The audio amplifier repair that wasn't

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Күн бұрын

Пікірлер: 36

@JBuster941 3 ай бұрын

Maybe the problem wasn´t with the board to begin with, but with the wiring: you have the relatively long high-impedance input wires close to the output wires. That can cause enough coupling for the amplifier to start oscillating at a high (supersonic) frequencies, which may not be immediately evident until you connect an oscilloscope to the outputs. In fact, the amplifier may now still be oscillating even though it seems fixed. If that is the case, using shielded wires may improve things.

@1pcfred 3 ай бұрын

I met the guy that made Sound Senders once. He was working out of a warehouse next to where a friend of mine worked. So that's how I was introduced to him. My buddy knew him and wanted me to meet this interesting fellow he knew. He was quite a card.

@jutukka 3 ай бұрын

You reformed the caps. By using it for a while.

@Sctronic209 3 ай бұрын

My first thought was capacitors.

@CoolDudeClem 3 ай бұрын

3:35 with the way modern music is declining, this is kind of noise is what the kids will be listening to not too long from now!

@thomasfowler2964 3 ай бұрын

Every time I open something that's broken, fail to find a fault, reassemble it, only for it to work immediately, I assume there is a solder blob or something conductive that's been rattling around in it, just waiting to fall into a problematic position.

@ohmbug10 3 ай бұрын

Technically speaking, it had a fart stuck crossways.

@jimdavis5230 3 ай бұрын

I've had this puzzling intermittent problem with an HF transmitter PA stage. Turned out to be dry soldered joints.

@darpmalone2064 3 ай бұрын

Perhaps a tiny loose piece of wire or metal was wedged somewhere causing a short?

@mixguru9669 3 ай бұрын

Could be the potentiometer 🤔

@TrevorsBench 3 ай бұрын

I think it's the perf board. I built a reverse RIAA circuit for testing phono stages on perf board using surface mount components. It worked fine the first day or two then it stopped working after that. I suspect the perf board was too thin and flexible to be reliable

@DonnieMulligan 3 ай бұрын

Damn Gremlins! Another good one John.

@bobisyouruncle1 3 ай бұрын

I would think that screwing down the board presses a bridge link against another contact.

@mechanoid5739 3 ай бұрын

That's what I was thinking.

@McTroyd 3 ай бұрын

Sounds like a voltage controlled oscillator on a modular synthesizer. Maybe the wiring was capacitavely coupling with something, and the wire moved when you took the amp out of the box?

@vidanmitkovski7785 3 ай бұрын

I had a case where while tracing the problem on the board there was a resistance between two traces. There was no components or problem with the multimeter. The board was also universal like they sell it on the internet. Tested another board in the same spot, but no problems. So I think that maybe the board is bad or condensation from over time made some component to go crazy.

@carloca71 3 ай бұрын

The heat sink looks quite close to the IC pins, maybe it was making contact while pressed in the box, my 2 cents 🙂

@michaelspiering7585 3 ай бұрын

Could you offer any advice for an output transformer for 2 12k5 12v low voltage tubes in push pull? I also use 12u7 tubes for preamp and phase splitter.

@amitghosh6966 2 ай бұрын

Nice video. Please do a review of 4 Transistor (2N3773) audio amplifier board and it's power output on various suppy voltages, harmonic distortion, Ampere consumption

@jeddak 3 ай бұрын

You've got the magic touch!

@krowwithakay 2 ай бұрын

Anyone know the song name used here: 3:35 thanks!

@Wuzz7 3 ай бұрын

Hey sometime ago you said you would do a video on how to make these acrylic boxes. But it's still not out yet. Are you still planning to make that video?

@JohnAudioTech 3 ай бұрын

I built a turntable cover out of acrylic in the last video. Much of the same principles apply to making a project case.

@Wuzz7 3 ай бұрын

@@JohnAudioTech thanks for the reply. Haven't watched that one yet. Best of luck

@davidkclayton 3 ай бұрын

This is one of those times when cold spray and a heat gun is utilized find intermittent problems.

@chrisharper2658 3 ай бұрын

I try to thermally shock the semiconductors to see if I can force a permanent failure with freeze spray and the tip of a soldering iron.

@rudge3speed 3 ай бұрын

That's how I fix things!

@H4zuZazu 3 ай бұрын

Oh, i had something like that: i altered a circuit assamled the device doesn't work, disassemle works - wtf. okay while powered on slowly close the case to see why it is doing that - nothing. Still works, never figured out what was the fault.