Kenwood KR-6030 vintage stereo ,Old Man Trying to Save a Buck

[Agent24]

I pulled up an interior picture of the 6030 and it looks like I am missing a fuse holder on the power board. Don't know what the guy who had it before me did other than he said he put a new plug and cord on it. Anyway I am plugging along. I'd appreciate any help or advice, or ... Cheers!

The F2 fuse holder is not missing, it was never there to begin with.
The schematic shows F2 as connecting to nothing on one side (Pin 3 of the power board) so it is not used for your model. There will be some other model that uses it.
You will notice that Pin 3 next to F2 is not fitted either.
So that is not a problem.

F3 next to it is the fuse for the dial lights, it seems. It should be a 1 Amp fuse.

F1 is beneath some wires and is the mains side fuse. It should be a 6 Amp fuse.
I would check to see if it is blown, if nothing works, even after cleaning the switch.

Note that this fuse holder has a direct connection to MAINS via the neutral side, or what is supposed to be neutral, assuming you have a polarised and correctly-wired mains plug.
So be very careful around the power supply board and especially that F1 fuse holder when the set is plugged in!

[DrDos]

Thanks Agent24, That info is awesome. I get nothing when I try to fire it up. I currently only have an analog meter but will try to see what I get looking for the voltages. I'm glad the ceramic is still good it looked kinda fried on one side. Leme get to checkin the power board, oh and the relay yes, it's the one that is supposed to click just after turning the unit on speaker safety I guess. Thanks

[DrDos]

I wonder, if it is the switch (on/off - speakers) I have a single pull single throw 250v switch to use to bypass the carbonized points in the current switch, although I cleaned the switch and I show continuity from 0 to 100% by turning the unit on (not plugged in). Would that work? I'm going to test the supply board now. Thanks

[DrDos]

Well tough job. Pin 8 seems to have something like 40 to 45 volts. Pin 11 seems to show closer to 72 volts. Having a hard time finding pin 5 but none of the pins on that side shows less than 10volts and 3 are. OMG I was just poking around the side of pins and the lamps all lit up. I now have a lighted dial and have no idea what I did. Any thought or maybe something else to check?

[DrDos]

Okay so now the lights come on but if I move the reciever around on the table they go off and on like there is a short. Unsure how to check that.

[DrDos]

When the lights came on I decided it was time for a digital meter. Since they go on and off just from moving the stereo around I think the problem lies in the on/off switch but that wouldn't explain why the relay doesn't click soon after you turn it on.

[DrDos]

Sorry for all the posts. Do you notice anything wrong with the switch that stands out to you? Question: There are 3 wires that hook up to the switch and provide headphones. There is a broke resister on one of the wires. Can I disconnect al the wires for the headphones and still have the unit work? It will take me some time to get a resister. What I mean by broke is that one of the wires coming out of the resister is broken right at the end of the resister itself. No room to solder it back on. I appreciate your advice. At least things are starting to happen now.

[Agent24]

When the lights came on I decided it was time for a digital meter. Since they go on and off just from moving the stereo around I think the problem lies in the on/off switch but that wouldn't explain why the relay doesn't click soon after you turn it on.

Bad connections somewhere, could be the switch, could be old and cracked solder joints (very likely for something this old).
I would check the underside of that power supply board, you may find a lot of joints that need re-soldering.

The relay not coming on could be a lot of reasons, including, yes, bad capacitors.

I think the first thing here is to get the set into a state where it can turn on and stay on, then you can start checking all the DC voltages and make sure they are okay.

[Agent24]

Sorry for all the posts. Do you notice anything wrong with the switch that stands out to you? Question: There are 3 wires that hook up to the switch and provide headphones. There is a broke resister on one of the wires. Can I disconnect al the wires for the headphones and still have the unit work? It will take me some time to get a resister. What I mean by broke is that one of the wires coming out of the resister is broken right at the end of the resister itself. No room to solder it back on. I appreciate your advice. At least things are starting to happen now.

The switch looks okay but I can't see the contacts very well from that angle.
I also can't see a broken resistor either.
What part did you clean?

The headphone circuit being attached or not won't affect the ability to power on etc.

The switch is actually two switches.

There is the rotary part at the front which selects between headphones and speaker outputs,
And the mains power switch which I expect is inside the grey rectangular part underneath.

The rotary part should not affect power to the unit, it could just cause problems with audio at the outputs.

However, there seems to be a connection between this switch and part of the regulator circuit for the 14V rail.
So this switch might also control that rail, but it only seems to feed the radio tuner section.

So if you are having problems with the dial lights coming on and off, you have other problems unrelated to the rotary part of that switch.

[DrDos]

Now that I have a digital I get 38v on 8 and 38v on 11. The dial lights are on. Checking the speakers out I get 0.0 looking for AC in the lines and 0.0 using a DC check. I'm going to hook up speakers and see what happens. Thank you very much for your help I really appriciate it. I do have a smell coming from it. It's not a burning smell really but like someone left the iron on for a while. Nothing seems to be getting hot.

[DrDos]

Dial lights come on now when I turn the unit on. I just disconnected the wires for the headphones, I don't use them anyway. I'm going to check speakers.

[DrDos]

Well, The on/off switch is a little funky in that lights will fluctuate on and off as I turn the switch. They stay on if I leave the switch alone. The tuner is working. I get signal and the other meter zeros in but I get no sound from the speaker connections. Is it AC or DC that comes out when sound is working? I haven't found pin 5 yet to test. Checking on problems with these recievers there was mention of faulty regulators Q1 2SC789 and 2SD526. I know nothing about these regulators but at least we have power, lights and new posibilties. Again I really appreciate your help with this. Looking forward to next instructions.

[DrDos]

Okay, the set turns on and stays on. Had it on for over an hour. I found pin 5 and there is not a wire connected to it. Lights only fluctuate when I mess with the switch. Ready to start checking DC voltages tomorrow. Is there a system I can follow? Cheers!

[DrDos]

Well, I am resoldering the boards. Finished the power board and tone control board also the speaker board. Undoing the bootm and will do the tuner board next. Unfortunatly working on the tone board I broke one of the potentiometers and have to wait till my retirement income comes in to purchase another. Anyway, if a solder joint even looked at me wrong it got redone so we'll see. It's going to take more time and I will have to get a solder sucker now. I also have to order some fuses since I have 10amp fuse where a 6amp is required and a 3amp where the 1amp is required. I also have a 10amp where the incoming power connects. I am unsure but I think it should be a 15amp instead of 10. Well, back to soldering, cheers!

[DrDos]

Well well well, I put it back together and not only did the relay click but I am listening to some great ROCK music. Not all the outputs are working though but I have the right side of B working. I just can't thank you enough for your help. I will post about that in the appropriate forum area or ask the guy running this show. Cheers!

[Agent24]

Great to hear! Bad solder joints are very common in old amplifiers (and many other electronics) due to the age and heat cycling.

The fact you only get one channel working could be something to do with the speaker selector switch, or maybe one channel of the amplifier is bad, or something else.

[DrDos]

I'm going to order new caps for the power amp board and the speaker board where the relay is. Gonna change the lamps also. There are four transisters. If one was bad would that knock out the A side of the speakers? What would you do next if you were working on this reciever?

[Agent24]

I'm going to order new caps for the power amp board and the speaker board where the relay is. Gonna change the lamps also. There are four transisters. If one was bad would that knock out the A side of the speakers? What would you do next if you were working on this reciever?

Bad caps won't (generally) give you no audio output at all, unless one is gone open-circuit in the audio signal path, for example.
Normally you get other issues, like distortion, low output, etc.


Well, I would check the speaker selector switch to begin with.
Test continuity to the A-output to the Right channel and see if there is a connection.

You said you got signal from the Right channel on B-output.
So that proves the power amp is working at least on the Right side.

If you can't get anything from Right side A-output, that is probably the switch, or something wrong between the switch and the speaker terminals.

The left channel not working is a bigger issue, as that could be anything, at this point.


I assume the only test tool you have is the multimeter?

[DrDos]

Ill have to be honest. I did all kinds of cap research, writing down numbers values and size to order and buttoned the thing up and put it on a shelf. I'm gonna take it out again because (and this is really strange) I noticed as I was buttoning it up there was a wire connecting a black speaker output A (negative) to red speaker output B (positive). It was soldered in place like it belonged there. Well, this didn't make any sense to me. It seems to me it would short the speaker out or something. I could understand red to red or black to black but not this. Unfortunetly I forgot about it after I removed the wire so I didn't check it out. Now I will open it up again, turn it on, and see if I get any AC out of the side A. If not I will attempt to read the schematic to find what wires go from switch to where? I will keep you informed. Thank you for your help.

[DrDos]

Well now I get nothing, no sound, Relay clicks but then I think it clicked off. I guess it's in the switch. I will have to find a replacement if it is at all possible. I'll do some more investigating on the switch.