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Luxman K-118 w/ New Belts Won't Play & Won't Make Sound!

Discussion in 'Tape' started by Johnny_Law, Jun 2, 2018.

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  1. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Put new belts in this, now it appears the flywheel is operating correctly, however the tape will not play. It will play very slowly if I squeeze the pinch roller against the capstan. Check out the short video I made.

    I'm at a loss. The pinch roller / head assembly appears to engage correctly. The pinch roller appears to get pushed against the flywheel shaft / capstan correctly. Everything else appears to work. The tape simply won't spin! First thought is to suspect the pinch roller itself, but it feels somewhat tacky (not hard / slick), just like the pinch rollers in a Technics player I have that works fine, so I'm not sure. I took a pic of it for good measure.

    I noticed that without a tape in there, the take-up reel does move slowly, and the pinch roller appears to rotate normally in contact with the capstan.

    FF/REW uses a different belt and a different gear mechanism and work great.

    Does this seem like a pinch roller issue to everyone, or suspect something else is going on?



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    Last edited: Jun 2, 2018

     

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  2. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Video added, showing the idler ass'y and the take up reel. This seems to be imparting some torque to drive the take up reel. Is this the critical torque for playback? Perhaps this is the culprit. However, I lightly sanded the idler ass'y's rubber belt, to no avail.

     
  3. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Well a trip to my local Ace yielded no good MacGuyver replacement rubber for the pinch roller or idler. Anyone have advice as to where to purchase replacements?
     
  4. Johnny_Law

    Johnny_Law AK Member Subscriber

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    So apparently it's just THAT TAPE that the player doesn't want to play. :crazy: I put in Dire Straits and it plays fine. I'll try a few more tapes and see what happens.

    However ... it won't make any sound. UNLESS I TOUCH THE HEAD WITH A SCREWDRIVER. I thought it was an alignment issue, so I went to adjust the screw, and lo and behold the sound popped in and out. Is this a symptom of a magnetized head? Time to do some research.
     
  5. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Well, the player likes Genesis too. I guess The Outfield isn't in Luxman's approved music list. :dunno:

    Measured the R/P head both channels are at ~220 ohms. Seems fine.

    So maybe the R/P head isn't GETTING the correct amount of power? I'm trying to make sense of the manual to figure out how to start going upstream looking for test points. All I can see is that there's supposed to be 0.25mV coming out of the RP head into the PB EQ AMP? And it tests at 0mV. Would love any help deciphering the manual and figuring out how to test this thing.
     
  6. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Well this old issue of Popular Mechanics is making me think the head is bad anyway:

    "A monaural cassette player will have only one R/P tape head, with two connections in the tape head. The stereo cassette player will have four lead connections going to the tape head. The shielded lead of the tape head connects to the ground or a grounded circuitry. You should hear a loud hum when the screwdriver blade touches the amplifier lead. [CHECK!]

    "Okay, now we have a loud hum noise indicating the amplifier is good, but the tape head is defective. Let's do another test, using the ohm-meter.

    "Unsolder the connecting lead from the tape head and connect the ohmmeter across the tape-head terminals. A normal resistance reading may be found from 100 to 800 ohms. [MINE IS 220 OHMS] Check both head terminals in a stereo tape head. When no reading is indicated, replace the tape head.

    "The defective tape head may have a continuity reading and still produce poor frequency response. When this occurs you may have a weak or tinny sound. [YES, WEAK!] It sounds as if the speaker is mounted inside a tin can. Check the tape head for excessive wear marks on the tape area's front surface. Replacement of the tape head is the only answer to poor frequency response."
     

     

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  7. hdrobien

    hdrobien Well-Known Member

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    Concerning the sound issue, the transport frame may need to be connected to ground (chassis). When in the chassis the ground connection is made through the screws.
     
  8. Tony75

    Tony75 Well-Known Member

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    Location:
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    Also with the sound, the wires connecting to the head can fail at the solder joint point. These will simply need to be re-soldered. Alternatively the other end of the head leads where they connect to the PC board may also need to be re-soldered as these joints also can go dry..
    Hopefully it is a simple thing like this.
    Cheers
    Tony
     
  9. rojoknox

    rojoknox Active Member

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    Greetings from RojoLand!

    I'm confused. The original complaint is that the tape wouldn't play except if the pinch roller is pushed against the capstan, and even then very slowly. Further, at least two other tapes played fine. Why are we messing with the head here?

    I saw nothing about testing the "Outfield" tape in another machine. Does it play properly in another deck? The symptom, to me at least, suggests a tight cassette. Can you "fluff" the tape — that is, FF to the tail and then REW back to the head? Another fix for a bound cassette is to slap it against your hand a couple times.

    On the tapes that did play fine, was the speed consistent or was there audible wow/flutter? Drive belts can be in need of replacement.

    (And if you put an ohmmeter across the head, you might well have lightly magnetized it; use a head demagnetizer before playing any tape you care about.)

    Good luck,

    J. E. Knox "The Victor Freak"
     
  10. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Thanks - I tried it with the transport screwed into the frame, and no change. :(

    Thanks Tony. I didn't try re-flowing the solder to the head but I will try this.

    You're correct, my original "why won't this tape play?" problem has changed to a "why won't this tape that plays make any sound?" issue. I tried "fluffing" The Outfield but it still won't play. However, Genesis and Dire Straits both rotate fine. The speed is constant. Drive belts are new. It just doesn't make any sound!
     
  11. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Ok, swapped a head from a working Technics deck (heads looked identical btw), and same symptoms. No sound until I touched the positive lead on the head with a screwdriver. So, can't be the head. Swapped the heads back.

    Here's an interesting observation: insulated screwdrivers don't work. Sound only comes back if I'm holding the bare metal of the screwdriver! It must be transferring some kind of small electrical charge.

    So now I'm thinking something electrical, something other than the head / tape mechanism, is causing this problem. I suppose I should try to start going upstream of the head, measuring any reference points along the way using the manual. Either that or forward from the power supply.
     

     

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  12. hdrobien

    hdrobien Well-Known Member

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    Check solder on the head connector located on the circuit board.

    Check continuity between the heads wires and the board.

    I am pretty sure that it is a grounding issue.

    Are all boards in place and screwed ?
     
  13. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Checked solder - re-flowed - tested continuity - all good.

    Starting at the head leads, I then used the screwdriver to touch each next solder joint until the jump-starting phenomenon disappeared.

    It stopped after S501 (metal box-looking thing) on the main PCB, described by the repair manual as "Magnet SWEQ16401-S (Rec/Play SW)".

    Here's the connector with the head leads (CB503 - re-flowed), and then the S501 contraption, and a view of the connections on the other side of the PCB.

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    The tight lines of joints are the S501. In this pic, the second from rightmost joint were the last things to cause the buzz when touched with the screwdriver.

    [​IMG]
     
  14. hdrobien

    hdrobien Well-Known Member

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    It is the switch that connect the heads either to the playback circuit or the record circuit. It is driven by a solenoid (plunger/magnet).

    It must have a bad contact (possibly oxidised) or a bad solder. Resolder all pins and try to spray deoxit inside (but I far as remember the contacts are buried deep inside and not really accessible just by spraying from the outside).
     
  15. dhnash

    dhnash Well-Known Member

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    It is also possible that S501 is a reed relay in which case DeoxIT will not be able to reach the contact surfaces.
     
  16. hdrobien

    hdrobien Well-Known Member

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    No, this is a "regular" relay, used in many tape decks of that era, like Akai.
     

     

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  17. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Ok I took the dang thing out and apart and it looked gross, so I cleaned all the contact surfaces. Put it back in and ... drum roll ... still nothing. :(

    Oh, and I verified that there's resistance through the coil. 147 ohms or something like that.

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    Before:

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    After:

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    Last edited: Jun 16, 2018
  18. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Now it has decided to only play for a second or two, then stop. For no apparent reason. It stops in FF too, but not in REW.

    Getting ready to go on a hike just to throw it off the top of the tallest mountain I can find.

    Edit: Took player cassette assembly apart again and back together, plays fine now. Seems like it could use some new rubber on the pulley that drives the take up reel.

    Back to figure out why it won't make any noise.
     
    Last edited: Jun 16, 2018
  19. Johnny_Law

    Johnny_Law AK Member Subscriber

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    May have just solved it. Jumped emitter and collector of Q203a and b, sound comes back in full, stays for a little while and gradually fades away. These guys must not be switching on.

    2SC1775 -> 512-KSA992FBU. Gotta get my hands on a pair of those.

    Woops, jumping C203b works too, but jumping C203a doesn't. They're 2.2uF/50V, let's throw em onto the order list anyway.

    And going farther upstream, touching / jumping the bias pots doesn't do anything. I think that confirms the problem is Q/C 203 a/b.
     
    Last edited: Jun 16, 2018
  20. Johnny_Law

    Johnny_Law AK Member Subscriber

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    Well, while I think I've solved the 'making sound' problem, it's having 'playing tape' issues again - and I think it has to do with the LED infrared sensor used for the counter. What's happening is that the counter occasionally is stuck on one number, and the tape will stop playing. The other times, it will start counting at some speed (and the speed seems to vary, sometimes slow sometimes fast), and if too far slow or fast it'll stop the tape, if somewhere in the middle, it'll keep playing.

    I'm not sure how to test an infrared LED with a multimeter - to the Internet!

    Edit: Well, what I really need to figure out is whether or not the digital counter is actually linked to the play/stop decision. If it's totally independent (like an analog counter), then obviously there's something else going on.
     
    Last edited: Jun 16, 2018

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