To test voltages on amplifiers without the output-transistors you should not disconnect the small bias-transistor in the middle. It plays an important role in generating the correct B-E voltages. That's why you were getting 37V everywhere. It also often helps to put a 100 ohm resistor from B-E instead of the output transistors. Then you should have the output at 0V and ~0.7V from B-E on the output transistor treminals.
LoL Capacitors don't have a sound... They can only be built well or bad, last long or die early... The only thing that they can do to sound is if they are used in a filter circuit which if you replace with every single brand, so long as the capacity is the same, with all do exactly the same thing.. they don't make sound... The circuit does... Judging by the amount of likes that your comment has, seems like a lot of other people don't understand Capacitors either LoL...
These are just the kind of amps I'd like to find. I'm still trying to figure this stuff out, so a simple unit and cheap/free so if I blow it up no big loss.
Great work, and as a tip always in amplifiers start from the end, this means checking output transistors. In most cases no need in unsoldering them, if they are shorted then remove them, then check the output resistors, since when we get C to E short on both, that resistors sometimes burn, since we get both rails potential on them. After that check the Base resistors, they also go open or a bit burned if output transistor gets a short to Base, if so then most likely drivers also got some kick. Good luck in next projects ^.=.^
I love watching you revive junk from the dump. I have found that WD-40 will soften dried heat-sink grease, allowing it to be cleaned off. I don't know if you really had the time to let those insulators soak in it, but with a little time, it has worked for me.
If it's running that hot you probably should adjust the bias. I saw bias adjustment potentiometers in there. Just measure across the emitter resistor on each channel and adjust for about 10 to 15 millivolts.
that was my first Amplifier back in 1988 when i first left school. it had a habit of cutting out every time it was too loud rather than distorting. Was running it to Tannoy 607 speakers
@@DrCassette bust my OT all the same. wasnt too much for fix around 50euro nowadays prices, used and old toshiba silver thing for a while till it was fixed. you could turn that up near full but never sounded as warm.
hi, great video! was seeing an offer for the exact same model, around US$20. wondered if thats a pretty good deal for such a "dxxn" junk you mentioned in the video. 😅
I'm glad you managed to fix your amp :o) i'm still stumped with mine :o/ ... I have the same problem as your friend had, one of the channels not working and I replaced all the caps and the transistors seem fine...just getting a lot of abnormal negative voltage on the channel which doesnt work. I'm slowly prodding along troubleshooting at the best of my abilities :o) By the way, It was nice to hear The Beloved's Sweet harmony again :oD
+MsMad Lemon If you get a high amout of DC voltage on one of the speaker outputs, this could be due to a shorted output transistor. If those are fine, go back one step and check the driver stage. A schematic is always helpful. Just blindly replacing capacitors never helps, usually those are fine.
+DrCassette Thank you, actually the output transistors are fine as I swapped left and right to test, I have a feeling it is the driver stage. i'm getting high negative voltages at the base of the output transistor. i'm getting -21.2v but the schematic states the voltage at that point should be -0.66v... I checked the same point on the working right channel as a reference and it's indeed -0.66v as it should be. Do you know what the cause of such high negative voltages at transistor bases is?
+MsMad Lemon Sorry for the late reply... Check Q707, 709, 711 and the resistors and the trimmer potentiometer surrounding them. I'm very sure this is not a capacitor related problem.
Hallo, ich hätte eine Frage, wenn gestattet: Die großen weißen, Quaderförmigen Widerstände vor der Endstufe, die mit den drei Beinchen, wie mißt man die, und wieso haben die drei Anschlüsse? Hello, I would have a question, if allowed: The large white, cuboid shaped resistors in front of the amplifier transistors, with the three legs, how do you measure them, and why does they have three connections?
Es handelt sich um Drahtwiderstände mit Mittenanzapfung, das heißt, der mittlere Anschluss ist bei der Hälfte des Gesamtwiderstands verbunden. Man könnte alternativ auch sagen, es sind zwei gleich große Widerstände in einem Gehäuse, die miteinander verbunden sind. Das kann man entsprechend messen, wobei man aber zunächst den Widerstand nur zwischen den Messspitzen des Multimeters messen sollte, indem man diese miteinander verbindet. Diese Drahtwiderstände haben meist einen sehr geringen Wert von unter einem Ohm, deswegen fällt der Widerstand der Leitungen und Messspitzen des Multimeters ins Gewicht und muss vom Messergebnis abgezogen werden. In der Endstufe bieten diese Widerstände die Möglichkeit, über den Spannungsabfall den Ruhestrom der Ausgangstransistoren zu messen, deswegen sind die Anschlüsse auch nach oben heraus verlängert, damit man besonders einfach mit dem Messgerät herankommt.
Tyler Hanson I had a Sony receiver with the same setup and I did put heat sinks on the driver ICs in that unit. Yes indeed, I could do the same in this Aiwa amp.
I would be inclined to clean & lubricate the bias pot's, and adjust the quiescent current to spec's. I'm not sure what was meant by 'integrated' amplifier, when the output stage is discrete transistors.. A late model 'Marantz' has 2 integrated circuits (containing the output stage) mounted on a 'herringbone' heatsink. As the driver IC's get hot, also do the electrolytic caps surrounding them; worth replacing for just a few dollars in the process of assembly...
***** Sind das noch echte Wega oder schon umgelabelte Sonys? In den frühen 80ern hatte Sony mal in ein paar Serien die Topmodelle mit einigen der allerersten Schaltnetzteilen ausgestattet. Das bereitet mittlerweile gerne mal Ärger.
Sowohl als Auch ;) Habe einen Linearnetzteil-Sony (müsste V120 sein), das ist auch mein primärer Verstärker, klingt einfach schön, bleibt kühl, läuft und ist zuverlässig :) Die andere Kiste steht unten, ist IIRC ein JPS351. Der müsste noch von Wega selbst stammen.. Hatte letzteren aber noch nicht offen.
***** Hmm, ich habe den JPS351 mal eben gegoogelt, das sieht für mich auch schon sehr nach Sony aus. Das dazu passende Cassettendeck jedenfalls ist ein umgelabeltes Sony, denn die Sony-Version hatte ich mal. Wega war damals noch sehr gut darin, den zugelieferten Sony-Geräten ein sehr eigenes Aussehen zu geben, da wurde noch viel Aufwand getrieben.
Elna is just a s good as Nichicon, Rubycon, etc... I remember you saying that you had some old ones that were bad, well, electrolytics have a lifespan of 10 years, so that's normal.
NoBudgetTech Elna of course is better than all those cheap no name brands, but from all the quality brand they happen to be the ones I've had the most trouble with over the years. 10 years is way too short. From experience, it's more like 40 years.
From experience I'd also say 30+ years, but they're still rated for a certain amount of hours and you can't blame them for going bad after their life expectancy has been met. Also I've seen hundreds of bloated Japanese caps but not a single bulging ELNA ;)
+Raymond Leggs Sony owned a part of Aiwa since the early 80s. That's when Aiwa's quality started going downhill. In the 90s Sony took over Aiwa completely and used the brand name to sell cheap junk.
My videos or UA-cam videos in general? The video files look perfectly fine on my PC, and I do render with the settings UA-cam recommends. I have however noticed that UA-cam's video processing makes my videos look a bit crappy from time to time :(
DrCassette Its not just your videos, EC projects and the EEV channel all suffer from short breakups at seemingly random points, it happens on both my Mac using Chrome and i get the same effect watching the videos via a Playstation 3, so it dont seem to be platform specific. I am in Canada so maybe other people using youtube servers in other regions may not see the effect, but i am finding it very annoying. Old videos seem un effected.
Neil Robinson I am from Germany, and I have seem these artifacts on the EEVblog, too. DrCassette thankfully does not seem to be affected by this. Although EEVBlog was the only channel so far where I spotted these artifacts.
HW1099 Just watching the video again and the artifacts are still there, at the point where Dr Cassette wobbles the rectifier bridge there is a fairly bad break up. As i said i have seen the very same effects on a few channels, i hope youtube sort it out soon.
Neil Robinson has to do with the new 50/60fps video. EEVBlog and DrCassette both upload in high framerates. some monitor/graphics combinations can't handle that and suffer from tearing occasionally.
Hell, for free and your skills, This could be sold to buy something better, Liked, back in the day we would crack open the case in the protection unit an stick a dime in it across the contacts, usually worked until amp would over heat under heavy load
it might be running hot because you forgot to adjust the quiescent current and it is now way to high! because changing transistors nearly always changes the quiescent current. but it could simply be bad thermal design. also if it happens to be a pure class B amplifier ,forget what i just said. :D
DrCassette at 11:11 the trimpot on the bottom right corner of the video seems like it's the quiescent current control. but it could also be a dc offset adjustment. just try it out and see if it does something :D
I looked it up in the service manual, these are called 'preparation current' adjustments. The manual specifies voltages present on two test points, so I'll check that.
Elna caps are very good, and vincent audio stuff is the "white van scam" sort of stuff,they are very cheaply built,and then sold with massive price points.
PetruV Both wrong. Out of all name brands, Elna caps gave me the most trouble. And Vincent is (although from China) a highly regarded brand for HiFi and High End audio equipment. The amp I was talking about was not cheap at all, the transformers and heat sinks were so heavy we could barely lift that unit!
That's interesting,but i have not worked with large elna caps, so you must know better.I actually remembered, the crappy brand was "Marc Vincent", not just vincent
Would not want to use that as a main amp but it would be OK for backup or in another room. hopefully someone must have use for this and it will keep going. (-:
Vincent amp? Isn't that one of those "white van" phony things. Fake tubes/valves in a window? Yeah, the box does say $3K. Worth about $50. Check out: ua-cam.com/video/_PcfyLl-QLM/v-deo.html
To test voltages on amplifiers without the output-transistors you should not disconnect the small bias-transistor in the middle. It plays an important role in generating the correct B-E voltages. That's why you were getting 37V everywhere. It also often helps to put a 100 ohm resistor from B-E instead of the output transistors. Then you should have the output at 0V and ~0.7V from B-E on the output transistor treminals.
Let's come together
Right now
Oh yeah
In sweet harmony 🌹
Excellent track... Love it.
Elna are not crappy capacitors. Elna Silmic II are some of the best sounding caps available.
LoL Capacitors don't have a sound... They can only be built well or bad, last long or die early... The only thing that they can do to sound is if they are used in a filter circuit which if you replace with every single brand, so long as the capacity is the same, with all do exactly the same thing.. they don't make sound... The circuit does...
Judging by the amount of likes that your comment has, seems like a lot of other people don't understand Capacitors either LoL...
@@PeterMilanovski correct, except it's not only about C but also ESR (equivalent series resistance) and leakage current
@@PeterMilanovski caps don't make the sound better, but they certainly do make the sound worse if they are of a bad brand or going bad
ELNA's are known for making audio grade caps. so usually more high end than nichicon's
These are just the kind of amps I'd like to find. I'm still trying to figure this stuff out, so a simple unit and cheap/free so if I blow it up no big loss.
Great work, and as a tip always in amplifiers start from the end, this means checking output transistors. In most cases no need in unsoldering them, if they are shorted then remove them, then check the output resistors, since when we get C to E short on both, that resistors sometimes burn, since we get both rails potential on them. After that check the Base resistors, they also go open or a bit burned if output transistor gets a short to Base, if so then most likely drivers also got some kick. Good luck in next projects ^.=.^
+Sader Dragon furry
I love watching you revive junk from the dump. I have found that WD-40 will soften dried heat-sink grease, allowing it to be cleaned off. I don't know if you really had the time to let those insulators soak in it, but with a little time, it has worked for me.
weasel2htm Hmm, good idea. I'll try that next time.
Elna capacitors are quite good quality, they are used in many audio applications. So don't be fooled by a name you haven't heard of.
I know Elna capacitors well, that's why I had a closer look at them. Over the years I encountered several bad Elna capacitors.
@@DrCassette I have Elna Capacitors in my 1973 amplifier and they are the original one's... I think that it's time to check their ESR and EPR...
If it's running that hot you probably should adjust the bias. I saw bias adjustment potentiometers in there. Just measure across the emitter resistor on each channel and adjust for about 10 to 15 millivolts.
Mark Zacharias There are directions in the service manual that I will follow once I get the time to work on this again.
I enjoyed this video. I do like it when something broken can be fixed. Did you end up selling this amplifier?
I gave this amplifier to a friend. As far as I know he still has it.
that was my first Amplifier back in 1988 when i first left school. it had a habit of cutting out every time it was too loud rather than distorting. Was running it to Tannoy 607 speakers
That's intentional design, it's a protection circuit to protect the amplifier and the speakers from getting damaged.
@@DrCassette bust my OT all the same. wasnt too much for fix around 50euro nowadays prices, used and old toshiba silver thing for a while till it was fixed. you could turn that up near full but never sounded as warm.
hi, great video! was seeing an offer for the exact same model, around US$20. wondered if thats a pretty good deal for such a "dxxn" junk you mentioned in the video. 😅
I'm glad you managed to fix your amp :o) i'm still stumped with mine :o/ ... I have the same problem as your friend had, one of the channels not working and I replaced all the caps and the transistors seem fine...just getting a lot of abnormal negative voltage on the channel which doesnt work. I'm slowly prodding along troubleshooting at the best of my abilities :o) By the way, It was nice to hear The Beloved's Sweet harmony again :oD
+MsMad Lemon
If you get a high amout of DC voltage on one of the speaker outputs, this could be due to a shorted output transistor. If those are fine, go back one step and check the driver stage. A schematic is always helpful. Just blindly replacing capacitors never helps, usually those are fine.
+DrCassette Thank you, actually the output transistors are fine as I swapped left and right to test, I have a feeling it is the driver stage. i'm getting high negative voltages at the base of the output transistor. i'm getting -21.2v but the schematic states the voltage at that point should be -0.66v... I checked the same point on the working right channel as a reference and it's indeed -0.66v as it should be. Do you know what the cause of such high negative voltages at transistor bases is?
+MsMad Lemon Here's a link to the schematic with notes:
s15.postimg.org/3rs5x4d2z/20151121_031109.jpg
+MsMad Lemon
Sorry for the late reply... Check Q707, 709, 711 and the resistors and the trimmer potentiometer surrounding them. I'm very sure this is not a capacitor related problem.
+DrCassette Not a problem for the lateness, thank you so much for helping out :o)
Hallo, ich hätte eine Frage, wenn gestattet: Die großen weißen, Quaderförmigen Widerstände vor der Endstufe, die mit den drei Beinchen, wie mißt man die, und wieso haben die drei Anschlüsse?
Hello, I would have a question, if allowed: The large white, cuboid shaped resistors in front of the amplifier transistors, with the three legs, how do you measure them, and why does they have three connections?
Es handelt sich um Drahtwiderstände mit Mittenanzapfung, das heißt, der mittlere Anschluss ist bei der Hälfte des Gesamtwiderstands verbunden. Man könnte alternativ auch sagen, es sind zwei gleich große Widerstände in einem Gehäuse, die miteinander verbunden sind. Das kann man entsprechend messen, wobei man aber zunächst den Widerstand nur zwischen den Messspitzen des Multimeters messen sollte, indem man diese miteinander verbindet. Diese Drahtwiderstände haben meist einen sehr geringen Wert von unter einem Ohm, deswegen fällt der Widerstand der Leitungen und Messspitzen des Multimeters ins Gewicht und muss vom Messergebnis abgezogen werden.
In der Endstufe bieten diese Widerstände die Möglichkeit, über den Spannungsabfall den Ruhestrom der Ausgangstransistoren zu messen, deswegen sind die Anschlüsse auch nach oben heraus verlängert, damit man besonders einfach mit dem Messgerät herankommt.
You could probably mount some little heatsinks to those ICS
Tyler Hanson I had a Sony receiver with the same setup and I did put heat sinks on the driver ICs in that unit. Yes indeed, I could do the same in this Aiwa amp.
Sweeeeeet ☺
Thank you 🎵
Great you video
I would be inclined to clean & lubricate the bias pot's, and adjust the quiescent current to spec's. I'm not sure what was meant by 'integrated' amplifier, when the output stage is discrete transistors..
A late model 'Marantz' has 2 integrated circuits (containing the output stage) mounted on a 'herringbone' heatsink.
As the driver IC's get hot, also do the electrolytic caps surrounding them; worth replacing for just a few dollars in the process of assembly...
'Integrated Amplifier' in this case means it's a preamp and a main amp in one unit.
Schönes Video! Sehr interessant. Hoffe, meine beiden Wega-Verstärker spielen noch lange, bevor ich mal sowas hier anfangen muss :)
***** Sind das noch echte Wega oder schon umgelabelte Sonys? In den frühen 80ern hatte Sony mal in ein paar Serien die Topmodelle mit einigen der allerersten Schaltnetzteilen ausgestattet. Das bereitet mittlerweile gerne mal Ärger.
Sowohl als Auch ;)
Habe einen Linearnetzteil-Sony (müsste V120 sein), das ist auch mein primärer Verstärker, klingt einfach schön, bleibt kühl, läuft und ist zuverlässig :)
Die andere Kiste steht unten, ist IIRC ein JPS351. Der müsste noch von Wega selbst stammen.. Hatte letzteren aber noch nicht offen.
***** Hmm, ich habe den JPS351 mal eben gegoogelt, das sieht für mich auch schon sehr nach Sony aus. Das dazu passende Cassettendeck jedenfalls ist ein umgelabeltes Sony, denn die Sony-Version hatte ich mal. Wega war damals noch sehr gut darin, den zugelieferten Sony-Geräten ein sehr eigenes Aussehen zu geben, da wurde noch viel Aufwand getrieben.
Gerade mal recherchiert, es scheint tatsächlich ein Sony TA-F5A-Klon zu sein. Muss man Ihnen lassen - das eigene Aussehen hat die Kiste :D
The driver IC's in some Sony receivers run very hot too.
+Bri G.
Yes indeed, I had a Sony receiver with a similar design. I installed heat sinks on the driver chips. Still ran very hot.
What capacitor meter do you use?
Борис Борисов
This one: ua-cam.com/video/b3dPBnYixs4/v-deo.html
Elna is just a s good as Nichicon, Rubycon, etc... I remember you saying that you had some old ones that were bad, well, electrolytics have a lifespan of 10 years, so that's normal.
NoBudgetTech Elna of course is better than all those cheap no name brands, but from all the quality brand they happen to be the ones I've had the most trouble with over the years. 10 years is way too short. From experience, it's more like 40 years.
From experience I'd also say 30+ years, but they're still rated for a certain amount of hours and you can't blame them for going bad after their life expectancy has been met. Also I've seen hundreds of bloated Japanese caps but not a single bulging ELNA ;)
aiwa is sony?
+Raymond Leggs
Sony owned a part of Aiwa since the early 80s. That's when Aiwa's quality started going downhill. In the 90s Sony took over Aiwa completely and used the brand name to sell cheap junk.
Sad.
Is it me or do a lot of new videos suffer from artifacts at multiple points recently ?
My videos or UA-cam videos in general? The video files look perfectly fine on my PC, and I do render with the settings UA-cam recommends. I have however noticed that UA-cam's video processing makes my videos look a bit crappy from time to time :(
DrCassette Its not just your videos, EC projects and the EEV channel all suffer from short breakups at seemingly random points, it happens on both my Mac using Chrome and i get the same effect watching the videos via a Playstation 3, so it dont seem to be platform specific.
I am in Canada so maybe other people using youtube servers in other regions may not see the effect, but i am finding it very annoying.
Old videos seem un effected.
Neil Robinson I am from Germany, and I have seem these artifacts on the EEVblog, too.
DrCassette thankfully does not seem to be affected by this.
Although EEVBlog was the only channel so far where I spotted these artifacts.
HW1099 Just watching the video again and the artifacts are still there, at the point where Dr Cassette wobbles the rectifier bridge there is a fairly bad break up.
As i said i have seen the very same effects on a few channels, i hope youtube sort it out soon.
Neil Robinson has to do with the new 50/60fps video. EEVBlog and DrCassette both upload in high framerates. some monitor/graphics combinations can't handle that and suffer from tearing occasionally.
Hell, for free and your skills, This could be sold to buy something better, Liked, back in the day we would crack open the case in the protection unit an stick a dime in it across the contacts, usually worked until amp would over heat under heavy load
it might be running hot because you forgot to adjust the quiescent current and it is now way to high! because changing transistors nearly always changes the quiescent current. but it could simply be bad thermal design. also if it happens to be a pure class B amplifier ,forget what i just said. :D
TheNiggiboy Did you see an adjustment for that? I didn't.
DrCassette at 11:11 the trimpot on the bottom right corner of the video seems like it's the quiescent current control. but it could also be a dc offset adjustment. just try it out and see if it does something :D
I looked it up in the service manual, these are called 'preparation current' adjustments. The manual specifies voltages present on two test points, so I'll check that.
:)
Elna Silmic and Nichicon Muse Kz are very good caps for audio. The first warmer and sweet, second more detailed and sweet. Choise depended 🤔🙄
Elna caps are very good, and vincent audio stuff is the "white van scam" sort of stuff,they are very cheaply built,and then sold with massive price points.
PetruV Both wrong. Out of all name brands, Elna caps gave me the most trouble. And Vincent is (although from China) a highly regarded brand for HiFi and High End audio equipment. The amp I was talking about was not cheap at all, the transformers and heat sinks were so heavy we could barely lift that unit!
That's interesting,but i have not worked with large elna caps, so you must know better.I actually remembered, the crappy brand was "Marc Vincent", not just vincent
Would not want to use that as a main amp but it would be OK for backup or in another room. hopefully someone must have use for this and it will keep going. (-:
Big box with almost nothing inside. :-)
Those solder pads look terrible like an inexperienced previous owner messes with it. You never know what people are thinking when they eff with stuff.
I know that amp is cheap, but it is honest.
I agree, it's not fancy, but very well usable. I gave this amplifier to a friend, who still uses it.
Vincent amp? Isn't that one of those "white van" phony things. Fake tubes/valves in a window? Yeah, the box does say $3K. Worth about $50.
Check out: ua-cam.com/video/_PcfyLl-QLM/v-deo.html
No, Vincent is a legitimate German High End audio manufacturer. www(.)vincent-tac(.)de