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Troubleshooting a 5000X, Recap Pending.

Discussion in 'Exclusively Sansui' started by davros, Sep 13, 2018.

  1. davros

    davros AK Subscriber Subscriber

    Messages:
    185
    Location:
    Winston Salem NC
    So I am in the process of bringing my Fathers 5000X back into service. It has sentimental value to him, as well as to me, He is recently retired and lives alone now. Having this back working will make a big difference in his day.

    So, below is the thread where I described the condition of the receiver.
    http://audiokarma.org/forums/index.php?threads/looking-for-recap-list.834925/

    By recommendation, I have been working on making sure the unit works before I start recapping it.

    At this point I have cleaned the unit, Deoxit all pots and switches, and verified operation.

    Phono Good!
    Aux Good!
    Tape Good! (I have a R2R)
    AM and FM... Not so Good...

    Fm is pulling in 2 stations good enough without static, One will flash the Stereo light. There are a handful of other stations that I can hear, but are weak and unclear.

    AM is the same.

    Antenna is a 6 foot length of Twin-Lead hooked up to 300 Ohm terminals, and twisted together at the opposite end.

    I have cleaned the Tuning capacitor IAW Dr*Audio's Tuner Cleaning Post.

    Additional note... The Tuning meter barely moves on FM, and the signal meter twitched once.
    On AM the signal meter only moved once (to a 3), and that was only on an area of high static.

    On Board F-1219 I checked IC201, 202, 203, and 204 by Jumping pin 3 to pin 7 to bypass each IC. There was loss of gain on all except IC201. IC201 had no change.

    Voltage on pin 7 of all 4 IC's was between 11-11.5 Volts, except IC201. It was reading in the mV.

    I suspect IC201 as being bad, but without the proper alignment gear I have no way to verify.

    Please, any thoughts are appreciated. I would like to fix the actual issues before I work to start the recap.

    My plan is to recap the power supply, EQ board, and Power Amp. (Filter caps and Coupling caps included)
    I ordered the caps to do the FM / AM and Multiplex boards as well but would prefer to leave those be.

    Thanks for the help!
    Marc
     
    Last edited: Sep 14, 2018
    smurfer77 likes this.

     

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  2. Bruno Primas

    Bruno Primas Active Member

    Messages:
    142
    Just to check, do you have the switch on the back set to "distant" or "local"? Should be set to "distant".
     
  3. davros

    davros AK Subscriber Subscriber

    Messages:
    185
    Location:
    Winston Salem NC
    I just looked, and this 5000X does not have the "Distant/Local" or the speaker damping switch.

    I looked at my 5000 (No Letter) and it has both switches.
     
  4. Bruno Primas

    Bruno Primas Active Member

    Messages:
    142
    I wonder why some have it and some don't? I have a 4000 and that model has the local/distant switch.
     
  5. davros

    davros AK Subscriber Subscriber

    Messages:
    185
    Location:
    Winston Salem NC
    So I have recapped the power supply while waiting for my IC's to come in.
    This included Filter caps/Coupling caps/Ripple Filter/Filter Block/Diode Stack, and assorted "point to point caps.
    No change to FM Reception at that point. I tested the unit after periodically to make sure I didn't mess anything up.

    The IC's came in and I replaced the first 3 (IC 201,202,203)
    I can now tune many more stations, although they are still weaker than I would expect.
    The strongest stations are very loud, while the weaker are clear but much softer. FM Stereo only light on the 3 strongest stations.

    My meters still are not working. The Tuning meter deflects a little, but my signal strength meter seems dead.

    While adjusting VR203 (Tune meter adj) the volume increases and decreases, sometimes with static. I'm surprised the signal go's through that point... I cleaned and Deoxited all three pots again, and the static went away. Those cheap little Variable Resistors don't seem like good candidates to be in the Audio Path...

    The only adjustment that make any difference to the volume is VR203.
    VR201 and VR202 make no discernible difference.

    I've read nearly every post I can find on the 5000X FM issues, and seem to be drawing a blank.

    Any advice or input?

    Summary...
    Voltage is 13.2 Volts to F-1219 Board
    Tuning cap is clean as a whistle
    Bad IC's changed and reception across the board but seemingly weak.
    No Meters...

    Thanks!
     
  6. davros

    davros AK Subscriber Subscriber

    Messages:
    185
    Location:
    Winston Salem NC
    So as I stated above, I have improved my reception but it is still not as I feel it should be.

    Dozens of channels now that I hooked up a 12' dipole made out of twin-lead.

    The strong channels are LOUD and clear. The weak stations are Clear and soft. I have to turn the volume know up a quarter turn to get the same volume as the strong stations. Only 4 stations get good enough signal for stereo to kick in. The stereo doesn't sound good, and just sounds "weird" Alternating from Tinny to breaking up. When I change to Mono its loud and clear.

    The schematic shows (to me) the signal passing from the F-1219 board to the F-1006-2 board. Poking around, I decided to test the Diodes and found D404 unresponsive on my flukes diode test mode. I de-soldered one end and it is open, no reading in diode or using the resistance selector.

    I don't know enough about Tuners to tell what this diode does, but its is directly involved with a tuning trap and a filter. I am ordering a 10 pack of these IN34A Gemanium Diodes.

    While I'm not sure what it does, I know its supposed to work. Maybe this will help the FM issue...
     
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  7. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,659
    Location:
    Fort Dodge, Iowa
    Usually RF detectors.
     
  8. davros

    davros AK Subscriber Subscriber

    Messages:
    185
    Location:
    Winston Salem NC
    upload_2018-9-22_10-31-5.png

    This is the Diode that is Open. Would this just affect the MPX, or would it mess up the entire FM signal?
     

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  9. davros

    davros AK Subscriber Subscriber

    Messages:
    185
    Location:
    Winston Salem NC
    I replaced the open diode with a new IN34A.

    This not only fixed my Stereo sounding "weird" issue, but all of my FM is coming in stronger now.

    I'm in the ballpark of 8 Stations with the Stereo light lighting, and the separation is spot on. I get every station I expect for my area.

    My strong stations no longer blow me out of the water, and the weak stations are clear and loud, albeit without stereo.

    If I had an O-Scope I would do an alignment (i.e. Learn) but alas I do not have one.

    Cleaning, recap, and FM are all complete.

    I'll be reassembling and test it for a few days, then either pack it up for my dad, or hold it until his next visit.
     
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  10. smurfer77

    smurfer77 AK Subscriber Subscriber

    Messages:
    1,479
    Location:
    San Francisco
    One day I will fix up my old man's amp. The old man is now gone, but the amp I will bring back to life (it's in Australia and I'm in the USA, so it will have to wait...)

    :lurk:
     

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