Onkyo TX-6500 MKII - Main caps leaking

youdiejoe

New Member
Hello all,

I recently stumbled across an Onkyo TX-6500 MKII on Craiglist here in Los Angeles for under $100 and snapped it up without even turning it on.

Luckily it powers up fine, all inputs work, though many of the lights are dead so I have a LED light replacement set on the way. The exterior was in good condition but covered in cigarette tar residue, took some careful cleaning to knock down the gunk without removing the printed faceplate letters and numbers.

The lights arrive tomorrow so I thought I'd start cleaning the pots today, they were very dirty and from looking at the top down with cover off I could see this unit would need a decent tear down to get into them. Downloaded the service manual from HiFi Engine and flipped over the unit to remove the bottom plate. Once inside I find 2 puddles under the main caps, one has leaked quite a bit more than the other. Okay, deal with that later, jumped into the pots and switches with Deoxit, opened the sealed volume pot and got it too. All sounds MUCH BETTER, but I do notice that the left channel is slightly thin and tin sounding compared to the right channel, any chance this would be in relation to the leaking main caps?

Did some searching here and found a few other TX-6500 owners posts and gleaned what info I could from their issues. Obviously I need to replace, at least, these 2 main caps.

Here comes the question...

I found these KEMET replacements on DigiKey

https://www.digikey.com/product-detail/en/kemet/ALF20C273EL063/ALF20C273EL063-ND/8681300

They seem to match the spec, a little smaller in size than the originals, but would these work?

I've never replaced caps on a unit, I would put my level of ability at novice so I'm not sure what precautions I need to take with removing the old caps (unplug it 1st...)

Any tips, pointers and LA local tech recommendations gladly taken!

Thanks!

RandyIMG_0609.jpg IMG_0610.jpg IMG_0611.jpg
 
Replacing large filter caps is not horribly difficult. The most important thing is to be absolutely sure you replace the wiring at exactly the same position as when it was removed. If not done correctly, there could be a big boom. Take lots of quality photos of the wiring, like the the ones you have already taken. Put your bottom cap pics here on your thread so people can get an idea of the type of cap you have. Filter caps can be replaced with slightly higher uf and voltage numbers, but within reason. The cap also should be the same type as the existing caps. Some caps have screw type contacts and others have solder posts.

You have a wonderful piece of equipment which has one of the best tuners of the era. I have the 8500MkII and had it recently rehabbed by blhagstrom. It was well worth the cost. There is nothing made like these Onkyos anymore and saving them from the landfill is worth the cost, IMHO.
 
All sounds MUCH BETTER, but I do notice that the left channel is slightly thin and tin sounding compared to the right channel, any chance this would be in relation to the leaking main caps?
not main caps as only 2 shared by both channels .. change anyway if out of spec or damaged
 
You don't want those caps. Minimum purchase is 216 and well they don't have any in stock. So many other choices. But if you want help from someone that doesn't have an Oink open in from of them,

Capacitance 24000µF
Voltage 63V
Diameter ?
Height ? any limits?
Connection type screw terminals, solder lugs...

I think you will find a snap in that might work.

Call Tom at Northridge Electronics and see if he is still doing repairs. His website is kinda thin is the reason I say give em a call. There are others.
 
You don't want those caps. Minimum purchase is 216 and well they don't have any in stock. So many other choices. But if you want help from someone that doesn't have an Oink open in from of them,

Capacitance 24000µF
Voltage 63V
Diameter ?
Height ? any limits?
Connection type screw terminals, solder lugs...

216, Yikes! Thanks for seeing that...

From another 6500 MKII user on this forum the measurements are:

Diameter: 50.8 mm
Height: 101.6 mm

as far as a limit, I'd say there is a little room maybe 10-15 mm taller

Replacing large filter caps is not horribly difficult. The most important thing is to be absolutely sure you replace the wiring at exactly the same position as when it was removed. If not done correctly, there could be a big boom. Take lots of quality photos of the wiring, like the the ones you have already taken. Put your bottom cap pics here on your thread so people can get an idea of the type of cap you have. Filter caps can be replaced with slightly higher uf and voltage numbers, but within reason. The cap also should be the same type as the existing caps. Some caps have screw type contacts and others have solder posts.

You have a wonderful piece of equipment which has one of the best tuners of the era. I have the 8500MkII and had it recently rehabbed by blhagstrom. It was well worth the cost. There is nothing made like these Onkyos anymore and saving them from the landfill is worth the cost, IMHO.

I've been looking for one of these for years, my best friend's father had one, brand new back in 1980, it's made a lasting impression on my then teenage brain.

here are a couple more detailed photos

IMG_0618.jpg IMG_0620.jpg
 
The caps are "snap in" type. Because the wire on those caps is a heavy gauge usually, it will be a bit of a PITA to work with. I picked up a tip here that works great with snap ins. Find some O-ring, non insulated, crimp on connectors. Crimp on to the snap in contacts and solder them too. This now gives you some nice big rings to attach and solder your connections to.
 
old ones are solder lugs . screw type or snap in can be used here .. solder lugs i dont see anymore .
 
It would take some kind of adaptation to put a ring lug on a screw type cap. Stick with what cap is in there originally.
Not to difficult that adaptation, more likely not needed. A ring terminal will fit on the screw connection and maybe all the wires will fit into ring terminals. If you were thinking a solder ring, well a nice chunk of solid 12-10-gauge copper from a chunk of romex could link the two ring terminals. But like you said, stick with the original and like I said why would anyone do that.
 
Ordered a pair of the Kemet caps from Mouser (link above) they should be here by the middle of next week.

Wired in the LED light set today, they look great, I'm keeping the original lamps on the tuner dial ends as they are still working, I have the LED replacements on standby when needed.
 
Man, those caps really did leak. Good buy for $100 though, especially around here.

Tell me about it, I still need to scrub that off the bottom plate.

I saw it on the Craigslist free page, the listing was for a sewing machine and the amp was sitting on top of the sewing machine in photos, I recognized the button and knob layout immediately. I shot off an email and asked if they wanted to get rid of the amp too . . . "not free, $80 and come get it right now as we are taking everything to the dump today if it's not gone" when I got there he said he had several more emails after mine asking the same question, I got lucky.
 
The main caps are in, and before I start tearing into the replacement I wanted to ask if using 3 bus bars to collect all of the wires routing through caps would be a good idea? A way to reduce the 3 big clumps of wires and make it a little easier to manage.
 
Update: last year, 3 days after my last post, I had a heart attack and luckily it was a minor one. Tests showed I had a blocked artery and it was fixed with a stent the next day, all is well now. Phew!

SO a couple of months later I finally finished installing the new main caps and mounts (photo included) and found that the left channel amp had stopped working altogether. My interest in the unit was for the phono preamps and the tuner, since this unit has a pre-out I connected another power amp and on it goes and sounds great! As lovely as the unit is, it's mainly collecting dust in my garage. I should find a new home for it with someone who would show it more use.

IMG_1408.jpg IMG_1399.jpg
 
Last edited:
Update: last year, 3 days after my last post, I had a heart attack and luckily it was a minor one. Tests showed I had a blocked artery and it was fixed with a stent the next day, all is well now. Phew!
Wow, scary. Thank goodness it was minor.

SO a couple of months later I finally finished installing the new main caps and mounts (photo included) and found that the left channel amp had stopped working altogether. My interest in the unit was for the phono preamps and the tuner, since this unit has a pre-out I connected another power amp and on it goes and sounds great! As lovely as the unit is, it's mainly collecting dust in my garage. I should find a new home for it with someone who would show it more use.

View attachment 1534294 View attachment 1534299
Wow, that's too bad. My interest in your post is that I just bought a TX-4500 MKII on ebay yesterday and I can't wait to get it. I was researching any issues I might run into. Those new caps look solid - I wonder what might be wrong with the left channel?
 
Back
Top Bottom