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Discussion Starter · #1 ·

I Have a HK 3490 stereo receiver that powers a pair of old B&W DM 602 S1 speakers.

The receiver I purchased about 3 years ago.

I have mainly 2 problems that occured in time.

1st is the volume knob that started to behave randomly. Well I think is not a big deal , using the remote the volume works properly so I guess I have to clean with contact cleaner solution the device inside(the volume IC)

The 2nd problem is much more tricky. There's all kinds of background noise that coming out of my speakers. To be specific there's white noise coming from the tweeters and pink noise from the mid/bass. The noise is not constant it increases and decreases randomly.

That problem occured about half a year ago (fun fact: just when the warranty have expired). 

With the receiver disconnected from all the analog and digital inputs the noise is still alive and kickin'.

When I mute the speakers from the mute button the noise is still there.

No difference if the speakers are bi-wired or not , there's still the same noise.

I put the AC unit plug in a diferent power socket( a separate power branch) and it makes no difference.

The noise is very audible in the headphones too.

All that things goes in one "sad" direction: defective unit. Well , I 'm still not dramatized the situation too much

because I have a friend which is a electronics "geek" . He would probably help me but I have to give him a starting point.

I'm very happy with the HK3490/B&W combination , I love the "old school" sound ,not very much bass but with the proper speakers position I can deal with that. Adding a subwoofer is an option but because of the  lack of bass management (like most multichannel AV receivers have) I have to think twice.  Maybe it's better to buy a pair of standfloor speakers with good response on the bass side.

Cheers to all

Edy
 

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Quote:
Originally Posted by ed1em2  /t/1519918/hk-3490-background-noise-and-volume-knob-problem/0_50#post_24410265


I Have a HK 3490 stereo receiver that powers a pair of old B&W DM 602 S1 speakers.


The receiver I purchased about 3 years ago.


I have mainly 2 problems that occured in time.


1st is the volume knob that started to behave randomly. Well I think is not a big deal , using the remote the volume works properly so I guess I have to clean with contact cleaner solution the device inside(the volume IC)


The 2nd problem is much more tricky. There's all kinds of background noise that coming out of my speakers. To be specific there's white noise coming from the tweeters and pink noise from the mid/bass. The noise is not constant it increases and decreases randomly.


That problem occured about half a year ago (fun fact: just when the warranty have expired). 


With the receiver disconnected from all the analog and digital inputs the noise is still alive and kickin'.


When I mute the speakers from the mute button the noise is still there.


No difference if the speakers are bi-wired or not , there's still the same noise.


I put the AC unit plug in a diferent power socket( a separate power branch) and it makes no difference.


The noise is very audible in the headphones too.


All that things goes in one "sad" direction: defective unit. Well , I 'm still not dramatized the situation too much


because I have a friend which is a electronics "geek" . He would probably help me but I have to give him a starting point.



I'm very happy with the HK3490/B&W combination , I love the "old school" sound ,not very much bass but with the proper speakers position I can deal with that. Adding a subwoofer is an option but because of the  lack of bass management (like most multichannel AV receivers have) I have to think twice.  Maybe it's better to buy a pair of standfloor speakers with good response on the bass side.

Cheers to all

Edy

Contact Harman customer service about the problem. It might be a fairly cheap fix.


Most subs have built-in BM. Matter of connecting the output from the 3490 to the input and run the output to the B&Ws.

Or just connect the sub out of the 3490 to the sub and set the XO to control the sub, letting the B&Ws continue full range, connected to the 3490 speaker level out.
 
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Discussion Starter · #3 ·

Thanks for the quick feedback!

Regarding the sub ,in the 2nd option , assuming I'd play with the bass control knob on the receiver , isn't still a possibility to suffer from the wellknown "bass coming from more sources" issue? 

Thanks again.
 

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Depends on where the sub is located, and the XO.

Any XO point ≤80 htz is non directional.

I run my main L/R full range on my DVD-A player as it only provides 100 htz XO, way too high! But the subs are then going up to 100 while the mains start rolling off around 60.


For my stereo sources I set my P7 pre to 50. The P7 has separate sub level controls for the Multi-channel and stereo outs. So they are set to different levels.
 

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Has anyone else had the problem with the volume control on the HK 3490 skipping around randomly? The remote control adjusts volume fine, but using the dial on the unit causes volume to behave erratically and skip up and down.


I have been in contact with HK tech support to resolve the problem. They initially indicated that in many cases the "threads slip which causes volume malfunction" and that the fix is to replace the "volume knob." I was told that if I pull out the knob hard, it will easily come out and the new one can be inserted without removing the upper or front panels. This seemed odd...


Anyway, they sent me a replacement part, but what I received does not look anything like the volume control on the unit. In pulling up the HK3490 service manual, it appears the part they sent me is the "tuning knob" or "standby knob" which does not seem to have anything to do with the volume control. I was passed on from the tech support team to the parts team, who is now telling me that I should take the unit into an authorized service center. Whether it's a language barrier or terminology mix-up, it has been a frustrating and fruitless experience.


Can anyone help?


Thanks in advance.


dm
 

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I have a suggestion for you; forget the 3490 and all its problems and get a Music Hall 15.3 amplifier for $550.


You have some pretty good speakers there, and the new amplifier will sound significantly better with them than the H-K ever did.


On a totally different subject; I hope you have some very solid stands for those speakers; it makes a big difference to proper performance.


Most wood stands are not rigid enough.


The Sanus Steel Foundations stands might make a big difference, if you can use them.
 

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My parents own a 3490; it developed the same volume knob problem, just jumping up and down randomly as it's adjusted. Contact cleaner eventually fixed it, although the knob had to be removed (by pulling directly out) and replaced in order to get a proper clean. As I recall, adjusting the volume with the remote worked properly and volume adjustment seemed more accurate if the knob was turned quickly, and a finger was placed on the glowing inside ring.
 

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Quote:
Originally Posted by dpmacd  /t/1519918/hk-3490-background-noise-and-volume-knob-problem#post_24541773


Has anyone else had the problem with the volume control on the HK 3490 skipping around randomly? The remote control adjusts volume fine, but using the dial on the unit causes volume to behave erratically and skip up and down.

The volume control on the HK3490 is a TC9459F chip. The volume control knob is probably what is known as a shaft encoder - basically a pulse generator that does about the same thing as the push buttons on the remote. Shaft encoders are usually highly reliable, and typically never need service.


The service manual can be downloaded from here: http://www.harmankardon.com/resources/Brands/harmankardon/Products/ProductRelatedDocuments/en-US/ServiceManual/HK3490%20sm.pdf


Below is a detailed picture of that area of the AVR:


Quote:
The 2nd problem is much more tricky. There's all kinds of background noise that coming out of my speakers. To be specific there's white noise coming from the tweeters and pink noise from the mid/bass. The noise is not constant it increases and decreases randomly.

That problem occured about half a year ago (fun fact: just when the warranty have expired).

With the receiver disconnected from all the analog and digital inputs the noise is still alive and kickin'.

When I mute the speakers from the mute button the noise is still there.

No difference if the speakers are bi-wired or not , there's still the same noise.

I put the AC unit plug in a diferent power socket( a separate power branch) and it makes no difference.

The noise is very audible in the headphones too.

All that things goes in one "sad" direction: defective unit. Well , I 'm still not dramatized the situation too much

because I have a friend which is a electronics "geek" . He would probably help me but I have to give him a starting p

Since the noise is there no matter what, and its in all channels this failure suggests a problem in the TC9459F chip or some area to the right of the TC9459F volume control chip in this block diagram

 

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Discussion Starter · #9 ·

Yes , that's the part(shaft encoder) that i've replaced. I told that on a PM sent to @dpmacd. Just removed that little board with the  encoder on it , went to an electronic components shop and purchased a new encoder. All that matters is a question of exactly the same size and dimensions. It was a very quick and easy fix.

 

But the second problem(background noise) is still unsolved. 

Big thanks for your kindly input here.
 

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Had a similar problem but only with the volume control. The volume knob never worked from the first day. The remote could change volume but the knob wouldn't. Since my unit was discontinued, I persuaded an authorized repair center to get me the encoder (Part No CSR2A037Z) and send it to me for repair. This fixed the problem. Tis same part is used in a few other units as well.

Just an FYI
 

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Hello,
I had the white noise problem but only on the left channel thou. I have manage to fix this by replacing the muting transistors Q301 and Q303 in the power amp section. The part number is KTC3200GR. You can easily find the corresponding transistors for both channel if you have hk3490 service manual. From q301 to q306. I remember one tech guy claiming that somehow Harman manage to supply themselves with faulty transistors of this kind when they build those amps.
 

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Hello,
I had the white noise problem but only on the left channel thou. I have manage to fix this by replacing the muting transistors Q301 and Q303 in the power amp section. The part number is KTC3200GR. You can easily find the corresponding transistors for both channel if you have hk3490 service manual. From q301 to q306. I remember one tech guy claiming that somehow Harman manage to supply themselves with faulty transistors of this kind when they build those amps.
Hi Levski, thanks for sharing this!

I have been having a similar problem. My HK3490 (using Infinity P362 speakrs) is six years old and I feel like the problem is getting slowly worse. I am getting white noise from the left channel and about 30% as much white noise from the right channel. The the noise increases the more I turn up the volume. I've tried using different outlets, unplugging all other connections, switching speakers and the constant smooth static noise persists (most prominently from my tweeters).

Would you advise I try cleaning the inside components with contact cleaner? I think I might end up having to try the fix that you mentioned. Where did you get the components and did you do the soldering/replacement yourself?
 

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Hello Carl5000,

The problem you describe look very similar to what i had. Yes the white noise increases when you turn the volume up. I even disconnected the main-in pre-out jumpers on the back and the noise was still there. This is how i figured out that the problem is in the main amp section.

At first attempt cleaning dust is always good but that was not the case for me. The replacement of the transistors requires a basic soldering skill, but it requires full disassembly so please be confident if you to do it on you own.

Unfortunately the part mentioned above (KTC3200GR) is no longer in production. Got mine from a donor receiver. Just an option you can find a reseller on ebay or google the datasheet and ask for substitution from electronic shop. This part is relatively cheap so my suggestion is to replace any one of them pointed on the service manual since you both channels are infected :)
.
Hope that helps.
P.S. I really like that amp the sound is old school.
 

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Well my volume knob just failed recently. Coincidence ... no?

After frustration of searching for the spare part.. (shaft encoder?) decided to open this thing using a small flat screwdriver picking up the four clips on the back on it.

Inside was noting more then just a three pair of metal legs placed on 90 degrees on top and a circular shaped contact pattern on bottom.

Don`t know if it was just a fatigue or the fact that synthetic grease used for the knob was all over the place but after cleaning it white alcohol, pushing the legs up and put it back together it started work like a charm.

I know this is not a solution for most because desoldering the damn thing from the knob pcb is a real PIA. This is when no other option.

Shame because i have more then 10 years old avr 235 build white similar parts and never failed.
 

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Best to just avoid old HK units IMO, even their old flagships like the 7550 and HK 990 had major noise AC noise issues coming through the speakers with review units noted in places like Stereophile. Just hard to recommend their older gear compared to brands like Yamaha or Denon which have a fraction of the issues. It's a real shame because their receivers IMO have the best styling.
 

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Best to just avoid old HK units IMO, even their old flagships like the 7550 and HK 990 had major noise AC noise issues coming through the speakers with review units noted in places like Stereophile. Just hard to recommend their older gear compared to brands like Yamaha or Denon which have a fraction of the issues. It's a real shame because their receivers IMO have the best styling.
Nope this is still best money to value receiver so far. Will recommend NAD for stereophiles.
 

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I had the same issues!

Volume knob acts erratic when you try to change the volume, and the white and pink noise you mention. I had the receiver repaired (it was 2-3 transistors/capacitors they had to switch out). In total cost $190 to fix. $45 for parts, the rest was labor. Sounds perfectly clean now.

My issue was that white and pink noise coming out of my right speaker so much so that at lower volumes the hiss overpowered the music. But it never increased with volume, it remained constant. I took mine to an authorized HK repair center in IL (Electronic Express in West Chicago, IL). Took them 3 months to get the parts but I eventually got the receiver back.

And now I need to sell the Peachtree Nova 220SE I picked up to fill in the void :)
 

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HK-3490 DC Offset

Hi, I have a HK-3490 with DC Offset at both channels, output Darlinton transistors are OK...it is strange that both channels have the same DC Offset...Ch left is around -5.6v and Ch right is around -6.2v
Attached is the output schematic, which transistor should be encharge to control the DC offset
Thanks in advance
 

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Hello Carl5000,

The problem you describe look very similar to what i had. Yes the white noise increases when you turn the volume up. I even disconnected the main-in pre-out jumpers on the back and the noise was still there. This is how i figured out that the problem is in the main amp section.

At first attempt cleaning dust and soil is always good but that was not the case for me. The replacement of the transistors requires a basic soldering skill (i myself are newbie), but it requires full disassembly so please be confident if you to do it on you own.

Unfortunately the part mentioned above (KTC3200GR) is no longer in production. Got mine from a donor receiver. Just an option you can find a reseller on ebay or google the datasheet and ask for substitution from electronic shop. This part is relatively cheap so my suggestion is to replace any one of them pointed on the service manual since you both channels are infected :)
.
Hope that helps.
P.S. I really like that amp the sound is old school.
I am repairing one with DC at both channels, DC is around -6v but curiously if I put a 12k resistor in parallel to a 33k R303 the dc offset goes down and I can hear music without overheating my speakers with the DC.
I am suspecting on Q301 to Q306, what do you think guys?
This KTC3200 can be replaced with 2SC2705 or any other with similar characteristics
 
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