Phase Linear 400 Power Amplifier Refurbished

Рет қаралды 5,373

Күн бұрын

Пікірлер: 31

@Sunnbobb 6 ай бұрын

Thanks for the clamp down boards, they are very nice. I am also glad you posted a picture of the pl14 board. I would have gotten Q1 and 2 reversed had I not taken a close look. A couple tips: Change out C6 with a 470 1W capacitor for better, deeper, bass response. Also, bridge the legs of C6 with 2 IN4148 diodes, in opposite direction to each other. This is known as the Geppeto mod, and helps prevent latchup and oscillation. Joe of White Oak Audio can explain the technical aspects of this mod. Once again, thanks for the great video.

@briansilcox5720 5 ай бұрын

Excellent presentation. I rebuilt a Dynaco Stereo 400 last year, and it was a very satisfying project. Your ability to design and add PCB for upgrades is impressive.

@CIRCUITDESIGNER 4 ай бұрын

Yea, It was a fun project.

@Willco_Electronics 10 ай бұрын

Craig, I remember repairing Marantz receivers where the speaker protection relay would arch when the and burn up. It was caused by a diode in the bias circuit that was intermittent and caused the dc to slam to the minus or plus rail. When the relay opened, it provided a short to the speaker and a good path to ground for the arch.

@VikasGupta-bx5qv 3 ай бұрын

really like the format of this video. No fluff, all business. thank you.

@BlowProductions 8 ай бұрын

Hi from Belgium ! Good job !! Did you adjust the bias on the control board ? Do you sell protection board for speakers ?? thank you.

@CIRCUITDESIGNER 8 ай бұрын

I show bias check at 20.23 into the video. Offset was around .3 volts. I have a couple unpopulated protection boards left.

@ericwichmann9536 11 ай бұрын

I bought a used one sometime ago that was dead, I changed out the fuses because they were blown but I have not even powered it up lol.... I guess haven't really been curious about whether it works or not until now.

@garp32 9 ай бұрын

If the speaker fuses were blown.. don't bother testing it. You've got something shorted somewhere. I find most often it's a pre-driver failure. It won't always cook the output devices, BUT I recommend you check every transistor on the main board, and all of the outputs. The first TO-3 output transistors (RCA 410's) are drivers for the main outputs. Those usually don't go bad. If it's just the main fuse that went bad, it may have been inrush current trying to reform the old filter caps. Bring it up slowly on a variac or use a dim bulb to limit current. You'll likely need new filter caps. Easy to do and easily available.

@bellotasoft6297 8 ай бұрын

Dear Sir, I would like to ask a question about your protection circuit. What is the electrical current specification for the 1.75uH inductor? Or if you made it yourself, what is the AWG, number of turns, and diameter? I would be very grateful if you allow me to use your design to add to my amplifier. Thank you very much.

@CIRCUITDESIGNER 8 ай бұрын

It's 10 turns #14 enamel wound on 3/4 dia PVC pipe as a form.

@holgers5216 11 ай бұрын

just curious to know why you felt you had to give the LED's DC, they would work just as well with AC

@CIRCUITDESIGNER 11 ай бұрын

Too dim with AC. They only glow during half the cycle.

@ALLENWERK 11 ай бұрын

Fantastic! I admire your approach of attempting to maintain the original design with tasteful enhancements. When and where can we buy the pcb’s you built and incorporated!?!?!? Thanks again for sharing 👍

@CIRCUITDESIGNER 11 ай бұрын

I may have a couple extra blank PCB's around here. You would need the ability to solder SMD parts.

@n6dl321 6 күн бұрын

Yup, the original factory design just used double sided foam tape to hold the caps in place. What s/n? mine is 1242-119, circa 1969.

@Sunnbobb 7 ай бұрын

Great video. I'd be interested if you would be selling the unpopulated protection board. I'm restoring 2 PL400's, and really like your design. Thanks Richard

@CIRCUITDESIGNER 7 ай бұрын

I'll check an see how many boards I have left.

@Sunnbobb 7 ай бұрын

@@CIRCUITDESIGNER thanks!

@CIRCUITDESIGNER 7 ай бұрын

@@Sunnbobb I have 4 boards available.

@Sunnbobb 7 ай бұрын

@@CIRCUITDESIGNER Thanks, I sent an email.

@grabir01 8 ай бұрын

I have an old SAE I would like to have it put back online. I really miss listening to it.

@willtucker2774 11 ай бұрын

Cant remember, but i seem to think that they made a 700 as well.

@johnnytoobad7785 11 ай бұрын

Yes they did !

@Area51-t5n 8 ай бұрын

Yes they did, and they are a bit more popular and command more money . I have a 700b myself that I am doing all the white oak and a few other upgrades .

@ericanderson2987 6 күн бұрын

Yes, the Phase Linear 700 was their 1st Power Amplifier.