Vintage Stereo Amplifier Repair Advice

March 21, 2024 12:44 PM

I have a 1976 Sansui AU-9500 stereo amp with a TU-9500 tuner (and a Thorens TD-160). They’re the ones I grew up on (my dads), original everything including manuals and purchase receipt. I want to take it in for clean up and repair and need advice.

The amp probably has a sticky switch as 2 of the 4 input channels work well, the other 2 weren’t working, then were, now not. The tuner seems fine. The record deck is largely functional, except the signal is getting lost somewhere between the needle and amp. I just want someone to throughly go over it, fix all the minor stuff with love and care (while idk if this is a thing, should I be keeping it original? It looks like an uncle had some parts replaced in 2011 and idk how original or not that was).

Anyway…
When I was a kid (pre-internet) I remember my dad took it in for a clean at a trusted big audio install shop with family connections. The owner said “These things have a cult following. Those that want them will just steal them. Never leave them with someone you don’t know. I’ll even take it home at night for you because I don’t want to see it go missing.”

—How much $ should I pay in to keep something like this “original”?
—Is the paranoia well-founded? An internet search does suggest some people do love them.
—I’m in the Bay Area with no shortage of vintage electronics repair. I’ve put out some inquiries. How much do I need to worry about someone having prior experience with this equipment versus general knowledge?
—what is a reasonable price range?

I’m good with electronics. Just don’t want to fiddle with something personally valuable/irreplaceable.

Thanks in advance!

posted by rubatan to Technology (8 answers total)

People who work at record stores can recommend reputable repair shops in your area. That's a decent place to start.

You may not need to do anything that costs money, though. Is it working okay?

A tech will wipe it clean, carefully vacuum/brush out any dust, clean knobs and switches with contact cleaner (a product like Deoxit or Nu-trol, probably), and then check voltages at the various test points to make sure it's working as expected. Sometimes there are small adjustments to be made. YouTube almost certainly has a video of someone walking you through a routine servicing.

Here's the service manual for your amp.

Servicing the amp is probably a doable project for you. It's all solid-state, and there's a lot more room to work inside these vintage amps compared to modern gear. (You'll need a multimeter. If you need to replace any components, you'll need a soldering iron, and you'll want a dim bulb tester to make sure you don't cause bigger problems.)

You need some specialized gear (signal generator, oscilloscope) for the tuner. That's probably professional tech time.

Don't sweat the "original" stuff too much. The parts that usually need replacing are transistors, capacitors, and occasionally resistors, and modern replacement parts are actually better. You won't lose that sweet vintage hi-fi vibe replacing those small component. In fact, you'll restore it!

I'm in Portland, so I don't know about bay area pricing, but I will say prices on vintage audio gear has gone way, way up in the past 5 years. So it's easy to justify putting money into them if you're thinking about resale value. On the other hand, technician labor is more expensive, too.

Any competent technician should be able to work on this for you. The main thing to worry about with vintage electronics is the electrolytic capacitors. They've pretty much run their expected lifespan by 30-40 years, so 50 is pushing it. If you're handy with a soldering iron, I'd recommend just replacing all of them with modern equivalents before they crap out and potentially cause problems with other components. It may not be cost-effective to pay someone else to do that, though, which is why most shops recommend replacing things only when they become problematic. That's probably fine, too. If it were me, I'd want new electrolytic capacitors in the power and main amp boards at least. The rest of it can probably wait.

Enjoy!
posted by sportbucket at 2:18 PM on March 21 [3 favorites]

I think the guy saying that people want to steal your vintage stereo is exaggerating. I recall a discussion here a few years ago where some could barely get rid of a vintage working amp (hey just an Onkyo).

rubatan has good advice above. Sounds like you mostly have dirty switch problems, which is not hard to fix.
posted by ovvl at 3:40 PM on March 21

I’m definitely not the audiophile at our place, but we have a Sansui (currently AU x 701, previously AU 919) - not sure about yours, but some of the models are finicky to repair. You would probably want someone with familiarity with the model or at least the brand.

Could you get ripped off, absolutely, happened to us. By a repair person with a good reputation, too. (Unit was returned with missing parts and a shockingly and obviously bad workaround for the power problem.) Another time, we went with someone very local for convenience’s sake (for speakers, because they were huge and heavy) - came back with the original, highly sought-after drivers missing - btw those particular drivers weren’t the problem - and replaced with something generic the tech couldn’t even name. A later scan of said person’s reviews featured toaster repair… avoid anyone like that.

Ask your Reddit city sub for a rec, also check audiokarma and Steve Hoffman forums. Check Google and Yelp reviews of course as well.
posted by cotton dress sock at 3:59 PM on March 21 [2 favorites]

I'm very sorry, I somehow completely skipped the paragraph where you described how things are currently functioning!

Intermittent/missing audio in one or more sources could be as simple as cleaning the switches with contact cleaner. Open up the case, spray a little Deoxit or Nu-Trol on the contacts of the selector switch, and work the switch back and forth through its entire range 40-50 times. In fact, do that with all the pots (knobs) and switches.

If that doesn't improve things markedly, it's probably tech time, unless you feel like comparing voltage readings to the service manual and diagnosing the problem yourself. (Which is honestly kind of fun if you're into electronics.)

I found my tech on Yelp, but that was a long time ago, when Yelp was a good way to find things. Ask around at record shops, or contact a DJ at a community/jazz radio station. They'll know.
posted by sportbucket at 6:34 PM on March 21 [1 favorite]

I do not think you are being paranoid. I have a very similar Sansui amp, same vintage. About 30 years ago (!) I took it in for repair (one chanel was out) to a nearby place that had been recommended to me called “Saturday Night Audio” on Clark Street in Chicago. The guy called up to tell me it wasn’t worth fixing and he would sell me a “much newer and better” one at a discount with a trade in of the broken one. I was heartbroken but said OK. I thought about it for 5 minutes and decided I should get another opinion. I called him back to tell him I was coming to pick it up. 10 minutes later I drove up and the guy was standing outside by the curb holding my amp. He handed it to me and said “don’t worry about it, it’s fixed”. I came very close to being ripped off and losing my beloved Sansui. It has worked perfectly since then. The owner of your dad’s shop was right. Maybe more people coveted these things 30 years ago than now, but if you love it, I would be very careful who you leave it with
posted by Lylo at 10:55 PM on March 21 [1 favorite]

What city are you in?
posted by kensington314 at 11:22 PM on March 21

Response by poster: @kensington Bay Area but pass through LA often enough
posted by rubatan at 10:34 AM on March 22

Response by poster: FWIW I reached out to Skip Simmons, nationally known for guitar amps, who then just called me and we chatted for a bit, ending with “Don’t trust anyone without experience on your device and someone who you don’t know.” and he was very helpful referring me to a semi-local expert.
posted by rubatan at 10:12 AM on March 25