Sansui 881 Vintage Receiver Hum Fix

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Fixing the remaining 100Hz mains hum issues the 1974 vintage Sansui 881 Receiver had. Replacing the main filter capacitors and renewing some ground connections.
Part 1 (Restoration of this receiver) is here: • Sansui 881 Vintage Rec...
Here's the tutorial for properly fixing the common hum issues caused by design flaws in some of the 881 receivers (there are different versions of the PCB it seems): conradhoffman.c...
The capacitors I used are Mundorf Mlytic 10000uF 63V.
The tracks used for the soldering/timelapse portions of the video and testing the amp were kindly provided by Focus 10 aka Øystein Hansen. Thank you! Check out more of his work here: / user-993847645
Focus 10's tune "8-bit wannabe" is now also available as a single from CDBaby/iTunes/Spotify: store.cdbaby.c...
If you find this video helpful and/or entertaining please like, share, subscribe and/or consider a donation!
TWITTER: / thejanbeta
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Thanks!
#JanBeta #Sansui #VintageAudio

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3 окт 2024

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Комментарии : 126

@JanBeta 5 лет назад

HUM UPDATE: Testing the receiver in the living room before I gave it back to its owner, there was no hum at all. It probably was caused by some of my video lights or something else in the lab.

@thomaskitz1185 5 лет назад

Was the bottom on at the time of your first test? I serviced these when under warranty and I do not remember any service bulletins about hum in these. I do remember Marantz having a bulletin about adding a star washer to the grounds on their amps and receivers in models 1060 and 2270 and others in this era. Hope this helps others keeping this equipment going.

@toronado455 5 лет назад

great news! thanks for the update!

@JanBeta 5 лет назад

No, tested without the bottom. Should have thought of that but most amplifiers I serviced didn't hum even with the case open. That may have been the whole issue.

@thomaskitz1185 5 лет назад

@@JanBeta Another suggestion when doing a lot of work like your re capping do it in small steps and test in between . It will be more difficult to find problems that are sometimes induced by repair efforts. Keep up the quality videos.

@evensgrey 5 лет назад

@@JanBeta The case may be acting as LF shielding, blocking all the noise our modern switching supplies (which are just damn well everywhere, particularly DC-to-DC converters are in all kinds of things) and digital electronics produce. They aren't normally a lot of noise, but studio-style LED lighting still uses a lot of power, so lots of switching noise and lots of wiring to emit PCM frequencies.

@GadgetUK164 5 лет назад

Glad to see you revisit this! I know you had the clamp pretty tight, but one thing I would be worried about is the glue on the tape melting a little as the cap has heating and cooling cycles, and the cap slipping downwards. Great job though!

@JanBeta 5 лет назад

Didn't think of the glue melting. It's probably not going to make the caps slip because they are tightly clamped down but it might become an issue in the future.

@GadgetUK164 5 лет назад

@@JanBeta Yeah, I think if the clamp was tight it will probably be OK! I was just thinking back to when I've used PVC tape in similar ways and found it starts to slip off things as the glue weakens etc. Clamp will likely keep it there!

@intothevoid9831 5 лет назад

The caps rarely ever get even lukewarm in general operation. If your filter caps get warm, you have a problem.

@bayareapianist 5 лет назад

CAN you please test those replaced caps with an ESR meter to find out the conditions of them after 45 years?

@JanBeta 5 лет назад

I don't know if my ESR meter works well with high capacitances like these but I'm going to try.

@leonardodic3po607 5 лет назад

I see in the comments that you got to the bottom of the residual hum. You should post a short video update linked to this video. I was disappointed when you weren't completely satisfied with your repair, and then very pleased that you ultimately solved it. You should let viewers who don't necessarily read the comments know!

@djblackarrow 5 лет назад

I think the little Humm comes from your Audio Cable that are connected to your Smartphone. It works as a antenna. On the other hand, the amplifier is generally not properly shielded. Internal audio connections are certainly not shielded. This means that interference signals can enter the device at almost any point. I've learned to put Filter-Capacitors as near as possible to the Rectifier to get the best results. The transformer brings 3 amps between the two violett and one gray wires for the power amp, and the capacitors must be able to handle it. I think the red +45V and white -45V wire to the capacitors are a little bit long, so electromagnetic interferences can radiate out of these wires.

@sircupcakes7226 3 года назад

I have a 661 model and this video will be very helpful. Thanks so much Jane! You did a great job!!

@JanBeta 3 года назад

Glad to help! These are lovely receivers! :)

@psully311 5 лет назад

Ive enjoyed these videos very much. My dad had one of these in the 1970's with KLH Model 23 speakers & a turn table I can't recall the model of. Anyway while using it a teen to play albums there was always a hum, not severe just a low level hum in Phono selection, his words were "that's 60 cycle hum from the dimmer switch" that was nearby. I took it as fact & accepted it, but maybe these things just had RFI built into them from the get go. Thanks for the memories keep up the good work!

@JanBeta 5 лет назад

Nice! I think the dimmer switch might really have been an issue. When I took this receiver out of the lab and put the bottom plate on, the hum was completely gone. May have been introduced by some of my video lights.

@SaintKaede 5 лет назад

Very cool I have actually never seen someone take out those ridiculous sized mains capacitors so that's good to see it is possible to do so. Sie inspirieren mich, meinen alten Verstärker hier zu überprüfen, um festzustellen, ob er in Ordnung ist, da er seit achtunddreißig Jahren so viele verschiedene Bedingungen durchgemacht hat. Auch ich will dein Shirt wieder.

@JanBeta 5 лет назад

Thank you! As I said in the video, I usually leave the big filter caps in but in this case they had to be replaced.

@SoddingaboutSi 5 лет назад

I recently did a video on a Techincs Su3500 that had noticeable hum with the volume turned right down. It was clearly in the later stages of the preamp, and after much searching found it to be related to a ground loop problem. I added a ground to the balance control which almost totally removed all traces of it.

@JanBeta 5 лет назад

Nice! I think there's a lot of receivers and amps from back in the day that have grounding issues. No idea what the engineers were thinking.

@santi308 5 лет назад

In such a case where you have to change large old caps for a few smaller ones and the mounts are not able to hold it. It is better to open the old caps to take everything out and put the new ones inside, this is done in valvular equipment when you want to have the interior with the original aesthetic.

@ElectoneGuy 5 лет назад

foam insulation is another way to make up the extra space when smaller capacitors are used.

@hestheMaster 4 года назад

That is exactly what you should use to make up the difference in thickness. They make a tape that is 1/2" wide and is sticky on both sides! Just wrap it a couple of times.

@michaelbarras6950 2 года назад

They make brackets for those different size capacitors. They will mount in same position and screw holes. Wrapping stuff around a capacitor isn't a very good idea. You want to let the heat escape. Not insulate them.

@Krushernl 5 лет назад

Yes Jan keep it as it is. These old receivers are prone to hum and that makes it sound what it sounds. Apart from the 50hz hum that is. Great restauration.

@robertpendergast2620 5 лет назад

Very good repair job and a beautiful stereo. I have several Sansuis including a 221 with very good sound.

@gregwesson2319 5 лет назад

Commodores and vintage stereo systems? Good thing I don't live next door. I have a Sansui 881 and 770 tape player, both in great condition. Looking forward to setting them up soon with a Garrard LP player. Thanks for the walk through in case I need to replace the caps!

@herbmyers805 5 лет назад

Jan always leave a little color coded wire on the caps it makes reconnecting easy

@toronado455 5 лет назад

fantastic work on this receiver!

@JanBeta 5 лет назад

Thank you! It was really fun to work on it, too.

@amplifierexperts1983 Год назад

The 120Hz spikes are caused by a bad ground connection at the screw next to where the main filter capacitor grounds terminate on the PCB. The screw next to that gets poor contact and the symptom is 120Hz buzz in the output. Tighten screw. Optionally, scratch off some of the coating on the chassis next to the screw and add a jumper soldered to the chassis and to the PCB ground to ensure it doesn't recur.

@Inaflap 5 лет назад

That receiver looks cool.

@JanBeta 5 лет назад

Yes, it's a beautiful unit!

@j.r.qwertz 5 лет назад

A 3d printed bracelet for the capacitors would have been much nicer.

@olik136 5 лет назад

he 3d printed a ring of black plastic with his hands and used isolation tape as a filament...he also would have to use ABS for a 3d print- wich is extra effort - since normal PLA gets soft at 50°C and also shrinks afterwards

@MrJozza65 5 лет назад

I wondered about that, but 3d printed spacer might not be best if there is a heat build up. Alternative could be a wooden or plastic spacer drilled with a hole saw and a forstner bit for the center hole for the cap. Although the electrical tape works fine, I wonder if it will degrade over time, and the adhesive will get sticky and seep out from the tape; I've seen that happen on many a motorcycle/car wiring loom over the years.

@BEdmonson85 5 лет назад

@@olik136 Yeah and the adhesive on that tape will soften at even lower temperatures than the PLA. With the force from the screws on the clamp, that tape will start to slide out of the clamps once the unit warms up. I've seen it a number of times on audio amp repairs in jukeboxes and other vintage equipment. It would have been better to try to find lower value caps that could be soldered in parallel and secured on the underside of the chassis and just disconnect the old caps and leave them in place. But that's just my opinion. Ultimately if the customer is happy, I guess that's all that matters, eh?

@1959Berre 5 лет назад

Get yourself a sanitary PVC pipe. Those pipes come in different diameters. Just cut a PVC ring and adapt the diameter, if necessary, by removing a piece out of it untill it fits. You can insert one or more of these rings into the metal bracket.

@pvc988 5 лет назад

Metal capacitor clamps… Today, even just a blob of glue is too much to ask for, sometimes.

@JanBeta 5 лет назад

Yeah, unfortunately you are very right about that.

@krnlg 5 лет назад

"No user serviceable parts".. I mean I get the reasons companies say that but jeez, people might actually enjoy knowing how their stuff works! Being a "user" doesn't have to mean being dumb! :)

@davidwright9166 5 лет назад

A lot of times perfect is the enemy of good enough.

@paulmax3185 5 лет назад

Oh my! I didn’t realize that this old machine still had value. I recently threw away one of these that was in perfect working condition. Are people actually wanting to use these nowadays?

@zeerust2000 5 лет назад

Yes

@heberdua 5 лет назад

I learned a lot ! Great video!

@JanBeta 5 лет назад

Thank you!

@stefanmarinescu5086 5 лет назад

Great video and dedication! Nice! I would have liked to measure the old caps, just to see their shape.....

@JanBeta 5 лет назад

Thank you, I will see if I can get proper measurements. I don't know if my ESR meter plays well with capacities this high.

@januszkszczotek8587 5 лет назад

6:28 why is one silver ground wire connected to a black dot of the upper capacitor while the second ground wire is connected to the non-black dot of the lower capacitor?

@ElectoneGuy 5 лет назад

They are wired in series.

@bayareapianist 5 лет назад

Good observation. The amplifier needs a symmetric +/- power supply voltages to amplify the AC input signals. There are power transistors respectively for each +/- half cycles too.

@Batsu2005 4 года назад

I have a hum on my 661 that's driving me crazy. Unfortunately I have no idea how to work on electronics

@GameTechRefuge 5 лет назад

Might be worth getting a 3d printer. I've been considering it myself but I just don't have the space right now.

@JanBeta 5 лет назад

Yes, I'd definitely have use for one but the lab is really small so I can't really fit one in there. And I don't want one in the living room. ;)

@Ramdileo_sys 4 года назад

@Jan Beta that electrical tape is going to slide.... when the glue get softens over hit and time and especially under the pressure of those metal clamps... it will slide........ if it slides down ..... no problem the capacitors will go up ....... but if the tape slides up .. the capacitors will go down and shorten against the chassis .. watch out.. :-|

@JanBeta 4 года назад

Yeah, I probably should have come up with a better solution for that but it seemed to work fine. It's pretty thick electrical tape so you can clamp it down really tightly. Should not move much I guess.

@johnnyhawkins43 4 года назад

You can definitely do better than I could!!!!!!!!!

@shaney.phot_rod3187 5 лет назад

Question. .i have a novik power amp mixer it just stop working all i get is a great big humming sound with out no volume nobs turn up what could be my problem. Plz reply tanks

@JaySmith-cd1ln 5 лет назад

Nice one Jan! :)

@JanBeta 5 лет назад

Thank you Jay!

@jeanphilippeclain 11 месяцев назад

Très bonne vidéos. Bravo.

@JanBeta 11 месяцев назад

Merci beaucoup! (That's about all the French I remember, sorry!) :D

@RetroBerner 5 лет назад

Does it hum with the Loudness off?

@JanBeta 5 лет назад

The hum is completely gone now (see my pinned comment), it was just interference from other electrical appliances it seems.

@RetroBerner 5 лет назад

@@JanBeta Nice!

@deamondeathstone1 5 лет назад

Wel done, so was it the capacitors or the ground that fixed it?

@fernarias 5 лет назад

Grounding issue more likely.

@JanBeta 5 лет назад

I think a combination of both.

@markanne54 5 лет назад

Could you not get some 3D printed spacers for the smaller caps?

@JanBeta 5 лет назад

If I had a 3D printer then yes. I was actually thinking of cutting out a bottom plate from aluminum or something. I think my solution works reasonably well though.

@АнютаГрицюк 5 лет назад

Познавательно , интересно .!!!

@herbmyers805 5 лет назад

Tube lights can put hum in so turn them off

@JanBeta 5 лет назад

Oh, the hum is completely gone now (see my pinned comment).

@jaycee1980 5 лет назад

Ouch - the way they use the chassis for power ground returns is indeed very poor design. Rising contact resistance from the screws is definitely a recipe for introducing hum. The proper way to do it is what the website showing the fix does - to have one "star" point at the main filter caps

@JanBeta 5 лет назад

I think there is quite a lot of amplifiers/receivers from the seventies with similar grounding issues. I remember seeing a video about a Pioneer (I think) with a very similar design. And I previously worked on an old Dual amp that had a ground loop as per design, too. No idea what the engineers were thinking.

@zer0b0t 5 лет назад

I once had a humming issue with a radio and the problem was my neighbor's fluorescent lights.

@SRojas100 2 года назад

Nice video Jan B.!! I have a question for you. I have a pioneer VSX 528 K. It has an annoying humming noise. The solution for it was to connect a negative wire from the speakers' connections to a screw of the chassis case, to ground it. Do you know if this may cause damage to the receiver over time or it is totally safe to do it? Greetings!!

@tomdesaulniers 2 года назад

Hi Jan, great video, thanks. A quick question - I have a 9090 with a hum only while on stereo. If I switch to mono the hum goes away. Any idea why that would be?

@andrewdentuzo8278 4 года назад

I have installed a long line of LED lights under the kitchen cabinets and FM on my Marantz 2265B was affected to a point of not recognizing music or spoken words when turned on. Is any solution for that? Thanks

@JanBeta 4 года назад

I would guess it might be a problem with the power supply for the LED strip. Many of those are really crap and don't have proper shielding and filtering. The switching noise is probably introduced back into the mains supply and the Marantz has trouble filtering/shielding the high frequencies (that are probably similar to the FM frequencies) emitted. No easy way to fix this I think. Maybe try another power supply or try to connect the Marantz to another mains circuit.

@jaymartinmobile 5 лет назад

Is it my imagination or did you connect one of the new electrolytic capacitors reversed polarity? Black is usually negative on those.

@DarrenCoull 5 лет назад

Yes, I was wondering that - the cap nearest the camera? May be just a trick of the light, but sure looks reversed.

@DarrenCoull 5 лет назад

Correction, that's how the original was wired too, so must be correct!

@rztrzt 5 лет назад

C'mon Jan, do the mods! We wanna see the end result.

@JanBeta 5 лет назад

It doesn't hum anymore (see my pinned comment)!

@rztrzt 5 лет назад

@@JanBeta Ok cool.

@tinolonginotti1997 4 года назад

probably it was just a tightening of the screw. That's what i started with and solved the issue.

@yulienniscoromotomillanbla9206 4 года назад

Hola tengo un amplicador igual Sansui receiver 881 se Daño por corto de una corneta como resolver

@arnekarlsen528 4 года назад

1000uF is rather small value for this amplifier...doubling (2200uF) would have done it good (even maybe 4700uF). And there are other caps in the psu (4 secondaries), but they are low current supplies, not that critical, but the age...

@ivcaYNWA 4 года назад

I have 661 and even when there is no sound it still produce hum to the speakers. the funny thing is that it change with volume increasing but not necessary hum increasing with volume. when volume is at 4 it's less noise then when it's at 3 and 5. the similar situation is when volume is somewhere around 8. for the rest of time it increase with volume together. What can cause this hum?

@JanBeta 4 года назад

If it is a similar 100Hz (or 120Hz for 60Hz mains) hum then it’s very likely a capacitor issue, too. As I mentioned in the video there’s also various grounding issues ("dirty" ground connections in the signal path) in some models.

@Deepsouth34 4 года назад

How do you manage to hook me into these videos for hours???

@EdwinNoorlander 5 лет назад

It is still the bottom plate, Jan. 😜

@JanBeta 5 лет назад

Did I get it wrong again? Sorry! XD

@EdwinNoorlander 5 лет назад

Jan Beta at least you are consistent. 👍🏻

@JanBeta 5 лет назад

@@EdwinNoorlander D'oh! :D

@ewaldikemann4142 5 лет назад

Just curious: For you have an oscilloscope, why don't you measure out where the hum gets into the signal path...

@JanBeta 5 лет назад

Because I was pretty sure that the issue was capacitors/ground. Using the scope would probably show hum in the whole signal path as it was mains hum from the power supply section.

@Nukle0n 5 лет назад

could've maybe made an adapter out of wood or something, if you have some good drills

@JanBeta 5 лет назад

I thought about cutting some aluminum but decided it would be more efficient to just use plastic.

@dennisp.2147 5 лет назад

A short section of rattle canned PVC pipe would have made a better, more sanitary looking, spacer.

@JanBeta 5 лет назад

Maybe, but I don't have any fitting PVC pipe here. I think the electrical tape solution is not that bad looking (except for when you take the caps out of the clamps).

@metalmetal9527 5 лет назад

Say please, camcoder shoot this video.

@JanBeta 5 лет назад

It was filmed with an old iPhone 5s using the Filmic Pro app.

@metalmetal9527 5 лет назад

@@JanBeta thanks

@josephnealescratchcards 5 лет назад

❤️👍

@ianide2480 5 лет назад

Testing with an open case .....

@JanBeta 5 лет назад

Yep, turned out to be part of the problem. Assembled and connected to a proper audio source, the hum is inaudible. Should have thought of that before.

@sgpch1983 5 лет назад

there has to be a little bit of hum.. thats just the 70/80s flavor and sound of them.. i think a little tiny bit of hum must and should be there.. dont overdo it :)

@JanBeta 5 лет назад

Probably so, the hum is completely inaudible with the bottom case closed and in the living room. It probably was a mix of poor grounding and the filter caps.

@w9gb 5 лет назад

Electrolytic Capacitors have a variety of dimensions (Height, Diameter, Lead Spacing) as well as attach styles (Screw, Snap-In, PC mount, SMT, FP-type). www.cde.com/capacitors/aluminum-electrolytic CHECK Original components, before ordering replacements. CDE 500C113U050AH2B, 11,000 uFd at 50 VDC, 1-3/8” diameter, 2-5/8” Height www.cde.com/resources/catalogs/500C.pdf

@fernarias 5 лет назад

20 euros per cap, I pay 4.56 per cap for Nichicon snap in caps.

@JanBeta 5 лет назад

For 10000uF 63V 125C? I doubt that they are genuine for that price.

@fernarias 5 лет назад

@@JanBeta Mouser prices. It was for 10k 5ov which I buy quite a bit since they are in most 1970 to 1974 gear in the 60 watt range. The cheapest was 3.77 for TDK. It was 13 dollars for 12k 50V that were the same diameter size, 50mm, as the originals. The cheapest 10k 63v, same as you purchased, was 4.49 TDK.

@intothevoid9831 5 лет назад

@@JanBeta Nope, they're genuine. Mundorfs are just very expensive.

@sarreqteryx 5 лет назад

😬 jankier and jankier… a PCB or proto-board carrier would have worked better for the caps, and the resistors could have gone on it, too. also, I could see a bunch of dry solder points on that board they connect to.

@MrJozza65 5 лет назад

Maybe, but sometimes it's better to fix what needs fixing and get the unit up and running, rather than attempt a full and complete restoration & rebuild. I think Jan has done a top job on reducing/removing the hum, and getting this old tech back up and running for some more years.

@gh778jk 5 лет назад

I have no idea where you get the notion NOT to replace the power supply/filter caps on anything that is 30 years or more.... Those are the very first caps that go in the bin.... you don't even want to measure them out! Also, reusing those old carbon resistors isn't the safest idea either.... they will change in value over time and there are other and better (cheap) solutions for that these days You should do measurements with the unit closed... some units, which are completely ok, will start humming like mad, just by having the cover removed Paddy