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Technics SU-7600 Integrated Amp

T

tube-a-lou

Addicted Member
Hi all,

I got another great deal on nice amp could not pass it up, a Technics Su-7600. Really
clean looks like it was never touched inside, turned it on and left channel was out but!
I started taping the speaker relay and it worked so I'll have to clean it or replace it. I
added some pics, for a Technics I really like the way it's laid out, the size of the power
transformer and the separate boards, maybe it will need a cap change I would feel better
with that, and check out the wood cover.

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MacPhantom said:
Don't. Waste of time, money and resources. That amp will perform fine as it is once you have cleaned the pots, relay and switches.
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Please allow me to wholeheartedly disagree. Those caps are older than I am, and likely far outside of spec. At the minimal end of the spectrum, at least recap the power supply and anything else that would take out other items if they go boom.

Nice score, good luck!
 
Right, but the caps is not the cause of the initial problem. I personally wouldn't just replace the caps unless it was really really necessary. This ain't no 60 year old tube amplifier in which they were notorious for using those old wax paper capacitors.
 
onwardjames said:
Please allow me to wholeheartedly disagree. Those caps are older than I am, and likely far outside of spec.
Click to expand...
What do you base your claims on? Do you have any proper statistics on the relationship between the specs and age of capacitors?
onwardjames said:
At the minimal end of the spectrum, at least recap the power supply and anything else that would take out other items if they go boom.
Click to expand...
Have you ever had, or even just seen, an amp whose PSU caps "went boom" just because of age?
 
MacPhantom said:
What do you base your claims on? Do you have any proper statistics on the relationship between the specs and age of capacitors?

Have you ever had, or even just seen, an amp whose PSU caps "went boom" just because of age?
Click to expand...

I have owned countless receivers, and even had several ground-up restored (mostly for keeping them strong for the next 25 years).

Each and every one sounded better after the recap.

And yes, I've seen power supplies ruined by failed caps.

Can someone else reach over the top turnbuckle and allow me to tap out?? I cannot believe I'm having to defend replacing 45 year old caps. And no, this isn't the initial problem, and it can certainly wait. But, if one is serious about keeping this nice piece of gear running, a recap needs consideration.
 
MacPhantom said:
Don't. Waste of time, money and resources. That amp will perform fine as it is once you have cleaned the pots, relay and switches.
Click to expand...
If you define "fine" as "not up to spec", I agree. As it won't be up to spec.

Also I've seen PSU caps fall off the board with a nudge on many units.

I find it much more effective to just buy a new Omron drop-in relay than cleaning the old one.
 
I recently recapped and rebuilt this amp for my neighbour . You can use this relay :
https://www.digikey.com/product-det...r-brumfield-relays/PT271024/PB2295-ND/1127604
The coil resistance is a bit higher then original so you will need to up a bit R364 (from 330 Ohm to 430 Ohm 1 - 2 W). Amp also had bad 2SA798. It is very nice sounding unit and worth bringing into the shape.
Besides there are not so many caps to replace to even argue about it. If you do not plan to use film caps in place of some electrolytics up to let say 10UF in a signal path then the total cost is not going to exceed 40 USD for the parts (I am talking caps only). Unit comes apart easily so i do not see why not to do it. for PSU caps I used this one:
https://www.digikey.com/product-det...nics-cde/383LX123M063A052/338-2024-ND/2256627
 
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onwardjames said:
To the OP, I am sorry for igniting a recap vs no-recap debate. I hope this piece gets going, and sounds wonderful.
Click to expand...

No it's fine it happens sometimes, this is great audio talk, besides I took these bad boy's out today and replaced them
with a pair of Nippon Chemi-Con 10,000uf 63 volt and a few other ones and it does to my ears sound cleaner and better.
I mean look at these guy's extra lug's for support and all. So far it's sounding really nice.

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Discovered a slight motorboating in the phono section of the amp today, probed around
and when I hit one of the 0.68uf caps it got louder, well I knew it needed a recap anyway.
 
onwardjames said:
To the OP, I am sorry for igniting a recap vs no-recap debate. I hope this piece gets going, and sounds wonderful.
Click to expand...

Not too much to really debate about it with electrolytic caps in old electronics. They have a life span. It's not a matter of if they're going to fail, it's when. And as mentioned, if a person is content with running something on nice speakers out of spec and can sleep good at night, God bless 'em. Technics ain't Mcintosh...there's nothing overbuilt in there.

Funny, I've rebuilt, recapped, new resistors, etc., on 30 year old Carver gear and the difference was night and day....in sound quality AND measured. But to each their own.
 
MacPhantom said:
What do you base your claims on? Do you have any proper statistics on the relationship between the specs and age of capacitors?
Click to expand...

There's puh-lenty of info out there and puh-lenty of techs that will tell you so. Loss of capacitance, ESR changes, glue that's disintegrated the circuit board, etc.

MacPhantom said:
Have you ever had, or even just seen, an amp whose PSU caps "went boom" just because of age?
Click to expand...

Yes. If you haven't yet, just wait....it's fun.
 
tube-a-lou said:
Discovered a slight motorboating in the phono section of the amp today, probed around
and when I hit one of the 0.68uf caps it got louder, well I knew it needed a recap anyway.
Click to expand...

Well, so much for the "no need for recap" nonsense, lol. And thank you, @avguytx. I'm no tech, but my ears and brain tell me that recapping at this point is essential, if for maintenance alone.
 
Thanks everyone for there good wishes with the amp, These older amps are built so well
(carry over from tube amps maybe) that it mostly just needs a cap change and that's it.
Out of all my caps I don't have two 0.68uf caps!
 
I just did a recap of a Luxman amp and just changed the power supply section and it's left
and right boards that contain the power transistors, when I first put it on it didn't sound that
good so I checked the Bias and the reading was about .08mv I then raised it to about .016mv
and wow the sound just changed to that big Luxman sound I love. So something was going
on with the old caps which effected the voltage going though, anyone would like to comment
about this.
 
Ordered today the rest of the caps for the amp, tried Digikey for the first time (they had the 0.68uf caps I needed)
and ordered all Nichicon Gold series this time.
 
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