Fixing Pioneer VSX D1S Crackly Audio Output

General DAC/Amp/DAP Discussion
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So, struck with boredom as many of us probably are during these weird times, I decided to dig my dad’s old AV receiver (Pioneer VSX D1S) out of the basement to see if I could use it as a nostalgic, overkill headphone amp to drive my HD6XX.

Apart from a good amount of dust on the inside, it’s in incredibly good condition considering its age.

I plugged in the power, got my SDAC and plugged that into the LINE input, and plugged my computer into the DAC. The receiver fired up right away, relays clicking the exact same way I remember years ago. I could practically smell the cabinet that it sat in for years next to the TV.

Anywho, after plugging in a pair of sacrificial headphones (Just in case something went bang) and turning the volume knob up a bit, I could hear sound, but it was very crackly and fuzzy, the left channel being much worse than the right.

After a couple hours of fiddling with it, resetting it and trying different modes/inputs and trying my Hidizs Sonata HD as the DAC, the sound seemed to get gradually better.

Right now, if I turn it on, it will start off with lots of crackling, but when I turn the volume up probably 10-20%, it seems like the sound breaks through a barrier and sounds much cleaner, no matter what volume I have it set at.

When I turn it off, then back on, the same thing happens. Need to turn the volume up to a point where it gets clear, and then I can turn it back down again.

There also seems to be an imbalance between the left and right channels, and once it starts playing sound cleanly, there’s a very noticeable hissing noise when I pause the music.

Can someone explain what’s going on, and maybe give some suggestions on how to fix/improve the output? I’d love to have it to 100% again.

Cheers!

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Going of the age of the device, I would guess it is capacitors showing their age.

Corrosion/bad contact on the wipers in the main potentiometer. There are some sprays (electronics cleaner) to fix this. Or you replace the old one with a new one of the same ratings.

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I’ll start there then.

Wouldn’t a bad pot only sound fuzzy when changing volume though?

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Get some Caig Deoxit. D100. DO NOT GET THE SPRAY BOTTLE!!! I am shouting because Deoxit in a spray can wastes product, and it can hose something that does not appreciate it. Get the D100 in the needle applicator. You place a very small amount right where it is needed, no waste. .

I should mention a tiny amount on headphones plugs is a good idea. Go through the Pioneer and anoint the RCA plugs, speaker posts, switches, the rest of the pot’s. Etc. Remember tiny amounts do the trick.

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If you own tubes, this cleans the pins well too. 1 bottle will last forever.

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Thank you for the reminder I need a bottle of this lol

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Caig has this: The Caig Deoxit Tube Survival kit. It has D50L. Deoxit Pro Gold and cleaning brushes.

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Update:

I tried applying deoxit to the main pot and turning it a bunch and it didn’t really help.

I think the problem lies with a specific volume control IC in the preamp circuit.

In order to be able to use it, I’d need to fix that, and figure out how to tone down the headphone out volume because I can get my HD6xx up to an uncomfortable listening volume at 3 out of 30.
Yes. Just 10%. So now I’m looking into ways to tone it down. I can’t seem to find a gain adjustment anywhere. There is a speaker impedance switch but I’m not sure what that does…

I tried adding a small headphone amp in between the pre-out and the front amp in to attenuate the signal so that I could have the volume knob turned up higher (the problem seems to improve around 9:00) and that kind of works, but the crackly audio persists. It gets a bit better after everything warms up, but it’s still not great.

I’d love to use this as a cool phono pre-amp and headphone amp/source switcher but as it sits it’s not great. So if there are any more suggestions, let me know.

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Check out this page on Deoxit. It says the active ingredient is lighter fluid, and unsuitable for heavy corrosion. This is the first time I’ve ever heard of the product, and have no experience with it.

https://www.hagensieker.com/wordpress/2018/06/18/deoxit-what-is-it-what-isnt-it/

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Interesting.

I guess I should revisit the potentiometer again to see what else I can do. I didn’t use name-brand deoxit, just a contact cleaner that I got at home depot. so it might be different, might be the same.

over the top wording aside, that was a good article.

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Scraping is one positive way to remove surface oxidation. Sandpaper. Steel wool. Knife blades. Screwdrivers. The metal goes from dark to light as the surface layer is taken away. It’ll likely be copper in there.

White vinegar is one way to clean battery terminal corrosion (i.e., the white crust from an old burst battery), and will result in very visible changes.

Be aware that scraping or strong chemicals can cause other problems or a short circuit if you are not careful.

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