Help with Yamaha RX 1100U—No Sound Output

Discussion in 'Yamaha' started by BassKulcha, Aug 26, 2017.

  1. BassKulcha

    BassKulcha Unrepentant Anachrophile Subscriber

    Messages:
    801
    Location:
    NYC
    I picked up this RX 1100U from another Ak'er earlier this year and I was very happy with it. Recently, however, I went to turn it on as usual, but there was no sound. I checked the usual suspects—speaker selection, RCAs, and other inputs such as the phono and tuner...nothing.

    There was no pop or smoke or anything, it just stopped putting out sound. It still turns on and lights up fine (with the soft start click as usual—) I opened it up and the fuse looks fine, and it doesn't look like there is any obvious damage like toasted resistors or blown caps. I've hooked it up to other gear I have (turntables and tuners, only—I don't have any working CD players right now), but no luck there either.

    I like this Yamaha, and I'd like to keep it alive if it's worth it. Does anyone have any idea of what might be going on?

    Any help would be appreciated—

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  2. petehall347

    petehall347 the brandy coffee man

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    Location:
    uk.. the middle bit
    cant make out your pic ..maybe tape monitor selected or something .
     
  3. avionic

    avionic " Black Knights " Subscriber

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    36,813
    Location:
    Fort Dodge, Iowa
    Protect relay-- no softstart in this unit.
     
  4. avionic

    avionic " Black Knights " Subscriber

    Messages:
    36,813
    Location:
    Fort Dodge, Iowa
    Check the the pre-out/main-in jumpers on the rear panel. Unplug them and check for oxidation . Wouldn't hurt to clean them with alcohol and reinstall them. Check that the Mute button is not engaged.
     
  5. avionic

    avionic " Black Knights " Subscriber

    Messages:
    36,813
    Location:
    Fort Dodge, Iowa
    If the above doesn't improve things.Find another pre-amp source. Unplug the pre/main jumpers and plug a seperate pre-amp into the main-in of the RX. See if your amplifier section is working.
     
  6. BassKulcha

    BassKulcha Unrepentant Anachrophile Subscriber

    Messages:
    801
    Location:
    NYC
    Mute button not engaged (or tape monitor), but I'll give the jumpers a cleaning, and also check the amp section when they're out. Thanks for the tips, I'd really like to keep this one in service—
     
  7. avionic

    avionic " Black Knights " Subscriber

    Messages:
    36,813
    Location:
    Fort Dodge, Iowa
    Or... find another power amplifier. And connect the pre-out of the RX into the main- in of a different amplifier. This will tell us if the pre-amp portion of the RX is working or not.
     
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  8. BassKulcha

    BassKulcha Unrepentant Anachrophile Subscriber

    Messages:
    801
    Location:
    NYC
    Ok, so no corrosion on the jumpers, but I cleaned them with 91% IPA anyway and let them dry thoroughly.

    With the jumpers removed, I tried using the RX as an amp with a separate preamp. No sound from the turntable, like the speakers weren't even connected (I double-checked connections and switches—)

    I then tried using the RX as a preamp with a standalone amp with the tuner engaged (no TT this time—). With this, I got a low white noise from both speakers, but no radio signal. When the RX was switched off, however, the white noise got louder and louder over a few seconds, stabilized for about 6 seconds, decreased over another few seconds and then finally disappeared. Strange...

    Any ideas, or is this going to need a major going through? :(
     
  9. avionic

    avionic " Black Knights " Subscriber

    Messages:
    36,813
    Location:
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    Sounds like more than one issue. Or .. Possibly and power supply issue thats causing issues in both the amplifiers and the rest of the unit.Did you try to tune in any audible programming on the FM tuner ?
     
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  10. BassKulcha

    BassKulcha Unrepentant Anachrophile Subscriber

    Messages:
    801
    Location:
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    I did try the tuner, and still no sound. I think this may need more help than I can personally give it, unfortunately. Bummer...
     
  11. Roboturner91

    Roboturner91 AK Subscriber Subscriber

    Messages:
    919
    Have you tried the headphone jack?

    If neither the preamp nor the amp section work, I would think it's something with the power supply or transformer. Might be a relatively easy fix.

    Nice looking beastie inside and out, I wouldn't want to give up on it.
     
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  12. zaibatsu

    zaibatsu Active Member

    Messages:
    441
    If it's turning on and the relay is clicking on, the issue/s are probably quite minor.
    I wouldn't give up on it, worst case you'd just need someone to help out.

    Did you try all three speaker outputs?

    I'd do some simple continuity tests with the unit switched off and unplugged (meter in diode test mode) to make sure that the selected input RCA is reaching the preamp input, and also that the speaker relay's terminals (on the "speaker side" of it, on the underside of PCB) is shorting to the selected speaker terminal/s on the back of the unit. I'd also do some continuity testing on the pre-out / main-in jacks, to make sure those jacks haven't broken their connections from whatever they attach to inside.

    I'd be cautious of doing any in-circuit testing unless you've got a DBT, but you can certainly do some tests with the unit off to make sure it's not a simple broken connection.
     
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  13. BassKulcha

    BassKulcha Unrepentant Anachrophile Subscriber

    Messages:
    801
    Location:
    NYC
    I just wanted to give an update:

    I decided to bring the RX1100U into a local electronics shop to have them take a look at it (I also wanted to get an idea if they did good work for any future issues— )

    The explanation of the problem was a little confusing (I think because the owner is not the tech, so some details got lost in translation...) but the good news is that it's FIXED.

    The issue, ostensibly, was in the PREAMP section. I asked for specifics, and they gave me the numbers of two parts that they said were were replaced: Q120 (which I discovered from the schematic parts list is a transistor) and D123, which is a diode.)

    It seems to work great now, so I'm happy....

    Thanks to everyone who chimed in to help
    :beerchug:
     
    Last edited: Sep 14, 2017
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  14. zaibatsu

    zaibatsu Active Member

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    441
    That's great news, glad you got it going again!

    For interest / future readers I had a look at the schematic:
    Q120 is actually part of the power amp from what I can see (part of the VAS / a predriver), a 2SC2705.
    D123 is part of the PSU, which backs up what avionic guessed about an issue common to pre/power amps.

    Q120.png D123.png
     
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  15. SoCal Sam

    SoCal Sam Lunatic Member

    Messages:
    16,979
    Kudos. A less caring owner would have put it on the curb. BTW, the matching CDX-1100U cd player is a bargain for what you are getting.
     
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  16. BassKulcha

    BassKulcha Unrepentant Anachrophile Subscriber

    Messages:
    801
    Location:
    NYC
    Thanks—at this point I have an almost pathological drive to restore stuff, even if it can become a bit of a money pit. It goes without saying that I don't think my wife is as excited as I am about it, though... :rflmao:

    I don't have the CDX 1100U CD player, but I did get a great deal from AKer Drugolf for the RX 100U along with a CDC-610U Multi CD Player and a KX-R430 cassette deck, so I'm happy....
     

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