HK3490 Left Channel Volume Issues

PerfectCreature

As most of you are aware I have had the pleasure of enjoying the Harmon Kardon 3490 stereo amplifier for the last few years.
Unfortunately I am stricken with an issue I cannot figure out.
The left channel will on occasion, without reason and without any indication on how to reproduce this particular issue, fall short in volume compared to the right channel.
I have swapped my cables and my speakers around. Still on the left channel.
I swapped the A output and the B output thinking it may have been a bad post.
The issue still persists.
Does anyone have any clues as to what might cause the left channel alone to distort on occasion, and have a reduced volume compared to the right channel on a whim?
It has only cracked and blipped once, but has as of late started to produce this issue more and more. Either that or since I have become aware I am noticing it more and more.

I was considering getting it repaired, but I have no HK sourced repair centers even close to where I live.
I appreciate the help!

ZLTFUL

Weak or fading capacitor on that channel?
Weak or fading resistor on that channel?

I can't see it being the volume pot as it would typically only make noise while using the pot to adjust the volume...same with the balance pot.

Not sure where you are but pretty much every large town/small city has at least one good electronics repair guy that should be able to track down the issue for you regardless of brand.

PerfectCreature

I have made some calls, Harmon Kardon is unwilling to help, they just keep telling me get it serviced at a repair center that is 7.5 hours away. I called the center and was told they no longer service Harmon Kardon.
I guess I may have to purchase a new receiver. I am quite alarmed that after only 4 years of ownership it has faulty parts.

I have contacted several local electronics repair shops and they all stated that they are not familiar with them and indicated an unwillingness to repair.

I am wondering if this could be something that could be tackled by myself?

PerfectCreature

I know they are fairly stout, which is why I am confused. I am going to do some more tests and see if I can repeat the issue. I spoke to one repair facility who stated he could probably do the repair (it would require a nonrefundable $50 deposit, and an hourly labor fee and the cost of the "premium" parts as he called them) but would need to special order the proper parts from Harmon Kardon if I wanted the same quality parts, as he stocks generic parts.
He mentioned changing the source, tapping the unit, and lightly knocking it down to see if that would remedy the issue.
How do you know it uses digital volume control, could it be a software issue perhaps? I wonder resetting it will fix the issue.. I know I have the most current software, as it was built in 2010 and it was confirmed the software is the most up to date.

PerfectCreature

Interesting, I had noticed that, now that you mention it, that makes sense. I had a older Teac receiver that used to hit a max point and min point.

As far as the left and right. I will fiddle with it, see what the balance does.
Would you have an idea as to what would be considered strange, possibly what I should look for?

PerfectCreature

Okay, I have built a few computers, so I am familiar with the "try not to touch".
I will take some photos and upload them, perhaps some individuals who have fiddled more deeply into upgrading and repairing circuit boards could chime in.
I have a nice Fenix torch light that should be plenty bright enough.

PerfectCreature

I appreciate the condolences, I just would love for it to go back to its normal ways.
In retrospect, if this proves to be a hassle, I will just pick up a small HT receiver, and tuck it in the closet or sell it for someone else to fix and enjoy.
I've been heavily considering a Marantz 1403, it will be a significant step downward in terms of power, but should be in improvement in terms of listening experience due to the Audessy EQ and the ability to get a true 5.1 instead of just tossing the HK in reference mode for that surround effect.

PerfectCreature

I tried tapping and shaking the receiver and it did not cause any changes.
My wife stated it has been acting up all day yesterday.
It hasn't seemed to do anything yet.

I will next try changing the input and see of what that does.

I plan to open it up and see if I can notice anything

ZLTFUL

nbrowser wrote: »

erm the HK 3490 uses a digital volume control ala full on AVR...I have one, I'd suspect a capacitor going south personally or a output transistor. These things are built fairly stout so a bit of a failure is an oddity.

A competent repair facility should be able to handle fixing one of these things. I guess it's time to pull out the Yellow Pages (do they still make those) and make some calls.

The volume knob still contains contacts otherwise, it would have no idea you were turning it. Granted, it isn't a traditional potentiometer but it is still an electrical contact point. And is still a potential point of failure.
(I own a 3480 which uses a lot of the same parts as the 3490 i.e. volume control is identical)

But all of that is besides the point since I said it was unlikely to be the culprit anyway.

PerfectCreature

It has not acted up today. It ran for a few hours at various levels.
I am wondering if smacking and shaking the the unit up and down actually did anything....

PerfectCreature

Not entirely sure what it is. It has not done anything close to what it had been doing. I shook the receiver and lifted and dropped it up and down with a small thud a few times and reconfirmed all the connections.
I cannot be certain that all the issues were due to something that was connected wrong or loose.
In any case, It appears to be okay for the moment.
I will update if any issues arise.