Windy noise in R-900

Yes all RCA and inputs. Can't tell with the tuner because it is always on a station. The phone input is a whole lot of noisy, but it is more a hum
in both channels equally and gets louder with the volume. I don't have a tt so it doesn't matter to me. I suspect there are out of spec parts in that section.
There is indeed some RF in the house because I tried a cheap 25ft cable from my laptop and it buzzes like mad when connected to the receiver. There is a dimmer switch in the room that is noisy too, but doesn't affect this issue. The furnace is below about 20 feet away which may be my rf source.
I think it made the noise at the shop too but it is faint enough that the tech couldn't hear it. I am just being very fussy.
It is weird though, I would think that turning up the volume would make it louder but it doesn't.

I can't recall since my R900 is in the shop. But can you decouple the Preamp from the amp on R900 with a switch like the R1000 and R2000? That would isolate the section with wind. Also if spatial expander has switch. Switch it out and check. Even at dial to zero it will massage the signal on the TOTL receiver.

Without RCA on TT should not hum unless you have power wire going in front of jacks. Run power and signal wires separated.
 
The R900 has a decoupler switch, but no spatial expander switch. Turning the expander doesn't do anything. Neither does decoupling the pre/mains.
The power line doesn't run in front of the jacks, it goes straight down to the outlet.

I have a slightly noisy amp,if it doesn't get worse I will likey get it recapped sometime in the future to see where that goes.
 
Somewhat similar, mine is a 1070II, I will compare the fonts when I get home.
What can be expected from the fakes? More noise, short life, more distortion?

Why would a company go to the trouble of faking STKs in the first place? Is there really that big of a market that it is worthwhile to design and build an inferior ripoff chip?
 
Somewhat similar, mine is a 1070II, I will compare the fonts when I get home.
What can be expected from the fakes? More noise, short life, more distortion?

Why would a company go to the trouble of faking STKs in the first place? Is there really that big of a market that it is worthwhile to design and build an inferior ripoff chip?

There are fakes of everything these days. You can get ANY STK for very little money, very easily. But none of them are fine. It is probably super cheap to produce them, and I doubt any effort went into making sure they actually work as intended. So, no, you can never expect to get any sort of real function out of a fake STK. Their performance is usually quite random.
 
You have a fake STK, since you claimed it doesn't look like the original. There are only two types of STKs: fakes and originals. There are no third party parts, or reproductions. Sadly, it is impossible to find the real ones today.

Here's a classic fake STK. Does yours look similar?

http://www.ebay.com/itm/SANYO-STK00...134?pt=LH_DefaultDomain_0&hash=item540d2bb54e

Sure enough the font and style of the labelling is much like the pictured "fake" STK.
So it has more noise at idle. I can't tell a difference when actually playing a source, but I guess the noise is there. It will like be more noticeable if paired with a better set of speakers. I will look around for a NOS STK or perhaps a salvage from a parts receiver.

Question: Do these STK just pull out of the board or are they soldered in?
 
They are soldered in.

My biggest concern isn't that it's noisy, it's that it can probably blow up at any minute (especially if you try to play it loud), and depending on how the amp is designed, can easily take the speaker connected to it right along with it. This is hopefully a more sophisticated design, which switches off the speakers when there is excessive DC on the output.

Does it have a relay click shortly upon power on? If so, you're probably safe.

NOS STKs are very hard to find, I've never seen one. Your best bet is pulls from scrapped amplifiers. I just took out a STK0029 from an amp with a blown channel. I will keep it and hopefully be able to fix another amp in the future, with it.
 
Damn STK's

Why did they built good amplifiers with those darn chip amplifier in the first place ?

That's what I look for at first when buying rig.

STK ?.... nope for me.
 
Thanks Zoom, there is a relay click on power on, so there is some measure of protection. There was damage when the original one blew so there will likely be some collateral damage when this one blows.
I found what is advertized as an original Yamaha STK 1070II on the interweb. I will contact the seller to find out if it is legit before buying.
 
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So I have secured what I hope is a NOS STK, should fix up the noise issue, which has been getting a little worse,

STK1070II_zps7bebooql.jpg


The supplier has one more if anybody needs one.

I don't know if I should attempt this myself or send it out. Should get some cap redone while it is open. Gee this thing is starting to cost more than a new one. Oh well, the price we pay for nostalgia.
 
I have a broken R900 with at least 1and probably 2 "good" Yamaha 1070II stk's. I say "probably 2" because one is still installed in the unit (the known good one) and the other is in my parts bin, waiting to be installed. There is also a spare voltage amp(STK) I was going to repair this unit, but have been losing interest lately so I would probably part with it for what I have in it . There is also a spare amp board with enough parts left in it to repair this unit. The receiver is very clean and worked well until I ran it too hard and smoked one channel. By repairing and selling this unit you could probably recoup your costs and then some. PM me if you have any interest.
 
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