Onkyo A-7090 - Anybody have firsthand experience with these?

PTL-Pioneer

Super Member
Hi all

Just wanted to know if anyone has had any experience with an Onkyo A-7090?
Its a dual mono integrated rated at 100 watts per channel. I have one in my sights but it is very hard to get any real information out there about it. Any weak points? Are they repairable etc.

And of course most importantly, what do they sound like!!

Hopefully someone can chime in, any comments/input as always much appreciated
 
I have 2 of them, one I bought new in 1979, the other a couple of years ago on Ebay. All I can tell is you can't go wrong with one if it is working OK. Very versatile, 3 phono inputs including a MC and 2 MM, pre-out main-in controlled by a button in the front, 2 tape monitors, bass and treble have 2 settings where effect takes place, low and high filters, etc. Really, really underrated at 110 wpc. Very clean sound. If you get one I"ll be glad to send you the scanned images of the instruction manual.
 
Thanks for the reply! I got the original owners manual with it as part of the purchase (bought as spares or repair as owner said was in storage for years) Also the faceplate writing has taken a beating :(
I deoxed all buttons and switches, it fixed the scratchy volume pot, but the dodgy right channel is present throughout.
My concern now is that i will have to replace some transistors on that channel. And a lot of them are NLA. Trying to gather a list of possible candidates and their replacements.
Generally i shotgun any board i work on, mainly due to the fact i neither have the electrical theory knowledge or true understanding of schematics in order to get a targeted approach to resolving the issues.
I should have all the required capacitors needed except for the filter caps, there a 100 euro to spend on those
 
I am thinking now it is the pots on this just need a damn good clean.
Last night i went to town with the deoxit - i believe this unit has those black Alps pots in the volume and balance control. I got into every little hole in the bottom of the pot cases, here is hoping that when i fire this up again today my dodgy channels will be gone
 
Very often it's just dirty contacts on the protection relay that cause a channel to occasionally drop out. I wouldn't change out any components on the boards until you rule out the relay contacts.

Try tapping on the protection relay while it's playing, see if the channel in question goes in and out.
 
If you have soldering ability, check for cracked joints that could need reflowed.

Also, the Service Manual is on hifiengine.

If it's the outputs, they are TO-3 case and MJ21193 MJ21194 are modern replacements. And a very quick perusal of the SM lists transistors that there are definitely modern equivalents if not even better options should it come to that. But do the basic checkout first.

Separate the preamp out and feed it to another amp, and send a preamp signal to the amplifier section (even using a Walkman headphone jack to RCA cable if needed) to see if you can isolate the problem to pre or amp sections.
 
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I am thinking now it is the pots on this just need a damn good clean.
............if they're not already beyond that.

These have one sweet sounding amplifier section. But, the pots and switches are below the par of later Onkyo gear, and most any other gear for that matter. Truly, the switches and pots on these are not great with the exception of the volume/attenuator pot which i think is one of the better stacked ALPS units.

Also, use great care and no harsh cleaner on the face plate. The silk screening will clean off these easier than most dirt.
 
Alas, It came to me missing a bunch of the faceplate writing.
Turned it on again today, definitely the volume pot is acting up, although much less touchy than before, right channel comes in lovely and then sometimes drops out and comes in etc, messing or tapping the knob has a reaction. When it comes on and i stop touching the knob it sounds great. Balance pot works like a charm now at least thats something!
On headphones no issues at all, sounds great
Is there a suitable replacement for these to be had, nothing much in the way of identifiers on the pot - cannot see a specific model number or anything like that?
I am not averse to opening them up but not if i cannot find a replacement pot, the balance and volume are stacked together (2x sandwich)
Even with my deoxiting the other switches i know they need proper attention .i.e faceplate off and get right in there, but they do work if a bit stiff.

Visually the soldering on the pots looks good
 
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Can the moderators please move this to the DIY section of the forum, it may get more attention there, not sure how/if i can do this myself
 
Solid state is a pretty good place for it, but whatever. Have you tried any of the suggestions listed besides deoxiting the controls? Relays, cracked solder joints, etc are all good places to start before assuming bad transistors.
 
The volume pot appears to be a sealed ALPS pot. before turning it on, give the volume knob a bunch of turns back and forth. Might clear up some of the contacts, albeit just temporarily. Don't just look at the switch solder joints...it could be bad RCA inputs, resistor/transistor joints (especially ones that get hot to begin with), etc. that's also why I suggested trying to determine which portion of the amp is having the problem by isolating them into preamp / power amp sections by removing the jumpers or flipping the switch (which, btw, could also need a good cleaning...problematic on Yamaha units of that vintage or older). And there's the relay that has already been suggested. You'll need to have the cover off while powered up to check that, and be very careful due to live voltage, but using a wooden spoon handle or chopstick to tap or lightly wiggle the relay could reveal that it's the culprit.
 
You can get cleaner into the "sealed" pot. Place the De-Oxit snorkel right on top of each seam in the pot and gently squeeze the trigger on the can so the cleaner just starts to dribble out. You will see it slowly wick down into the seam. Then work the control back and forth 30 times. Should take care of it, but the channels cutting out when you bump the knob may mean the control is damaged. Try cleaning and let us know if it fixes it. You should also tap on the speaker relay with a non metallic object and see if the channels cut in and out. If so, the relay needs to be replaced.
 
Thank you all, I have given the volume pot 2 treatments with deox including all other switches and pots also. The balance is now working perfectly, but volume is not. Better than it was but still still goes in and out. Turning the pot can resolve the issue and both channels sound perfect then.
That's why I was doggedly suggesting I thought it was only the volume pot causing the issue, as a deox improved it, but still not perfect. I got plenty of deox into each pot without much trouble
I will investigate the relay carefully per your advice.
 
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This might sound stupid, but if i plug in headphones and speakers selector switched to off, then use the volume pot I assume the dodgy pot should still cause an issue. I.e. cutting in and out.
But if volume pot works nicely in that scenarios could I then be relatively sure it is the relay?

Apologise if that sounds ridiculous
 
This might sound stupid, but if i plug in headphones and speakers selector switched to off, then use the volume pot I assume the dodgy pot should still cause an issue. I.e. cutting in and out.
But if volume pot works nicely in that scenarios could I then be relatively sure it is the relay?

Apologise if that sounds ridiculous
Yes, the headphones are less of a load so a relay with bad contacts can still work with headphones, and the volume pot would still be bad with headphones. Increasing the volume making it work is a telltale sign of a bad relay.
 
Update:
I tried the headphones and issue persists with volume, however, i tapped the relay while amp was playing music. Immediate response to this, so it looks like it is time for a new relay.
I dug up a thread which recommends the below relay.
Omron MY2-02-DC12

I do however have some of these
MY4-02 DC24.
Will this work or will it just not activate given the recommended is a 12v relay?
PITA having to order a box of these and pay 20 bucks shipping.
 
MY4 has 4 switches in it and twice as many pins as the MY2. Also you must use the correct voltage. Order from Digikey and choose USPS Ground shipping and the shipping cost will be around $3.00.
 
Ok i will grab the recommended replacement, hopefully that will resolve the issue completely.
Is there anything else i should be looking out for? In Ireland shipping is 20 minimum unless order is over 50 unfortunately
 
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