Kenwood KD-3070 Is there a way to test the motor?

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snavarre
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Kenwood KD-3070 Is there a way to test the motor?

Post by snavarre » 03 May 2019 16:16

Hi, I recently picked up a Kenwood KD-3070 Direct Drive for $5 at a thrift store. It's missing the cartridge and headpiece. It powers on, the strobe lights up, but the motor won't spin. I can hear a slight high pitched tone coming from it when I hit the 33 and 45 speed buttons. I tried dropping some oil in the oiling hole. Still won't work. The motor spins freely. I took the bottom off the deck off and see accessing the motor itself doesn't look too difficult for someone like me. Is there a way to test it? I'm on the fence whether to restore this or sell it for parts or as a fixer upper. I see what was advertised as a replacement motor just sold on eBay for under $20 with shipping, but the motor sold had a slightly different part number than I see in the service manual. Currently I can't find any other motor listings. Thanks in advance!

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by Coffee Phil » 03 May 2019 17:33

Hi snavarre,

Welcome to the forum.

The service manual is on this site: https://www.vinylengine.com/library/ken ... 3070.shtml

Sadly there is not much on the internals of the motor. You can check the power supply to the motor and the wiring to the speed switch and user controls.

You might look at the manual of the KD 500 the motor may be similar and that manual has the schemo of the motor internals. Even with the manual fairly advanced knowledge of electronics will be required.

If the power supply and switch wiring checks out eBay of Organ Doner (https://organdonorparts.com/) may be your best option.

Phil

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by snavarre » 03 May 2019 17:56

Thanks, Phil! I've been lurking here for a month or so. Cool site. Have been a vinyl nerd for a long time running a Pioneer PL-510a most of the time. I recently picked up a used Philips GA-212 and this site helped me get it going again. It sounds great! Thanks for the recommendations on the manuals and organ donor site. Had never seen that site. I've already checked out the manuals. That's how I figured out the motor I mentioned on eBay had a slightly different part number even though it was listed as the one for the KD-3070. The motor looked the same, but the circuit board i believe is different. I think next I need to actually take the motor out and put my eyes on it as as you mentioned see if another would be compatible. Much appreciated!

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by snavarre » 05 May 2019 19:29

I just found a motor on eBay that's listed as one for a Kenwood KD-2070, but the part number is the same. T43-0009-05. Yay!

I figured out why the motor won't work. Completely roached out and leaked somehow!

https://photos.smugmug.com/Kenwood-KD-3 ... Ntj-XL.jpg

https://photos.smugmug.com/Kenwood-KD-3 ... RJK-XL.jpg

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by snavarre » 22 May 2019 20:16

Thought I'd finish off the story in case it can help anyone else with one of these turntables. Well, the KD-2070 motor did indeed fit and works great. (Was $27 with shipping) As I mentioned above it was missing the headpiece and cartridge, but luckily I discovered the set I had on spare Pioneer PL-510A from about the same time period uses pretty much the same setup, so I swapped it out. Another issue I was having was getting the tonearm to lift and return either when hitting the Cut button or when it reached the end of a side. I happened to be looking through the manual I downloaded here for instructions on setting up the tonearm tracking weight, etc., and there was a diagram that showed the plastic arm that's supposed to control this action. Somehow it was on the wrong side of the stopper. (I believe this turntable was dropped by someone prior to me buying it) So, I put it in the correct position as shown in the manual and *bingo* it works a it should! I've had it hooked up to a Kenwood KD-4400 (I picked up for $5) via BSR EQ-3000 and big 80's Infinity speakers. Wow. Fantastic sounding! Another discarded turntable comes back to life.

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by Coffee Phil » 23 May 2019 18:41

Hi snavarre,

I'm glad this story has a happy ending!

That motor looks too nice to dump into the bin. It reminds me of the outer rotor hysteresis synchronous motor in my R-O-K Rondine 2. Maybe I'm weird but I think those motors are a thing of beauty. The components on your board make me believe that the circuit is very similar to that in my Kenwood KD 500. I see a little RF oscillator coil to generate the RF signal used to commutate the motor. Your circuit board is much larger than the one in the KD 500 and looks to have about the same amount of sand so it is much more neatly laid out. The KD 500 has the more conventional inner rotor.

Phil

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by snavarre » 24 May 2019 05:19

Phil, thanks for taking the time to respond. :-)

The motor is cool for sure. Is it common one would corrode like that? I have not thrown it away, but the downside is the rust colored stains it leaves on everything it touches. And I'm not sure what it's leaving behind. lol Reminds me of when a battery goes bad. Seems really odd the motor would be completely bombed out like that, but the rest of the underside looks really clean. Go figure! Still some cleaning up to do to the exterior, but I'm a happy record playing camper. 8)

Best, Steve

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by Jim Leach » 27 May 2019 03:05

Good save!

Looks to me that something was spilled in there...

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by poutrew » 27 May 2019 06:21

You know, you might want to be careful with that old motor. That yellowish - orange color reminded me of leaking PCB - polychlorinated biphenyl. I have no idea how it got into the motor, or what part might it might have leaked from , but you want to tread very carefully if indeed it is old PCB because it is toxic... :(

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by snavarre » 28 May 2019 21:14

Thanks! Yeah, I'm not going to mess around with it. It's truly weird in that it's all contained inside the motor housing with no sign of any liquid or rust color anywhere else. So happy to have it working with the new motor...

Next project: Fixing the 5 pin DIN cable on my Philips GA-212 because there's a ground hum in the right channel that will not go away anymore. But that's a thread for a different day... :-)

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by snavarre » 08 Dec 2019 18:51

I can't get the 45 RPM speed calibrated with this motor. 33 1/3 is right on. I'm using the adjustment pot via the bottom of the unit. No matter how I turn the screw and the nob on the top it won't synch up with the strobe. Any ideas? Thanks.

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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by Coffee Phil » 10 Dec 2019 18:29

Hi snavarre,

There is a service manual here: https://www.vinylengine.com/library/ken ... 3070.shtml however it doesn't show the internals of the motor. I'm guessing it is similar the circuit in the KD500 which is also in the library. The motor is physically different however as you have the external rotor motor.

When you say you can't adjust the speed on 45 do you mean that the pots run out of range or that they are too erratic?

Phil

snavarre wrote:
08 Dec 2019 18:51
I can't get the 45 RPM speed calibrated with this motor. 33 1/3 is right on. I'm using the adjustment pot via the bottom of the unit. No matter how I turn the screw and the nob on the top it won't synch up with the strobe. Any ideas? Thanks.

snavarre
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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by snavarre » 10 Dec 2019 19:46

Phil, yes. The pots run out of range. I've read others have maybe tried cleaning it? Thank you.

Coffee Phil
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Re: Kenwood KD-3070 Is there a way to test the motor?

Post by Coffee Phil » 11 Dec 2019 02:11

Hi snavarre,

It the speed is too low that means the total resistance in the timing circuit is too high. If the speed is too fast the total resistance is too low. For each speed there is the user pot, likely a trim pot on the motor board and a fixed resistance. Check all of the 45 components and if any are off value replace it. If they are all correct you can make a change in the fixed resistor to center the user pot and trim pot.

Phil
snavarre wrote:
10 Dec 2019 19:46
Phil, yes. The pots run out of range. I've read others have maybe tried cleaning it? Thank you.

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