It's so nice to have these videos to guide us through difficulties with units like this. I have this model on the way for a coworker who has no stereo and wants one for Xmas. Doesn't give me a whole lot of time. I appreciate your invaluable help! I have no idea what I'll find when I begin testing his unit. Thank you so much!!
Was my first amp in the 80's and i miss him till today ... Same problem, burned transistors AND the bulb ... Brings back so much good memorys ... Thank you ! Greets from Germany, stay safe.
Nice story behind this amp ... A friend had a Corvette Stingray with a bad engine ... I gave him this amp and 4000 German Mark for the car in 1984 ... lol Loved the Stingray also ...
Just picked up a Kenwood KR 720 , sounds great but has issues with indicator lights . Took it apart but couldnt really see any bulbs staring at me so I bailed and put it back together . Now I can see why but Im thinking I better just live with it . You are light years ahead of me as far as audio tech. Thanks for the reality check though.
Rob, thanks for this video, I was looking to pick one of these up and wanted to see what I may be up against. It seams that components that get warm/hot do eventually have solder joint issues. Heck even old Volvo's 240 series with overdrive had issues with their Siemens O.D. relay un soldering themselves. (ask me how I know) LOL
I just bought one of these recently. The left side is not as loud as the right. There's probably a 30% difference between each side. I get the same thing with headphones. What parts should I be looking at first?
Hello!! Is it complicated to replace the tuner bulb? I found a KR-710, is really similar to yours. I remembered the red and green light but it just the first one that turn on.
Rob...I just found this excellent video. What a wealth of info...thank you! I bought this exact receiver in Aug 1982 when I moved into my freshman dorm. It's been in my basement for a number of years, but I recently re-foamed the Cerwin Vega speakers (purchased with the Kenwood amp) and hooked it up to see what would happen. It still works and the radio sounds great, but there are a few issues that maybe you have some thoughts on: 1 - when I plug rca's into either of the tape ports, they are very, very quiet, and have a slight hum when turned up. 2 - when I plug rca's into the phono port it's the opposite, plenty of volume, but noisy and crackly. 3 - the power lights only light at very high volume and mostly on the right. But maybe the most important question is: should I be afraid to use it with the original caps in it? Do they need to be changed? Any thoughts you have would be greatly appreciated, as you are significantly more knowledgeable than myself. Great video. Best
The phono input is 1/10 the level that the tape-in is at so it will be very loud ( and distorted ) if used for input from a phone or Bluetooth player. The tone-amp (the first stage from the tape-in) is probably working because the phono preamp and the stereo goes through it too. So it would be between the tape pushbutton switch and the audio input device. Test the audio input device by plugging it into some with an aux in. The curious part here is that it is both channels so that if it was a bad cap or a bad solder joint it would have to be bad luck to be both. Make sure you're using tape-in and the tape switch is pressed:-) Otherwise borrow a scope and trace the signal from the input through the device and see where it disappears. If I remember right the bulb on the dial indicator had an effect on the power meters but I go though that in the video.I would figure out what is causing the problem first and then change the caps. Also do a close close inspection for solder joint problems on the power section of the amp. Good luck!
@@RobsFixitShop Rob, Thanks so much for the reply. I did figure out that the phono was not going to be a reasonable input from my aux cord (hd projector), but the tape seems to working nicely after playing with the volume on the input and receiver. I will check all of the solder joints. If all sounds good and looks good should I be worried about using the receiver without replacing the caps?
It's so nice to have these videos to guide us through difficulties with units like this. I have this model on the way for a coworker who has no stereo and wants one for Xmas. Doesn't give me a whole lot of time. I appreciate your invaluable help! I have no idea what I'll find when I begin testing his unit. Thank you so much!!
Thanks for the overview! You helped me replace the bulb on the tuner.
Great to hear!
Very cool project! Also liked the KR-4200!
Thanks, I use it up in my wood shop!
Was my first amp in the 80's and i miss him till today ...
Same problem, burned transistors AND the bulb ...
Brings back so much good memorys ...
Thank you !
Greets from Germany, stay safe.
Nice story behind this amp ...
A friend had a Corvette Stingray with a bad engine ...
I gave him this amp and 4000 German Mark for the car in 1984 ... lol
Loved the Stingray also ...
Just picked up a Kenwood KR 720 , sounds great but has issues with indicator lights . Took it apart but couldnt really see any bulbs staring at me so I bailed and put it back together . Now I can see why but Im thinking I better just live with it . You are light years ahead of me as far as audio tech. Thanks for the reality check though.
Nice showing" how to" repair on a stereo unit. Glad you showed it!
Great done
I got the kr710 and i like them very much 👍
How do you remove the tuner bulb holder? I don't see clips or fasteners. Thank you!
I have my original from '81. Can you fix mine????
Thanks a ton Rob, indeed very useful and I do have the same unit with same problem. Thanx again
Rob, thanks for this video, I was looking to pick one of these up and wanted to see what I may be up against. It seams that components that get warm/hot do eventually have solder joint issues.
Heck even old Volvo's 240 series with overdrive had issues with their Siemens O.D. relay un soldering themselves. (ask me how I know) LOL
I like the sound, I have it up in my wood shop.
Although NFB will kind of fix it, output transistor beta ideally should be matched. For Darlington transistors, beta1 x beta2 = beta3 x beta4.
nice work
I just bought one of these recently. The left side is not as loud as the right. There's probably a 30% difference between each side. I get the same thing with headphones. What parts should I be looking at first?
Rob could you help me with my kenwood kr-v 7020 I need it fixed. Hit on button and it just clicks continuously
where can i get mine repair its not turning on
I had this amp early 80s....loved it...untill i got nad amp and tuner...with some cerwin vega 12 inch speakers...and made some noice...lol
nice work :), i see a weller soldering station on the table, can you tell me the model, it is somehow WECP-20? Thanks.
It is a wes51 and I really like it. I've had for many years and it still works like a champ.
i love mine but the only thing wrong the high speed red light only work when the volume is half way and louder
hello sir can ask where you get the diagram of that
I put a link to a folder with the schematic and other stuff I used when I worked on it in the video description. Good luck!
Hello!! Is it complicated to replace the tuner bulb? I found a KR-710, is really similar to yours. I remembered the red and green light but it just the first one that turn on.
It's a little tricky to get it out. I replaced mine with leds
@@RobsFixitShop Yeah, that's what i thought. And now that you have pronounced the magic word "tricky" i think i can live with it the way it is xD.
Rob...I just found this excellent video. What a wealth of info...thank you!
I bought this exact receiver in Aug 1982 when I moved into my freshman dorm. It's been in my basement for a number of years, but I recently re-foamed the Cerwin Vega speakers (purchased with the Kenwood amp) and hooked it up to see what would happen. It still works and the radio sounds great, but there are a few issues that maybe you have some thoughts on:
1 - when I plug rca's into either of the tape ports, they are very, very quiet, and have a slight hum when turned up.
2 - when I plug rca's into the phono port it's the opposite, plenty of volume, but noisy and crackly.
3 - the power lights only light at very high volume and mostly on the right.
But maybe the most important question is: should I be afraid to use it with the original caps in it? Do they need to be changed?
Any thoughts you have would be greatly appreciated, as you are significantly more knowledgeable than myself.
Great video.
Best
The phono input is 1/10 the level that the tape-in is at so it will be very loud ( and distorted ) if used for input from a phone or Bluetooth player. The tone-amp (the first stage from the tape-in) is probably working because the phono preamp and the stereo goes through it too. So it would be between the tape pushbutton switch and the audio input device. Test the audio input device by plugging it into some with an aux in. The curious part here is that it is both channels so that if it was a bad cap or a bad solder joint it would have to be bad luck to be both. Make sure you're using tape-in and the tape switch is pressed:-) Otherwise borrow a scope and trace the signal from the input through the device and see where it disappears. If I remember right the bulb on the dial indicator had an effect on the power meters but I go though that in the video.I would figure out what is causing the problem first and then change the caps. Also do a close close inspection for solder joint problems on the power section of the amp. Good luck!
@@RobsFixitShop Rob, Thanks so much for the reply. I did figure out that the phono was not going to be a reasonable input from my aux cord (hd projector), but the tape seems to working nicely after playing with the volume on the input and receiver. I will check all of the solder joints. If all sounds good and looks good should I be worried about using the receiver without replacing the caps?
@@jjg825 I think it should be fine without a recap.
@@RobsFixitShop Super. Thanks! Cheers
JUST ONE QUESTION, IS IT REALLY WORTH IT TO RESTORE AND FIX IT, SINCE WE CAN BUY ONE ON INTERNET FOR JUIST $100.
I enjoy the adventure!
If You go the easy way, buy a new one. However, this is a great audio equipment.
Hi do you do repairs full time???
No, I just have fun trying to figure out how to fix things
I bought one and it also doesn’t work