Guidance with 9090 AUX issue

corry2403

Active Member
Hello folks,

Purchased from the States in March, I am very, very happy to report that it's really quite beautiful and apart from a couple of minor scratches and dings on the wood case it practically looks brand new !! All lights and meters working, the glass, face plate, rear panel and knobs are mint condition and it seems all functions are AOK with the following exceptions;

1. With my CD player connected to AUX, and with the Tape Selector on 'Source', regardless of which input I select the AUX device drowns it out.

It's strange, for example, I'll be listening to vinyl and I'll power up the CD player (AUX) in readiness for playing a CD afterwards, after the CD player powers up, about 2/3 of the output of the phono section gets sucked out (or whatever input I'm listening to at that point), the AUX output then comes over the top of it at normal volume. Power the CD unit off and after a pause of about five seconds the output bumps back up again! It's making me a little concerned that there's been a bit of dodgy modding somewhere...also making me doubt if I getting the full experience from each input source, volume and quality wise. Note that the same issue occurs when I'm listening via headphones.

2. The balance control is a little scratchy towards the extremity of the left-channel. I'll look at cleaning the pot in the next week or so when time allows.

3. It's initially a little bright compared to the AU-7500 it's replacing, but then that was straight out of the box and it's pretty much been packed and in transit for the last two months so I'll run it in for a bit to see how it settles.

So, overall, very relieved. I'm hoping the AUX issue is a fairly straight-forward fix, anyone else come across this one before? Any suggestions re resolution would be greatly appreciated. I'll probably be looking at a recap etc. a little further down the track once I've gathered some coin again :-)

If I posted an image of the internals would anyone be able to spot if anything's been done to it fairly easily?

As ever, any help greatly appreciated :thmbsp:
 
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As I recall there are several wafers on the selector switch. Check and make sure that all the switches on all the wafers are turning with the knob.
 
Also check the output voltage of the CD some of them have outputs as high as 1 Volt the AUX input on the 9090 is designed for an input of 100mv min they don't list a maximum but most units of this vintage will start distorting at 300 to 350 MV. If you are putting in 1V or more you will get crosstalk. Here is an article about radio interference on AU-20000. I know that this is not your problem but it is indicative of what can happen.
 

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Having a potter - is that like sitting on the 'loo?

Ha! Sadly no.

It's what we guys do in our shed/garage/workshop, you know, potter about? Usually involving tools and a furrowed brow.

Obviously these places could potentially be used for other activities but probably best we leave it there eh? :nono:

:-)
 
Happy to report that after a bit of a clean of the pots, switches and inputs all issues have been resolved!

It's still a little bright (regardless of source) and it's become apparent that I'm getting resonance feedback through the pick-up, the speakers are quite close to the main turntable and all on a wooden floor. I don't really have much in the way of choice with the physical layout at the moment either.

I've got the speakers (Celestion Ditton 44's) on short Iso stands and the turntable is a relatively high-end Kenwood KD 990 set on a very solid timber rack unit (inc. castors).

I'll try adjusting the force on the cartridge tonight see if that helps, I'll also investigate if there are other options with regards to damping the turntable further. Any other tried-and-tested suggestions?
 
set up

I'll probably post in another more relevant thread re the resonance issue...here's the listening 'space' anyhoo, that's pretty much all the width I have to work with!

 
Happy to report that after a bit of a clean of the pots, switches and inputs all issues have been resolved!

It's still a little bright (regardless of source) and it's become apparent that I'm getting resonance feedback through the pick-up, the speakers are quite close to the main turntable and all on a wooden floor. I don't really have much in the way of choice with the physical layout at the moment either.

I've got the speakers (Celestion Ditton 44's) on short Iso stands and the turntable is a relatively high-end Kenwood KD 990 set on a very solid timber rack unit (inc. castors).

I'll try adjusting the force on the cartridge tonight see if that helps, I'll also investigate if there are other options with regards to damping the turntable further. Any other tried-and-tested suggestions?

Put some foam, and or carpet scraps under the speakers...that will help, layer plywood, foam, and plywood under the turntable too.
 
Try closing the dust cover of the turntable while playing.

Also try scraps of carpet under the castors of the shelving unit.
 
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