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I am sure that there are those... who have lost faith.... :)

Discussion in 'General CB Services Discussion' started by guitar_199, Jul 24, 2021.

  1. guitar_199

    guitar_199 Sr. Member

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    I know that have have been perched on this "velvet milk stool" for a long time.... but I got up this morning...sat here and ran the Internet for a while.....and then ... I looked up. Up... to the top shelf of my desk-shelf. The SBE Console V is up there..... and it is laughing..... laughing at me!!!!! It knows..... that there are only 10 more caps left to complete this re-cap.... and that I have let it sit here for most of a year.

    As of this moment, it is down on my bench. The soldering station is heated up and ready..... the remaining caps on the board still have their little red dots..... and the new ones to replace them sit in the parts cups in front of me.



    And, as the Joker says so slowly and deliberately in "The Dark Knight Rises"......

    "Here............................................ we .................................... go!
     
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  2. kopcicle

    kopcicle Sr. Member

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    ^^^^ this :)
     
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  3. guitar_199

    guitar_199 Sr. Member

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    Interesting what you find in here!!!!!

    Looking over another area of the board... near the crystal filter... I found two freshly unsoldered pads (meaning I took it out!!!) and there it nothing in it. Looking on the top side.... C609. I guess I had better investigate that before going much further!
     
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  4. guitar_199

    guitar_199 Sr. Member

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    Mystery solved. C609 is a 47uF 50 volt. I was short one in the kit and meant to order another... and never got "a round tuit". At least I know.
     
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  5. guitar_199

    guitar_199 Sr. Member

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    While I am still missing the cap mentioned above, all the rest of them are done.

    Now, it's time to figure out what I've got!

    Fired up the signal generator on Ch 20 ( no particular reason ) with mod at 30%, hooked it up. Meter shows way up there a little over S9.... but no sound. Looking at this schematic snippet, I wonder why????? All C609 is is the emitter bypass for the AF amp just before the audio IC. I wonder if that could have anything to do with it????

    AF-Amp.png

    Anyway, have to stop for now. The guys at work just finished a huge Oracle database upgrade and we all have to VPN in an check out our various applications to make sure they are still alive. Can't wait to get C609 in and installed. Then I think I am going to just walk through the AM receive side just to see what the stages look like. I've had this thing since about 1981 and it has NEVER seen an alignment while I had it. I doubt the pawn shop I got it in did one either.

    but I think I do want to walk through the alignment process slowly just to get familiar with going through the thing.

    By the way, I mentioned I had the generator set to Ch20. SOMETHING must be semi-right. When I step off of Channel 20 either way (like....19 .... or 21...) the needle drops to the bottom. I'd like to think that means something good. Even better that it pops right back up when I go back to Ch 20.

    Yeeeeee hah!!!!!!!

    Bob
     
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  6. Rwb

    Rwb Sr. Member

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    see ya put stuff aside n buy later but later is too late
     
  7. guitar_199

    guitar_199 Sr. Member

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    But not necessarily "never"! :ROFLMAO:
     
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  8. Low_Boy

    Low_Boy Sr. Member

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    Lol.... did you remember to hook the speaker back up. Just like yesterday I fixed a radio turned it on hooked up the dummy load and keyed the mic. Oh no nothing. I looked down and the mic was not plugged in. Lol
     
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  9. NightThumper

    NightThumper Sr. Member

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    Guitar Man…did you say Oracle Database Upgrade??? Ah music to my ears for sure…Select from Prospect_Base where Id_number in(select I’d-number from prospect_sales…ahahahaha too much fun. Carry on….I digress a smidge…
     
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  10. guitar_199

    guitar_199 Sr. Member

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    I didn't have to disconnect it. This is a one piece chassis and the speaker stayed hooked up. I DID catch a VERY VERY low hum in it... so I know things are working..... just not all the way.

     
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  11. guitar_199

    guitar_199 Sr. Member

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    Yeah.... lets just say my outfit got "a little behind" in upgrades. We tend to "stay stable" once we work..... but our old version was running into "end of life" so our DBA set about to bring us from 11g up to 19c.

    All of us just have to make sure we still work.

     
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  12. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    Use the DVM, check Voltage on [119] as well, make sure you are getting power thru to the stage so it can amplify, else - good catch!

    The easiest way to see if C609 is the problem child, is to measure voltage on the emitter leg of Q601 - if its LESS than the posted voltage - you found the culprit - it's producing power, but as a switch turned on - not in linear fashion.

    Why?

    C609 - if it's a dead short - pulls all the power thru Q601 like it's a dead short of solder blobs done at a Galaxy Factory so the Emitters leg voltage reading DROPS - remove C609 to test the theory - you would restore some audio drive and DC voltage should return - not very flattering sound - which is why the C609 is there, to add dynamics to the audio signal.

    Without the caps ability to pass just Audio signal thru itself and keep DC thru the Emitter Resistor the audio signal is swamped out by the DC power flowing thru Q601 and thru the now-flat-sucking DC-bias power-hungry Aluminum-Beer-can of a capacitor called C609 which if operating properly, should only sip audio at parties is now trashing the power-feed and buss-bar buffet all while passing out in a cationic Karaoke-Krakatoa moment in a vain attempt to dazzle subsequent stages by singing a Titanic-tanking rendition of "My Heart Will Go On" - making Q601 - your new found - silently on but deafeningly effective, censor of a switch.
     
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  13. DoctorAudio

    DoctorAudio Active Member

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    Did you capture a video-gate of it laughing at you? ;)
     
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  14. Low_Boy

    Low_Boy Sr. Member

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    Sometimes when something just isn't right you may find one cap in the wrong way.
     
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  15. kopcicle

    kopcicle Sr. Member

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    Or half of them in the wrong way. Problem is


    Which half ?
     
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