I'm a total NOOB!!

[steamshooter]

Yamaha K-950. It can play for hours without a prob, or it might take twenty mins. It sounds like a really dirty pot that's being turned. This is in left channel only. My little non-technical brain is saying bad solder joint somewhere. Am I off base here? How do I identify a bad joint? Last nite it played about six hours before acting up, this AM, it's fine. What types of questions should I be trying to answer to narrow down the culprit?
Start with the left output jack and work my way back to the head?
Any suggestions would be helpfull and appreciated.
Thanks
Brad

 

[willysan]

What happens when your turn the volume pot? Does it sound O.K.? Perhaps the pot is performing badly.

Finding a bad solder requires a good magnifying glass and lots of patience. Bad solders tend to show cracks and look opaque whereas good solders look smooth and shiny. You'll need a good soldering iron to fix them.
Good luck,

Willysan

 

[Rob]

I find both a hot air gun and a can of freeze spray very useful tools in locating intermittent connections and marginal components.

Rob

 

[steamshooter]

The volume is actually a slider. I don't hear any noise in it at all. It's been cleaned and re-cleaned. It makes no difference where the slider is positioned it still crackles. Usually two or three slight crackles and then it just goes nuts. There seems to be a pattern to it. Even with the output turned down I can still see the "noise" on the left meter. It makes no difference if there's a tape in or not. The noise only occures in "play" mode. Sitting idle it's as quiet as a mouse.

How are the hot air gun and freeze spray used?

Yesterday, nary a sound all day-go figure.
Thanks for the help, keep the ideas coming.
Brad

 

[willysan]

Using the freeze spray is simple; just spray it on the "guilty"component and the quality of sound should change. The spray cools down those components that are too hot. Of course it works better with faulty transistors and IC's. I'm not sure whether it would be useful to find a bad solder.

 

[steamshooter]

It played hard all weekend without a hitch. Kinda hard to find fault if it doesn't act up. I think I'll let it ride untill it rears its ugly head again.
Brad

 

[willysan]

Wise decision. Intermittent problems drive me crazy.
May I suggest "knocking" softly (let's say with a pencil) different components?. That may trigger the final collapse of one of them.
Good luck

 

[steamshooter]

I'll remember that willysan. But not untill it cuts up again. It's working fine. I'm not going to go poking around until it starts acting goofy again.
Brad

 

[EchoWars]

Read this thread. Most all of these old decks had a slide switch on the main board that was quite susceptable to dirt. DeOxit or ProGold should work well.

If I may make a suggestion...more descriptive thread title would be a good thing, as well as telling all of us what the hell a Yamaha K-950 is. I had to Google to see what piece of equipment we were even discussing, although hints here and there suggested a cassette deck.

 

[steamshooter]

OOPS! I didn't catch the fact that I left out the cassette deck part.:stupid: :withstpd: :dammit: "Sorry about that, Chief" For the time being it's working fine. Eventually I know it will act up again and I'll have to go back in.
Thanks for the help
:stupid:Brad

 

[Lefty]

Brad

I too have had this problem on some of the many vintage cassette decks that have passed through my hands. Almost all the problems were with the slide switch that switches the electronics from record mode to playback mode.

There is usually either a long flexiable cable operator or some kind of mechanical linkage that comes from the record lever. On switch operated decks this switch is activated by a solenoid.

This switch is usually a long silver rectangle looking thingee that mounts right onto a printed circuit board. It can take a lot of time to flush and exersize this switch enough to improve it. Of course be sure to leave power off the deck while you are spraying, operating and letting it dry out.

Sometimes it takes several attempts of doing this as there are many contacts on this switch but it has almost always solved the problems I have run across with noise or channel drop outs.

Good Luck
Lefty

 

[steamshooter]

If I understand Lefty and Echowars correctly, ya'll are talking about the same thing. A square tube around four inches or so with a plunger type thing? I sprayed the huss out of that, it was so funky it would hardly move by hand pressure. It was moving freely when I buttoned it back up. The goofy thing started acting goofy again tonight. I guess I'll squirt him again. If that doesn't do it I'll try willysan's ideas. At least now I have a plan of attack
Thanks all
Brad

 

[Lefty]

Brad;

Yep you found it alright. Often it's not enough just to spray it, you got to be actively moving the switch frequently while you are spraying it. These things really new how to suck up the dust and grit. Once it took me about four or five attempts over several days before it stopped messing with my tunes....:

Lefty

 

[EchoWars]

My own experiance....

Been cleaning switches and pots for a looong time. A few years ago someone told me about DeOxit and its big brother, ProGold. Since using these items I have come to the conclusion that about anything else is simply a waste of time.

Food for thought...

 

[steamshooter]

Update

I went after slide switch thingie again. Stood it up on end this time. I do believe we have a success! I will put it through it's paces over the weekend, just to make sure. So far, so good!
In the process, I discovered how to take the tape door off . Sure will be easier to clean and de-mag next time.

Thanks to all that helped
Brad