phase linear 400

GeorgeP

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Joined
Mar 22, 2023
Messages
107
here we go...unit is near pristine...listening to it now...
very happy with the purchase...
looks like the 400c board
clamp caps on power supply...
rectifier on the side too...
pl18 light board with 4 small lamps in the meters...
tell me what you think???
where to start??
1. Start with the relay board to save speakers, in case the amp fails. Then if an upgrade goes wrong, no speaker loss. Make up a good load box, don't use your speakers doing mods. I just built a nice one... but just start with no load, then connect the 300W 8 Ohms resistors on a piece of wood (easy). Then you can do one channel at a time at 4 ohms, putting them in parallel. Use the series connected 100W lamp to limit the power, in case of a failure...no flames!
2. Then, Replace the Control board, if that's a problem, the outputs getting replaced next anyway.
3. Then do the two input big cap mod, and replace the bridge rectifier for the higher current version.
4. Last but very important, replace the output devices for the new more superior ones.
5. Then do the cosmetics, meter boards etc... Working good, is better than looking good!
6. I would add the DC blocks at the input, and volume control's. Add a power switch to the front. Bring the relay board LED to the front panel...then you always know the offset and balance is correct, and a nice "ON" indicator that all is fine.
Have fun, be patient, and you will have a great amplifier.
 

gene french

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Mar 6, 2022
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guayabo de bagaces, guanacaste, costa rica....
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I forgot to fully tighten a screw holding the DCP board to output binding post and it resulted in a very similar condition after a few minutes of playing - very scratchy potentiometer.

Tightened the screw and all is well.
got same with old dirty rca jacks....
 

ABebar

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May 28, 2021
Messages
177
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Warrenville, IL
So, I checked all 7 glass fuses - two on the right channel backplane, two on the left, and all three supply fuses and they are all good. I checked the nuts on the DCP board and those are tight.
 

Gepetto

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So, I checked all 7 glass fuses - two on the right channel backplane, two on the left, and all three supply fuses and they are all good. I checked the nuts on the DCP board and those are tight.
Did you check the +/- 15 volt rails on the affected channel of the control board?
 

Gepetto

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I will say, the last time I used it was a party where I went to bed and there were still people there playing the music at extreme volume. It's very possible that something popped after I went upstairs and nobody said anything about it.
I'm stuck at work until 5. I can check all fuses when I get home tonight.
I bet that after your guests blew your amp, they all quickly went home :)
 
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