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Phase Linear 400

the board almost done ,doing the wires /jumpers now. Then the output trans and pre drivers. I have the white oak caps in and was thinking why didn't they put film by- pass caps on them?
When I'm done I won't have a Phase Linear 400 anymore ,but a White Oak mod .Which is not a bad thing by any means .
I have a 4000 pre amp to go with this ,not sure what kind of working condition it is in though. Ill post some pics tomorrow
 
The 4000 is a sad excuse for a pre-amp. The service bulletins are almost as thick as the manual.
When you test this for the first time leave the outputs on the bench. It bwill operaste with just the drivers in, thren add rows of outputs, checking each rows. You.ve changed a lot of things, it would be nice if you could isolate any problems.
 
I have a 2000 II also but its missing 2 knob covers working condition unknown.
I have Mcintosh C-33 that I'll try with it for now but I will work on the 4000 I .
I'll track down the Serivce B's first .
What about putting some film by-pass caps on the PS caps ?
 
I despise the 4000 because of all of the cracked solder joints on the motherboard and lousy support for the I/O jacks. I use a 3300. I have a 2000 that is on the list for mods. It has so many possibilities.
 
calman, Antique Electronics has some new aluminum billett knobs that are extremely close to the old ones. Put some on this 700-here--http://forums.phxaudiotape.com/kevin-s-i-want-a-phase-linear-700-b-white-oaked-thread-t2653-310.html

3.50 in lots over 10, very nice knobs.
 
Put the 0.1uf caps across each of the 4 diodes of the BR? That won't effect the rectifier ? I was thinking of putting 2uf 600v good cap arcoss each of the big caps .
Do you have any ideas for the 2000 pre mod ?
 
Nope, will not affect the rectifier, Does thre same thing there as on the caps, keeps hi freq stuff out , damps the switching noise, etc. 2 uf is a bit much is it not??

For the 2000, all electro's to audio grade , ceramics to poly, and the RC4136 op-amp, changed out with a brown dog adapter mounted with op2134's.
 
I don't know how you guys figure the value for the by-pass caps . I'll try them on the BR . Just to be sure ,4 caps just put them on the BR across each diode. I'll get the amp working first and then go back put them in . I have started to change out the pre-drivers and one had a mica and a pad which has a small tear . What is the best way to go , pads and mica ,mica and thermal grease ?
 
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DO NOT MIX MICA AND SIL_PADS. That's just asking for trouble. The best heat transfer still occurs with the mica and grease-----yep-----even after all these years. It was Joe that came up with the idea of bypassing all points on the BR. It works too.
 
Ok with the pre divers and one row (L>R) outputs trans. in and the unit connected to a DLT the unit powered up and the bulb went dim an nothing bad happened . I can hear it hum .So I can't get any accurate voltages readings until all the output trans. are installed ? I did check the bias on R38 and it was high at 289mv ,buts its an empty TO-3 socket,the right was OK at almost nothing .The trim pots are full CCW and are working .It appears something is drawing to much on the left. I'm not sure what I'm seeing here ,without all the outputs installed could the reading be inaccurate ?
 
Yes, as the bias also bias' the outputs. If the bulb went dim you're golden. I have seen bias as high as 580, so don't freak yet.
 
Also Dean and Ed Blackwood set the bias with a scope and watch until the "notch" disappears at around 360-375. And that's where they leave it.
 
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