Restoration Information
Audio Specifications Database
Audio Picture Gallery
Our Testing Procedures
FAQ
Phase Linear 400 Gallery
The stock circuit board is shown above. Chock full of old electrolytic and ceramic capacitors.
The rebuilt circuit board. All of the electrolytic capacitors were replaced with high-quality parts. All of the ceramic capacitors were replaced with polypropylene or other quality metallised-film capacitors. The bias controls were changed. It is getting difficult to find large trimmers, so we improvised. It worked out quite well, if I do say so myself! You can also see that all of the original emitter resistors were replaced (on the transistor sockets).
The original, puny power supply filter capacitors were changed out with new capacitors that have twice the storage capacity. The bridge rectifier was also exchanged for a more robust device. A power switch was added for convenience; stock Phase Linear 400's don't have a power switch!
All of the output transistors as well as the pre-drivers were changed (the 400 has a quasi-complementary output; all the output devices are NPN). There are six output transistors per channel. The four bottom transistors in the above picture are the pre-drivers. Originally, the 400 uses greaseless gaskets to isolate the output transistors and pre-drivers. These were swapped out with traditional mica gaskets and metal-oxide heatsink compound.
After all the work was done (including determining what was ailing the amp in the first place- the amp didn't work when the customer brought it to us, which is typical), the amp was idled for a while, biased, tested, listened to, the bias was rechecked, the amp was listened to some more, and finally returned to the customer as good as new. Maybe even better!
Although they manufactured preamplifiers and tuners, audio power amplifiers were Phase Linear's bread and butter.
The stock binding posts and RCA inputs.
D 'n A Electronics is a Father & Son business located in Kitchener, Ontario, Canada. We specialize in restoring hi-fidelity audio power amplifiers, integrated amplifiers, preamplifiers, receivers, and tuners. We've been repairing vintage audio equipment since long before it was considered vintage! It is our goal, and pleasure, to reliably restore hi-fi audio equipment to original operating condition (or better!). We accept shipments from across Canada, and many customers from Kitchener, Waterloo, Cambridge, Guelph, Hamilton, London, Toronto and surrounding areas find us to be within convenient driving distance. Thank-you for visiting our website, we look forward to serving you!
Some pictures of a Phase Linear 400 power amp we restored. You can check out it's specs here.
If you have a Phase Linear 400 amplifier that is in need of repair, call us at (519)513-1084, or email your enquiry to repairs@dnaelectronics.ca.