1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

Sony TC-K700ES transport issue?

Discussion in 'Tape' started by RMbA, Feb 9, 2018.

  1. RMbA

    RMbA Member

    Messages:
    89
    I'm looking at buying a Sony TC-K700ES and trying to figure out how much work it needs.

    It was used last time 3 years ago and was working properly then. When tried now, the transport doesn't move the tape and the deck automatically turns off the function (play, rewind or fast forward) with an audible click.

    Any ideas about what's causing the hangup?

    I'm going to take another look at it the day after tomorrow, mostly to confirm that the electronics are okay.
     

     

    Please register to disable this ad.

  2. hdrobien

    hdrobien Well-Known Member

    Messages:
    519
    Location:
    France
    Check that the small lamp that lights the cassette compartment is ok.
     
  3. RMbA

    RMbA Member

    Messages:
    89
    Is that PL101?

    I can't locate it on the schematics. What does it mean if it's not on?
     
  4. hdrobien

    hdrobien Well-Known Member

    Messages:
    519
    Location:
    France
    Is it on ? Can you see the light ?

    Yes It is PL101 (PL1001 on the schematic).
     
  5. RMbA

    RMbA Member

    Messages:
    89
    I don't have access to the deck at the moment—it's still in the seller's possession. But I'm going to check it out tomorrow (Sunday) morning.

    Now I see the lamp in the schematic. I assume it's incandescent and, if it's out, it may be why the transport (PLAY, FF, REW) isn't operating (assuming there's voltage present in the circuit at that point).

    Am I correct that any 5v 60ma incandescent will work as a replacement if it is burned out (and the correct voltage is present)?

    I'm wondering if the lamp is visible (to see if it looks burned out) without opening up the case (which I doubt the seller will want to do).
     
  6. revox-b77

    revox-b77 AK Subscriber Subscriber

    Messages:
    3,042
    Location:
    Fingerlakes, NY
    If it is not functional I would offer a price that reflects it's condition. IE. Not much. Then take it home and repair. The seller is only going to want more if you fix it.
     

     

    Please register to disable this ad.

  7. hdrobien

    hdrobien Well-Known Member

    Messages:
    519
    Location:
    France
    To cut a long story short, the lamp generates light that is sent to the reel tables through a kind of prism.

    Behind the reel tables are photo transistors that generate electric pulses when the reel tables are rotating.

    If the logic processor does not sense the pulses it will go to stop mode.

    Btw the TC-K700ES is one of the finest models ever made by Sony
     
  8. RMbA

    RMbA Member

    Messages:
    89
    Spent a few minutes looking over the K700ES tonight.

    First, when powered up, the pilot light is ON.

    Second, applying a input source, the VU meters are working, but there's no audio output at the phones jack.

    Third, the transport produces an audible click when pressing FF or REV, but neither works.

    Fourth, the PLAY mode eats tape because the take-up reel is not working.

    The seller is firm at $75, which he believes he can get on eBay selling the deck for parts.

    Any thoughts or suggestions?
     
  9. hdrobien

    hdrobien Well-Known Member

    Messages:
    519
    Location:
    France
    There are several problems.

    One is related to the reel motor, maybe stuck or a power failure.

    Another is about audio output. If there is audio on the output socket it could be a defective phone amp ic, or a defective phone output volume pot.
     
  10. RMbA

    RMbA Member

    Messages:
    89
    Too many unknowns for the price.

    If there had been a noisy pot, I would have considered it as a reasonable fix, but troubleshooting the phone amp electronics is miles beyond my capability. Strangely, there was NOT a phones volume control on the front panel, although it's shown on the schematic and parts illustration.

    Thanks again for your time and expertise.
     
  11. hdrobien

    hdrobien Well-Known Member

    Messages:
    519
    Location:
    France
    ?

    The K700ES has a phone volume control between the monitor switch and the rec volume control.
     

     

    Please register to disable this ad.

  12. RMbA

    RMbA Member

    Messages:
    89
    Right you are! I missed it—and so did the seller!

    If there is output at the phones jack, it would certainly remove that concern. So I have to have another look at it.

    Now I'm wondering if there's any way to confirm, without getting under the cover, that the take-up reel problem is more likely due to binding from old lubricant rather than a failed motor. If one motor is powering both supply and take-up reels through a belt, and seemingly the supply reel is working okay, is it more likely that the problem is lubrication rather than the motor?

    If it's "simply" a matter of disassembling the transport module to clean and re-lube the shaft, that's doable for me.
     
  13. hdrobien

    hdrobien Well-Known Member

    Messages:
    519
    Location:
    France
    On this model the reels are gear driven, so no belt involved.

    If you can rewind but not play or fast forward, the gear assembly that swings between shaft to a reel or another is possibly stuck.

    [​IMG]
    The white gear in the middle of the picture is the motor shaft. The black gear underneath swings between the reels to transmit rotation (picture from a TC-FX1010 but similar to the K700ES).
     
  14. RMbA

    RMbA Member

    Messages:
    89
    That's helpful. I'll check out whether it will actually rewind if a tape in inserted with side 2 up.
     
  15. RMbA

    RMbA Member

    Messages:
    89
    I picked up the K700 this afternoon. Turns out that neither the REW nor the FF is working.

    There is audio output at the earphones jack, however.
     
  16. restorer-john

    restorer-john Addicted Member

    Messages:
    6,553
    Location:
    Australia
    The reel motor is notorious in those decks.

    It has a felt friction clutch on the shaft idler which is an absolute pain. Can you hear the reel motor spinning in FF or REW? If it's actually dead, you may be able to find one- the part number is X-3575-382-1 (it's used in the 700es/II, 555esr, 333esr and 333esx). The part is NLA according to Sony, but various service centres might have one- you never know.

    The motor itself is a Mabuchi RF-510T and it can be opened up to clean and repair brushes and commutator, but it is usually the felt washer/nylon that goes.

    The reel motor is driven by a discrete H-bridge and those transistors are pretty tough. Q705 is a suspect if the motor is fine, as is Q717 and the fusible R38.

    Do not play more than a second or two with no takeup operational. Even though the mech will shutoff, it doesn't take much to create a tape ball around the takeup capstan. Use you fingers to trip the tape in switch and operate it without a tape.
     
    Last edited: Feb 15, 2018

     

    Please register to disable this ad.

  17. RMbA

    RMbA Member

    Messages:
    89
    Thanks for the info.

    I've got to get the transport out of the chassis and disassembly it to see what's going on, but don't really have a clue at the moment as to the step-by-step to do that.

    The motor is pretty widely available for $15-25, but not sure any of them come with the requisite "washer/nylon. I assume they don't.

    Not sure how to do your last suggestion, "Use you fingers to trip the tape in switch and operate it without a tape."
     
  18. RMbA

    RMbA Member

    Messages:
    89
    Does the TC-K700ES use the same belts and pinch rollers as the TC-K333ESA and TC-K333ESL? Are the transports virtually the same in these three decks?
     
  19. hdrobien

    hdrobien Well-Known Member

    Messages:
    519
    Location:
    France
    No the transports are not the same, and the belt part numbers are different.

    TCM110: TC-K700ES/730ES/555ESII actuated by plunger

    TCM200: TC-K750ES/850ES/950ES TC-K770ES/870ES/970ES TC-K790ES/890ES/990ES TC-K808ES/909ES actuated by mode motor
     
  20. RMbA

    RMbA Member

    Messages:
    89
    Somewhere I read that the TC-K700ES has the same transport as the K333EX, the K333ESR, the K555ESR, and the K730ES.

    Is any of that accurate?
     

Share This Page