ฝัง
- เผยแพร่เมื่อ 14 ก.ค. 2024
- I'm repairing a Sony TA-F550ES amplifier from the early 90s that had some intermittent sound issues.
TA-F550ES Service Manual:
elektrotanya.com/sony_ta-f550...
I replaced the original Omron G5R-2232P protection relays with the currently available equivalent Omron G2RG-2A4 24VDC type which can be purchased from many electronics parts stores.
TIME STAMPS:
0:00 Introduction
2:21 A Look inside
6:49 Setting the Idling Current
10:48 Troubleshooting
13:39 Disassembly
22:18 Replacing the Speaker Protection Relays
26:43 Dust Removal & Reassembly
28:55 Cleaning Potentiometers & Switches
45:12 Reassembly
46:11 Final Test Run
48:32 More Cleaning & Full Reassembly
50:45 Thank you & Good night
--------------------------------------------
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#JanBeta #Sony #VintageAudio #VintageHifi #Repair #Sony550ES #SonyTAF550ES #Amplifier #Hifi #SpeakerRelays #Omron #IntermittentChannels #IntermittentSound #IdlingCurrent #Disassembly #Reassembly #Teardown #Service #Restoration #Refurb - วิทยาศาสตร์และเทคโนโลยี
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90s stereo equipment! Back in the day we need substantial hardware to enjoy our music. These days people listen to (mono)blue tooth speakers or in ear headphones, it's actually quite crazy!
Yeah, the younger generation doesn't appreciate the old school sound for the most part. Although there are exceptions, as witnessed by the recent vinyl revival and such. Plus, I have to admit that the modern headphones and portable speakers sound a lot more decent than what was available during my youth. But they are still no match for a decent analog amp with large speakers actually moving some air. ;)
It is absolutely worth to service this amp. The Sony ES series are still valuable today. High quality build. Enjoy it Jan.
Convenience won, and I think many people cant't afford large houses anymore. I can't...
Since the 70ies everything is being downscaled - just take a look at the big receivers of old. 90ies were good but it was the decade were things went downhill.
I have the same 550ES and it’s a nice heavy piece of kit. I need to do some repairs on mine so the disassembly process shown is useful
I love 90s stereo amplifiers. They sound so good.
The interior of that amp looks so good. It looks carefully designed and assembled. Well worth your time to bring this amp back to full function. I hope you enjoy listening to music with it. Cheers!
It's not mine to keep unfortunately. But its owner is very happy with it. :)
@@JanBeta Then, I'm certain the owner will be very pleased with it for years to come! Aloha.
I like how the transformer looks like a giant capacitor.
I think even the plastic cover is color matched to the larger filter capacitors! :D
I use a T-AF630ES....in storage for 15 years runs like a charme when revived. The ES series was the top range of Sony. Can run 4 and 8 ohm speakers. I had 4 ohm 401 on them back in the day until these died. Now I'm running 8 ohm Yamaha's. And a Sony 55ES, will buy a Sony CD player of this range soon. And a Technics turntable of course.
New sub. Love these older Sony amps. I hate the newer ones; ever since the Sony Corp. of Japan decided it would be cheaper to have their stuff manufactured in Mexico, and other such countries. The build quality went RIGHT down.
Ahh, the sound of alcohol soaked q-tips on metal contacts... Anyone else getting goose bumps all the way down their spines? It's like chalk on a blackboard! :D
Nice repair! Reminds me that I really have to clean the potis in my old Fisher amplifier. It's not as fancy as this Sony, but it still has a decent sound for being, like, 35 years old or something... ;-)
I have the TA 700 es - it's a wonderful amp ( weights a Tonne ) had it serviced recetly . The engineer said that to buy a n amp of that Quality today would cost thousands , I got mine for £200 from Fleabay. Best thing was the Tape monitor function , My amp is connected to a Studer Reel to reel and an Aiwa xks7000 Tape deck. Love me some Analogue sound
Nice! I bet the 700 weighs quite a bit more than this model (which already is around 12kg)! Very decent amps indeed. :D
Awesome amp you ha e there! Love seeing you fix these things. I'm looking forward to more
More coming soon! I have quite a bit of work to do on my own hifi equipment soon. Things are slowly falling apart. :D
Excellent video Jan. Great job repairing/restoring the Sony. I'm on the tail end of the same task with an old Pioneer A-447 stereo amplifier that I saved from landfill. It spent the majority of its life in the front bar of a hotel, a lot of it during the times that smoking was still allowed indoors. I even went to the extent of stripping it apart to send the chassis off to get electroplated in gold zinc.
Repairing 1990s tech is so rewarding. The electronic repair wasn't too bad... but restoring the amplifier back physically has been quite a journey!
Sony und Kenwood waren DIE Stereoanlagen der 90er 😀
JA! Sehr gutes Zeug und extrem weit verbreitet bei den Leuten, die damals Wert auf ordentlichen Sound gelegt haben. Die anderen hatten alle diese fürchterlichen Kompaktanlagen. :D
pretty good explanations on how to diagnose an amplifier, thank you
Many thanks for this video, I like amps from 90s era , that is why I have bought my ADCOM GFA 555MK2 and 545MK2 , They are phenomenal amps ,sounds awesome and build like a tanks.
I love 90s Sony separates. So cool. My parents had the full stack. Amplifier, record player, dual tape deck, cd player, and radio tuner. Same era as the amplifier you showed here but theirs was a higher model. I'm pretty sure it cost them nearly 2 grand back in the day! And they still have it all. I'm pretty sure it will be mine one day. I cant wait to service it and play around. Really enjoyable watch Jan. Good work.
Good tip on diagnosing noise on switches versus relays.
Jo Jan! Das Video kam genau zur richtigen Zeit! Ich habe den gleichen Verstärker und dein detailiertes Video hat mir wirklich sehr geholfen die Relais zu tauschen!
Mein Sony spielt jetzt wieder wie neu. Tausend Dank!
Oh, das freut mich! Ich hoffe, dein Amp wird dir noch lange Freude machen. Ist ein sehr feines Teil auf jeden Fall! 👍
Thank you. Very informative and well-produced video.
Thanks! Glad you liked it. :)
Genau diesen hatte ich auch.
War ein tolles Teil, was ich sehr lange genutzt habe.
Wurde erst ersetzt, durch einen 5,1 Reciever
Toll, das du den reparierst
Great job!
Yes, very informative and intertaining 🌝
Very interesting, I own a Denon PMA-560 amplifier that I've had since 1993 and I know it has some dust in it's contacts but since it pretty much just sits connected and i never really do anything with the selecting switches or pot meters anymore (all settings are handled before the input from an external sound board) I havn't really thought it necessary to do anything about it yet.
The front layout of the amplifier in this video is remarkably similar to mine and watching this I think I'm about ready to do my own deep cleaning on mine.
Thank you Jan, always fun and informative to watch 😊
Well done, thank you!
Bin ich froh dass ich diese video's entdeckt habe...😃
Freut mich, dass die Videos hilfreich sind! :)
Hi I have the same model amp and have the same intermittent sound outs . Really interesting and informative vide. I will try cleaning my solenoids if I can get them apart.
Thanks for the video. Something off the usual content.
Hope you enjoyed it! I love to tinker with audio electronics from time to time. The channel actually started out as a vintage hifi channel before I got into retro computing. :D
Hi Jan.
I just bought this amplifier used and I have followed your guide. Thank you. I did notice that you didn’t mentioned the RCA connectors on the back. Mine had cold soldering so that the left channel dropped out every now and then. So my advice is to resolder the connectors to the PCB.
Back when Sony made heavyweight amps. My two home cinema receivers from the early 2000's are poles apart. Both look outwardly similar, but the older one is far more substantial internally. Not everything improves with miniaturisation.
Yeah, they don't make them like that anymore unfortunately. Thankfully most of the 70-90s stuff is still serviceable and can be fixed these days. I still prefer the old equipment over any new receiver/amp, even if the newer ones are a tiny bit better technically (regarding signal to noise etc).
Unfortunately its an oxymoron comment because to service this old stuff you have to use modern parts
I still have mine. I need to clean the volume potentiometer. It’s staticky when going up and down. This is awesome.
Should be an easy fix then. I think you can reach the volume pot with contact cleaner without even taking the front panel apart! :)
@@JanBeta I was hoping you would say that :D I'll give it a shot this weekend and let you know how I make out. Thanks JanBeta
Hey WHAT is happening here, I had EXACTLY this model back in my later youth. And I still love it. 😍
Noice! Very decent amp. Hope yours continues to give you lots of joy and doesn't act up anytime soon! :D
@@JanBeta I think it is still in active use, why do I think that? I had to sell it many many many years ago because of money problems, like so many other retro things. But one day... I will get it back. Sad story, I know, but that's life.
Pretty nice amp, those MUSE caps are decent. Btw that STK ic can be rebuild but it's a lot of work. This is the problem with these amps using these STK or RNS ic-s, like Technics, Panasonic, etc. These ic-s are very difficult to find, and sometimes this is the reason why these older amps getting thrown out, the lack of that ic and too much hassle to rebuild.
Ай-ай-ай...😊 Потенциометры надо было всё-таки разобрать и почистить. Пропшикивание поможет ненадолго. За видео спасибо!👍
Geiles Video 😂❤
Sony serie ES,eccellente!
You have to admire how these were put together. Its like Jan says - "Built to be repaired" , Don't suppose many amps are built like these anymore . Good Job, you can do mine next time ! LOL
Even if Amps look repairable these days they remove part numbers off components in many devices that make them difficult and potentially hazardous to fix. I was trying to see if the schematic was in the lid like some of the older amps.
Yeah, different times. The 90s stuff is already less serviceable than the earlier devices but still reasonable to work on. Modern equipment often isn't reasonably fixable at all unfortunately. Unless you replace the whole innards or something.
The days when the schematics came with the device were magnificent!
@@christopherdecorte1599 mostly they do that to stop chinese manufacturers stealing the designs
Very nice seeing some non-Commodore stuff! More of that 🙂
I have some more audio stuff coming up pretty soon. And some Atari shenanigans. ;)
@@JanBeta Excellent! - Looking forward to these 🙂
japanese equipment of that era are so well build, nice trick to find dirty relay contacts.
Nach einigen Jahren herumprobierens diverser Reinigungsmitteln für Switches und Potis(für das Metallteil) bin ich bei Edelstall- und Chromepolitur für die Küche gelandet. Es entfernt jede Oxidation in sekunden ohne die Oberfläche aufzurauen. Auf Wattestäbchen auftragen und reinigen, anschliessend mit Wasser und danach Isopropanol spülen.
Ah, klingt nach einer guten Idee! Radiergummis funktionieren auch sehr gut, aber für heftigere Verschmutzungen ist Politur sicher eine vernünftige Lösung. :)
1990’s! Do the Carver series from the 80’s next. Carver m1.0t and m400t cube amps. Incredible machines.
it is one of the ES series, so not just mid-range, but even considered towards high end imo.
oh jan! i had the same generation of Sony amp back in the day, I was only 16-17 at the time i bought it i had to pay it off (lay by) and sadly had nothing but troubles with it and had to return it several times as it was dead. it eventually did get fixed.
Oh, you must have gotten a bad one then. In my experience, the Sony stuff from the era was really decent most of the times. I had a lesser model myself around that time and I absolutely loved it.
I always put a 120mm fan on the top of my amp to help the heat out. It won't need to spin very fast. I run a 12v fan at 5v (USB) and i can't feel any heat when touching the top of the case.
That's a good idea. I remember some amps from the era (especially Technics) had fans pre-installed from factory to keep the transistors a bit cooler. Most of them were temperature controlled even. :)
I do the same. I also installed a large aluminum heatsink on the stk.
On some equipment you could change the air flow profile and create dead zones around chips and components where air doesn't flow. Be careful!
I have a sony F311 on the list of repairs needed.
I just love the look of sony equipment from this era.
Similar issues with switching and a bit of cracking or loss of channel when i move the balance.
Might put it on the list for this weekend now you motivated me 😉
Chances are it just needs some contact cleaner in some strategic spots. The pots and switches in these are usually the main problem if you get noise and crackle in the signal. Hope you manage to fix it!
@@JanBeta I am not really familiar with audio stuff so had it on the backburner and was a bit reluctant to even open it up.
Seeing you work on a similar model does give some good insights.
Didn't know about setting the bias so a little bit more knowledge gained from you.
It's a great amplifire. The ES iin the Sony serie stands for Elevated Standards - the ES is the high(er) end stuff
Oh, I didn’t know that. Makes perfect sense! The standard is indeed quite elevated regarding build quality and down-to-earth circuitry. :D
One, often overlooked, aspect of relay replacement is coil resistance. It is prudent to ensure, the value isn't appreciably lower, than that of the factory fitted. Moreover, holding and must drop-out voltages may differ, which can lead to timing issues under certain cicumstances. Then there's contact material variation, which again, affects performance.
Good point! I found the ones I used recommended as replacements in several forums and the resistance doesn’t seem to be too far off. Would have been worth mentioning of course, thanks for the tip!
@@JanBeta Thank you Jan, that's very kind of you!
Very nice amp. I'm surprised they were still using STK modules during this time period.
Judging by the amps I’ve worked on, they were quite commonly used in the early to mid nineties. Marantz did it a lot, in the PM-50 for example and some of their higher class amps, too. I guess it was a relatively inexpensive way to get good quality driver circuits at the time. Many STKs actually sound great and have good specs, the only trouble is that they often break because of heat/too tight integration. At least most manufacturers seem to have stopped using them as the power amp modules at that point. :)
It's a Sony! (and it still has the sticker to prove it)
Yes! I loved those stickers back then. Sony made some awesome stuff in that era and the stickers were kind of a badge of honor. :D
Can you imagine when they assembled these, how many times folks put in the transformer before putting in the speaker terminal board. Then having to take out the trans lol.
Haha, I hope they had the order of operations down when they assembled these at the factory. :D
more videos like this
I have some more audio stuff coming up pretty soon. :)
I've just been gifted a nice 90s Technics Amp/tape deck with separate CD and Vinyl decks after years of saying I don't need a 'fancy' stereo and I love it! It might need some work in future so good to get some tips, cheers!
Baking soda is very messy. There is a super glue accelerator spray which bonds parts in few seconds :). You could have used water pump plier or vise grip to press the parts tighly together. My hats off to all of your commodore repairs :)
I love using baking soda to add some body to the glue. The problem in this particular case was to make the switches still moveable while getting the contacts as closely together as possible. Clamping down too much wouldn’t work because they would get stuck. So far, my workaround works very well. Hope it’s going to last. :)
That cylindrical transformer is a wild thing.
Yeah! Very heavy toroidal transformer. Lots of copper in there I guess, judging by the weight and the power output. :D
The transformer, though round, is not necessarily toroidal. In this era, Sony put traditional squarish transformers in cylindrical cases to make you think they were toroidal, at least according to one authoritative source.
Oh, interesting move. I guess it doesn’t make too much difference functionally but a real toroidal transformer would of course be neater. 🙃
I feel like working on my amp unit now lol.
So rewarding! :D
I rapired electronics and SONY has most qualitiy build of midrange HIFI companies
Yep, very well made equipment indeed!
good old amplifier/welder
Gott, ich hab die Quellenschalter schon Kohlrabenschwarz gesehen. Wichtig, die Kondensatoren vor dem STK3102II leiden und wenn die sterben, stirbt auch der STK für den es nur sehr schwer, wenn überhaupt Ersatz gibt. Ansonst sind die ES Geräte von Sony echt toll. Das leidige Relaisthema.. man kann die reinigen, aber will man das überhaupt. Es gibt ja Ersatz. Ansonst schönes Video.
Great Video thank you. Maybe it would be better to work with an 1 khz Sinus signal at input for testing and an osziloscope at the speaker out connectors. Then you can see every problem very quick. 100 % would be 4 or 8 ohms power resistors for load.
Yup, would have been a good way to test things usually and I’ve done that a couple of times in previous videos when testing amplifiers. In this case, I had already heard the amp before I got it on the bench and was pretty sure about the fault(s) so I decided to skip that step. :)
I know this video is pretty old, but 10 - 15 minutes is not really enough before setting the bias. I found that after an hour it stops drifting. I would usually hook up 2 multi meters at the same time for each channel, and at 30 minutes start to tune it, and keep on checking and tuning until there is no drift for 15 minutes.
For those potentiometer tabs I would try a vice to crush them in or a hammer and tapered chisel or tap to hammer them down flat. The vice may work best for the control it offers but may not be able to bend the metal in a specific direction as easily as the hammer method would.
(PLEASE! Do not use superglue(Cyanoacrylate) on electronics. It's corrosive and it gases Cyanide while curing which is also corrosive. It's also a jerk thing to do to the next service guy who comes along to fix it.)
I have the 530ES. Same problems with the switches and pots, all scratchy. Also there is a significant loss in high frequencies. I think it needs a good recap on the preamp/tone control stages.
I found that cleaning the switches and pots already improved the high end quite a bit in this particular one. Recapping with good brand caps is always a good idea for equipment that is a couple of decades old in my opinion though. :)
@@JanBeta I agree. Your video will be a good guide on how to disassemble mine when I start the TLC. They look identical in appearance, maybe there is a power difference. Thank you.
Maalesef aynı sorunları ben de yaşadım. Yağsız kontak temizleyici kullandım. Volum potansiyometresi idare edemez duruma gelince değiştirmek istedim ve tabii ki bulamadım. Sonunda Çin den 2x4 pinli benzer pot alarak monte ettim. STK yandı. Yine orijinal bulamadım replika stk3152 taktım. Röleler değişti. Kapasitörlerden biri bozulunca DC offset problemi oldu ve tiz hoparlör yandı. Şimdi kötüleşen kapasitörleri değiştirmekle meşgulum. Artık ülkemizde bu tür ürünleri satın almak çok zor. Onun için sonuna kadar uğraşıyorum çünkü tamir ettirmek de pahalı. Bir amatör olarak bunları yaparken zorlanıyorum ama değer.
@@ynahit3746 Siz çok dert yaşamışsınız gerçekten. Benim de korkum STK'nın arızalanması. DC offset işi de fenaymış, hoparlörlerin cross over devrelerini geçemez diye düşünürdüm.
@@borayurt66 STK yı korumak için kasanın üzerine STK yı hizalamaya çalışarak 12 cm lik PC kasa fanı yerleştirebilirsiniz. 12 voltluk fan 5 voltluk cep telefonu şarj aleti ile de çalışıyor. Hızlı dönmesi gerekmez sıcak havayı çeksin yeter. Unutmadan cızırtıya sebep olan elemanlardan bir tanesi de MUTE tuşu.
I still have a Harman Kardon 90s Stereo amplifier that has an extremely good sound but suffers from similar shenannigans.
I think most of the amps from that era need some cleaning and general TLC at this point in time. Most of the times, a bit of contact cleaner in strategic spots is going to resolve the issues at least temporarily in my experience. :)
Great video. I'm going into my TA-F808ES with similar problems to your 550ES this year. Could you explain baking soda on super glue?! Why? Thanks.
The baking soda just acts as both a kicker (to make the glue stick VERY quickly) and as a filler. The result is a very solid plastic-like material. It's a quick and dirty method to get the superglue to become extremely robust and fast acting. It's widely used by model making hobbyists. :)
Ah this is great. I had never heard of this! I build a lot of models and use 2 part epoxy a lot but never this trick. Thanks again. People like you is why TH-cam can still be great. @@JanBeta
Nice video. If you don't find service manual of amplifier how will you know the setting for idling current? Thank you.
That's quite non-trivial but doable. As far as I know, you basically feed the amp a 1kHz sine wave at line level, monitor the outputs on the speaker terminals with an oscilloscope and then adjust to the point where there's the highest output before the waveform starts to clip. Not 100% sure if that is the "professional" way to do it (because I'm just a hobbyist myself), so please do some research before attempting something like that. It's very easy to blow up the transistors in case you set them up incorrectly.
@@JanBeta Ok! Thank you. 😊
Hello, can you comment on the weird and thick base of this amp seen in the video? It looks like a concrete bunker but is surely not a Sony G-chassis at this price point.
I think it might actually be what Sony called a "G-chassis". This amp is from the ES series after all. It's just a metal frame covered in thick felt to minimize vibrations, no concrete or extra weight or anything like that involved. I've not seen any other amps from that series from the inside so I'm not sure if there's something else they added to make it a real g-chassis. Certainly, the felt helps a bit with minimizing vibrations but I would guess probably close to unmeasurable, more of a marketing thing from Sony.
Hi I want to replace some parts sony es amplifier, need audio grade capacitors like ELNA,Nichicon and resistors etc. Where can i find these online? I am in Europe.
I usually use Panasonic FC or FM capacitors, available from Reichelt.de for example. If you want to go full-on "audiophile", mundorf.com has you covered. Resistors etc are available from Reichelt or Conrad. There’s no point to go too high quality/price though. As long as the parts meet the specifications, you are not going to get any better sound with esoteric audiophile stuff, it’s just more expensive. Good brand, properly specced parts are the way to go in my opinion (and experience).
joonge ;) had you ever schonmal made ein shortschluss with your metallbennels from ths pulli? it knalls a lot ;)
Those es sonys have problematic fusible resistors which can drift with age, should be replaced also when restoring. Great video by the way, thank you
Ah, didn’t know that. I’m going to have a look. Thanks!
Also I have another question> How did you know the proper voltage that should be measured? Was 7V in the service manual? Thanks.
Yep, the voltages (actually 7mV, 7V would be WAY too high) and the whole procedure is described in the service manual. You should be able to find the exact service manual for your model online, too. Highly recommended to read through the thing before you start working on your amp. Sometimes there are some peculiarities you have to keep in mind before changing anything.
Ah excellent. Thank you. Yes, you can tell I'm somewhat of an amateur! (V vs Mv) haha@@JanBeta
Did you find what was the cause the amplifier to go protection mode?
The relays opened up after the amp was running for a while. I think that’s what the owner meant with the fault description they gave me. It wasn’t technically going into protection (as in the LED going red and the protection triggering the relays), it would just go silent after a while.
Bias must be adjusted in room temperature which is 21-22 Celsius - your room is far too cold as shown on your multimeter which was only 14-15 degrees 🥶 you must adjust it again. STK and some of the TO-257 transistors also resolder for dry joints. Always the same in thouse Sony.
Good call! I’m going to double check. I think the room temperature was slightly higher in reality (the multimeter is a couple of degrees off usually) but it still wasn’t 21-22C. Thanks for pointing that out!
@@JanBetarember also to resolder the STK ic and all the TO-257 housing transistors - the almost always have dry joints. Very importen. If the STK3102 break, replace it with STK3152
When things were just knobs and switches, rather than menus and pre-sets, audio gear manufacturers certainly lost their way as technology changed, going from serviceability to "bang it out cheap and maximise profits!!!", all at our expense...
I think there's still some manufacturers around these days that deliver decent quality, unfortunately mostly on the very high end "audiophile" and vastly expensive spectrum. Times have definitely changed. :/
I am wondering why you did not check the DC offset?
The DC offset is automatically set in this one, nothing much to worry about. But it would have been a good idea to check it anyway, you are right.
My friend... Sometimes it's the things you say that you may just assume that everyone knows that can make a headache repair an easier job. I'm working on a Sony as well, but not the same model. But they seem to be different versions of the same thing . Thank you for doing this one. One question... Why the baking soda with the super glue?
Thanks! Glad this was helpful! The baking soda acts both as a filler (to build up extremely solid material) and as an instant kicker for the cyanoacrylate glue. It's an old trick from the model making world, actually (I learned it a while back from Adam Savage's channel). If you haven't tried it, I recommend doing so. It's kind of a game changer. ;)
My Kenwood receiver from 1999 only has audio through the headphones jack. Not through the speakers. Anyone has a diagnoses for me? For many years I left it on standby instead of shutting it completely off with the other button. My bad!
Depends on what model it is. If it has a dedicated headphone amplifier, there’s likely something wrong with the power amp section. If it just derives the headphone signal from the regular power amp output, maybe you have an issue with the relays or somewhere else in the speaker protection circuit.
Nice refurbishing!
Was your ambient temperature really 14,7C? Yikes!
The room temperature reading on the DMM is usually a couple of degrees off, it was probably more like 17C or something. I have the window open and the heating turned off in the lab most of the time because of the soldering and contact cleaner fumes I produce. :D
What trouble if input is cracking sound?
My guess would be a dirty/corroded input selector switch. But as I said in the video, there's quite a few potentiometers and switches the signal travels through before reaching the amplification stage. All of those might need cleaning. Usually a bit of contact cleaner resolves the issues at least temporarily.
Hi Jan .
I have a Rotel RA01 amp. I am going crazy with the hum from the phono stage . Even if there is no turntable connected , the hum is still very loud . If there is no cables connected it goes quiet , but as soon as I plug in two phonos ( even with nothing connected at the other ends ) the hum surges .. Is my phono board ruined ? Can you help ?
Sounds like a grounding issue. I didn’t find any info about that particular Rotel but it probably has a ground screw for the phono that has to be connected to the ground wire of the turntable. If you just connect cables, they are going to act as antennas basically and pick up all the noise of the surroundings which then is amplified by the phono board. So the hum is normal. With a properly connected turntable the hum should go away. If that doesn’t help, maybe there’s an internal ground connection missing on the phono board or there’s some bad capacitors in the amp.
@@JanBetaThanks for quick response Jan .
Firstly, the Rotel RA01 was a great amp from around 2003 ( won what hifi amp of the year somewhere I think ) ..I have a Teac turntable 300 from around 2015 .It's a fully modern turntable with no earth connection on it or even needed. The amp has an earth bolt provided .
The problem happens as soon as any pair of phonos are connected to the amp, even if no turntable is connected at the other end . When I do connect the turntable, it goes down a little but still very present and unlistenable.
I'm sure it's not an earthing issue Jan, it just happens when a wire is connected . ( With no phonos connected at all , all is quiet ) but I need my turntable . If I knew what and where those capacitors were , I might have a go at replacing them myself ...can you help ?
Thanks anyway 😊 0:44 0:44
@@JanBeta Hi again . I looked at the circuit board just below the phono stage on the Rotel amp and couldn't see any bad soldered joints ( although I don't know what I'm looking for ) . After I put the case back on again , I tried another suggestion I was given using a mobile phone . I used my 1 metre long stereo phono ( red & black ) cable with a stereo 3.5 mm jack at the other end ... I used a phone radio app , found a station , turned the volume ( on the phone ) down low and plugged it in to the Rotel phono amp section . The music came through loud and clear of course , but as I pressed pause on the radio app ( to stop the music and allow me to listen for the hum ) ....there was none ? The hum had gone ? As soon as I unplugged the jack from the headphone skt on the phone , it came back in force ....but for the time it was connected to the phone , there was no hum ?
What does this mean Jan ?
@CaptainDarrick I‘m still pretty sure it’s a ground issue. You can try adding a ground wire to your turntable. That should help eliminate the hum. Here’s a good explanation: www.soundswow.com/ground-turntable-without-ground-wire/
Ground in this case doesn’t mean earth by the way. The ground wire just brings ground levels from both devices to the same level. If they are at different levels for some reason, you naturally get lots of noise in the signal.
bias resistor often gets flakey.
you'll see it cook itself if it goes far out of spec.
so einen hatte ich damals, der hatte wirklich Dampf
Ja! 120W bei 4 Ohm sind nicht gerade wenig! Und im Gegensatz zu moderneren Amps ist bei dem Ding auch noch alles entsprechend dimensioniert. :)
die gängigsten STK,s kriegst du immernoch bei IT-tronics germany ...liebe grüsse
Stimmt, von denen habe ich sogar schon mal Ersatz-STKs bestellt für einen Technics-Amp, den ich vor Jahren mal auf der Werkbank hatte und für einen Marantz PM-50 (der benutzt einen STK als Vorverstärker, so ähnlich wie der Sony aus diesem Video). :)
Put in a fan there and blow out the exhaust holes ..will solve it ..
I don't want to disassemble the switch after watching the video. I think it is safer to clean it with vinegar without disassembling it. Using an ultrasonic cleaner will shorten cleaning time. Then rinse with alcohol.
PCBs in the 90s looking sometimes pretty cheap material.. I guess due to there gigantic size.
when you say it isn't digital do you mean its a solid state analogue amp
Basically, yes. I also meant that later receivers/amps often had digital channel switches and all kinds of displays (that were rather prone to failure). This is just a very down to earth class A/B analog amplifier without any fancy shenanigans. Lovely device. :)
Looks like a lighter version of the 730ES.
I think it is! There were a couple of even beefier amps in the series. :)
Yeps the 630ES has the same setup. And a digital input.
Why did you put baking soda in that?!
Baking soda is a great kicker for superglue. It also adds structure quickly. Works really well, I recommend to try it out. Complete game changer. :)
@@JanBeta Ok, thanks for the info. I have to try it. 👍
GOOD OLD STEREOS FROM MY DAY 😊😊😊😊 GREAT SOUND NEVER BEAT IT WITH NEW JUNK FROM CHINA 🇨🇳
JAN DONT WRECK IT PLEASE
Why in the world did we move away from these designs, e-waste levels had to be better back then when things could be repaired. I mean, I get the power issue, it’s maybe 30% efficient, but there’s gotta be a tradeoff for that efficiency.
Though I guess nobody listens in stereo anymore, mono on a crappy Bluetooth speaker. I’ve done several “make it sound good on my phone” mixes and cringe when it all goes center to mono.
Most of it is due to maximizing profits I guess. I still have a bit of hope that eventually the "right to repair" movement is going to succeed in more significant ways. Would be better for the planet as well as for us tinkerers.
Calling this a midrange is strange. ES series were nearly always the high end devices, and audiophile quality.
Yes, definitely a higher end amplifier. I didn’t fully realize that while I shot the video. It’s very well made but relatively generic inside so it didn’t occur to me to be particularly high end. :)
@@JanBeta Real high end stuff are often very simple I guess :)
I think the only problem of these amplifiers were its switches, which Sony and probably most other companies changed for relays after this. And ICs on lower end models of course :) But you did a great job fixing these problems!
Bei der Montage mussten die Antennenbefestigungen des Schaltergehäuses zur Schaltermitte hin gebogen werden
I tried that but wasn't able to make it work. There was still too much wiggle in the switch housing for my taste. They are going to work and hold together without the glue though, it was just a preventative measure. :)
@@JanBeta In many cases, plastic degrades and breaks down over time, so gluing it together after a good wash and cleaning is the most rational method. It works well and that's the main thing. Good work worthy of respect. Taking off my hat!
You have to wonder why they didn't just use a ribbon cable instead of that goofy L-shaped PCB
My guess is that the board makes a more reliable connection and offers the shortest possible signal path. A ground plane in the board also offers better shielding than a ribbon cable. So it’s actually a good idea to use that strange board. :)
what's the point of put a toroidal and then put a shitty stk for preamp....garbage amp
Oh, some of those STKs actually sound extremely good. They were used in many higher end amps at the time for driving the power amp transistors (I know that at least Marantz and Denon used similar circuits in some of their higher end models, too).