Technics SA-80 minor issues

[Capt. 2110]

I got this amp broken for extremely cheap, and it's my entry into the world of vintage audio gear. It had a problem with the Power IC, so I replaced it and it works fairly well. But there are a few problems that it has that I was hoping to find the answers to.

Issues:
1. The right speaker is distorted or not playing at low volume (under "1" on the knob).
2. Depending on the input, the AUX ports sound distorted, as if they're being overdriven (they aren't).
3. The PHONO jacks are distorted and humming a little (might be the record player, as I can make it sound okay, but it's annoying and difficult)
4. Audio playing in AUX is audible in PHONO mode at high volume (I know this because I am stupid and had the switch on PHONO when I needed AUX )
5. FM and AM tuning is bad (I have a decent antenna, it's just bad reception for some reason)
6. The balance knob doesn't seem to do much until the very end, at which point it just turns off the other speaker.

Also, there's no relay click but it plays anyway. Does this model just not have a relay?
Does it just need a recap, or is there something else I can do?

Thanks!

 

[Tom B]

That is not a high end unit, hence it uses a 2 channel hybrid STK with 15w per channel.
It doesn't have a protect relay, just 2 fuses to blow hopefully before your speaker go bad
As you have a lot of issues, check the power supplies and make sure they are OK
Also check your soldering when you put in the new hybrid. Make sure you didn't bridge 2 pins By mistake, as they are very close together.
Aux can be heard on phono when you turn up the volume because the jacks are physically close together.
AM and FM tuning could be out of adjustment, but also check the 12vdc feeding the radio circuits.
Check solder connections for the hybrid as well as the regulated power supply section
The balance issue may be just low level design.

Good thing you got it cheap. Not sure how much effort and cost should be put into that unit.
Remember this You can't expect a Chevy Vega (4 Cylinder Aluminum Engine) to perform like a Chevelle SS396/375HP

 

[Capt. 2110]

I know, but I got it for about $5, so I figured it would be a decent entry point or at least something to learn with. Plus I found the STK for $8 NOS. What does STK stand for, if anything?
Ok, cool. Do you know which model in this line up (80, 100, 200, 400, 800, 1000 iirc) would be considered the beginning of the higher end models?
Will do. I've got to pull it out of its spot first, but I've gotten good and testing it.
I triple checked it when I replaced it. I didn't want to damage it if I could avoid it easily. I cleaned everything then too.
Is there any way I can reduce that, or is it just a part of the design?
I will. If they're out of alignment I won't worry about it too much.
Low level design referring to what exactly?

I know. Probably not much, but I find it kinda fun to play with.
I don't necessarily want a Vega to perform like a Chevelle. I just want the Vega to be as good as I can make it without too much effort. Replace spark plugs, fluids, and filters, etc. Something like that for the system.\

Thanks for the reply!

 

[roger2]

It is good that you are having fun with this unit

Doing a recap should not be used as a troubleshooting method. Follow Tom B's suggestions. He is very knowledgeable.

IMHO when looking around for a unit that is further up the pecking order, consider Kenwood, Sansui or Pioneer from 1980-ish or earlier. These brands all have dedicated and active forums here on AK. More information and assistance is readily available about specific models of those brands. Many "known issues" have already been documented and can be found using AK search tool or google search of AK.

Not knocking Technics, but some design aspects of their models was somewhat outside the mainstream, so possibly not the best units to be learning with.

welcome to AK

 

[SVI2004A]

Afaik STK was adopted from Sanyo ThicK film (the format of this Hybrid ic series)

 

[Capt. 2110]

Ok. I saw that the Pioneers had cap issues, so I wanted to make sure I didn't have to do that yet.
What would you say about a Pioneer SX-600T? It's from ~1970, but looks like it's a high end unit.
Probably not. I think if I replace it I'll keep it though, just as something to mess with/use for testing.

Did any high end machines use these kinds of components? Mostly asking out of curiosity.

Thanks for all the help!

 

[roger2]

Any and all of them can and do have cap issues and lots of other issues. That is part of the vintage landscape. Often, specific amp models have issues that become known to the community. Also, some popular units may have multiple threads detailing recap/refurb efforts. Those are the reasons that I suggested the brands I did. Pioneer, although it is not a brand that I have much experience with, has exceedingly good documentation given to the site by MTF (markthefixer), on many of that brand's popular models, just as an example. Kenwood and Sansui forums have similar threads documenting many models. IMO this type of documentation is newbie-friendly. But there is nothing wrong with diving into the Technics stuff either. And yes there most certainly are some amazingly beautiful high-end Technics pieces.

One either learns to repair, buys (hopefully) properly refurbished gear, or generally pays others to repair and/or refurbish. And sometimes you get lucky...for a while

What do you mean by "these kinds of components"? If you are referring to STK's then SVI2004A is an expert on those and Technics amps. I am not certain that genuine STK's are still available, but I am sure that he knows. That is another part of the learning curve associated with vintage amps...that there are lots of counterfeit transistors floating around and many of the original semiconductor devices are no longer available (NLA).

here is a great Technics thread
http://www.audiokarma.org/forums/index.php?threads/80s-technics-integrated-amps.438913/

The answers to most questions can be found using either AK Advanced search or Google advanced search with audiokarma.org as the site