical experience is with home and automotive electrical systems. I did manage to repair a few SS radios and car tape decks long ago by replacing shot diodes, transformers and caps with good ones from junked units. Have been using electrical contact cleaners and Radio Shack's de-oxit (same stuff but theirs is 40% and De-Oxit is 80%) for decades so have plenty in the garage. My only test equipment is an analog VOM and was told to steer clear of the local electronics repair shops to have anything adjusted or repaired unless it was something simple so hope they sound good enough when done to either keep or sell.


2007-10-10 5:21 pm
IF the outputs are bad, put in 15024's. But only if they are bad. There are a couple of failure modes on old PL's that sound a lot worse than they are. Usually resulting in +75V to the speaker output, which makes a horrible buzz until the rail fuse (or voice coil) opens. Replacing all the electrolytics will deal with one of those failure modes - a leaky 100uf bootstrap cap. A good once-over on the circuit board reflowing oxidized connections will catch most of the rest of them.

When the outputs fail, there is usually *smell* associated with it as well.
I had a similar experience with a 700B that sat in my closet for several years. When the time came to resurrect it, I wound up on the Phornix Audio Community site.

Phase Linear is the brand most spoken of especially power amps. Lots of expertise to take advantage of. You may be surprised at the potential of what you have and may even find a buyer for yours without even plugging in a soldering iron.