…more Phase Linear (round 2)

My neighbor was thrilled to find someone local who could repair has Phase Linear audiophile gear.  One of his friends was also a Phase fan, and his gear had been sitting for a longtime in disrepair.  So now I had 3 more Phase Linear units to repair: a Phase Linear 2000 preamp, Phase Linear 200 power amp, and a Phase Linear 400 power amp.

All three units were very dirty (cigarette smoke yellowing) and dusty.  After cleaning, each looks excellent.  It was obvious that all three units had not been in use for many years.

Here is a summary of each repair:

  • Phase 200 power amp: straightforward repair.  Someone had previously replaced one of the two filter caps, and now one of them had lost almost all of its capacitance.  I replaced both with fresh new uniform inventory, and the amp came right to life.  Clean and distortion-free audio across the entire spectrum, and without clipping until slightly above 100 watts per channel.  Runs cool, also.  This amp looks like a keeper.
  • Phase 2000 preamp: required a lot of work.  The primary defects were several broken solder joints, bad caps in the phono preamp section, dirty control pots (several of which that were so dirty that they did not turn freely), and dirty push-button switches.  The neighbor wanted a more complete job, so all electrolytics were replaced, in addition to the necessary repairs.  A final issue is that one of the tuner input jacks (self-shorting) was broken, so I repaired it good enough to use, but should be replaced with a good original jack at some point in the future.
  • Phase 400 power amp (has PL400C drive board): my neighbor thought that this would be a fast easy fix, but it had a number of problems.  Two bad transistors (Q1 and Q2, one dud in each channel) and their accompanying trim pots (both of which had lost continuity on the wiper) were the main problem.  Also, the amp was running so hot that you could fry eggs on it, which was partly incorrect bias adjustment and partly (in my opinion) insufficient heatsinks.   (As a comparison, note that the Series Two model 400 has a lot more heatsinks.)  Even with cooler bias set, though, this original 400 still runs very hot and needs a cooling fan in my opinion.  Finally, two meter lamps were burned out.   I tried to upgrade the meter lamps with a set of 8 new LED meter lamps, but they were very directional in their light output, and perpendicular mounting into the meter housing simply did not provide sufficient light upward into the viewing area.  Very disappointing, so the only solution was to revert to the old-style lamps.  Since the neighbor wanted a more thorough repair job, the final servicing consisted of: replaced all of the electrolytics and all out-of-tolerance carbon resistors on the PL400c board; replaced both sets of Q1 and Q2 transistors for each channel and reset the DC offset;  all new 10-ohm precision resistors in the output stage and set the bias cooler according to the Phase factory service manual; installed 8 new original-style meter lamps.

[UPDATE 04-29-2013:]

Phase Linear 5100 series two Digital Tuner

Phase Linear 5100 series two Digital Tuner

pl5100-2-2

defective caps

Servicing of Phase Linear tuner 5100-II.  Symptoms were that the tuner would not visibly power-on.  Problem traced to a defective capacitor mounted adjacent to a heat-sinked chip.  I replaced the defective cap and another cap in close proximity to the heatsink.  No further problems reported 30 days later.

 

Here are a few quick photos of these units during repair:

Phase Linear 200 power amp —



Phase Linear 2000 Preamp —



Phase Linear 400 power amp —



_


Valid XHTML Valid CSS