Phase Linear 400 Power Amplifier Refurbished

Рет қаралды 2,862

Күн бұрын

I always wanted one of these back in the 1970's. Found one as is on Ebay so I thought I would give it a try at repairing it. I tried to keep it as original as possible. I did however, design a couple of PCB's to fix a couple issues.

Пікірлер: 22

@AudiophileStooge 8 сағат бұрын

beautiful work!

@grabir01 Ай бұрын

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

@Willco_Electronics 3 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.

@BlowProductions 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 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.

@ALLENWERK 4 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 4 ай бұрын

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

@Sunnbobb 7 күн 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 14 сағат бұрын

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

@Sunnbobb 13 сағат бұрын

@@CIRCUITDESIGNER thanks!

@bellotasoft6297 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 Ай бұрын

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

@ericwichmann9536 4 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 2 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.

@holgers5216 4 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 4 ай бұрын

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

@willtucker2774 4 ай бұрын

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

@johnnytoobad7785 4 ай бұрын

Yes they did !

@Ms_Dana 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 .