Hello Sakis,
Time off was "fun", turning a new page. I am glad you are doing well, and didn't doubt that you would.
Hi Johan,
Watch out for Sakis. He will give you good information!
🙂
-Chris
Time off was "fun", turning a new page. I am glad you are doing well, and didn't doubt that you would.
Hi Johan,
Watch out for Sakis. He will give you good information!
🙂
-Chris
Kenwood KR-4600
Hello all!
After spending 25 years in defense electronic, mostly satellite, I am now starting to repair Vintage Stereos as a hobby. If I appear ignorant, its because I am just learning this awesome trade.
After repairing a few very easy stereos, My best friend asked me to repair his Kenwood KR-4600, no output. I cleaned the heck out of the controls and sound came back great in the Right side, very noisy on the Left. I injected a tone into the aux port are realized I had very low gain on the left. Well like a dummy when probing with my old analog scope I shorted the output. Dang it!
The drivers are:
2SC1735 (NTE382)
2SA850 (NTE211)
The power amps
2SD586
2SS616
The power amps are the same as in the original post, What did you replace the power amps with, AND did it work?
Thanks to all and hope all of you are doing great.
Hello all!
After spending 25 years in defense electronic, mostly satellite, I am now starting to repair Vintage Stereos as a hobby. If I appear ignorant, its because I am just learning this awesome trade.
After repairing a few very easy stereos, My best friend asked me to repair his Kenwood KR-4600, no output. I cleaned the heck out of the controls and sound came back great in the Right side, very noisy on the Left. I injected a tone into the aux port are realized I had very low gain on the left. Well like a dummy when probing with my old analog scope I shorted the output. Dang it!
The drivers are:
2SC1735 (NTE382)
2SA850 (NTE211)
The power amps
2SD586
2SS616
The power amps are the same as in the original post, What did you replace the power amps with, AND did it work?
Thanks to all and hope all of you are doing great.
Any one that uses NTE transistors in a Japanese amplifier should seek better fire insurance ....
Hi shair00,
I feel more strongly. If you use any replacement brand of semiconductor, you may as well throw gasoline on it and throw a match at it. NTE and ECG are very poor quality and you don't even know what the real part number they used is.
You can find the specs for those parts, then find current replacement numbers that will work, can be matched and has expected characteristics.
An old scope wouldn't hurt an amplifier. Maybe the scope ground got involved with the wrong point in the circuit? I started with a 500 KHz Stark tube 'scope, recurrent sweep only - no trigger. Was that ever fun to use.
The first thing you will find out is that there are no short cuts. Either you do it the right way, the best job you can do, or it's the wrong way (like using ECG / NTE / SK or whatever. There are no good replacement brand parts. Also, get used to the idea that fake markings are a real problem. Buy from authorized distributors like Digikey, Mouser, Newark, Allied ... you get the idea.
Cleaning fluid. Liquid tools. Use as little as possible and avoid spray delivery systems. A tiny dropper is all you need as it is the slip ring that is noisy, not the carbon track that used to have a protective coating on it that was just washed out. Oil the bearing while you are there. Single weight, no additive. 3n1 or sewing machine oil are not the right types of lubricant. Plastics require different lubricant, like a silicone or maybe lithium white grease. "Lubriplate" is a good general lubricant for plastics.
Use a controlled temperature soldering station with a grounded tip. There are some great digital display types that cost $90 - 120 CDN, all the same manufacturer. Weller is just expensive. If you intend to work with an uncontrolled temperature iron (like 25 or 40 watt), just stop and pursue another hobby. Without the correct tools, all you will do is cause damage. The correct tools cost some money, but they are not terribly expensive either. Besides, with the right tools you will actually enjoy what you are doing.
-Chris
I feel more strongly. If you use any replacement brand of semiconductor, you may as well throw gasoline on it and throw a match at it. NTE and ECG are very poor quality and you don't even know what the real part number they used is.
You can find the specs for those parts, then find current replacement numbers that will work, can be matched and has expected characteristics.
An old scope wouldn't hurt an amplifier. Maybe the scope ground got involved with the wrong point in the circuit? I started with a 500 KHz Stark tube 'scope, recurrent sweep only - no trigger. Was that ever fun to use.
The first thing you will find out is that there are no short cuts. Either you do it the right way, the best job you can do, or it's the wrong way (like using ECG / NTE / SK or whatever. There are no good replacement brand parts. Also, get used to the idea that fake markings are a real problem. Buy from authorized distributors like Digikey, Mouser, Newark, Allied ... you get the idea.
Cleaning fluid. Liquid tools. Use as little as possible and avoid spray delivery systems. A tiny dropper is all you need as it is the slip ring that is noisy, not the carbon track that used to have a protective coating on it that was just washed out. Oil the bearing while you are there. Single weight, no additive. 3n1 or sewing machine oil are not the right types of lubricant. Plastics require different lubricant, like a silicone or maybe lithium white grease. "Lubriplate" is a good general lubricant for plastics.
Use a controlled temperature soldering station with a grounded tip. There are some great digital display types that cost $90 - 120 CDN, all the same manufacturer. Weller is just expensive. If you intend to work with an uncontrolled temperature iron (like 25 or 40 watt), just stop and pursue another hobby. Without the correct tools, all you will do is cause damage. The correct tools cost some money, but they are not terribly expensive either. Besides, with the right tools you will actually enjoy what you are doing.
-Chris
Fortunately I did not have to replace the power transistors.
If I were in your shoes I'd probably try to find a similar (defective) amp and use it for parts.
Good luck
Johan
Hi Johan,
Without the ability to test transistors properly, or test for proper operation first, you are ill advised to do this. The only thing that is worse is to move parts from the good channel to the bad channel.
When does a donor unit make sense? When you need a special transformer or tuning cap. Cosmetic items for sure, but reusing any semiconductor that handles power is a very risky (read silly) thing to do. Besides, proper new parts don't often cost that much to begin with. Some old parts are known to fail in certain products and a better sub is the only way to really fix it reliably.
-Chris
Without the ability to test transistors properly, or test for proper operation first, you are ill advised to do this. The only thing that is worse is to move parts from the good channel to the bad channel.
When does a donor unit make sense? When you need a special transformer or tuning cap. Cosmetic items for sure, but reusing any semiconductor that handles power is a very risky (read silly) thing to do. Besides, proper new parts don't often cost that much to begin with. Some old parts are known to fail in certain products and a better sub is the only way to really fix it reliably.
-Chris
Hi Chris,
I was only referring to the power transistors, which IIRC are impossible to find and so are suitable equivalents. Also I assumed that it was already determined that at least one of them had failed.
As it is a repair for a friend I also assumed that getting it back to decent working order would be enough.
So in the absence of new suitable parts I suggested a suboptimal solution.
Totally agree with you about (not) using used parts and yes, too many assumptions...
Cheers,
Johan
I was only referring to the power transistors, which IIRC are impossible to find and so are suitable equivalents. Also I assumed that it was already determined that at least one of them had failed.
As it is a repair for a friend I also assumed that getting it back to decent working order would be enough.
So in the absence of new suitable parts I suggested a suboptimal solution.
Totally agree with you about (not) using used parts and yes, too many assumptions...
Cheers,
Johan
Hi Johan,
No problem. The newer products that On-Semi is making is just super stuff. They have included some of Toshiba's technology and are making some of the best parts available.
15 or so years ago I had a solid contact for Japanese parts. Not once had I ever received a fake from him. But as soon as he shut down his business, buying Japanese parts became impractical except for special circumstances. The stock i have left is dwindling, but the On-Semi parts are replacing the those. I am now a solid On-Semi fan. Fairchild also makes superb products.
-Chris
No problem. The newer products that On-Semi is making is just super stuff. They have included some of Toshiba's technology and are making some of the best parts available.
15 or so years ago I had a solid contact for Japanese parts. Not once had I ever received a fake from him. But as soon as he shut down his business, buying Japanese parts became impractical except for special circumstances. The stock i have left is dwindling, but the On-Semi parts are replacing the those. I am now a solid On-Semi fan. Fairchild also makes superb products.
-Chris
Thank you all for your help. I did find the exact part so I will be replacing them with the same parts that came out of them. I do indeed have a temperature controlled soldering Iron. My son bought me a digital storage scope for my birthday, nice to have one. I didnt know replacement parts were cheap and/or low quality. I do intend to do the right job, no short cuts. Thanks for your help again!
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