I think it’s fantastic that your taking the time out to make these videos an passing down the hobby , I been repairing consumer electronics for forty years, I’m also repairing vintage audio at the present time after work/weekends etc . Never find enough spare time to make videos, your great at explaining things thanks
Thanks Joseph. I'm hoping some younger folks will take an interest. Us older guys aren't getting any younger, and when we're gone I fear that this may become a lost skill.
Thanks for the affirmation, Justin! Gotta transfer what I've learned from others before I shuffle off this mortal coil. Which, despite the name, is not an inductor. 😁
Great job ! Thanks for the video Over 30 years I have owned all together maybe half a mill in audio I buy sale trade all these years many friends who oen pawn shops helps also 😆 But these older Sansui amps are a Gem espically when paired to the right speakers like the ole 4400 series JBL Thanks again
@@raygianelli3612 Thanks for posting this interesting video Ray. I would like to ask you about your test up to 500KHz. Have you had the chance to compare with the other channel that still has the fast transistors?. I am curious because I have a similar amp and i used essentially the same ON parts as you did but I could only test it (to almost 500KHz) without the possibility of comparison with the original parts and also without having access to THD or other measuremnts. I wonder how the MJ21193/4 compare with the original power transistors, or if THD measurements show any difference between these and the fast ST transistors. Thank you!
@@JoeGoesXtreme Hi Jose. That was the purpose of running it up to 500 KHz, so I could compare channels. There was little dropoff in amplitude. My distortion analyzer only goes up to 110 KHz, so I had to bypass it to make the test. There was no difference up to 100 KHz. I don't believe there will be an audible difference with the replacement transistors. We shall see!
@@raygianelli3612 I do believe that frequency response will be OK, however the reason for the fast transistor according to what i understand is to minimize the delay (if i could say so) in negative feedback loop. If you have sudden loud passage and signal in a feedback slightly delayed then it would lead to instant input stage overload leading to distortion. Some people hear it some don't, some do not pay attention and do not notice.
@@denissartisskis1625 Deniss, that is VERY interesting! And something that wouldn't show up during distortion testing or frequency sweep, neither of which use sudden transients. Thanks for posting this; guess I've got some reading to do!
Nice looking amp and a great repair I like your video's very much so please keep 'em comming ! I noticed a notch on the side of the bottom trace did that clear up when the switches were cleaned ?...cheers.
@@andymouse You bet. Only Caig Faderlube for pots, Caig Deoxit and MG Chemicals Nutrol or Super Contact Cleaner for switches or other metallic contacts.
Whew... Ray this is Great! this leaves me with a question though... Do ONLY output transistors needing matching??, or are other semiconductors further back in the circuit (cascaded fails) that need matching for gain too ?? Love the explanations with schematics ! thank you for any answer here. :- )
Nice job ray 👏 have a ? I own a sansui au919 how will the replacement transistors effect the transition time of the amp as they are not as fast as original ones i also work on my own equipment and collect vintage sansui have a au719 two tu719s,au919, ta500 and various sansui components thanks ray...termiteaudio
Hi Glenn. It took a friend who's smarter than me to explain the reasoning behind an amp with a high frequency response like the 919. It was designed to reduce intermodulation distortion (IMD), which is caused by a delay between the output transistors and the negative feedback loop. A faster amplifier will have lowered amounts of IMD. Does this translate to an audible improvement? I have to leave that to the listener, but personally I believe that, like the vanishingly low amounts of THD most modern solid state amps exhibit, I think not. I don't think I can discern the difference between an amp with .01% THD and .1% THD. And I feel the same applies here. YMMV. Kind of a moot point, since high speed transistors in a TO-3 package are NLA. Apologies for the long winded response!
@@raygianelli3612 thats ok ray 👌 i was just curious as i have a 919 if i need to replace them if it would seriously effect sound quality hopefully i never need to as i dont drive it hard. I leave that job to drive my 4 polk s55 towers to my 160 w rms solid state monoblocks thanks 😊 termiteaudio
Good Day Ray. It seems to me that you got the unit which was rebuilt by Echo ? How i guessed that ? In AU-919 Driver board F2839 and F2845 (Main Filters rectifire and capacitance multipliers board) are not connected via bolts and the only place where i saw modified unit like this was the Echo's thread. I did similar mod as i am rebuilding 919 for AKaer. . Nice video by the way
Hey Ray.... Where are you located? I have both a 919 and a 717 that need repairs. Also have a Kenwood that needs service but that's another story for another time. Thanks!
Has you checked all fusible resistors? Maybe some are out of specification due to overcurrent changing their value making them higher resistance and changing voltage of power supply. This may explain why one channel gave more power than the other.
A good point. However, this unit went through a comprehensive rebuild about 10 years ago, and all fusible resistors, electrolytic caps and many small signal transistors were replaced. Also outputs, and all trimmer resistors. But you're right, these are almost always way high in resistance when found in Sansui amps.
@@denissartisskis1625 fusible resistor I said or also known as fusistor. A fusible is only a fusible but a fusistor is a resistor that is flameproof and makes a role as a fusible too due to the fact that it is prone to open when certain current pass through it avoiding the cascade effect and reducing the chances of a catastrophic failure. Besides, I bet the farm that this Sansui amp has one slow-blow fuse in the primary of power transformer.
As a rookie I don’t know what to think lol. Right now I use inline 12dB attenuators on my au 7900. I’m to scared to try it without them and it’s totally restored ugh There is a lot of unfortunate misinformation in this thread. The earlier poster stating that earlier era equipment was designed with 150m sensitivity is correct (and that what the tech was probably trying to explain to his customer). However, that design standard most typically applied to pre 1980 equipment. As you go back earlier than the early 1960s, the aux input is sometimes designed to accommodate a raw tape head. The increase to a 2V input standard arose with the introduction of the CD player, to accommodate a perceived increase in dynamic range with that format. Applying a 2V nominal signal to an older 150mV stage can result in overload on high transients. It should not cause equipment damage in most instances, however. Signal overload is much less of an issue with tubed stages, as they have much better overload tolerance and distort more gently when overdriven. But it happens all the time with early era SS stages, which are easily driven into clipping distortion. The typical solution when this happens is to install fixed value signal attenuators at the input jacks. Often 6db is sufficient, but sometimes up to 12db may be required. The poster stating that most vintage equipment places the volume or loudness control before the first preamp stage is absolutely wrong. Particularly for equipment designed around a 150mV input level, that signal is frequently immediately amplified past the selector before routing to the tone, volume and loudness shaping circuits. I encounter vintage preamp stage overload from newer digital sources frequently, some of the latter displaying output voltages well in excess of 2V. The amount of overload, and the resulting level of distortion, varies from case to case. It has absolutely nothing to do with digital v analog, and everything to do with voltage sensitivity. It is a real electronics mismatch, and not some fictitious "digestive" issue.
![ตีสิบเดย์ [FULL] | คู่รักแซฟฟิก "หลิงหลิง - ออม" จากซีรีย์ "ใจซ่อนรัก"](http://i.ytimg.com/vi/zs8AfphGn2w/mqdefault.jpg)
I think it’s fantastic that your taking the time out to make these videos an passing down the hobby , I been repairing consumer electronics for forty years, I’m also repairing vintage audio at the present time after work/weekends etc . Never find enough spare time to make videos, your great at explaining things thanks
Thanks Joseph. I'm hoping some younger folks will take an interest. Us older guys aren't getting any younger, and when we're gone I fear that this may become a lost skill.
@@raygianelli3612 So true!
Ray, excellent video as always! Thank you for your dedication and thorough explanation of the repair.
Thanks Rob. That Sony camera shoots nice video, and I thank you for that!
@@raygianelli3612 Hi Ray, where are you based?
I am in Costa Rica Central América.
Best Regards.
@@treadmillrepair754 I'm in the north end of South Florida. :)
It's great to see that someone else uses the curve tracer 👍 I've had mine for years
I just discovered this channel and I subscribed. It was really enjoyable to see a repair video of such an iconic amplifier.
Thank you for showing the work you do. Helps me learn this vintage equipment and electronics in general.
Thanks for the affirmation, Justin! Gotta transfer what I've learned from others before I shuffle off this mortal coil. Which, despite the name, is not an inductor. 😁
I enjoy so much your explanations and most important your positive vibe. Thanx Ray!
👌
Love your videos ray,you always have a unique way of given something for a learning experience is awesome Than you for that.
Thanks Ray, just discovered you as well and subscribed up, very fun to watch the troubleshooting process, love the transistor matching as well.
Another great video! Thanks Ray
Great job ! Thanks for the video
Over 30 years I have owned all together maybe half a mill in audio I buy sale trade all these years many friends who oen pawn shops helps also 😆
But these older Sansui amps are a Gem espically when paired to the right speakers like the ole 4400 series JBL
Thanks again
Nice video, Ray. Glad to see those OnSemi's are working in the short run. I hope they pass an extended burn-in. Keep the videos coming!
Me too! I ran it up to 500 KHZ, and the left channel only dropped a little. I suspect that at audio frequencies it should be fine.
@@raygianelli3612 Thanks for posting this interesting video Ray. I would like to ask you about your test up to 500KHz. Have you had the chance to compare with the other channel that still has the fast transistors?. I am curious because I have a similar amp and i used essentially the same ON parts as you did but I could only test it (to almost 500KHz) without the possibility of comparison with the original parts and also without having access to THD or other measuremnts. I wonder how the MJ21193/4 compare with the original power transistors, or if THD measurements show any difference between these and the fast ST transistors.
Thank you!
@@JoeGoesXtreme Hi Jose. That was the purpose of running it up to 500 KHz, so I could compare channels. There was little dropoff in amplitude. My distortion analyzer only goes up to 110 KHz, so I had to bypass it to make the test. There was no difference up to 100 KHz. I don't believe there will be an audible difference with the replacement transistors. We shall see!
@@raygianelli3612 I do believe that frequency response will be OK, however the reason for the fast transistor according to what i understand is to minimize the delay (if i could say so) in negative feedback loop. If you have sudden loud passage and signal in a feedback slightly delayed then it would lead to instant input stage overload leading to distortion. Some people hear it some don't, some do not pay attention and do not notice.
@@denissartisskis1625 Deniss, that is VERY interesting! And something that wouldn't show up during distortion testing or frequency sweep, neither of which use sudden transients. Thanks for posting this; guess I've got some reading to do!
This Eico 443 is a very good curve tracer.
I have a vintage B&k 520b and one Peak Atlas DCA 75 Pro for curve tracer.
Best Regards.
Thanks Ray
Top notch!!!
Nice looking amp and a great repair I like your video's very much so please keep 'em comming ! I noticed a notch on the side of the bottom trace did that clear up when the switches were cleaned ?...cheers.
Seems to have. I cleaned pots ans switches, and it hasn't recurred.
@@raygianelli3612 Thats great ! may I ask what cleaner you use for pot's and switches please ?
@@andymouse You bet. Only Caig Faderlube for pots, Caig Deoxit and MG Chemicals Nutrol or Super Contact Cleaner for switches or other metallic contacts.
@@raygianelli3612 Cheer's !
Whew... Ray this is Great! this leaves me with a question though... Do ONLY output transistors needing matching??, or are other semiconductors further back in the circuit (cascaded fails) that need matching for gain too ?? Love the explanations with schematics ! thank you for any answer here. :- )
Yes. Small signal transistors in a differential configuration also need to be matched.
@@raygianelli3612 thank you! these little details so valuable.
Nice job ray 👏 have a ? I own a sansui au919 how will the replacement transistors effect the transition time of the amp as they are not as fast as original ones i also work on my own equipment and collect vintage sansui have a au719 two tu719s,au919, ta500 and various sansui components thanks ray...termiteaudio
Hi Glenn. It took a friend who's smarter than me to explain the reasoning behind an amp with a high frequency response like the 919. It was designed to reduce intermodulation distortion (IMD), which is caused by a delay between the output transistors and the negative feedback loop. A faster amplifier will have lowered amounts of IMD. Does this translate to an audible improvement? I have to leave that to the listener, but personally I believe that, like the vanishingly low amounts of THD most modern solid state amps exhibit, I think not. I don't think I can discern the difference between an amp with .01% THD and .1% THD. And I feel the same applies here. YMMV. Kind of a moot point, since high speed transistors in a TO-3 package are NLA. Apologies for the long winded response!
@@raygianelli3612 thats ok ray 👌 i was just curious as i have a 919 if i need to replace them if it would seriously effect sound quality hopefully i never need to as i dont drive it hard. I leave that job to drive my 4 polk s55 towers to my 160 w rms solid state monoblocks thanks 😊 termiteaudio
Good Day Ray. It seems to me that you got the unit which was rebuilt by Echo ? How i guessed that ? In AU-919 Driver board F2839 and F2845 (Main Filters rectifire and capacitance multipliers board) are not connected via bolts and the only place where i saw modified unit like this was the Echo's thread. I did similar mod as i am rebuilding 919 for AKaer. . Nice video by the way
Deniss! Good to hear from you. I got this in for repair from a guy in Tennessee. He said it was rebuilt by Scottrt of AK
Hey Ray.... Where are you located? I have both a 919 and a 717 that need repairs. Also have a Kenwood that needs service but that's another story for another time. Thanks!
Lake Worth in sunny south Florida. Where it's currently not sunny but pouring down rain. 😁
which camera are you using to shoot these videos? great autofocus!!
Sony ZV-1.
@@raygianelli3612 thanks a lot ;)
Sir I need Your Help please help me recently i lost my sansui au 717 volume potentialmeter now what to do guide me ?
Has you checked all fusible resistors? Maybe some are out of specification due to overcurrent changing their value making them higher resistance and changing voltage of power supply. This may explain why one channel gave more power than the other.
A good point. However, this unit went through a comprehensive rebuild about 10 years ago, and all fusible resistors, electrolytic caps and many small signal transistors were replaced. Also outputs, and all trimmer resistors. But you're right, these are almost always way high in resistance when found in Sansui amps.
@@raygianelli3612 😄👍
@@salvadorrodenas3071 I do not think AU-919 has any fusible.
@@denissartisskis1625 fusible resistor I said or also known as fusistor. A fusible is only a fusible but a fusistor is a resistor that is flameproof and makes a role as a fusible too due to the fact that it is prone to open when certain current pass through it avoiding the cascade effect and reducing the chances of a catastrophic failure. Besides, I bet the farm that this Sansui amp has one slow-blow fuse in the primary of power transformer.
What are your thoughts on plugging a Bluetooth bluMe into auxiliary of au 919? I’ve heard sometimes the voltage from the Bluetooth can be too high.
CD players put out about 2 volts, so I can't imagine Bluetooth would be an issue.
So would 2.1 be ok?
Think my Bluetooth is 2.1
@@darinlaflertheobsessedcook2376 It's made to be plugged into an existing stereo. It should be fine.
As a rookie I don’t know what to think lol. Right now I use inline 12dB attenuators on my au 7900. I’m to scared to try it without them and it’s totally restored ugh
There is a lot of unfortunate misinformation in this thread.
The earlier poster stating that earlier era equipment was designed with 150m sensitivity is correct (and that what the tech was probably trying to explain to his customer). However, that design standard most typically applied to pre 1980 equipment. As you go back earlier than the early 1960s, the aux input is sometimes designed to accommodate a raw tape head. The increase to a 2V input standard arose with the introduction of the CD player, to accommodate a perceived increase in dynamic range with that format. Applying a 2V nominal signal to an older 150mV stage can result in overload on high transients. It should not cause equipment damage in most instances, however.
Signal overload is much less of an issue with tubed stages, as they have much better overload tolerance and distort more gently when overdriven. But it happens all the time with early era SS stages, which are easily driven into clipping distortion. The typical solution when this happens is to install fixed value signal attenuators at the input jacks. Often 6db is sufficient, but sometimes up to 12db may be required.
The poster stating that most vintage equipment places the volume or loudness control before the first preamp stage is absolutely wrong.
Particularly for equipment designed around a 150mV input level, that signal is frequently immediately amplified past the selector before routing to the tone, volume and loudness shaping circuits.
I encounter vintage preamp stage overload from newer digital sources frequently, some of the latter displaying output voltages well in excess of 2V. The amount of overload, and the resulting level of distortion, varies from case to case. It has absolutely nothing to do with digital v analog, and everything to do with voltage sensitivity. It is a real electronics mismatch, and not some fictitious "digestive" issue.
Мастер с большой буквы!👍
Эдуард, после этого Адкома я не чувствую себя мастером!
@@raygianelli3612 не повод расстраиваться!)