Any ideas for a weird problem????

[skippy1969]

I have a Yamaha YST-C11 that is acting very strange.
When it is cold the unit powers on and you can get very faint sound through the line in.
But as the unit gets warmed up it starts to play loud then soft thenloud then soft again,as this happens the receiver and cassettes start to work and the cd works but it play sloooowly.
Then once it is warmed up say 5 minutes or so it starts playing LOUD and proud and sounds awesome! The CD still plays slooooow and the receiver wont pull in stations in stereo mode but it will in mono mode. :annoyed:
You can then play it for hours with no issues,until it cools down,then it acts up the same way.
Any ideas,I'm stumped???????? :nugget:

 

[Fatdog]

Maybe an issue with bad caps?

 

[redbenjoe]

skippy--
until norm,ramon,frank and the smart boys jump in to help out--

lemme guess that you have an erratic power supply --

so any other serious big power replacement is worth a temporary try

 

[Ken]

lemme guess that you have an erratic power supply

Brilliant deduction! Darn, Ira, not much gets by you, does it?

This looks like a job for supa dupa, although it could be so many different things that someone is going to probably have to open that bad boy up. Long distance troubleshooting isn't going to cut it on this one, I'm afraid

Boy, look at the size of the heat sink on the back...

 

[redbenjoe]

is there a 12v dc adaptor jack ?

then you could test it off your car battery

 

[skippy1969]

is there a 12v dc adaptor jack ?

then you could test it off your car battery

No Ira,just a 120 volt cord.

 

[oldskool69]

You likely have a power supply issue as stated by the elder statesman. I would hazard a guess that the voltage supply rails are failing and a new transformer may be in order....

 

[Superduper]

I concur. It's a voltage issue. I wouldn't throw out the transformer just yet though. More testing is in order. Check for connectivity issues (contacts, cold solder joints, etc.) Also check the Diodes to make sure that none have failed. Also check the large filter capacitor to ensure that it's not leaking. Also check the voltage at the secondary windings before the rectifier diodes.

 

[monchito]

with the elder and all the gentlemens after him

 

[skippy1969]

Thanks for your input guys.
Well I know one thing,whatever is wrong with it ,I know it is beyond my abilities and budget. :annoyed:
Even If parts were available for this sucker,I'll bet it would cost a small fortune to fix it.
I guess she'll just be headed for the junk pile....
Or someone who wants a garage radio to leave on 24 hrs a day,it works great like that......

 

[redbenjoe]

dont give up on such a rare/great sounding box --

even if you try a lesser/common/available power supply
it may still sound better than 95% of all boxes

am i wrong ??

 

[Superduper]

Thanks for your input guys.
Well I know one thing,whatever is wrong with it ,I know it is beyond my abilities and budget. :annoyed:
Even If parts were available for this sucker,I'll bet it would cost a small fortune to fix it.
I guess she'll just be headed for the junk pile....
Or someone who wants a garage radio to leave on 24 hrs a day,it works great like that......

I'm sure you are joking about the junk pile. I wish all my boombox problems were just power related. Original parts are nada, but if there is one aspect in repair where ingenuity is well received, it would be in the power supply since it's not normally too picky. Give it the power it wants and the boombox is happy. Let one of the more creative guys here take a stab at it. I know I'd be very interested in tinkering with it, if it was just headed for the trash bin.

 

[MasterBlaster84]

Skippy don't send that sweet Yamy to the junk pile. :'-(

 

[roddy@radiohier]

sounds like some kind of power supply issue as stated. But what's wierd is that the CD plays slow. Never had that before.

 

[oldskool69]

Skippy...you're gonna have to dissassemble her and take lots of photos of the power supply section which should be on it's own board. And get a service manual online. Post the power supply section so we can see it. I'm sure you have a very good multimeter. I think we can walk you through this one...the key is to find out what rails have the issues and then check the associated components (caps, etc.) the rails feed to.

If your comfortable with that, I'll pitch in as best I can. I know others will for sure. If you're totally left thumbs with electronics, and don't have a local shop that won't tear your wallet a new one, you could possibly send it to one of our handy members.

 

[Radio raheem]

Personally im with skippy it would be on my scrap heap too BUT and i say BUT you have people like norm and freddy backing you skipper so i say GIVE it a worl man if she is truly knackered then you can bin her BUT we all might lern something here bud, so go for it.

 

[blah blah]

trying is the first step in failing... :'-( i mean you can't succeed if you don't try dig into it skippy. i cancel my dibs if you don't fix it!

 

[skippy1969]

Don't worry guys,I won't junk it. I was just kidding. I will see if someone wants to fix it for me.

 

[blah blah]

yea i've threatened numerous boxes with axes, hammers and trashcans, no response at all, better to fix