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Vintage Audio Repair

Started by nab, September 16, 2021, 06:36:09 PM

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nab

I set myself up for a great pick up today. Made plans to meet with a seller in town to meet at an appointed time, a week in advance. I was lucky enough to have a list of what he was selling, curtesy of the local record store, which also made the initial handshake contact for me and vouched for me. The seller just sold 22,000 records to my local store (yes, that's the correct number). This was as close as "business" as I've gotten.

Thanks to the list, I was able to research the models he had, and work up a good price for offering. I warned him in advance that I wouldn't be paying ebay prices, and on the phone he seemed cool with that. He knew he was going to get the kind of price he could without doing the ebay work himself and seemed cool with it.

And I arrived at the door, knocked, and was greeted by the seller.

And he told me he wasn't ready because he didn't have time to haul them out (within the week's advance notice I gave and all the groundwork laid by the local record store the week before that). Said he'd text me in the upcoming week or two.

Won't be waiting for that text. Good luck with the ebay/marketplace selling duder.

So I expected to have an epic post here tonight, but all I've got is this sad story.

mopper_smurf

Here Comes The Flood - a weblog about music
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Apparently people don't like the truth, but I do like it; I like it because it upsets a lot of people. - Lemmy

Buffalo Budd

We had a power surge in the basement a couple of nights ago and my Sansui R-70 went out. I'm hoping it's simply a fuse but wondered if any of you experts have some insight into if they even have them. I can't find much online and have been combing through the manual but still at a loss.
Everything is connected, because it's all being created by this one consciousness. And we are tiny reflections of the mind that is creating the universe.

Caravan2001

Quote from: Buffalo Budd on April 12, 2022, 05:38:45 AMWe had a power surge in the basement a couple of nights ago and my Sansui R-70 went out. I'm hoping it's simply a fuse but wondered if any of you experts have some insight into if they even have them. I can't find much online and have been combing through the manual but still at a loss.

Could be any number of things. I don't know that model, but it could be just a fuse. It could be more than one thing.  Just pop the top of and have a look.  If you see scorch marks, that's not a good sign lol.  But pop it  open, any fuses will most likely be very visible.

Buffalo Budd

Fuse was indeed the problem.
 :beers:
Everything is connected, because it's all being created by this one consciousness. And we are tiny reflections of the mind that is creating the universe.

rowjimmy

Get yourself some proper surge protection.

nab

April 13, 2022, 07:37:27 PM #96 Last Edit: April 13, 2022, 07:49:18 PM by nab
Quote from: Buffalo Budd on April 12, 2022, 05:38:45 AMWe had a power surge in the basement a couple of nights ago and my Sansui R-70 went out. I'm hoping it's simply a fuse but wondered if any of you experts have some insight into if they even have them. I can't find much online and have been combing through the manual but still at a loss.

Make sure the replacement was a quick acting fuse of the same amperage. Any replacement from a hardware store or auto parts place that meets the specs should work. There's nothing magic about the ones Sansui put in originally. They're just there to make sure the amperage doesn't get too high.

Extra volts is ok. For instance, if the fuse was 1A 125V (Should be printed on the end of each fuse), it's ok to replace with a 1A 250V, but not with a 2A 125V. The amperage is the important metric. A unit with a higher amperage fuse will still work, but it weakens the protection the fuse is providing, since more power is allowed to go through before the fuse trips. This means that the components the fuse is protecting will be subjected to more power and might cause them to fail. Volts is the available energy, amps is the rate of flow, and resistance is control on the rate of energy flow. 

ETA: If the power surge caused the fuse to blow, then it was working as designed. But, as caravan points out, there's many reasons that fuse could have blown and not enough info in the post to really diagnose. But, I'm hoping that replacement in kind for the fuse is the cure, and the extra power from the surge is the problem, that it didn't cause any other damage, and that you're listening for a long time still. Ultimately, replacing the capacitors in the unit will help with long term stability. They act as power reservoirs in the chain, and while not quite resistors, failure of the capacitors leads to instability in the power regulation which can cause all sorts of problems later on. Unfortunately, it's not use that kills capacitors, but time. I pulled all the capacitors from a Technics SA-300 that looked new old stock inside, and was very lightly used. Sixty percent of them were faulty (from minor to major degrees) just from time.

nab

Here's a handy infographic that explains the relationship between volts, amps, and resistance (ohms).

Hope it helps. 

kellerb

got any other infographics?  F=MA, Pythagorean theorem, e=mc^2 ?

Buffalo Budd

Whoa, didn't think I'd come in here and see that.
Thanks for the detailed response nab. I have a local electronics guy by my house and he knew exactly what I needed. The surge protector is there but it works a lot better when I have the receiver plugged into it.  ::)
Everything is connected, because it's all being created by this one consciousness. And we are tiny reflections of the mind that is creating the universe.

nab

So, with the move and all, things slowed down around here for repair.

But I got started again, this time with something for me.

Picked up this Realistic LAB-400 from the record store. The owner asked me to restore it, and I made an offer on it instead. Offered him what he paid for it ($100), plus a Pionner PL-12d I had already restored and had been listening to for the last year. Actually bought it from him before I knew how to restore stuff, so he got it back in better condition than he sold it. As a bonus, he gave me all of his spare turntable parts, said he was done doing it himself, and that he'd rather pay me to do it.

Some may scoff at the Realistic brand. It was Radio Shack's house brand. This was one of thier top of the line offerings in 1979. It was manufactured by CEC, at the same time they were making the much more collectable Marantz 6300. This is all the same parts as the 6300 in a different brand package.

Cleaned it up and tested it. It works just like it's supposed to, and holds a steady 33.3. Japanese direct drive late 70s turntable at its height. Most of the way to a Technics, in the ways that matter anyway.

Good to be back.


nab


nab


nab

Man, I was really hoping you guys might show some pictures of your gear and discuss, but I guess I'll keep up the convo talking about my own adventures.

A few weeks ago, the record store took in three classic Pioneer pieces. A CTF9191 (a massive wood cased totl cassette player) and an SA-8500 (60 wpc integrated amp), along with a Technics 1600 turntable. I expressed interest in the SA-8500, and the owner traded it to me for the labor to refurbish the Technics and his father's JVC turntable.

But the SA-8500 made me work for it. Static bursts in the left channel. I started by replacing all the capacitors in the preamp section, as well as the transistors, as I thought at first that it was in the preamp section and I had the parts onhand. Didn't go away, but I had a great preamp for a week in the unit.

Then I started attacking the amplifier section, but ran out of parts onhand when it came to the driver and output transistors. Usually I wouldn't go all shotgun like this, but all the transistors and capacitors in both sections so far were known troublemakers, so it was kind of a preventaive maintenance/fix the problem session.

Had to wait a couple weeks for work to settled down and wait for more parts, but they showed up today. Once I popped the driver transistor pair into the left side, bingo!

And now she sings. I'll complete the right side refurb some day, and fix the light, but really enjoying the sound of this amp this evening.


nab

May 22, 2022, 07:30:18 PM #104 Last Edit: May 22, 2022, 07:32:28 PM by nab
Also completed a re-veneer of a Pioneer SX-580 I've been working on for my Father In Law today.

I was lucky with the sticker on the original veneer. That panel came off in one pull complete. I cut out the sticker and attached it to the new veneer in the same spot to keep the original look.