I was listening to my PL400 at medium to high volume and the Watts Abundant DC protection kicked in.
Brought the unit to the bench and put it on the DBT, sure enough the 75W bulb did not dim, problem with the right channel.
Removed all of the output transistors and found one shorted and one other testing good, but did not match (previously replaced). With the right output transistors removed I tested the unit on the DBT and the bulb dimmed normally and the DCP relay clicked.
I then took the time to test all of the right channel back plane resisters and diodes, all tested good. I tried the unit on the DBT and the bulb would not dim this time, and there was some smoke, shut things down and saw that one of the empty output transistor sockets was arcing and smoking.Two questions, are these sockets still available? any one have a good used one left over from a Whiteoak back plane conversion?
Also what is a matched set of transistors? Are they the same date code? measured in some way?
So I need a socket and at least six matched output transistors.
Brought the unit to the bench and put it on the DBT, sure enough the 75W bulb did not dim, problem with the right channel.
Removed all of the output transistors and found one shorted and one other testing good, but did not match (previously replaced). With the right output transistors removed I tested the unit on the DBT and the bulb dimmed normally and the DCP relay clicked.
I then took the time to test all of the right channel back plane resisters and diodes, all tested good. I tried the unit on the DBT and the bulb would not dim this time, and there was some smoke, shut things down and saw that one of the empty output transistor sockets was arcing and smoking.Two questions, are these sockets still available? any one have a good used one left over from a Whiteoak back plane conversion?
Also what is a matched set of transistors? Are they the same date code? measured in some way?
So I need a socket and at least six matched output transistors.