Extremely glad I stumbled on this! Recently picked up a Kenwood KR-6600 that also needs a good cleaning and is having problems with one channel. First time restorer here, so this video is so helpful! Well done, and I’ll certainly be subscribing
Greetings! I have the 6030 in at the shop to get my Left channel back, I am really looking forward to getting it back and hooked up. YUP u gotta get the dust out so rcvr will be better able to dissipate heat. these have a nice weighted tuning knob. The style is SO much nicer than the sleek black units. I think the only REAL issue is a lack of beefy contacts in the power switch. I just took the sw. out of the circuit and plug into a power strip. some have wired a 120 v a.c. relay coil to the contacts and the contacts to turn on the primary winding of the transformer. Dude, I wish you well with this project. I believe you will be very pleased when you get it working.
Now this is right in my comfort zone! This is the sort of thing I'm used to tinkering with. I've got a Trio KR-6400 receiver. I fished it out of a skip on the day Michael Jackson died. I took it home, dragged a damp cloth across it and pressed it into service as my main amp for the next 9 years. During that time I dismantled it and cleaned all the pots. Eventually though, the sound became intermittent again and this time it was because of dirt in the tape monitor switches. These aren't as easily cleaned because they're pretty much sealed. Having several other working amps lying around, I substituted one of them and intended to sort the Trio out when I got round to it. Three years have now passed and though the Sherwood receiver I'm using is ok, it lacks facilities and doesn't get that last ounce of quality from a signal like the Trio did when it was healthier. You put me to shame. I'm a lazy, lazy man... The point of all this is if you're chasing the missing channel fault, I suspect it could be the press buttons for tape monitor. I'm kind of hoping so anyway because then you can figure out how to clean the sealed swiches (they're probably similar to mine) because I can't see how to get inside them without damaging them and I don't fancy trying to source replacements...
Like the Pioneer you restored, this one was also purchased at a US military "Exchange Post" as indicated on the rear. Looking forward to the next video.
Manuel, if I were you, I would deal with the dead channel first of all, so that you can set the power supply to normal operating conditions. I'm also thinking it should be the relay contact, or the Monitor switch, as a shorted power transistor would instead give a loud hum, and prevent the relay from closing. I've been dealing with a Kenwood receiver these days too, older though: a TK 140 from 1968. It came out nicely, very powerful.
About that power switch: the dark brown and discolering of the metal suggests to me that the both parts of the contacts have been very hot due to contact resistance. The inrush current for the two electrolytes could have anything to do with that, it could damage the surface, and raise resistance. I would try to add some spring to add tension on that contact. First thing I do when one channel is out is to get my fingers over every contact of the input switch at a low volume, listening for the hum coming through. It is just a habit for quick result. If no hum, the pre-amp or power amp is at fault, and then I try the same on the inputs of PCB for the power amp. Takes 30 seconds, and shows a lot. The other switches.... difficult to clean, I feel sorry for you now, getting trapped in this dust bowl from the '70. I use a Marantz here since that period, with an open multi deck input switch, it fails horribly. And taking it apart is not really an option.
I did adjust the tension of the switch to make the contact stronger when activated as it was a little loose. Opening up switches is a real pain, but sometimes there is no alternative.
Given the internal state of that power switch I'd be inclined to add an inrush limiter to it, and maybe even add a small ceramic cap in parallel with the switch contacts to damp the sparking.
I have the same switch on my Pioneer SX-450. That power switch issue is common; it's a shame that Alps doesn't make them anymore, as many old receivers could use new ones.
Greetings, I just picked up a Pioneer sx650 a nice unit pushing 35 per channel. I would not expect that issue from a receiver. I took the sw. out of the circuit and plug the receiver into a power strip. I have heard of others wiring a 120 v relay's coil to the sw. when energized the relay's contacts turn the unit on.
I wonder could the Radio board was replaced with a board using a Silicon Labs Radio Chip and replacing the tuning capacitor with a tuning pot and powering it of a LM7803 to upgrade the AM and FM reception?
Interesting receiver Manuel and the dust, so much dust. I'm interested to see the fault in the one channel but most interested to see what the FM tuning issue is, no doubt you will nut it out, thanks Manuel 👍🙂
This is a really interesting one! I am eager to learn just what is the cause of the missing audio. How did you fix the fuse holder issue? Photos? I have a Pioneer SX-939 that has died on both channels. Don't have the equipment, money, or time to work on it...really wish I could get it working again though. Like the one you have, the Kenwood in this series, mine is a really nice unit and sounds great when working!
Just discovered your channel and I have enjoyed it very much. Question: With an old, poorly kept receiver like this one, why didn't you check for DC offset issues before you plugged in speakers? (Or did I miss that step?) Cheers! 👽✌️ Also, that's not dust all over that receiver. This amp was owned by a heavy smoker. 🤮
I guess I'll never understand why techs would power an unknown condition amp with speakers OR loads connected even with current limiting. Initial power up of a solid state power amp should always be done sans load or speakers with bull limiter and Variac while monitoring the dc output with a volt meter. Speakers could easily be fried with even a 40V B+ supply. Also the power supply could be overtaxed by a short.
As I said in the intro, the owner said the one channel was not working, hence the other was, hence he had the amp powered up very recently without any major fireworks.
@@electronicsoldandnew Sorry sometimes my demented sense of humor boomerangs on me. I do enjoy your channel you've actually gotten me to appreciate German radios don't think I'll ever work on one the prices are too high.
Extremely glad I stumbled on this! Recently picked up a Kenwood KR-6600 that also needs a good cleaning and is having problems with one channel. First time restorer here, so this video is so helpful! Well done, and I’ll certainly be subscribing
Welcome to the channel. Good luck with yours.
Greetings! I have the 6030 in at the shop to get my Left channel back, I am really looking
forward to getting it back and hooked up. YUP u gotta get the dust out so rcvr will be better
able to dissipate heat. these have a nice weighted tuning knob. The style is SO much nicer
than the sleek black units. I think the only REAL issue is a lack of beefy contacts in the power
switch. I just took the sw. out of the circuit and plug into a power strip. some have wired a
120 v a.c. relay coil to the contacts and the contacts to turn on the primary winding of the transformer. Dude, I wish you well with this project. I believe you will be very pleased when you
get it working.
👍
After watching that I am compelled to pull out my old receiver and given a thorough cleaning... thanks.
😊
Now this is right in my comfort zone! This is the sort of thing I'm used to tinkering with.
I've got a Trio KR-6400 receiver. I fished it out of a skip on the day Michael Jackson died. I took it home, dragged a damp cloth across it and pressed it into service as my main amp for the next 9 years.
During that time I dismantled it and cleaned all the pots. Eventually though, the sound became intermittent again and this time it was because of dirt in the tape monitor switches. These aren't as easily cleaned because they're pretty much sealed. Having several other working amps lying around, I substituted one of them and intended to sort the Trio out when I got round to it.
Three years have now passed and though the Sherwood receiver I'm using is ok, it lacks facilities and doesn't get that last ounce of quality from a signal like the Trio did when it was healthier. You put me to shame. I'm a lazy, lazy man...
The point of all this is if you're chasing the missing channel fault, I suspect it could be the press buttons for tape monitor. I'm kind of hoping so anyway because then you can figure out how to clean the sealed swiches (they're probably similar to mine) because I can't see how to get inside them without damaging them and I don't fancy trying to source replacements...
👍
Like the Pioneer you restored, this one was also purchased at a US military "Exchange Post" as indicated on the rear. Looking forward to the next video.
thanks
Always loved those silver faces. Altho my receiver's more esoteric...mine's a 1965 Fisher 800C
👍
An interesting project, I'm not sure that I'd know where to start on this, but I'm sure that you will sort everything in you usual excellent manner.
I’ll certainly try 😊
Manuel, if I were you, I would deal with the dead channel first of all, so that you can set the power supply to normal operating conditions. I'm also thinking it should be the relay contact, or the Monitor switch, as a shorted power transistor would instead give a loud hum, and prevent the relay from closing. I've been dealing with a Kenwood receiver these days too, older though: a TK 140 from 1968. It came out nicely, very powerful.
I agree.
00:17 "...a new project ... which ... should be a short one ..." ! See you after many hours... 😊
Yes, you understand perfectly how these things go 😊
About that power switch: the dark brown and discolering of the metal suggests to me that the both parts of the contacts have been very hot due to contact resistance. The inrush current for the two electrolytes could have anything to do with that, it could damage the surface, and raise resistance. I would try to add some spring to add tension on that contact.
First thing I do when one channel is out is to get my fingers over every contact of the input switch at a low volume, listening for the hum coming through. It is just a habit for quick result. If no hum, the pre-amp or power amp is at fault, and then I try the same on the inputs of PCB for the power amp. Takes 30 seconds, and shows a lot.
The other switches.... difficult to clean, I feel sorry for you now, getting trapped in this dust bowl from the '70. I use a Marantz here since that period, with an open multi deck input switch, it fails horribly. And taking it apart is not really an option.
I did adjust the tension of the switch to make the contact stronger when activated as it was a little loose.
Opening up switches is a real pain, but sometimes there is no alternative.
Looks like an intetesting project.Thanks for the look.
👍
Given the internal state of that power switch I'd be inclined to add an inrush limiter to it, and maybe even add a small ceramic cap in parallel with the switch contacts to damp the sparking.
👍
Those dreams are free Manuel, shame restorations are not ! :-)
I have the same switch on my Pioneer SX-450. That power switch issue is common; it's a shame that Alps doesn't make them anymore, as many old receivers could use new ones.
👍
Greetings, I just picked up a Pioneer sx650 a nice unit pushing 35 per channel. I would
not expect that issue from a receiver. I took the sw. out of the circuit and plug the
receiver into a power strip. I have heard of others wiring a 120 v relay's coil to the sw.
when energized the relay's contacts turn the unit on.
👍
I wonder could the Radio board was replaced with a board using a Silicon Labs Radio Chip and replacing the tuning capacitor with a tuning pot and powering it of a LM7803 to upgrade the AM and FM reception?
That’s a little radical for this set 😊
This device looks a little bit like an electronic ghost town. Good luck for your way through it.
True. Thanks.
Interesting receiver Manuel and the dust, so much dust. I'm interested to see the fault in the one channel but most interested to see what the FM tuning issue is, no doubt you will nut it out, thanks Manuel 👍🙂
👍
I have similar one to finish. During desoldering boards I broke the frequency selection string... I hate fixing it ;-)
Not a fun task, I know
I'm guessing the dust may have killed the channel!
probably 😊
I have my dads Kenwood KR-3010 to try and fix up .
Get into it. It’s worth it.
I have the same unit and it's completely dead. Not sure where to begin on repairing it.
This is a really interesting one! I am eager to learn just what is the cause of the missing audio.
How did you fix the fuse holder issue? Photos?
I have a Pioneer SX-939 that has died on both channels. Don't have the equipment, money, or time to work on it...really wish I could get it working again though. Like the one you have, the Kenwood in this series, mine is a really nice unit and sounds great when working!
I soldered the fuse holders temporarily while I wait for new parts to arrive.
That Pioneer of yours is a beauty.
Just discovered your channel and I have enjoyed it very much.
Question: With an old, poorly kept receiver like this one, why didn't you check for DC offset issues before you plugged in speakers? (Or did I miss that step?) Cheers! 👽✌️
Also, that's not dust all over that receiver. This amp was owned by a heavy smoker. 🤮
I normally check, but can’t remember if I reported that on this video. It was some time ago.
It's the relay switch
I have a choice between a kenwood kr6030 or a sony str6800sd , any thoughts?
I’m afraid I haven’t had any experience with the sony.
I guess I'll never understand why techs would power an unknown condition amp with speakers OR loads connected even with current limiting.
Initial power up of a solid state power amp should always be done sans load or speakers with bull limiter and Variac while monitoring the dc output with a volt meter.
Speakers could easily be fried with even a 40V B+ supply.
Also the power supply could be overtaxed by a short.
As I said in the intro, the owner said the one channel was not working, hence the other was, hence he had the amp powered up very recently without any major fireworks.
I see a loose fuse holder in your pic
yes, mentioned in the video
Manuel, Don't jinx yourself you never know you might have to rebuild coil in the FM portion, sorry I couldn't resist.
HaHa.
@@electronicsoldandnew Sorry sometimes my demented sense of humor boomerangs on me. I do enjoy your channel you've actually gotten me to appreciate German radios don't think I'll ever work on one the prices are too high.
Your sense of humour is very welcome here. 😊
I know its heresy but I wash these units in the sink and blow dry. Never had an issue.
Be careful with coils retaining moisture.
You'll probably need to realign the FM discriminator.
definitely
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