Kenwood KR-2090, No Power

[babcoccl]

So picked up a Kenwood KR-2090 in really nice shape (except for no power) for $20 today in hopes that I can use it for my desk receiver in my office. I was hoping that it was the thermal fuse issue but continuity on the primary is in at 10.5 Ohms. So I don't think I got lucky on that front.
Checking the V at the primary and secondaries I actually hear a faint crackling (almost like someone picking the ends of a fine toothed comb) coming from the transformer and the primary ranges in between 0-1V with secondary running between 0-100mV.
Am I in search of a new transformer? I think so but just wanted to check with the experts. Thanks!

 

[babcoccl]

Update, I took the faceplate off, I'm trying to get to the power switch and turning the receiver on again, now that I can see the lamp, the lamp will flicker on and off. I'm reading other places that this might be due to a power switch issue.

 

[babcoccl]

Ok, hosed the power switch down with Deoxit and with the unit unpluged, worked the power switch knob back and forth about a dozen times. Plugged in and the lamp glowed up to near full-on before fading back into flickering. I'm thinking it's worth it to get the power switch disassembled but...looking at it I'm unsure of how to go about doing that. Am I looking at needing to desolder the switch housing from the board to get a good angle on it? Thanks.

 

[mbz]

Remove fuse Fm2. the main 2Amp fuse, then measure the AC voltage between the fuse holder tabs, careful, this is mains 117V?ac.
This should confirm that the switch is/not ok. Do you have a dim bulb tester? Try power up with it. Remote possibility is that there is
a significant current draw? Maybe tired main caps? or...

 

[babcoccl]

Remove fuse Fm2. the main 2Amp fuse, then measure the AC voltage between the fuse holder tabs, careful, this is mains 117V?ac.
This should confirm that the switch is/not ok. Do you have a dim bulb tester? Try power up with it. Remote possibility is that there is
a significant current draw? Maybe tired main caps? or...

Yup I have a dim bulb tester, was fine.
I removed the 2A fuse and measured across, power on was 122.9V.
Annnnd....after letting it sit overnight after hosing it with deoxit, while I was taking the above measurement, it fired right up when I flipped the power on. So problem resolved? While I have it in this state of disassembly should I be cleaning anymore of the power switch or anything?

 

[Watthour]

It would be best to remove and service the switch contacts. The flushing with Deoxit is only temporary. The switch should be able to be serviced without desoldering anything.

https://audiokarma.org/forums/index...e-help-with-this-kr-3090.389797/#post-4928545

 

[babcoccl]

It would be best to remove and service the switch contacts. The flushing with Deoxit is only temporary. The switch should be able to be serviced without desoldering anything.

https://audiokarma.org/forums/index...e-help-with-this-kr-3090.389797/#post-4928545

Thanks for the link, didn't know how to take this switch apart very helpful!
I opened it up and got the bar out etc. The switch contacts actually looked like they have a nice black finish on them so I started lightly scrubbing the wheel with the end of a micro screwdriver. Lo and behold there was shiny metal underneath. I found it harder to clean the "pinchers" ( not sure of the technical term for what grabs the wheel contacts but I got some 400 grit sandpaper between a few of them. Washed it again with dexoit and letting it dry out now. Thanks for the help!

 

[babcoccl]

Back in action, thanks for the help

Tuner sound is good, phono is a little light on treble and a little heavy on bass. Tuned the knows to about 2/3s treble and 1/3 bass to get it to sound balanced. Any suggestions for this (other than sound is personal preference) or should I call this a success and move on?

 

[Watthour]

Speakers can also color the sound, so your preference may be affected by more than the amplifier/receiver,

 

[babcoccl]

Speakers can also color the sound, so your preference may be affected by more than the amplifier/receiver,

Right, I used the same speaker, FM tuner sounded balanced with knobs at the middle, switching to Phono resulted in lots of bass little treble which required the adjustment.

Also, here's another question. Why doesn't the Stereo lamp illuminate when on Phono but does on FM Auto?

 

[Watthour]

The "STEREO" indicator is only used to identify stereo decoding from FM broadcasts. The other inputs to the unit (tape, phono, auz) obviously do not use the tuner, and are assumed to be two-channel. .

 

[Watthour]

My guess is that the phone preamplifier section of the 2090 could use a little attention, or the phono cartridge may be suffering. Does the table sound good through another amplifier? If so, the HA1457 ICs in the phono preamp and/or some of the surrounding components could be getting muddy.

 

[babcoccl]

My guess is that the phone preamplifier section of the 2090 could use a little attention, or the phono cartridge may be suffering. Does the table sound good through another amplifier? If so, the HA1457 ICs in the phono preamp and/or some of the surrounding components could be getting muddy.

Thanks for your help Watthour.

I fully disassembled the power switch (realized where the carbonation actually is, grey box) last night and actually polished the contacts. Looked like there had been a small fire in the box . Anyway, unit now powers on fine and stays lit and functions.

Problems I'm running into now:
- Unit sounds muddy as I had mentioned I'll look into what you had mentioned above (even worse than the BOTL unit it is)
- When volume is over 1/3 of the way up, the lamps will start "strobing" to the music (e.g. lamps dim at high hat crashes, loud entrances in the song, etc. etc.). I've searched the forums but might not be searching with the correct terms because I've come up empty.

Thanks again for the help.

 

[Watthour]

The dial lamps dimming with the more powerful sections of music program are indications that the power supply is lacking a bit. This could still be due to the power switch contacts being resistive, or it could be that you're pushing the unit to the limits of its power supply. Pioneer SX-450s and SX-550s exhibit this behavior routinely when there is actually nothing wrong - Other than the power supply is giving all it can to make a 15-20W output. It's becomes even more apparent if connected to power-hungry (lower efficiency) speakers.

The 2090 is in the same size class, so it could be a similar situation.

 

[sregor]

Dumb question - what turntable. If one of the newer ones with built in preamp, have to use an aux or tape input. If you use phono input with one of those, get very loud bassy and often distorted sound. Phono quality should be reasonably good.....

 

[babcoccl]

The dial lamps dimming with the more powerful sections of music program are indications that the power supply is lacking a bit. This could still be due to the power switch contacts being resistive, or it could be that you're pushing the unit to the limits of its power supply. Pioneer SX-450s and SX-550s exhibit this behavior routinely when there is actually nothing wrong - Other than the power supply is giving all it can to make a 15-20W output. It's becomes even more apparent if connected to power-hungry (lower efficiency) speakers.

The 2090 is in the same size class, so it could be a similar situation.

Well, I understand the concept but the speakers I'm trying to drive are powered bookshelf speakers, nothing that beefy so I wouldn't expect they would draw that much.

 

[babcoccl]

Dumb question - what turntable. If one of the newer ones with built in preamp, have to use an aux or tape input. If you use phono input with one of those, get very loud bassy and often distorted sound. Phono quality should be reasonably good.....

Both a pioneer PL-400 and a AT-LP60 the Audio technica is a modern one with built in pre-amp (but I switch it off when going to the receiver). Both produce the same results.