@@SoddingaboutSi I had no idea Sansui went back to the 1960's Simon. You learn something new every day. I'd love to own a sweet valve stereo setup. The audio is magical, as I mentioned earlier.
I have one of these, so will be fettling it soon. I know it's 2 years old, but the service manual can be found Ok for these free online. When balancing on the side, a coaster or strip of ply supports the main transformer, makes it more stable. But space on there for the MPX I think, the 250 has that built in IIRC, or perhaps a DIY one can be added. Worth adding a soft start IMO, I actually had a small valve spark internally each time I switched it on (a few years ago now), so i added some zenner chains to tame the HV until the tubes warmed up, but some type of soft start would be nice for the HT.
Hi, I did a simulation of the 220 tone circuit, the tone controls as standard on the 220 (and 250) have a big bass and treble boost, perhaps suited to a full range single cone speaker. A suitable HiFi adjustment is to change: 1. Change C61(0.03u) to 150n and move it next to R58/C63. 2. R58 -> 68k, R50 -> 68k. 3. C63 -> 120p, C67 -> 470p 4. C69 -> 27n, C71 -> 33n, C65 -> remove 5. Add Rboost of 1M parallel to C69 That should give a reasonably flat < 1dB response with useful bass and treble, and a bit less loss. Perfection cannot be attained without another buffer stage, IMO, a defeat switch would be nice, a relay from the 'Noise filter' switch perhaps
Very nice receiver and nice refurbishment, Simon. I do test equipment, aside from a Kenwood KR720 that I did for music at the bench, but I like the idea of "re-stuffing" those multi-section metal can capacitors to maintain "the look" in older gear. Thank you for showing us your work - I would have liked to have seen where (on the schematic) you install the resistor that corrected the bass boost. Regards, David.
very nice reciver simon. i was suprised when you said distortion was 3rd harmonic i normaly find its second in a valve amp. as for magic eyes the phosphour seems to die rather than the emision.
Great video! Measurements through the tone circuits are always problematic! Some receivers have a tone bypass switch - I have a Heathkit AR-1302 and measure amp performance with tone bypassed - only way to get an objective measurement. Had a problem with the Loudness switch but corrected with a Deoxit treatment. Enjoyed your use of the HP-8903 with Millett software. All good stuff. Keep them coming!
++++++++++++++++++UPDATE+++++++++++++++ Turned out that the strange frequency response I was getting from this receiver was the result of a stuck contact on one channel of the loudness switch. Although the loudness switch appeared to work it clearly wasn't correctly.
A lovely receiver and an interesting video, thank you. I know there is a risk of hum loops but I'd be keen to add a safety earth via a 3 core mains lead.
A true classic one of the only type we might see in the US good design bad caps and poor resistors but good transformers and they can’t be fixed I was surprised at the tubular chassis being reused all of the coupling caps will be Leakey or shorted I was surprised at your tube tester not being a a transconductance type the type you have is a emissions type which is ok 👌 for service go/no go testing gain VS THD of the tube it’s self shows it’s age most power tubes are rated at 1,000.00 hour’s and a hint much better for a tube amp to hav a shorted output than open power tubes arc with no load
Thanks so much for sharing, I have the same model it is working but can’t get FM stations and the magic eye is not bright. Im thinking to get it cleaned by professional.
Great Receiver Simon And Some Very Nice Work From You, Sounds Lovely !! I Have a Transistor Sansui AU101 Amp And It Sounds As Sweet As a Nut Have Not Even Re-caped It Thanks For Uploading Regards mike.
That bass hump looked like the loudness contour was still in circuit. The switch would close to short it out and make the response flat. The 2% distortion is probably normal for what was a mid Fi domestic receiver. Not really high end HiFi. Nice to see the magic eye, they tend to be one of the first valves to lose emission.
A bit dusty, but it sounds very nice :-D Looking at the rear of the radio, you could build a decoder in a dicast box and fix it to the rear, include a small transformer and it can plug into that two pin mains outlet on the back. An add on that does not modify the radio :-D I think there are single chip decoders out there.
A very nice receiver Simon, shame no stereo decoder, I had a pioneer very similar to that from 1969 that had a decoder but in no where near as good condition as yours, the 10 Watts output was more than enough with my old celestion speakers
Thanks for the video. I liked the information you provided. One question. I have this exact 220 Model Sansui. It works pretty good but I wonder if you could post your capacitor shopping list? I would like to recap mine like you did yours. Funny thing I have the same Fox Electronics in mine as well. 1975 same year as well dated. Could these been factory? Same as sloppy sodering as well in mine.
Well done, sounds good without the heavy bass. Never owned an audio distortion analyzer. Does it measure both even and odd content at the same time? Or can it separate the two?
The audio analyser is a pure sine wave generator and distortion analyser in one. So a pure signal is fed into the input and the output checked for any change in the quality of the sine.
@@SoddingaboutSi I'm professing my ignorance about that piece of test gear. Never had a use for one, though I still have some high end audio gear which I never use anymore, since the hearing loss caused from said items. Since it measures the departure from a pure sine wave, it is measuring both odd & even harmonic content in the output then. Thanks Simon, Paul.
Hi Simon, I’ve got a marantz 1072, and it seems similar to the receiver in the video, it seems to have lost midrange and treble, and bass is overwhelming! Any suggestions or advice.Thanks Mike
@@SoddingaboutSi thanks Simon, I’m using the aux input, and tried the tuner input and still the same, even using the headphones produced the same mid and high cut! Interestingly I have two of these amplifiers it’s just the one that has this issue, unfortunately.
Its rated at 10 watts per channel into 8 ohm which it can just meet with these used valves thd around 2% which althogh sounds high is probably mostly 2nd harmonics.
You seem like a respectable technician, so I can't imagine why you would consider sending that receiver out into the wild without replacing that multi stage capacitor. Even if they measure perfectly, at some point one or more of those fifty year old caps will fail. So now you have a cap constrained within a metal container that at some unknown point in the future will blow up. That is the literal definition of a time bomb. There really is no excuse for leaving it this way. I hope by the end of this video you will have reconsidered this decision. Otherwise, despite your skills, it's your decision making that defeats all of your other abilities. Such a shame to see.
