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Great video! Educational and really well executed. Congratulations. It was a joy to watch!

You don't know what you are going to do? You are going to keep looking till you can find a matching amplifier, for a reasonable price and have glorious stereo tube amps.

I wonder what the squarewave would look like with the original parts in that

on the power cord where does the neutral go?

I just have a simple question if that exists. I have a Sony TA-4650 which until recently performed nearly flawlessly. The other night I wanted to play an LP and within 30, the speakers cut out. the unit recycled and then I played something through the AUX input and it was fine. Went back again to the phono selcetion and BANG.. speakers went out again. If I have anything connected to the phono input but dont feed it an active signal, like playing an lp, I can hear from one channel that fluttering sound. Could I have damaged the phono stage and is that something that could be repaired?

What size lamp is the power button?

I must have an older 4650 because the speaker relay switch is vertical and where you have plugs I have wire wraps? Also you have a capacitor your power supply board that is absent on mine. In its place is a transistor.

How can you do any analogue design without an oscilloscope?

Did you ever do any more videos on the Pioneer SX-1010?

Excellent video on the Legendary SX-1010.

Kind of an unusual piece of gear. I would be torn between restoring it to its proper function, with all the precision, and knowing that for the most part, there is almost no application that requires or even benefits from such precision.

Great job👍 working through the schematics and using proper logic to find the root of the problem. YT needs more techs like you to show proper electronics Ttroubleshooting

I suspected an "open". Well I got lucky due to poor soldered Xstr.

i have one of those, i see 4 ohm speakers are becoming more common again

Great work. I ended up with 13 Power Designs supplies. I was going to start fooling around with them in August. Your effort here helps me immeasurably.

Pls send me Pioneer GM -222 car Amplifier mother Board Price available

Hi. what company made this 1.5k resistor?

Would this work with the 400w 6550/kt88 ppp williamson design?

When you have fluctuating voltages manually set the range, on the DVM to eliminate auto-ranging annoyances.

Very good video, Still Learning . Did you check the heat after you installed the Tip's? It cool at first than will heat up the board will actually heat up to 128 degrees to 158 wow that's hot? I have the same problem w some Pioneer SX-950 sx850 which has another 2sd313 for the lamps. I found that its not current that heats them up. Its the input of 40vac to 26vdc them to 13.5vdc and w mind also 40vac to 26vdc than a 100 ohm Resistor (Heater) cuts it down to 17.4vdc than to 2sd313 (Heater) to 5.4Vdc -6.4vdc After recap. looks like a bad design?

Just 2c... You could induce oscillations just by the fact you have everything out on a benchtop without a chassis, with leads running every which way. Sitting transformers one way or moving them a couple of degrees can upset stuff too.

Those 200 ohm resistors should be fed from the same source. Feeding one from the others output can increase your problems.

I have the A9-c it sounds great when you put a signal in it but I hear alien noises when at idle and it’s annoying I might have to make a shield any thoughts

Bạn phải thay thế điện trở r13 và điện trở r14 bằng nhau và bằng 1,5 k ohm như thế nguồn mới cân bằng + - 24v như nhà sản xuất thì hai điện trở này đang khác nhau r13 = 1,2 k ohm , r14 = 1,5k ohm như thế đo điện áp 24 v ko cân xứng . Và bạn phải thay tất các transistor loại a và visai a 726s trên bo công xuất và bo chỉnh âm sắc bass , tress , các tụ 2,2 mf nối tầng , bo bảo vệ , bo radio , b sẽ có môt máy thu tuyệt vời .

I've never seen so low value resistors in tube amp power supplies. 1.5k is quite ordinary, up to 20k easily ... But it's not only resistors, this is caused quite probably with too much of capacitance (you made a big slow oscillator). I've first heard of motorboating when somebody wrote that you should avoid too high capacitors because of it ... But I am too ignorant to be sure about it.

The very audible slow, 'blat, blat blat' motorboating noise coming out the speaker Is most often caused by a bad ground connection on the negative end of the power supply filter caps. Dry solder joints or a ground connector lug not tightly or cleanly bolted to the chassis. The filter caps can't pass sufficient amperage to ground, they begin to charge up but then collapse so setup a regular, high voltage (intrusively loud) pulsing. This seems like a lower frequency parasitic oscillation. Lead dress can cause it, it might have been interesting to try suspending some grounded tinfoil over the wires sprawled all over the table to see if the oscillations stopped. I can't see enough to read your finely drawn circuit diagram and component choices so pls excuse me if my comment is unrelated or unhelpful.

Do you have your old oven? Where did you get the zener diodes? All the resistors in my oven were crumbling.

That is a metric butt-ton of filtering for what you have going on. Too much of a good thing is still too much... There is a mathematical solution to this. More or less, X capacitance requires X resistance for X filtering. It is not an arbitrary number. I can't give you a number off the top of my head,, but, it is an easy-to-find number on the interwebs.

I’m working on a ten-ten currently with the same issues , thanks for the suggested parts list and video

Awesome Video!

Good job and it is an obligation to change the electrolytic capacitors of devices over 20 years old.

Hi, Nice video. I have recaped my SX1010 and now its powering on, but relay is not actuating, so output is not there. What could be the possible problems? Kindly reply. Thanks in Advance.

Do you maybe know how to voltmod memory on this thing? I can't find anything on youtube or forums

I have seen index knobs with a keyed sleeve the set screw hits. This binds the assembly securely at any clocking. While still satisfying the flatted pot shaft.

IF time allows, I'd be interested in the software/firmware to inject a tone and do output harmonic analysis. Shall look for ideas and I also appreciate the effort you placed in restoring a Heathkit amplifier. I ask because an HP analyzer goes for considerable amount of money even today. Just love your simple set up. The stereo on left looks like a Pioneer? LOL Again, thank you on behalf of us on your channel. Well done. I learn a lot from your experience.

I would say this video is well done. I know it's a couple years old at this point, but wanted to say thank you! This is much help in the current GTX 260 Comp for a first time modder.

Excellent explanation of the phenomenon. Very innovative and cool breadboarding technique.

Could you share your parts list?

I see you use relay sockets for prototyping like I do. Super cool.

Totally love this mess! Congratulations!

A clear explanation and demonstration of the problem.

Clever of you to use octal relay sockets for prototyping. I've taken a much more traditional approach with a wooden board and sockets mounted on L-brackets. It's a very nice explanation of motorboating :) and it will occur in class AB or V amps with high-Z power supplies (e.g. tube rectifiers, thin wire on power transformer) if the voltage sags under load.

So, if this is 4010, then is it twice as good as 2005? Hell, it's twice the voltage and twice the current. Quad Damage! :) Looking at the panel, it reminds me of Nagra recorders. Every single detail here is fantastic. This PSU is absolutely freakin' BEAUTIFUL on the outside, a bit chaotic inside. Made with good quality components, maybe save for electrolytic caps (I don't trust them), obviously very high end gear. Down to a millivolt, soooo damn nice! I've never heard of oven stabilization in PSUs. And no PCB, all turret board like those old vacuum tube guitar amps, haha! A joy for ever. I like your oven replacement mod, keeping the PSU fresh and going :)

When you do the voltage measurements on the pins of the vfets (vfets not yet inserted), what do you use as reference? Chassis ground or speaker ground?

Very nice trip by the schematic!! Awesome content.

Be careful when you change the power line voltage setting with the multi-plug. Two female pins broke off internally when i tried this. The pins are very weak design. I managed to solder the broken parts onto the pins again.

couldnt you just use 2 opamps?

This video is really interesting. this is all really neat.

Ignore the HF noise on the waveforms -- that's not the THAT 1646's fault. It's present when the board is powered down as well. From reviewing scope screenshots after filming the video, it's clear that the "square wave" produced by my sign gen is substantially more square than the "pulse wave," as I suspected. Picture of the square wave: messingwithelectronics.com/wp-content/uploads/2022/08/THAT-1646-Sw-Wave.bmp And the pulse wave: messingwithelectronics.com/wp-content/uploads/2022/08/THAT-1646-Pulse-Wv.bmp