TEAC A-4010S RTR- Left channel is not working.

Discussion in 'Tape' started by frankiebull, Feb 3, 2018.

  1. frankiebull

    frankiebull Active Member

    Messages:
    211
    Location:
    Oklahoma City, Oklahoma
    Picked up one of these a week or so ago. It needed the belts replaced and the pinch roller mechanism cleaned up. From what I read here on AK that usually takes care of most issues. No such luck. It got everything working fine mechanically but the left channel does not play or record. The VU meters light up and the needles peg to the right then back to the left when I turn it on, but that's it. I can record with it but not the left channel.

    I read all the threads on this unit and do not see much about this problem. One thread talks about a similar problem and the author thinks it is related to tape/source monitor switch. I don't seem to have a problem with the switch. I was hoping someone could point me in the right direction. Cosmetically, it's not the greatest but if I can get it working for not much investment and learn something along the way, then that would be a good thing. Any ideas?
     

     

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  2. audiojones

    audiojones Jonesin' for audio Subscriber

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    Check the cables and connectors that go between the amp and the transport unit, could be a loose or dirty connection at the multi-pin plug or maybe a wire broke loose on the transport end when you were working on it.
     
  3. frankiebull

    frankiebull Active Member

    Messages:
    211
    Location:
    Oklahoma City, Oklahoma
    I cleaned and secured all connectors, visually inspected for broken wires. I see nothing that looks out of the ordinary. Could this be from worn heads? I didn't think so since it does the same thing playing back in both directions. Could it be a bad VU meter?
     
  4. audiojones

    audiojones Jonesin' for audio Subscriber

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    Does the left side work when the deck is switched to Source? It might be recording fine on both channels and just not playing the left side back. Also do you know if the tape had something recorded on the left side before you tried recording onto it or was it a blank tape? If Source isn't working then double check your jack connections, you might not have a signal going into the machine.

    If the left output is working when the deck is switched to Source but not in either direction when it's switched to Tape then it's an issue somewhere between the output of the head reversing relay (that relay screwed to the back of the transport unit) and the Tape / Source switch. That narrows it down to the head reversing relay, the wiring and connections between it and the amp unit, the head amp circuit on the amp board and the Tape / Source switch itself.

    If the left side doesn't work in Source mode when a signal is going into the deck then there's an issue between the input and the Tape / Source switch. That narrows it down to the input from your amp / receiver, the tape deck's amp board or the Tape / Source switch. It's important to know if the deck shows a signal or not in source mode first though, and if it doesn't try swapping the left / right input jacks and see what happens.
     
  5. frankiebull

    frankiebull Active Member

    Messages:
    211
    Location:
    Oklahoma City, Oklahoma
    If I turn the INPUT knob all the way up the VU meter comes up to a good level and the right VU pegs to the right. The sound through the head phones is very poor on the left side.
    The tape I used was already recorded on both channels. I was planning to record over anyway so I used it to see. I recorded 1 song with the 4010 and played it back. Nothing on the left channel. I played it back on my A2300S and still nothing on the left side. The right side quality was pretty good but not great.

    Swapped input jacks and no difference.
     
  6. Jonny Ramone

    Jonny Ramone Super Member

    Messages:
    1,864
    Try de-oxiting the switches first. The relay could be the issue, but the deck is pushing 50 now. I have a 4010 SL that's parked for a similar reason; those caps weren't designed for 40+ years of reliable service.
     

     

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  7. audiojones

    audiojones Jonesin' for audio Subscriber

    Messages:
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    Yes, first and foremost if you haven’t done so already aggressively clean the switches especially the tape / source switch as well as the pins on the connector that goes between the top part of the deck (transport) and the bottom part of the deck (amp section). Spray contact cleaner in the back of the switch and exercise it very thoroughly. Do the same with the multi-pin connector on the amp, spray it thoroughly and insert / remove the connector a bunch of times to clean any oxide from the terminals.

    The input knob is split so you can independently raise left and right volume, so don’t jack up the right side and peg the meter (it’s not good for any meter especially those old meters). If thorough cleaning of the switches and contacts doesn’t clear it up then you’ve probably got an issue with a component on the amp board since you’re not getting a clear signal coming into it. I’d really focus on that Tape / Source switch though, sometimes it’s hard to get them working properly after all these years.

    Also make sure your heads are spotlessly clean and that the tape lifters are pulling all of the way up to allow full contact between the tape and the heads. Very often the pinch roller linkage on these machines gets gummed up and only pulls up part of the way, so even though the pinch roller is pulled in the tape lifters may not be completely pulled up out of the way.
     
  8. frankiebull

    frankiebull Active Member

    Messages:
    211
    Location:
    Oklahoma City, Oklahoma
    I cleaned all the pots and switches. I have cleaned the tape/source switch several times. Will try it again. I'm concerned about the playback knob. It was very scratchy sounding before any cleaning and although it sounds better (less scratchy) the left and right controls did not free up like the other two knobs did. I can still operate them independently but it takes more effort.

    FYI - I have the AR-40S amplifier. That's the one that you have to take the top off the amp to get to the connections.

    This is a real concern. Visually, I'm not sure the heads are any good at all. Will try to get some close up photos.

    Another concern, if this proves to be the issue, it would be way over this novices head.

    I did not think to check this.

    Thanks for this advice. I didn't know I could hurt it.

    I'll do more cleaning but it will have to wait. I got called for an out of town job and won't be home for a few days.
     
  9. kermit z

    kermit z Loud Music saves Lives!! Subscriber

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    9,478
    Location:
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    When AJ says aggressively he is seriously correct. Like with many switches in many vintage gear, you need to spray and play with it a lot. I had a similar issue with my A3300SX. It was working great over the years, but sat for a number of months. A few weeks ago I played a tape and 1 channel was out. Messed with connections and tried it again, but no luck. Today I put another tape on and all was well. But eventually the left channel went out again. I pulled the cover off the bottom and sprayed Deoxit on every thing I could get to, volume, source/tape switches and played with them for awhile. Then a few hours later, I put on a recording I made of Miles Davis, John Coltrane, and George Benson and I'm in tape nirvana ;) I love how I can get 5 albums on this single reel. Anyway, the key is play with it for a bit to help clean. This ultimately may not be the problem, but its the easiest and cheapest to do. I have an A4010S and have never had the issue....Go figure.
     
    Last edited: Feb 10, 2018
  10. frankiebull

    frankiebull Active Member

    Messages:
    211
    Location:
    Oklahoma City, Oklahoma
    DSCN1815.JPG DSCN1816.JPG DSCN1817.JPG
    I don't know. I've cleaned and cleaned. Mildly, moderately, AGGRESSIVELY...Nothing works. I did check to see that the tape lifters were operating properly and getting out of the way. All is good there. I knew the heads were bad when I bought the darn thing but I'm not convinced they are not just shot.
     
  11. audiojones

    audiojones Jonesin' for audio Subscriber

    Messages:
    7,106
    Location:
    Central NJ
    Well the heads do look worn but they also look really filthy. They should be spotless and have a mirror-like finish so the tape will make full contact with them and slip effortlessly over them with a minimal amount of friction. Polish them up with a little dab of light duty aluminum polish on a Q-tip (do the tape lifter pins and guides too). Polish them with a side to side to side motion the way a tape would travel over them, and make sure to remove all residue and clean everything with alcohol before you load up a tape.

    It seems pretty clear that you've got an issue with the left side of the AR-40S amp unit however. If cleaning and exercising the switches, cleaning and tightening the connector pins on the cables between the transport and amp unit and cleaning the contacts on the head reversing relay didn't get any response at all from the left side then it's going to require digging a little deeper (as in component level repair).

    The fact that the left channel won't play in forward or reverse, left channel won't record at all and that you can't even get a clear signal into the left channel of the amp in the source mode is pointing to a failure in the left channel of the amplifier unit or its wiring to the deck unit. I seriously doubt the left side of the forward play head and the reverse play head and the record head have all gone bad. Worn heads or not you should be getting something from one of them but polish them up anyway and see if anything changes. :dunno:
     
    Last edited: Feb 10, 2018

     

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  12. frankiebull

    frankiebull Active Member

    Messages:
    211
    Location:
    Oklahoma City, Oklahoma
    I'll try some polish. All I used was alcohol. It got a lot of grime off but did nothing for the rusty looking stuff.

    Not sure about this. Not sure I know where the head reversing relay is located.
     
  13. audiojones

    audiojones Jonesin' for audio Subscriber

    Messages:
    7,106
    Location:
    Central NJ
    Mentioned it in post #4, it's the relay screwed in to the back of the transport section. Part #11 and 12 in the diagram below:

    image.png
    However the head reversing relay will only affect the playback function, it won't cause a record malfunction or the input signal problem you are having. You may have several problems stacked on top of each other but since everything seems to be happening only in the left channel I think I'd be focusing on the amp section. Dried out capacitors, corroded trimmer pots, faulty transistors, power supply issues etc.
     

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