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Post by u2nmg93 on Feb 6, 2018 21:50:37 GMT -5
I have a Proton amp that has quite a bit of static on the right channel. The left is clear and both have audio, the right is just lower and has a lot of static. I've tried cleaning the inputs and outputs, the lights are all burnt out and I removed them just in case, no change in sound. Removed and cleaned the main relay and tested all the main transistors that check out. Gauges work and it should look pretty cool when lit up. The matching, preamp Proton 1100 also has the right channel messed up with no audio out. Haven't gotten into it yet. I have a copy of the service manual for the amp, PM me if you need a copy. Need to know what to check/where to go next, couple of spots have gotten warm but nothing obviously burnt. Relay got pretty warm on the right channel but connecting a speaker at the point before it goes into the relay still has the static. Any help is greatly appreciated!
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Post by mastertech on Feb 7, 2018 13:06:18 GMT -5
Have you checked for any DC on the outputs?
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Post by u2nmg93 on Feb 7, 2018 14:19:53 GMT -5
I have right around 1mV DC on each channel.
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Post by mastertech on Feb 7, 2018 14:25:20 GMT -5
And have you checked idle current and offset? (Alignment page of manual)
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Post by u2nmg93 on Feb 7, 2018 16:22:10 GMT -5
Yes, they were out a little on both channels but are as close to spec as I can get them now.
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Post by mastertech on Feb 7, 2018 16:54:08 GMT -5
At this point you have to do some eliminating. I would try crossing the channels after the filter and at least rule that out. Just lift 1 side of each cap in the picture and attach a wire to the leg of 1 going to the pad of the other. And then vice versa. See if the noise changes or stays the same.  |
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Post by u2nmg93 on Feb 7, 2018 22:20:40 GMT -5
Static stayed on the right channel after installing the jumpers.
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Post by mastertech on Feb 8, 2018 11:13:40 GMT -5
Ok. So now I would like to really isolate that right channel. So remove all of the following components and recheck for the noise.
Remove Speaker relay (you will have to test at a point before relay like you already did)
Remove; C653,R720,R704,R806,R807.
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Post by u2nmg93 on Feb 9, 2018 23:32:34 GMT -5
Removed the relay, 4 resistors, and capacitor and still have static on the right channel.
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Post by mastertech on Feb 10, 2018 13:01:53 GMT -5
Well it looks like it is narrowed down to something in the amp section itself as shown in the attached picture. Since there is no DC on the output my first guess would be a capacitor. If you have an ESR meter you can start testing caps and if you don't you will have to start replacing them. You can do them 1 or 2 at a time and test or just change them all at once. Your choice. If it ended up not being a cap we would have to go from there. I would just do the electrolytic caps first and see if there was any change.  |
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Post by u2nmg93 on Feb 12, 2018 23:27:49 GMT -5
I do have a cheap ESR meter, I'll dig in and see what I can find.
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Post by u2nmg93 on Feb 17, 2018 21:11:30 GMT -5
I checked all the caps, they had between 1-2 percent voltage loss and an esr of 3ohm or less. I went ahead and replaced all the electrolytic caps that I tested. Still working through the rest of them as I still have static on the channel.
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Post by mastertech on Feb 19, 2018 19:49:47 GMT -5
Keep at it. You will find it.
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Post by u2nmg93 on Feb 26, 2018 16:47:34 GMT -5
I got thorough all of them in the channel that were in the picture and readjusted the two pots and still have static in the channel. Is there something else that could be causing it? All the ESRs were less than 1 ohm and no more than .2% voltage loss on any of the ones I didn't replace. I replaced all the electrolytic caps in both channels.
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Post by mastertech on Feb 26, 2018 20:35:59 GMT -5
I can not give you a specific part that is causing the static. You have to replace parts in that channel until the static is gone. This is providing that there is not a broken trace somewhere. Did you replace all the caps in that channel or just the electrolytic caps?
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