Help with first repair attempt

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EndersShadow
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Help with first repair attempt

Post by EndersShadow » Sun Nov 30, 2014 11:50 am

I am in need of some help/advice from everyone.

My dad purchased a Yamaha R-300 YEARS ago. It was his first piece of vintage hi-fi equipment along with a Turntable (long gone), a set of Boston Acoustic A-500's (Think thats the right model #) that my dad still has. I have some really great memories of coming down and asking my dad to put on some music and then jamming out with him.

He (like me) keeps everything, and so he gave it to me a couple years back and it worked great for a short time. Then one channel started getting static in it when you turned the volume knob, and then IIRC went out all together and I put it on a shelf where it has rested for a couple years.

My goal has always been to get it back in working order, and also replace the cheap cover (vinyl over MDF) with a real wood cover and then pass it along to my daughter (too young for it right now) for use in her room.

I am wanting to "attempt" my first repair on this amp, but I need some help that may or may not be possible.

I was recently Karma'd a DMM meter from Mark, but have NO IDEA how to use it. I know that knowing how to use this would help me diagnose/test what could be wrong on the Yamaha.

I also need some help understanding the schematics and how important the certain parts are so I know which are worth paying for higher cost caps from companies like sonicap, erse, dayton, etc.

I know I could just pay someone to fix this, but I want try to tackle this myself if its something that isn't too difficult

I want to eventually move up to be able to repair/recap some of the Carver amps, as well as do some DIY stuff myself.

I am wondering if there are any members out there near in the Indianapolis, IN area that know how to do this, and would be willing to meet with me to help walk me through testing/measuring to determine what is wrong, and then perhaps help me figure out what parts to order (as well as if its worth replacing other parts). Then if possible help me with resoldering it.

This is a long term project with no real drop dead date, and if its not realistic, I will just find someone to repair the
integrated locally, but I was hoping to make this my first attempt to play with electronics.

Here is a link to another site (same post) that I uploaded a schematic for the integrated (this forum wont let me upload a pdf file). Any help/advice/thoughts very much appreciated.

http://forum.polkaudio.com/discussion/1 ... empt?new=1
"You were on my Ignore List, but you are too damn entertaining, like a circus monkey, so I took you off" - H9
"We shouldn't laugh at people like you, we should pray for them. You have my prayers for a speedy rehabilitation you sad, silly little man" - Jstas

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Robert R
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Re: Help with first repair attempt

Post by Robert R » Sun Nov 30, 2014 1:15 pm

Step One would be to try it and confirm that the symptoms are as you remember, namely one channel out. If that is still the case, move on to next step; if not, let us know what you are finding now - you don't need a meter just yet.

Step Two - get a can of Deoxit D5 and open your amp up to where you can squirt a shot of the Deoxit (contact cleaner that contains Cramolin) into the volume control. There will be two sections, one for each channel. Work the control end to end a bunch of times, then retest the amp.

If things improve you are on the right track. While you're at it, treat all the other controls and switches, too.

Be aware that at this age there might be additional failures from just sitting around, with old, dried up electrolytic capacitors failing. They can be (and often are) completely worthless without appearing swollen or showing any signs of having leaked. At some point those should probably all be replaced, and that's a long, tedious process. But try to get it functioning first.

Robert R
"You know what folks? I'm happy."

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EndersShadow
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Joined: Thu Jun 30, 2011 3:58 pm
Location: Indiana

Re: Help with first repair attempt

Post by EndersShadow » Sun Nov 30, 2014 3:15 pm

Robert R wrote:Step One would be to try it and confirm that the symptoms are as you remember, namely one channel out. If that is still the case, move on to next step; if not, let us know what you are finding now - you don't need a meter just yet.

Step Two - get a can of Deoxit D5 and open your amp up to where you can squirt a shot of the Deoxit (contact cleaner that contains Cramolin) into the volume control. There will be two sections, one for each channel. Work the control end to end a bunch of times, then retest the amp.

If things improve you are on the right track. While you're at it, treat all the other controls and switches, too.

Be aware that at this age there might be additional failures from just sitting around, with old, dried up electrolytic capacitors failing. They can be (and often are) completely worthless without appearing swollen or showing any signs of having leaked. At some point those should probably all be replaced, and that's a long, tedious process. But try to get it functioning first.

Robert R
Thanks Robert! I will take that advice and spray it down with DeOxit and compressed air as well.

Then we will see where we are at.
"You were on my Ignore List, but you are too damn entertaining, like a circus monkey, so I took you off" - H9
"We shouldn't laugh at people like you, we should pray for them. You have my prayers for a speedy rehabilitation you sad, silly little man" - Jstas

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