This is a history of my PL400 restoration/White Oak conversion.
Last November I spotted a Craigslist ad for a Phase Linear 400 amp and 2000 preamp, both with
wooden cases, listed for $50. I assumed the seller had made a mistake and meant to list them
for $500. I immediately sent an email to the seller that I had just retired, moved to Oregon
and I would love to own a set of Phase Linears. The seller sent me a message explaining there
were a few issues with the items and, with their questions, were looking for a good home for
them. After calling the number they emailed me, the wife asked me to call her husband back
to arrange to pick them up. After setting an appointment at 2PM with the husband I grabbed
$50 and sped to their home. The husband answered the door and explained the issues (pre amp
phono input and on off switch not working) took my $50 and helped me load them. (The wife did
not appear and, from her husbands comments, was sad to see them go.)
The first thing I do with a new aquisition is clean and polish. On opening the case of the
PL400 I discovered that somebody had modified the wiring and glued new capacitors into the case.
(see photo). A review of all the paperwork I received from the orginal owners were receipts from
a company in Texas indicating that they had paid about $900 for a restoration of both units.
(including shipping back and forth). In order to test the PL400 I installed fuses to my speakers
(and glad I did) and after running the amp for about 3 hours both 5 amp fuses blew. I decided
at that time that a proper restoration was in order. (Glue does not, in my book, constitute
restoration)
After a lot of research (Audiokarma which led me to Phoenix Audio) I decided to replace the
glued in capacitors with the White Oak capacitor assembly and restore the orginal wiring.
Contacting Joe at White Oak, he was able to supply an assembly and mounts for the restoration
of the side of case. Using a hammer and chisel I removed the glued in capacitors and discovered
they were also glued to the transformer. It took me a few hours to locate matching case screws
and an upgraded (35 amp) bridge rectifier. (hammering around the rectifier left me uncertain of its
condition). I then recovered the transformer and touched up the paint I had scratched.
I also discovered that White Oak had a replacement control board and led board.
Since I had no confidence in the quality of the previous work, I decided to do a full White
Oak conversion.
I am good at cleaning, polishing, disassembly and assembly but my only knowledge of electricty
is that it hurts when improperly applied. My brother in law (Electronics Guru and Master Solderer)
has all the tools (meters, signal generator, variac, occiloscope etc.) to handle the repairs.
He had spent a day at the Naval Weapons Laboratory learning soldering. (if they found, under a microscope,
a nick on a strand of wire it was rejected).
My brother in law restored the wiring and soldered in the new bridge rectifier. Replacing both 5 amp
fuses he brought the amp on line with his variac and measuring the dc offset found both
channels at 80 volts. I contacted Joe at White Oak and he recommended all transistors
should be tested. He then found the shorted output transistor and after removing it
measured the dc offset at 21 volts each channel. In a moment of inspiration he checked
the 5 amp fuses and found one had blown. Replacing the fuse the offset now measured between
14/18 mv.
A stroke of good fortune occurred when laatch55 had noticed an Audiokarma post that I needed
a replacement transistor (Delco Xpl909) and, for which I am forever indebted, sent me
at his own expense 2 xpl909's and 2 rca 410's.
Before installing the replacement transistor he measured all the outputs again and discovered a second shorted
transistor. Replacing both shorted transistors he then measured dc off set at 4/5 mv.
He then replaced the control board with the new White Oak board and upgraded the meter
lights to the White Oak led board. Bringing the unit up on the variac the bias would not
adjust at all. Working on his previous inspiration I suggested he check the 5 amp fuses
and sure enough one was blown. Replacing the fuse he adjusted the bias to 350 mv R/L.
The dc offset then measured 18 mv each side.
I have been running the PL400 all week and everything is perfect. I now have one of the best
PL400's on the planet.
Thanks again to Joe at White Oak and laatsch 55 for their invaluable assistance.
And special thanks to my Electronics Guru/Master Solderer without his help I would be
staring at a pile of parts.
Last November I spotted a Craigslist ad for a Phase Linear 400 amp and 2000 preamp, both with
wooden cases, listed for $50. I assumed the seller had made a mistake and meant to list them
for $500. I immediately sent an email to the seller that I had just retired, moved to Oregon
and I would love to own a set of Phase Linears. The seller sent me a message explaining there
were a few issues with the items and, with their questions, were looking for a good home for
them. After calling the number they emailed me, the wife asked me to call her husband back
to arrange to pick them up. After setting an appointment at 2PM with the husband I grabbed
$50 and sped to their home. The husband answered the door and explained the issues (pre amp
phono input and on off switch not working) took my $50 and helped me load them. (The wife did
not appear and, from her husbands comments, was sad to see them go.)
The first thing I do with a new aquisition is clean and polish. On opening the case of the
PL400 I discovered that somebody had modified the wiring and glued new capacitors into the case.
(see photo). A review of all the paperwork I received from the orginal owners were receipts from
a company in Texas indicating that they had paid about $900 for a restoration of both units.
(including shipping back and forth). In order to test the PL400 I installed fuses to my speakers
(and glad I did) and after running the amp for about 3 hours both 5 amp fuses blew. I decided
at that time that a proper restoration was in order. (Glue does not, in my book, constitute
restoration)
After a lot of research (Audiokarma which led me to Phoenix Audio) I decided to replace the
glued in capacitors with the White Oak capacitor assembly and restore the orginal wiring.
Contacting Joe at White Oak, he was able to supply an assembly and mounts for the restoration
of the side of case. Using a hammer and chisel I removed the glued in capacitors and discovered
they were also glued to the transformer. It took me a few hours to locate matching case screws
and an upgraded (35 amp) bridge rectifier. (hammering around the rectifier left me uncertain of its
condition). I then recovered the transformer and touched up the paint I had scratched.
I also discovered that White Oak had a replacement control board and led board.
Since I had no confidence in the quality of the previous work, I decided to do a full White
Oak conversion.
I am good at cleaning, polishing, disassembly and assembly but my only knowledge of electricty
is that it hurts when improperly applied. My brother in law (Electronics Guru and Master Solderer)
has all the tools (meters, signal generator, variac, occiloscope etc.) to handle the repairs.
He had spent a day at the Naval Weapons Laboratory learning soldering. (if they found, under a microscope,
a nick on a strand of wire it was rejected).
My brother in law restored the wiring and soldered in the new bridge rectifier. Replacing both 5 amp
fuses he brought the amp on line with his variac and measuring the dc offset found both
channels at 80 volts. I contacted Joe at White Oak and he recommended all transistors
should be tested. He then found the shorted output transistor and after removing it
measured the dc offset at 21 volts each channel. In a moment of inspiration he checked
the 5 amp fuses and found one had blown. Replacing the fuse the offset now measured between
14/18 mv.
A stroke of good fortune occurred when laatch55 had noticed an Audiokarma post that I needed
a replacement transistor (Delco Xpl909) and, for which I am forever indebted, sent me
at his own expense 2 xpl909's and 2 rca 410's.
Before installing the replacement transistor he measured all the outputs again and discovered a second shorted
transistor. Replacing both shorted transistors he then measured dc off set at 4/5 mv.
He then replaced the control board with the new White Oak board and upgraded the meter
lights to the White Oak led board. Bringing the unit up on the variac the bias would not
adjust at all. Working on his previous inspiration I suggested he check the 5 amp fuses
and sure enough one was blown. Replacing the fuse he adjusted the bias to 350 mv R/L.
The dc offset then measured 18 mv each side.
I have been running the PL400 all week and everything is perfect. I now have one of the best
PL400's on the planet.
Thanks again to Joe at White Oak and laatsch 55 for their invaluable assistance.
And special thanks to my Electronics Guru/Master Solderer without his help I would be
staring at a pile of parts.
