Question about Audio & Video Receivers
I have a technics sa-gx 500 it works great but after it's on for 2+ hours the display locks up on me when I try to lower the volume with the remote, also the volume locks up when I try to lower it, sometimes if I raise it then lower it it will go down otherwise I must do it manually. I also get a strange screaching sound through the surround speakers when ever I change the volume level every time I press the remote volume button. Any ideas what's going on?
The noise you hear when increasing or decreasing the volume control is due to dust particles inside the potentiometer, you should use a contact cleaner to get rid of the noise by spraying it inside the volume control. Radio Shack should have the contact cleaner or you can google it.
The other failure could be some dry solder joints around components that overheat such as the amplifier IC or transistors, high power resistors, etc.
Posted on Oct 17, 2008
The circuit of the device gets heated and board acts as it hanged and the device reacts like this.just get your circuit board dry soldered so the solderin joints will become firm .and it will work properly.
Posted on Oct 11, 2008
You can get all the help you need, I don't recall seeing that anybody told you that you only get one answer. If you rate somebody a FixYa!, it would be there responsibility to help you further.
I have been fixing these types of receivers for over 18 years and am willing to help you as much as possible. Since this is not a hands-on type of situation it may be difficult to get you the correct answer right away. Troubleshooting electronics is not an easy thing to do in this manner. It is always much easier when a technician has the equipment in front of them and has the proper test equipment do these type of repairs. It will also require at least some basic knowledge on your part, so you can understand the help you are receiving. Having said that, leet's see if we can figure out your problem.
Many technics have a common problem with bad solder connections. The main amp board will get them from overheating and after a few years they will cause the type of problems you are describing. If you have a soldering iron and solder, and also have decent soldering skills, you should be able to fix this yourself. Most Technics have an access panel on the bottom that will make the most common area available to resolder. The access panel will need to be removed.If it has never been removed before you will need to clip the metal tabs holding it in place. If it has been removed in the past, you can remove the access panel by taking out one or two screws that hold it in place. Turn the unit over and look at the bottom of it and you should be able to determain if it has been removed before or if you need to clip the metal tabs to remove it. It will be covering the area right below the components on the heat sink.
Please be sure to have the unit unplugged from the wall outlet before you ever open it or take off the access panel.
Removing the entire board is actually a better way to get to these solder connections, and it will give you access to all the solder connections.
Let me know if you are willing and able to take out the entire board. I can give you directions for it on my next post.
The solder connections you would need to resolder will have a grainy look to them or will have a ring shaped crack on it around the component lead. All of the bad ones need to be resoldered, so the only way to be certain you have gotten all of them is to remove the entire board to examine it visually. The access panel only lets you see a small amount of the solder connections, but they are the most common ones to go bad.
Let me know if you would like further help from me and what you have found after examining the main amp board.
You can address your post to me directly like this: @tech48 , or @Dave , or @who-ever-you-want if you wish to comminicate with somebody else.
Posted on Oct 17, 2008
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