Phase Linear 400 Amplifier Upgrade to WOPL

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laatsch55 said:
Oh yeah , smokers are always a gas!!!
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There's still smoke in 'em and I'm not planning on letting it out but you never know. I used a fan while performing the clipping tests and that helped big time. I still waited until the load resistors cooled before going to the next frequency but that didn't help the fuse.
 
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laatsch55 said:
No, the copper ones......
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Oh - those are way cool. Some of the machines you used to form the heat sinks are classics. I did not see the "wave" you mentioned but the end result is a work of art. That second bend had to be a bitch! I was following your thread but don't always follow up with comments - must change my ways. Your machine shop is awesome - maybe one day I'll get to see it in person.
 
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After 2 days of thinkin on it, there is a better way to finish the second bend, stay tuned.......
 
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laatsch55 said:
Dennis, I don't know if it will make a difference but bias on a pl 14 board which is what I'm assuming you have should be taken with positive on the base bus bar and negative on the common tie point for the emitter resistors. Ya might try that and see if there is a difference.
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Well - I've found two different bias adjustment procedures - just downloaded another PL 400 SM from the Carver site. Here's a photo of the S/N from the back of my 400 - maybe someone can shed some light. I will be installing the WO controller board this week though.

DSC_0214.jpg
 

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Is it really 240vac Dennis?? Put the positive probe on the Base bus bar, the negative on the common tie point for the emitter resistors. Adjust to 385mv. Let amp idle for another half hour adjust again. The negative rail should be withinin 20mv of the positive As long as your probes are on either side of the 10 ohm resistor on the backwall you're good to go.
 
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It was built for WOP power. I'll recheck the bias voltage tomorrow. I thought I had my test results with me but they didn't seem to make it home.
 
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Here's an updated set of data results. The amp get pushed pretty hard with the sine wave clipping test. I gave up at 20 kHz as I only had five spare fuses for the mains. I guess I'll have to get some more.

I'm still not sure if the bias adjustment procedure that I followed is correct for the version of amp that I have. I downloaded another PL 400 SM and the procedures for setting the bias are different.

View attachment Phase Linear 400 Series I Test Results.pdf
 
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laatsch55 said:
Is it really 240vac Dennis?? Put the positive probe on the Base bus bar, the negative on the common tie point for the emitter resistors. Adjust to 385mv. Let amp idle for another half hour adjust again. The negative rail should be withinin 20mv of the positive As long as your probes are on either side of the 10 ohm resistor on the backwall you're good to go.
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Dennis, If it's wired for 240 you should only have a little over 40 volts on the positive and negative rail to ground when plugged into 120 volts AC. Looking at your test results it looks like it is wired for 120 volts. Some 400's came with dual voltage power transformers.
 
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Skratch said:
Dennis, If it's wired for 240 you should only have a little over 40 volts on the positive and negative rail to ground when plugged into 120 volts AC. Looking at your test results it looks like it is wired for 120 volts. Some 400's came with dual voltage power transformers.
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Yeah - I bought it in Italy and when I returned home I rewired it for 120. That and a preamp - Soundcraftsmen - had to be rewired. All the other audio equipment I acquired overseas had a 120/240 switch.

Both the PL and Soundcraftsmen had good documentation regarding the rewire so it was pretty straight forward. That was several decades ago though.
 
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The bias procedure should not be that different from the 400,700, D500. All should be around 380-385mv. Now the pl0171 board is different, so is the PL400C board.
 
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Here are some photos of the new buss bar for the power supply capacitors. It's a little smaller than a BABB but maybe we can call it a MABB - that's one up on a SABB! The hole spacing for the cap interface is a tenth of an inch or so longer than the orginal as the new caps won't rotate due to their configuration.

DSC_0024.jpg DSC_0025.jpg DSC_0032.jpg DSC_0033.jpg DSC_0034.jpg
 
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