Phase Linear 400 issue help!

[laatsch55]

Maybe MJ will now put the tight to his as well.

 

[enoyes12]

Make sure you let me know when your in town

 

[laatsch55]

I will sir.

 

[enoyes12]

laatsch I've had the amp sitting here plugged in and noticed the left side heat sinks are warmer than the right, feels about twice as warm. not hot just noticeably warmer on the left

 

[laatsch55]

Do you have a service manual?

 

[enoyes12]

yup

 

[laatsch55]

Have you set the bias yet?

 

[enoyes12]

I knew you were heading there, no I haven't. I'll have to read on how to do that

 

[laatsch55]

It can have a very large effect on the heating AND distortion figures.

 

[enoyes12]

I can see it on the schematic but don't know enough on how to read it to know which one it is

 

[laatsch55]

R38 is a 10 ohm resistor (brown-black-black) that is between the base bus bar and the emitter tie point. Positive lead on the base side, hegative lead on the emitter side. Be sure it's powered down and PS caps bled. If you slip with the leads in there when it's on it's usually an output or two that goes and Q8 or Q9, and Q7, Q10 and a couple diodes. Not worth it to hurry on that.

 

[enoyes12]

I also noticed a hum when I reversed the plug so I cut a notch in it on the hot side so i don't plug it in upside down

 

[laatsch55]

That is also no myth as you now know...

 

[enoyes12]

I see a (sliver black black brown) at the point I think your described

 

[laatsch55]

Should have sleeves on the leads also..

 

[laatsch55]

Silver is the tolerance...

 

[laatsch55]

You don't have to get on the resistor leads, put a lead on the base bus bar and that big wad of emitter resistor leads...

 

[enoyes12]

ok i think I found it. left side is reading .465 and the right is reading .162. I tried turning the pots but no change

 

[laatsch55]

On 400's with a factory board I try to keep them around 300MV. No change on either one?

 

[enoyes12]

nope, pots shot?