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Recording levels not equal on cassette tape

Discussion in 'Tape' started by Xavier Ihrig, Nov 30, 2018.

  1. Xavier Ihrig

    Xavier Ihrig New Member

    Messages:
    16
    Location:
    Big Rock, TN
    I have a JVC KD-A5 that plays tapes normally, but when I go to record onto it, from the radio or any other source, the left meter reacts normally and the right meter doesn't react unless I turn the levels past peaking compared to the left meter. The levels coming out do represent the meters, so the right output is significantly quieter. I've checked to see if the receiver was bad, it wasn't, and I made sure that it wasn't R/L cable input related. I'm thinking that it could be a bad capacitor in the system. I've taken it somewhat apart, but I'm still unable to see any problems. I'll upload photos when I can, but if anyone has some quick advice or experience with this machine, all comments will be appreciated. Thank you in advance!
    -Xavier
     

     

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  2. rojoknox

    rojoknox Active Member

    Messages:
    122
    Location:
    Gresham OR
    Greetings from RojoLand!

    Try connecting a single audio channel to both inputs using an RCA F-to-2M "Y" adapter. If the deck indicates differing levels with a common input signal, then you're looking at a calibration at least, recapping at most. If levels come out the same, then your stereo source (or cabling) is suspect.

    Take care,

    J. E. Knox "The Victor Freak"
     
    Wolfman181 likes this.
  3. SterlingOne

    SterlingOne Active Member

    Messages:
    103
    I think you just might want to turn pots back and forth or use de ox to clean them.
     
  4. Grenadeslio

    Grenadeslio Super Member

    Messages:
    2,786
    The tape deck is suspect, heads may need alignment etc. Try recording from a different source (receiver etc) before tearing into the current one.
     
  5. Xavier Ihrig

    Xavier Ihrig New Member

    Messages:
    16
    Location:
    Big Rock, TN
    I didn't have a y connector, but I just switched the input cable, putting the right cable into left and left cable into right, it didn't fix the right meter.

    I tried using some deoxit on the input level, it didn't fix the meter at any rotation, so I don't suspect the pots to be a problem.

    I attempted to record from the original receiver, using radio, aux and a CD as inputs, then switched to a different receiver, then tested plugging the sources directly into the record inputs on the tape deck. They all gave the same response, with the right meter not working.

    Here are the photos, I decided to take it apart to try and find anything that could be wrong. The inside was pretty dusty, so I cleaned that up, but after the problem started.

    Thank you guys for all your help so far!
    20181130_145812.jpg 20181130_145801.jpg
     

    Attached Files:

  6. SterlingOne

    SterlingOne Active Member

    Messages:
    103
    Well, sounds like a cap has gone south.
     

     

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  7. Xavier Ihrig

    Xavier Ihrig New Member

    Messages:
    16
    Location:
    Big Rock, TN
    I checked out both of the boards inside, I couldn't find any caps that were puffy or cracked. I found a small spot that looks like it shorted, but I'm not positive that's what's wrong. rojoknox mentioned in a previous post about this deck that there's only one place to get the service manual, so I'm looking forward to it coming in the mail.

    The component around the suspected area is written to be a X505. I'll edit in a photo tomorrow when I'm back at my workshop. I'm dreading having to desolder anything that I don't need to, but it's looking like I'm going to have to in order to get clear photos of the board.
     
  8. Xavier Ihrig

    Xavier Ihrig New Member

    Messages:
    16
    Location:
    Big Rock, TN
    Here's a view of the bottom and top of the board, as well as the location. I'm still waiting on the service manual. The board in the close ups is the smaller of the two in the zoomed out photo.
    20181204_113901.jpg 20181204_114111.jpg top of board.jpg
     
  9. Bob

    Bob AK Subscriber Subscriber

    Messages:
    2,380
    Location:
    West coast
    my suggestion is to use a mono signal to record on your deck to determine whether the
    recorded signals play back at the same level, or whether the meter's gain circuit
    is off. if the signal playback is at the same level then its the meter circuit, if the
    signals are different then its in the record circuits to the lower channel.

    the next test is to playback a mono-type tape made elsewhere to determine whether
    the problem may be in the playback side of things.

    x505 seems to have either damage or left-over flux (brown stuff), and the r536/d520
    seems to have some solder shrinkage but the pix needs more detail to further
    distinguish.
     
  10. Xavier Ihrig

    Xavier Ihrig New Member

    Messages:
    16
    Location:
    Big Rock, TN
    I tried recording on to it, the right channel was representative of the meter while recording, and played back on the same and different machine. I then played a prerecorded mono tape and the levels we're fine for both channels.
     
  11. Grenadeslio

    Grenadeslio Super Member

    Messages:
    2,786
    Most likely the record portion of the play head is damaged or misaligned as I mentioned earlier.
     

     

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  12. Bob

    Bob AK Subscriber Subscriber

    Messages:
    2,380
    Location:
    West coast
    if its a 2 head deck, the record and playback are built-in and are "aligned". since
    the record heads still work (eg not dead - just unlabalanced), I'd suspect the
    recording circuit driving that weak channel's electronics.

    there's still the "obvious" discoloration/damage.
     
  13. Xavier Ihrig

    Xavier Ihrig New Member

    Messages:
    16
    Location:
    Big Rock, TN
    Would the record head all of a sudden quit working? When I first got the deck it worked fine, but I tried recording from my turntable and the right channel just cut out. This would have probably been something to mention before.

    It is a 2 head deck, and I'm able to follow the wires connected to the record head back to the first board. I'll look for any connections that look sketchy along the path. EDIT: Which set of wires do you recommend that I follow?

    record heads 2.jpg record heads.jpg
     
    Last edited: Dec 5, 2018 at 12:27 PM
  14. Bob

    Bob AK Subscriber Subscriber

    Messages:
    2,380
    Location:
    West coast
    if it records, even at a lower signal, then there's little chance it's the solder points coming
    out of the heads, you can "try" checking the resistance of each channel, they should be
    close.

    and even if the heads don't match, or is open (unlikely since it does record), any problems
    with the heads mean you'd have to find an identical match (no replacing it with any other
    model nor heads from a different manufacturer), then you'd have to do the entire cassette
    alignment with jigs, and factory alignment tools.

    based on that possibility it would not be worthwhile to do so, and IMHO not the problem.
    however you can check all those possibilities but I would warn you to put some
    removable no-residue tape over all the heads to prevent accidental electrical and
    mechanical damage that will destroy them.

    I'd look at the service manual to determine which leads off the heads are from the recording
    heads and trace them back to the PCBs, then from there, depends on your ability. if you can
    power up the unit while still having access to the PCBs, then you can at least trace the
    circuit by following the schematic and ensuring the voltages are ok.

    I'd work from the signal input from the back of the deck - following the electrical path
    to the recording head in question.
     
  15. Xavier Ihrig

    Xavier Ihrig New Member

    Messages:
    16
    Location:
    Big Rock, TN
    I got the service manual finally, and this is the recording diagram shown.

    I'm not versed in how to follow the path back with a multimeter, or what I should be looking for with the different settings on the multimeter. I can trace continuity, but other than that I'll need some help. Is there a specific part I should check that is shown in the diagram?

    Thank you all for being patient with me, I am extremely grateful for all the help!

    service diagram.jpg
     
  16. Bob

    Bob AK Subscriber Subscriber

    Messages:
    2,380
    Location:
    West coast
    the diagram is a functional block diagram and is a chart of the various functions - eg a road map.

    the bottom left side is the recording section - with the tape path, the erase heads work then
    the recording heads to "apply" music to the tape..

    you may wish to re-try your recording tests but with varying the bias.

    otherwise, you will need the schematic to do any troubleshooting. if the schematic has
    voltages, then you need to confirm (for both channels) that they're in spec.

    the service manual should also have a section on calibrating the record and/or playback
    electronics using a test tape. I would look at it to see what you can adjust without
    triggering major surgery. if it's not clear, post here. IOW don't change until its
    clear that it is needed and, more importantly, reversible.
     

     

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